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PRACTICE GUIDELINE: FULL TEXT

ACC/AHA/HRS 2008 Guidelines for Device-BasedTherapy of Cardiac Rhythm AbnormalitiesA Report of the American College of Cardiology/American Heart Association Task Force on PracticeGuidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update forImplantation of Cardiac Pacemakers and Antiarrhythmia Devices)

Developed in Collaboration With the American Association for Thoracic Surgery and Society of Thoracic Surgeons

ublished by Elsevier Inc. doi:10.1016/j.jacc.2008.02.032

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hythm Society request that thillenbogen KA, Estes NAM IIammill SC, Hayes DL, Hlatk

tevenson LW, Sweeney MO. Aardiac rhythm abnormalities: aeart Association Task Force oCC/AHA/NASPE 2002 Guintiarrhythmia Devices). J Am C

ndrew E. Epstein, MD, FACC, FAHA,FHRS, Chair*

ohn P. DiMarco, MD, PHD, FACC, FAHA,FHRS*

enneth A. Ellenbogen, MD, FACC, FAHA,FHRS*. A. Mark Estes, III, MD, FACC, FAHA, FHRSoger A. Freedman, MD, FACC, FHRS*eonard S. Gettes, MD, FACC, FAHA. Marc Gillinov, MD, FACC, FAHA*†abriel Gregoratos, MD, FACC, FAHA

onathan L. Halperin, MD, FACC, FAHA§ §

the American College of Cardiology Foundation Board ofssociation Science Advisory and Coordinating Committee,oard of Trustees in February 2008.iology Foundation, American Heart Association, and Heart

s document be cited as follows: Epstein AE, DiMarco JP,I, Freedman RA, Gettes LS, Gillinov AM, Gregoratos G,y MA, Newby LK, Page RL, Schoenfeld MH, Silka MJ,CC/AHA/HRS 2008 guidelines for device-based therapy ofreport of the American College of Cardiology/Americann Practice Guidelines (Writing Committee to Revise the

deline Update for Implantation of Cardiac Pacemakers andoll Cardiol 2008;51:e1–62.

This article h2008 issue of H

Copies: ThiCollege of Camericanheart.odocument, pleareprints@elsevie

Permissions:tion of this docCollege of CaSociety. Pleaselsevier.com.

avid L. Hayes, MD, FACC, FAHA, FHRS*ark A. Hlatky, MD, FACC, FAHA

. Kristin Newby, MD, FACC, FAHAichard L. Page, MD, FACC, FAHA, FHRSark H. Schoenfeld, MD, FACC, FAHA, FHRSichael J. Silka, MD, FACC

ynne Warner Stevenson, MD, FACC, FAHA‡ichael O. Sweeney, MD, FACC*

Recused from voting on guideline recommendations (see Section 1.2,Document Review and Approval,” for more detail); †American Asso-iation for Thoracic Surgery and Society of Thoracic Surgeons officialepresentative; ‡Heart Failure Society of America official representative

Stephen C. Hammill, MD, FACC, FHRS

ACC/AHATask ForceMembers

Sidney C. Smith, JR, MD, FACC, FAHA,Chair

Alice K. Jacobs, MD, FACC, FAHA,Vice-Chair

Cynthia D. Adams, RN, PHD, FAHA§Jeffrey L. Anderson, MD, FACC, FAHA§Christopher E. Buller, MD, FACCMark A. Creager, MD, FACC, FAHASteven M. Ettinger, MD, FACCDavid P. Faxon, MD, FACC, FAHA§

Loren F. Hiratzka, MD, FACC, FAHA§Sharon A. Hunt, MD, FACC, FAHA§Harlan M. Krumholz, MD, FACC, FAHAFrederick G. Kushner, MD, FACC, FAHABruce W. Lytle, MD, FACC, FAHARick A. Nishimura, MD, FACC, FAHAJoseph P. Ornato, MD, FACC, FAHA§Richard L. Page, MD, FACC, FAHABarbara Riegel, DNSC, RN, FAHA§Lynn G. Tarkington, RNClyde W. Yancy, MD, FACC, FAHA

Former Task Force member during this writing effort

as been copublished in the May 27, 2008, issue of Circulation and the Juneeart Rhythm.

s document is available on the World Wide Web sites of the Americanardiology (www.acc.org), the American Heart Association (www.rg), and the Heart Rhythm Society (www.hrsonline.org). For copies of thisse contact the Elsevier Inc. Reprint Department, fax (212) 633-3820, e-mailr.com.Multiple copies, modification, alteration, enhancement, and/or distribu-ument are not permitted without the express permission of the Americanrdiology Foundation, American Heart Association, or Heart Rhythme contact Elsevier’s permission department at healthpermissions@

http://www.acc.org

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http://www.americanheart.org

http://www.hrsonline.org

mailto:[email protected]



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e2 Epstein et al. JACC Vol. 51, No. 21, 2008ACC/AHA/HRS Guidelines for Device-Based Therapy May 27, 2008:e1–62

TABLE OF CONTENTS

reamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e2

. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e3

1.1. Organization of Committee . . . . . . . . . . . . . . . . . . . . . . . . .e3

1.2. Document Review and Approval . . . . . . . . . . . . . . . . . . .e4

1.3. Methodology and Evidence . . . . . . . . . . . . . . . . . . . . . . . . .e4

. Indications for Pacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e7

2.1. Pacing for Bradycardia Due to Sinus andAtrioventricular Node Dysfunction . . . . . . . . . . . . . . . .e7

2.1.1. Sinus Node Dysfunction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e72.1.2. Acquired Atrioventricular Block in Adults . . . . . . . . . . . .e82.1.3. Chronic Bifascicular Block . . . . . . . . . . . . . . . . . . . . . . . . . .e102.1.4. Pacing for Atrioventricular Block Associated With

Acute Myocardial Infarction. . . . . . . . . . . . . . . . . . . . . . . . .e112.1.5. Hypersensitive Carotid Sinus Syndrome and

Neurocardiogenic Syncope. . . . . . . . . . . . . . . . . . . . . . . . . . .e12

2.2. Pacing for Specific Conditions . . . . . . . . . . . . . . . . . . . .e142.2.1. Cardiac Transplantation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e142.2.2. Neuromuscular Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e142.2.3. Sleep Apnea Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e142.2.4. Cardiac Sarcoidosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e14

2.3. Prevention and Termination of Arrhythmiasby Pacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e15

2.3.1. Pacing to Prevent Atrial Arrhythmias . . . . . . . . . . . . . . .e152.3.2. Long-QT Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e162.3.3. Atrial Fibrillation (Dual-Site, Dual-Chamber,

Alternative Pacing Sites) . . . . . . . . . . . . . . . . . . . . . . . . . . . .e16

2.4. Pacing for Hemodynamic Indications . . . . . . . . . . . .e162.4.1. Cardiac Resynchronization Therapy . . . . . . . . . . . . . . . . .e162.4.2. Obstructive Hypertrophic Cardiomyopathy . . . . . . . . . .e18

2.5. Pacing in Children, Adolescents, and PatientsWith Congenital Heart Disease . . . . . . . . . . . . . . . . . . .e18

2.6. Selection of Pacemaker Device . . . . . . . . . . . . . . . . . .e202.6.1. Major Trials Comparing Atrial or Dual-Chamber

Pacing With Ventricular Pacing . . . . . . . . . . . . . . . . . . . . .e212.6.2. Quality of Life and Functional Status End Points . . . . .e222.6.3. Heart Failure End Points. . . . . . . . . . . . . . . . . . . . . . . . . . . .e232.6.4. Atrial Fibrillation End Points . . . . . . . . . . . . . . . . . . . . . . .e242.6.5. Stroke or Thromboembolism End Points. . . . . . . . . . . .e242.6.6. Mortality End Points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e242.6.7. Importance of Minimizing Unnecessary Ventricular

Pacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e242.6.8. Role of Biventricular Pacemakers . . . . . . . . . . . . . . . . . . . .e25

2.7. Optimizing Pacemaker Technology and Cost . . . .e25

2.8. Pacemaker Follow-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e262.8.1. Length of Electrocardiographic Samples for

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e272.8.2. Frequency of Transtelephonic Monitoring. . . . . . . . . . .e27

. Indications for Implantable Cardioverter-Defibrillator Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e28

3.1. Secondary Prevention of Sudden CardiacDeath . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e28

3.1.1. Implantable Cardioverter-Defibrillator Therapy forSecondary Prevention of Cardiac Arrest and Sustained
Ventricular Tachycardia . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e28 r
3.1.2. Specific Disease States and Secondary Prevention ofCardiac Arrest or Sustained VentricularTachycardia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e29

3.1.3. Coronary Artery Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . .e293.1.4. Nonischemic Dilated Cardiomyopathy . . . . . . . . . . . . . .e293.1.5. Hypertrophic Cardiomyopathy . . . . . . . . . . . . . . . . . . . . . .e303.1.6. Arrhythmogenic Right Ventricular

Dysplasia/Cardiomyopathy . . . . . . . . . . . . . . . . . . . . . . . . . .e303.1.7. Genetic Arrhythmia Syndromes . . . . . . . . . . . . . . . . . . . . .e303.1.8. Syncope With Inducible Sustained Ventricular

Tachycardia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e30

3.2. Primary Prevention of Sudden Cardiac Death . . . . . . .e303.2.1. Coronary Artery Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . .e303.2.2. Nonischemic Dilated Cardiomyopathy . . . . . . . . . . . . . .e313.2.3. Long-QT Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e323.2.4. Hypertrophic Cardiomyopathy . . . . . . . . . . . . . . . . . . . . . .e323.2.5. Arrhythmogenic Right Ventricular

Dysplasia/Cardiomyopathy . . . . . . . . . . . . . . . . . . . . . . . . . .e333.2.6. Noncompaction of the Left Ventricle. . . . . . . . . . . . . . . .e343.2.7. Primary Electrical Disease (Idiopathic Ventricular

Fibrillation, Short-QT Syndrome, BrugadaSyndrome, and Catecholaminergic PolymorphicVentricular Tachycardia) . . . . . . . . . . . . . . . . . . . . . . . . . . . .e34

3.2.8. Idiopathic Ventricular Tachycardias . . . . . . . . . . . . . . . . .e353.2.9. Advanced Heart Failure and Cardiac

Transplantation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e35

3.3. Implantable Cardioverter-Defibrillators inChildren, Adolescents, and Patients WithCongenital Heart Disease . . . . . . . . . . . . . . . . . . . . . . . . .e37

3.3.1. Hypertrophic Cardiomyopathy . . . . . . . . . . . . . . . . . . . . . .e38

3.4. Limitations and Other Considerations . . . . . . . . . . .e383.4.1. Impact on Quality of Life (Inappropriate Shocks) . . .e383.4.2. Surgical Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e393.4.3. Patient Longevity and Comorbidities. . . . . . . . . . . . . . . .e403.4.4. Terminal Care. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e41

3.5. Cost-Effectiveness of Implantable Cardioverter-Defibrillator Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e42

3.6. Selection of Implantable Cardioverter-Defibrillator Generators . . . . . . . . . . . . . . . . . . . . . . . . . . .e43

3.7. Implantable Cardioverter-DefibrillatorFollow-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e44

3.7.1. Elements of Implantable Cardioverter-DefibrillatorFollow-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e44

3.7.2. Focus on Heart Failure After First AppropriateImplantable Cardioverter-Defibrillator Therapy . . . . .e45

. Areas in Need of Further Research . . . . . . . . . . . . . . . . .e45

eferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e46

ppendix 1. Author Relationships With Industry . . . . . . .e58

ppendix 2. Peer Reviewer Relationships Withndustry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e60

ppendix 3. Abbreviations List . . . . . . . . . . . . . . . . . . . . . . . . . . . .e62

reamble

t is important that the medical profession play a significant
ole in critically evaluating the use of diagnostic procedures

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nd therapies as they are introduced and tested in theetection, management, or prevention of disease states.igorous and expert analysis of the available data docu-enting absolute and relative benefits and risks of those

rocedures and therapies can produce helpful guidelineshat improve the effectiveness of care, optimize patientutcomes, and favorably affect the overall cost of care byocusing resources on the most effective strategies.

The American College of Cardiology FoundationACCF) and the American Heart Association (AHA) haveointly engaged in the production of such guidelines in therea of cardiovascular disease since 1980. The Americanollege of Cardiology (ACC)/AHA Task Force on Practiceuidelines, whose charge is to develop, update, or revise

ractice guidelines for important cardiovascular diseases androcedures, directs this effort. Writing committees areharged with the task of performing an assessment of thevidence and acting as an independent group of authors toevelop, update, or revise written recommendations forlinical practice.

Experts in the subject under consideration have beenelected from both organizations to examine subject-specificata and write guidelines. The process includes additionalepresentatives from other medical practitioner and specialtyroups when appropriate. Writing committees are specifi-ally charged to perform a formal literature review, weighhe strength of evidence for or against a particular treatmentr procedure, and include estimates of expected healthutcomes where data exist. Patient-specific modifiers andomorbidities and issues of patient preference that maynfluence the choice of particular tests or therapies areonsidered, as well as frequency of follow-up and cost-ffectiveness. When available, information from studies onost will be considered; however, review of data on efficacynd clinical outcomes will constitute the primary basis forreparing recommendations in these guidelines.The ACC/AHA Task Force on Practice Guidelinesakes every effort to avoid any actual, potential, or per-

eived conflicts of interest that may arise as a result of anndustry relationship or personal interest of the writingommittee. Specifically, all members of the writing com-ittee, as well as peer reviewers of the document, were

sked to provide disclosure statements of all such relation-hips that may be perceived as real or potential conflicts ofnterest. Writing committee members are also stronglyncouraged to declare a previous relationship with industryhat may be perceived as relevant to guideline development.f a writing committee member develops a new relationshipith industry during his or her tenure, he or she is required

o notify guideline staff in writing. The continued partici-ation of the writing committee member will be reviewed.hese statements are reviewed by the parent task force,

eported orally to all members of the writing committee atach meeting, and updated and reviewed by the writingommittee as changes occur. Please refer to the methodol-
gy manual for ACC/AHA guideline writing committees 1
or further description of the relationships with industryolicy (1). See Appendix 1 for author relationships withndustry and Appendix 2 for peer reviewer relationshipsith industry that are pertinent to this guideline.These practice guidelines are intended to assist health

are providers in clinical decision making by describing aange of generally acceptable approaches for the diagnosis,anagement, and prevention of specific diseases or condi-

ions. Clinical decision making should consider the qualitynd availability of expertise in the area where care isrovided. These guidelines attempt to define practices thateet the needs of most patients in most circumstances.hese guideline recommendations reflect a consensus of

xpert opinion after a thorough review of the availableurrent scientific evidence and are intended to improveatient care.Patient adherence to prescribed and agreed upon medical

egimens and lifestyles is an important aspect of treatment.rescribed courses of treatment in accordance with these

ecommendations will only be effective if they are followed.ecause lack of patient understanding and adherence maydversely affect treatment outcomes, physicians and otherealth care providers should make every effort to engage theatient in active participation with prescribed medical reg-mens and lifestyles.

If these guidelines are used as the basis for regulatory orayer decisions, the ultimate goal is quality of care and servinghe patient’s best interests. The ultimate judgment regardingare of a particular patient must be made by the health carerovider and the patient in light of all of the circumstancesresented by that patient. There are circumstances in whicheviations from these guidelines are appropriate.The guidelines will be reviewed annually by the ACC/

HA Task Force on Practice Guidelines and will beonsidered current unless they are updated, revised, orunsetted and withdrawn from distribution. The executiveummary and recommendations are published in the May7, 2008, issue of the Journal of the American College ofardiology, May 27, 2008, issue of Circulation, and the June008 issue of Heart Rhythm. The full-text guidelines are-published in the same issue of the journals noted above, asell as posted on the ACC (www.acc.org), AHA (http://y.americanheart.org), and Heart Rhythm Society (HRS)

www.hrsonline.org) Web sites. Copies of the full-text andhe executive summary are available from each organization.

Sidney C. Smith, Jr, MD, FACC, FAHAChair, ACC/AHA Task Force on Practice Guidelines

. Introduction

.1. Organization of Committee

his revision of the “ACC/AHA/NASPE Guidelines formplantation of Cardiac Pacemakers and Antiarrhythmiaevices” updates the previous versions published in 1984,

991, 1998, and 2002. Revision of the statement was

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eemed necessary for multiple reasons: 1) Major studiesave been reported that have advanced our knowledge of theatural history of bradyarrhythmias and tachyarrhythmias,hich may be treated optimally with device therapy; 2)

here have been tremendous changes in the management ofeart failure that involve both drug and device therapy; and) major advances in the technology of devices to treat,elay, and even prevent morbidity and mortality fromradyarrhythmias, tachyarrhythmias, and heart failure haveccurred.The committee to revise the “ACC/AHA/NASPEuidelines for Implantation of Cardiac Pacemakers andntiarrhythmia Devices” was composed of physicians who

re experts in the areas of device therapy and follow-up andenior clinicians skilled in cardiovascular care, internaledicine, cardiovascular surgery, ethics, and socioeconom-

cs. The committee included representatives of the Ameri-an Association for Thoracic Surgery, Heart Failure Societyf America, and Society of Thoracic Surgeons.

.2. Document Review and Approval

he document was reviewed by 2 official reviewers nomi-ated by each of the ACC, AHA, and HRS and by 11dditional peer reviewers. Of the total 17 peer reviewers, 10ad no significant relevant relationships with industry. Inddition, this document has been reviewed and approved byhe governing bodies of the ACC, AHA, and HRS, whichnclude 19 ACC Board of Trustees members (none ofhom had any significant relevant relationships with indus-

ry), 15 AHA Science Advisory Coordinating Committeeembers (none of whom had any significant relevant

elationships with industry), and 14 HRS Board of Trusteesembers (6 of whom had no significant relevant relation-

hips with industry). All guideline recommendations under-ent a formal, blinded writing committee vote. Writing

ommittee members were required to recuse themselves ifhey had a significant relevant relationship with industry.he guideline recommendations were unanimously ap-roved by all members of the writing committee who wereligible to vote. The section “Pacing in Children anddolescents” was reviewed by additional reviewers with

pecial expertise in pediatric electrophysiology. The com-ittee thanks all the reviewers for their comments. Many of

heir suggestions were incorporated into the final document.

.3. Methodology and Evidence

he recommendations listed in this document are, when-ver possible, evidence based. An extensive literature surveyas conducted that led to the incorporation of 527 refer-

nces. Searches were limited to studies, reviews, and othervidence conducted in human subjects and published innglish. Key search words included but were not limited to

ntiarrhythmic, antibradycardia, atrial fibrillation, brady-rrhythmia, cardiac, CRT, defibrillator, device therapy,evices, dual chamber, heart, heart failure, ICD, implant-
ble defibrillator, device implantation, long-QT syndrome, p
edical therapy, pacemaker, pacing, quality-of-life, resyn-hronization, rhythm, sinus node dysfunction, sleep apnea,udden cardiac death, syncope, tachyarrhythmia, terminalare, and transplantation. Additionally, the committee re-iewed documents related to the subject matter previouslyublished by the ACC, AHA, and HRS. References se-

ected and published in this document are representativend not all-inclusive.

The committee reviewed and ranked evidence supportingurrent recommendations, with the weight of evidenceanked as Level A if the data were derived from multipleandomized clinical trials that involved a large number ofndividuals. The committee ranked available evidence asevel B when data were derived either from a limitedumber of trials that involved a comparatively small numberf patients or from well-designed data analyses of nonran-omized studies or observational data registries. Evidenceas ranked as Level C when the consensus of experts was

he primary source of the recommendation. In the narrativeortions of these guidelines, evidence is generally presentedn chronological order of development. Studies are identi-ed as observational, randomized, prospective, or retrospec-ive. The committee emphasizes that for certain conditionsor which no other therapy is available, the indications forevice therapy are based on expert consensus and years oflinical experience and are thus well supported, even thoughhe evidence was ranked as Level C. An analogous examples the use of penicillin in pneumococcal pneumonia, forhich there are no randomized trials and only clinical

xperience. When indications at Level C are supported byistorical clinical data, appropriate references (e.g., caseeports and clinical reviews) are cited if available. Whenevel C indications are based strictly on committee consen-

us, no references are cited. In areas where sparse data werevailable (e.g., pacing in children and adolescents), a surveyf current practices of major centers in North America wasonducted to determine whether there was a consensusegarding specific pacing indications. The schema for clas-ification of recommendations and level of evidence isummarized in Table 1, which also illustrates how therading system provides an estimate of the size of thereatment effect and an estimate of the certainty of thereatment effect.

The focus of these guidelines is the appropriate use ofeart pacing devices (e.g., pacemakers for bradyarrhythmiasnd heart failure management, cardiac resynchronization,nd implantable cardioverter-defibrillators [ICDs]), not thereatment of cardiac arrhythmias. The fact that the use of aevice for treatment of a particular condition is listed as alass I indication (beneficial, useful, and effective) does notreclude the use of other therapeutic modalities that may bequally effective. As with all clinical practice guidelines, theecommendations in this document focus on treatment of anverage patient with a specific disorder and may be modified by
atient comorbidities, limitation of life expectancy because of

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oexisting diseases, and other situations that only the primaryreating physician may evaluate appropriately.

These guidelines include sections on selection of pace-akers and ICDs, optimization of technology, cost, and

ollow-up of implanted devices. Although the section onollow-up is relatively brief, its importance cannot be over-mphasized: First, optimal results from an implanted devicean be obtained only if the device is adjusted to changing

able 1. Applying Classification of Recommendations and Leve

linical conditions; second, recent advisories and recalls (

erve as warnings that devices are not infallible, and failuref electronics, batteries, and leads can occur (2,3).The committee considered including a section on extrac-

ion of failed/unused leads, a topic of current interest, butlected not to do so in the absence of convincing evidence toupport specific criteria for timing and methods of leadxtraction. A policy statement on lead extraction from theorth American Society of Pacing and Electrophysiology

vidence
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now the HRS) provides information on this topic (4).

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imilarly, the issue of when to discontinue long-termardiac pacing or defibrillator therapy has not been studiedufficiently to allow formulation of appropriate guidelines5); however, the question is of such importance that thisopic is addressed to emphasize the importance of patient-amily-physician discussion and ethical principles.

The text that accompanies the listed indications shoulde read carefully, because it includes the rationale andupporting evidence for many of the indications, and ineveral instances, it includes a discussion of alternativecceptable therapies. Many of the indications are modifiedy the term “potentially reversible.” This term is used tondicate abnormal pathophysiology (e.g., complete heartlock) that may be the result of reversible factors. Examplesnclude complete heart block due to drug toxicity (digitalis),lectrolyte abnormalities, diseases with periatrioventricularode inflammation (Lyme disease), and transient injury tohe conduction system at the time of open heart surgery.

hen faced with a potentially reversible situation, thereating physician must decide how long of a waiting periods justified before device therapy is begun. The committeeecognizes that this statement does not address the issue ofength of hospital stay vis-à-vis managed-care regulations. Its emphasized that these guidelines are not intended toddress this issue, which falls strictly within the purview ofhe treating physician.

The term “symptomatic bradycardia” is used in thisocument. Symptomatic bradycardia is defined as a docu-ented bradyarrhythmia that is directly responsible for

evelopment of the clinical manifestations of syncope orear syncope, transient dizziness or lightheadedness, oronfusional states resulting from cerebral hypoperfusionttributable to slow heart rate. Fatigue, exercise intolerance,nd congestive heart failure may also result from bradycar-ia. These symptoms may occur at rest or with exertion.efinite correlation of symptoms with a bradyarrhythmia is

equired to fulfill the criteria that define symptomaticradycardia. Caution should be exercised not to confusehysiological sinus bradycardia (as occurs in highly trainedthletes) with pathological bradyarrhythmias. Occasionally,ymptoms may become apparent only in retrospect afterntibradycardia pacing. Nevertheless, the universal applica-ion of pacing therapy to treat a specific heart rate cannot beecommended except in specific circumstances, as detailedubsequently.

In these guidelines, the terms “persistent,” “transient,”nd “not expected to resolve” are used but not specificallyefined because the time element varies in different clinicalonditions. The treating physician must use appropriatelinical judgment and available data in deciding when aondition is persistent or when it can be expected to beransient. Section 2.1.4, “Pacing for Atrioventricular Blockssociated With Acute Myocardial Infarction,” overlapsith the “ACC/AHA Guidelines for the Management ofatients With ST-Elevation Myocardial Infarction” (6) and

ncludes expanded indications and stylistic changes. The g

tatement “incidental finding at electrophysiological study”s used several times in this document and does not meanhat such a study is indicated. Appropriate indications forlectrophysiological studies have been published (7).

The section on indications for ICDs has been updated toeflect the numerous new developments in this field and theoluminous literature related to the efficacy of these devicesn the treatment and prophylaxis of sudden cardiac deathSCD) and malignant ventricular arrhythmias. As previ-usly noted, indications for ICDs, cardiac resynchronizationherapy (CRT) devices, and combined ICDs and CRTevices (hereafter called CRT-Ds) are continuously chang-ng and can be expected to change further as new trials areeported. Indeed, it is inevitable that the indications forevice therapy will be refined with respect to both expandedse and the identification of patients expected to benefit theost from these therapies. Furthermore, it is emphasized

hat when a patient has an indication for both a pacemakerwhether it be single-chamber, dual-chamber, or biventricu-ar) and an ICD, a combined device with appropriaterogramming is indicated.In this document, the term “mortality” is used to indicate

ll-cause mortality unless otherwise specified. The commit-ee elected to use all-cause mortality because of the variableefinition of sudden death and the developing consensus tose all-cause mortality as the most appropriate end point oflinical trials (8,9).

These guidelines are not designed to specify training orredentials required for physicians to use device therapy.evertheless, in view of the complexity of both the cognitive

nd technical aspects of device therapy, only appropriatelyrained physicians should use device therapy. Appropriateraining guidelines for physicians have been publishedreviously (10–13).The 2008 revision reflects what the committee believes

re the most relevant and significant advances in pacemaker/CD therapy since the publication of these guidelines in theournal of the American College of Cardiology and Circulationn 2002 (14,15).

All recommendations assume that patients are treatedith optimal medical therapy according to published guide-

ines, as had been required in all the randomized controlledlinical trials on which these guidelines are based, and thatuman issues related to individual patients are addressed.he committee believes that comorbidities, life expectancy,

nd quality-of-life (QOL) issues must be addressed forth-ightly with patients and their families. We have repeatedlysed the phrase “reasonable expectation of survival with aood functional status for more than 1 year” to emphasizehis integration of factors in decision-making. Even whenhysicians believe that the anticipated benefits warrantevice implantation, patients have the option to declinentervention after having been provided with a full explana-ion of the potential risks and benefits of device therapy.inally, the committee is aware that other guideline/expert
roups have interpreted the same data differently (16–19).

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In preparing this revision, the committee was guided byhe following principles:

. Changes in recommendations and levels of evidencewere made either because of new randomized trials orbecause of the accumulation of new clinical evidence andthe development of clinical consensus.

. The committee was cognizant of the health care, logistic,and financial implications of recent trials and factored inthese considerations to arrive at the classification ofcertain recommendations.

. For recommendations taken from other guidelines,wording changes were made to render some of theoriginal recommendations more precise.

. The committee would like to reemphasize that therecommendations in this guideline apply to most pa-tients but may require modification because of existingsituations that only the primary treating physician canevaluate properly.

. All of the listed recommendations for implantation of adevice presume the absence of inciting causes that maybe eliminated without detriment to the patient (e.g.,nonessential drug therapy).

. The committee endeavored to maintain consistency ofrecommendations in this and other previously publishedguidelines. In the section on atrioventricular (AV) blockassociated with acute myocardial infarction (AMI), therecommendations follow closely those in the “ACC/AHA Guidelines for the Management of Patients WithST-Elevation Myocardial Infarction” (6). However, be-cause of the rapid evolution of pacemaker/ICD science,it has not always been possible to maintain consistencywith other published guidelines.

. Indications for Pacing

.1. Pacing for Bradycardia Due to Sinus andtrioventricular Node Dysfunction

n some patients, bradycardia is the consequence of essentialong-term drug therapy of a type and dose for which theres no acceptable alternative. In these patients, pacing therapys necessary to allow maintenance of ongoing medicalreatment.

.1.1. Sinus Node Dysfunction

inus node dysfunction (SND) was first described as alinical entity in 1968 (20), although Wenckebach reportedhe electrocardiographic (ECG) manifestation of SND in923. SND refers to a broad array of abnormalities in sinusode and atrial impulse formation and propagation. These

nclude persistent sinus bradycardia and chronotropic in-ompetence without identifiable causes, paroxysmal or per-istent sinus arrest with replacement by subsidiary escapehythms in the atrium, AV junction, or ventricular myocar-ium. The frequent association of paroxysmal atrial fibril-

ation (AF) and sinus bradycardia or sinus bradyarrhyth- n

ias, which may oscillate suddenly from one to the other,sually accompanied by symptoms, is termed “tachy-bradyyndrome.”

SND is primarily a disease of the elderly and is presumedo be due to senescence of the sinus node and atrial muscle.ollected data from 28 different studies on atrial pacing forND showed a median annual incidence of complete AVlock of 0.6% (range 0% to 4.5%) with a total prevalence of.1% (range 0% to 11.9%) (21). This suggests that theegenerative process also affects the specialized conductionystem, although the rate of progression is slow and does notominate the clinical course of disease (21). SND is typi-ally diagnosed in the seventh and eighth decades of life,hich is also the average age at enrollment in clinical trialsf pacemaker therapy for SND (22,23). Identical clinicalanifestations may occur at any age as a secondary phe-

omenon of any condition that results in destruction of sinusode cells, such as ischemia or infarction, infiltrative disease,ollagen vascular disease, surgical trauma, endocrinologic ab-ormalities, autonomic insufficiency, and others (24).The clinical manifestations of SND are diverse, reflecting

he range of typical sinoatrial rhythm disturbances. Theost dramatic presentation is syncope. The mechanism of

yncope is a sudden pause in sinus impulse formation orinus exit block, either spontaneously or after the termina-ion of an atrial tachyarrhythmia, that causes cerebralypoperfusion. The pause in sinus node activity is frequentlyccompanied by an inadequate, delayed, or absent responsef subsidiary escape pacemakers in the AV junction orentricular myocardium, which aggravates the hemody-amic consequences.However, in many patients, the clinical manifestations of

ND are more insidious and relate to an inadequate heartate response to activities of daily living that can be difficulto diagnose (25). The term “chronotropic incompetence” issed to denote an inadequate heart rate response to physicalctivity. Although many experienced clinicians claim toecognize chronotropic incompetence in individual patients,o single metric has been established as a diagnostictandard upon which therapeutic decisions can be based.he most obvious example of chronotropic incompetence ismonotonic daily heart rate profile in an ambulatory

atient. Various protocols have been proposed to quantifyubphysiological heart rate responses to exercise (26,27),nd many clinicians would consider failure to achieve 80%f the maximum predicted heart rate (220 minus age) ateak exercise as evidence of a blunted heart rate response28,29). However, none of these approaches have beenalidated clinically, and it is likely that the appropriate heartate response to exercise in individual patients is toodiosyncratic for standardized testing.

The natural history of untreated SND may be highlyariable. The majority of patients who have experiencedyncope because of a sinus pause or marked sinus bradycar-ia will have recurrent syncope (30). Not uncommonly, the
atural history of SND is interrupted by other necessary

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edical therapies that aggravate the underlying tendency toradycardia (24). MOST (Mode Selection Trial) includedymptomatic pauses greater than or equal to 3 seconds orinus bradycardia with rates greater than 50 bpm, whichestricted the use of indicated long-term medical therapy.upraventricular tachycardia (SVT) including AF wasresent in 47% and 53% of patients, respectively, enrolled inlarge randomized clinical trial of pacing mode selection inND (22,31). The incidence of sudden death is extremely

ow, and SND does not appear to affect survival whetherntreated (30) or treated with pacemaker therapy (32,33).The only effective treatment for symptomatic bradycardia

s permanent cardiac pacing. The decision to implant aacemaker for SND is often accompanied by uncertaintyhat arises from incomplete linkage between sporadic symp-oms and ECG evidence of coexisting bradycardia. It isrucial to distinguish between physiological bradycardia dueo autonomic conditions or training effects and circumstan-ially inappropriate bradycardia that requires permanentardiac pacing. For example, sinus bradycardia is accepted asphysiological finding that does not require cardiac pacing

n trained athletes. Such individuals may have heart rates of0 to 50 bpm while at rest and awake and may have aleeping rate as slow as 30 bpm, with sinus pauses orrogressive sinus slowing accompanied by AV conductionelay (PR prolongation), sometimes culminating in type Iecond-degree AV block (34,35). The basis of the distinc-ion between physiological and pathological bradycardia,hich may overlap in ECG presentation, therefore pivotsn correlation of episodic bradycardia with symptoms com-atible with cerebral hypoperfusion. Intermittent ECGonitoring with Holter monitors and event recorders may

e helpful (36,37), although the duration of monitoringequired to capture such evidence may be very long (38).he use of insertable loop recorders offers the advantages of

ompliance and convenience during very long-term moni-oring efforts (39).

The optimal pacing system for prevention of symptom-tic bradycardia in SND is unknown. Recent evidenceuggests that ventricular desynchronization due to rightentricular apical (RVA) pacing may have adverse effects oneft ventricular (LV) and left atrial structure and function40–47). These adverse effects likely explain the associationf RVA pacing, independent of AV synchrony, with in-reased risks of AF and heart failure in randomized clinicalrials of pacemaker therapy (45,48,49) and, additionally,entricular arrhythmias and death during ICD therapy50,51). Likewise, although simulation of the normal sinusode response to exercise in bradycardia patients withacemaker sensors seems logical, a clinical benefit on aopulation scale has not been demonstrated in large ran-omized controlled trials of pacemaker therapy (52). Theseapidly evolving areas of clinical investigation should informhe choice of pacing system in SND (see Section 2.6,
Selection of Pacemaker Device”). w
ecommendations for Permanent Pacing in Sinusode Dysfunction

LASS I

. Permanent pacemaker implantation is indicated for SND withdocumented symptomatic bradycardia, including frequent sinuspauses that produce symptoms. (Level of Evidence: C) (53–55)

. Permanent pacemaker implantation is indicated for symptomaticchronotropic incompetence. (Level of Evidence: C) (53–57)

. Permanent pacemaker implantation is indicated for symptomaticsinus bradycardia that results from required drug therapy formedical conditions. (Level of Evidence: C)

LASS IIa

. Permanent pacemaker implantation is reasonable for SND withheart rate less than 40 bpm when a clear association betweensignificant symptoms consistent with bradycardia and the actualpresence of bradycardia has not been documented. (Level ofEvidence: C) (53–55,58–60)

. Permanent pacemaker implantation is reasonable for syncope ofunexplained origin when clinically significant abnormalities ofsinus node function are discovered or provoked in electrophysi-ological studies. (Level of Evidence: C) (61,62)

LASS IIb

. Permanent pacemaker implantation may be considered in mini-mally symptomatic patients with chronic heart rate less than 40bpm while awake. (Level of Evidence: C) (53,55,56,58–60)

LASS III

. Permanent pacemaker implantation is not indicated for SND inasymptomatic patients. (Level of Evidence: C)

. Permanent pacemaker implantation is not indicated for SND inpatients for whom the symptoms suggestive of bradycardia havebeen clearly documented to occur in the absence of bradycardia.(Level of Evidence: C)

. Permanent pacemaker implantation is not indicated for SND withsymptomatic bradycardia due to nonessential drug therapy.(Level of Evidence: C)

.1.2. Acquired Atrioventricular Block in Adults

V block is classified as first-, second-, or third-degreecomplete) block; anatomically, it is defined as supra-,ntra-, or infra-His. First-degree AV block is defined asbnormal prolongation of the PR interval (greater than 0.20econds). Second-degree AV block is subclassified as type Ind type II. Type I second-degree AV block is characterizedy progressive prolongation of the interval between thenset of atrial (P wave) and ventricular (R wave) conductionPR) before a nonconducted beat and is usually seen inonjunction with QRS. Type I second-degree AV block isharacterized by progressive prolongation of the PR intervalefore a nonconducted beat and a shorter PR interval afterhe blocked beat. Type II second-degree AV block isharacterized by fixed PR intervals before and after blockedeats and is usually associated with a wide QRS complex.

hen AV conduction occurs in a 2:1 pattern, block cannote classified unequivocally as type I or type II, although the
idth of the QRS can be suggestive, as just described.

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dvanced second-degree AV block refers to the blocking ofor more consecutive P waves with some conducted beats,hich indicates some preservation of AV conduction. In the

etting of AF, a prolonged pause (e.g., greater than 5econds) should be considered to be due to advancedecond-degree AV block. Third-degree AV block (completeeart block) is defined as absence of AV conduction.Patients with abnormalities of AV conduction may be

symptomatic or may experience serious symptoms relatedo bradycardia, ventricular arrhythmias, or both. Decisionsegarding the need for a pacemaker are importantly influ-nced by the presence or absence of symptoms directlyttributable to bradycardia. Furthermore, many of the indi-ations for pacing have evolved over the past 40 years on theasis of experience without the benefit of comparativeandomized clinical trials, in part because no acceptablelternative options exist to treat most bradycardias.

Nonrandomized studies strongly suggest that permanentacing does improve survival in patients with third-degreeV block, especially if syncope has occurred (63–68).lthough there is little evidence to suggest that pacemakers

mprove survival in patients with isolated first-degree AVlock (69), it is now recognized that marked (PR more than00 milliseconds) first-degree AV block can lead to symp-oms even in the absence of higher degrees of AV block70). When marked first-degree AV block for any reasonauses atrial systole in close proximity to the precedingentricular systole and produces hemodynamic conse-uences usually associated with retrograde (ventriculoatrial)onduction, signs and symptoms similar to the pacemakeryndrome may occur (71). With marked first-degree AVlock, atrial contraction occurs before complete atrial filling,entricular filling is compromised, and an increase in pul-onary capillary wedge pressure and a decrease in cardiac

utput follow. Small uncontrolled trials have suggestedome symptomatic and functional improvement by pacingf patients with PR intervals more than 0.30 seconds byecreasing the time for AV conduction (70). Finally, a longR interval may identify a subgroup of patients with LVysfunction, some of whom may benefit from dual-chamberacing with a short(er) AV delay (72). These same princi-les also may be applied to patients with type I second-egree AV block who experience hemodynamic compro-ise due to loss of AV synchrony, even without bradycardia.lthough echocardiographic or invasive techniques may besed to assess hemodynamic improvement before perma-ent pacemaker implantation, such studies are not required.Type I second-degree AV block is usually due to delay in

he AV node irrespective of QRS width. Because progres-ion to advanced AV block in this situation is uncommon73–75), pacing is usually not indicated unless the patient isymptomatic. Although controversy exists, pacemaker im-lantation is supported for this finding (76–78). Type IIecond-degree AV block is usually infranodal (either intra-r infra-His), especially when the QRS is wide. In these
atients, symptoms are frequent, prognosis is compromised, b
nd progression to third-degree AV block is common andudden (73,75,79). Thus, type II second-degree AV blockith a wide QRS typically indicates diffuse conduction

ystem disease and constitutes an indication for pacing evenn the absence of symptoms. However, it is not alwaysossible to determine the site of AV block without electro-hysiological evaluation, because type I second-degree AVlock can be infranodal even when the QRS is narrow (80).f type I second-degree AV block with a narrow or wideRS is found to be intra- or infra-Hisian at electrophysi-

logical study, pacing should be considered.Because it may be difficult for both patients and their

hysicians to attribute ambiguous symptoms such as fatigueo bradycardia, special vigilance must be exercised to ac-nowledge the patient’s concerns about symptoms that maye caused by a slow heart rate. In a patient with third-degreeV block, permanent pacing should be strongly considered

ven when the ventricular rate is more than 40 bpm, becausehe choice of a 40 bpm cutoff in these guidelines was notetermined from clinical trial data. Indeed, it is not thescape rate that is necessarily critical for safety but rather theite of origin of the escape rhythm (i.e., in the AV node, theis bundle, or infra-His).AV block can sometimes be provoked by exercise. If not

econdary to myocardial ischemia, AV block in this circum-tance usually is due to disease in the His-Purkinje systemnd is associated with a poor prognosis; thus, pacing isndicated (81,82). Long sinus pauses and AV block can alsoccur during sleep apnea. In the absence of symptoms, thesebnormalities are reversible and do not require pacing (83).f symptoms are present, pacing is indicated as in otheronditions.

Recommendations for permanent pacemaker implanta-ion in patients with AV block in AMI, congenital AVlock, and AV block associated with enhanced vagal tonere discussed in separate sections. Neurocardiogenic causesn young patients with AV block should be assessed beforeroceeding with permanent pacing. Physiological AV blockn the presence of supraventricular tachyarrhythmias doesot constitute an indication for pacemaker implantation excepts specifically defined in the recommendations that follow.

In general, the decision regarding implantation of aacemaker must be considered with respect to whether AVlock will be permanent. Reversible causes of AV block,uch as electrolyte abnormalities, should be corrected first.ome diseases may follow a natural history to resolutione.g., Lyme disease), and some AV block can be expected toeverse (e.g., hypervagotonia due to recognizable and avoid-ble physiological factors, perioperative AV block due toypothermia, or inflammation near the AV conductionystem after surgery in this region). Conversely, someonditions may warrant pacemaker implantation because ofhe possibility of disease progression even if the AV blockeverses transiently (e.g., sarcoidosis, amyloidosis, and neu-omuscular diseases). Finally, permanent pacing for AV
lock after valve surgery follows a variable natural history;

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herefore, the decision for permanent pacing is at thehysician’s discretion (84).

ecommendations for Acquired Atrioventricular Blockn Adults

LASS I

. Permanent pacemaker implantation is indicated for third-degreeand advanced second-degree AV block at any anatomic levelassociated with bradycardia with symptoms (including heartfailure) or ventricular arrhythmias presumed to be due to AVblock. (Level of Evidence: C) (59,63,76,85)

. Permanent pacemaker implantation is indicated for third-degreeand advanced second-degree AV block at any anatomic levelassociated with arrhythmias and other medical conditions thatrequire drug therapy that results in symptomatic bradycardia.(Level of Evidence: C) (59,63,76,85)

. Permanent pacemaker implantation is indicated for third-degreeand advanced second-degree AV block at any anatomic level inawake, symptom-free patients in sinus rhythm, with documentedperiods of asystole greater than or equal to 3.0 seconds (86) orany escape rate less than 40 bpm, or with an escape rhythm thatis below the AV node. (Level of Evidence: C) (53,58)

. Permanent pacemaker implantation is indicated for third-degreeand advanced second-degree AV block at any anatomic level inawake, symptom-free patients with AF and bradycardia with 1 ormore pauses of at least 5 seconds or longer. (Level of Evidence: C)

. Permanent pacemaker implantation is indicated for third-degreeand advanced second-degree AV block at any anatomic level aftercatheter ablation of the AV junction. (Level of Evidence: C) (87,88)

. Permanent pacemaker implantation is indicated for third-degreeand advanced second-degree AV block at any anatomic levelassociated with postoperative AV block that is not expected toresolve after cardiac surgery. (Level of Evidence: C) (84,85,89,90)

. Permanent pacemaker implantation is indicated for third-degreeand advanced second-degree AV block at any anatomic levelassociated with neuromuscular diseases with AV block, such asmyotonic muscular dystrophy, Kearns-Sayre syndrome, Erb dystro-phy (limb-girdle muscular dystrophy), and peroneal muscular atro-phy, with or without symptoms. (Level of Evidence: B) (91–97)

. Permanent pacemaker implantation is indicated for second-degree AV block with associated symptomatic bradycardia re-gardless of type or site of block. (Level of Evidence: B) (74)

. Permanent pacemaker implantation is indicated for asymptom-atic persistent third-degree AV block at any anatomic site withaverage awake ventricular rates of 40 bpm or faster if cardio-megaly or LV dysfunction is present or if the site of block is belowthe AV node. (Level of Evidence: B) (76,78)

0. Permanent pacemaker implantation is indicated for second- orthird-degree AV block during exercise in the absence of myo-cardial ischemia. (Level of Evidence: C) (81,82)

LASS IIa

. Permanent pacemaker implantation is reasonable for persistentthird-degree AV block with an escape rate greater than 40 bpmin asymptomatic adult patients without cardiomegaly. (Level ofEvidence: C) (59,63,64,76,82,85)

. Permanent pacemaker implantation is reasonable for asymptom-atic second-degree AV block at intra- or infra-His levels found at
electrophysiological study. (Level of Evidence: B) (74,76,78) v
. Permanent pacemaker implantation is reasonable for first- orsecond-degree AV block with symptoms similar to those ofpacemaker syndrome or hemodynamic compromise. (Level ofEvidence: B) (70,71)

. Permanent pacemaker implantation is reasonable for asymptom-atic type II second-degree AV block with a narrow QRS. Whentype II second-degree AV block occurs with a wide QRS, includ-ing isolated right bundle-branch block, pacing becomes a Class Irecommendation. (See Section 2.1.3, “Chronic BifascicularBlock.”) (Level of Evidence: B) (70,76,80,85)

LASS IIb

. Permanent pacemaker implantation may be considered for neu-romuscular diseases such as myotonic muscular dystrophy, Erbdystrophy (limb-girdle muscular dystrophy), and peroneal muscu-lar atrophy with any degree of AV block (including first-degree AVblock), with or without symptoms, because there may be unpre-dictable progression of AV conduction disease. (Level of Evi-dence: B) (91–97)

. Permanent pacemaker implantation may be considered for AVblock in the setting of drug use and/or drug toxicity when theblock is expected to recur even after the drug is withdrawn.(Level of Evidence: B) (98,99)

LASS III

. Permanent pacemaker implantation is not indicated for asymp-tomatic first-degree AV block. (Level of Evidence: B) (69) (SeeSection 2.1.3, “Chronic Bifascicular Block.”)

. Permanent pacemaker implantation is not indicated for asymp-tomatic type I second-degree AV block at the supra-His (AVnode) level or that which is not known to be intra- or infra-Hisian.(Level of Evidence: C) (74)

. Permanent pacemaker implantation is not indicated for AV blockthat is expected to resolve and is unlikely to recur (100) (e.g.,drug toxicity, Lyme disease, or transient increases in vagal toneor during hypoxia in sleep apnea syndrome in the absence ofsymptoms). (Level of Evidence: B) (99,100)

.1.3. Chronic Bifascicular Block

ifascicular block refers to ECG evidence of impaired conduc-ion below the AV node in the right and left bundles.lternating bundle-branch block (also known as bilateralundle-branch block) refers to situations in which clear ECGvidence for block in all 3 fascicles is manifested on successiveCGs. Examples are right bundle-branch block and leftundle-branch block on successive ECGs or right bundle-ranch block with associated left anterior fascicular block on 1CG and associated left posterior fascicular block on anotherCG. Patients with first-degree AV block in association withifascicular block and symptomatic, advanced AV block have aigh mortality rate and a substantial incidence of sudden death64,101). Although third-degree AV block is most oftenreceded by bifascicular block, there is evidence that the rate ofrogression of bifascicular block to third-degree AV block islow (102). Furthermore, no single clinical or laboratory
ariable, including bifascicular block, identifies patients at high

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isk of death due to a future bradyarrhythmia caused byundle-branch block (103).

Syncope is common in patients with bifascicular block.lthough syncope may be recurrent, it is not associated with an

ncreased incidence of sudden death (73,102–112). Evenhough pacing relieves the neurological symptoms, it does noteduce the occurrence of sudden death (108). An electrophys-ological study may be helpful to evaluate and direct thereatment of inducible ventricular arrhythmias (113,114) thatre common in patients with bifascicular block. There isonvincing evidence that in the presence of permanent orransient third-degree AV block, syncope is associated with anncreased incidence of sudden death regardless of the results ofhe electrophysiological study (64,114,115). Finally, if theause of syncope in the presence of bifascicular block cannot beetermined with certainty, or if treatments used (such as drugs)ay exacerbate AV block, prophylactic permanent pacing is

ndicated, especially if syncope may have been due to transienthird-degree AV block (102–112,116).

Of the many laboratory variables, the PR and HV intervalsave been identified as possible predictors of third-degree AVlock and sudden death. Although PR-interval prolongation isommon in patients with bifascicular block, the delay is oftent the level of the AV node. There is no correlation betweenhe PR and HV intervals or between the length of the PRnterval, progression to third-degree AV block, and suddeneath (107,109,116). Although most patients with chronic or

ntermittent third-degree AV block demonstrate prolongationf the HV interval during anterograde conduction, somenvestigators (110,111) have suggested that asymptomatic pa-ients with bifascicular block and a prolonged HV intervalhould be considered for permanent pacing, especially if theV interval is greater than or equal to 100 milliseconds (109).lthough the prevalence of HV-interval prolongation is high,

he incidence of progression to third-degree AV block is low.ecause HV prolongation accompanies advanced cardiacisease and is associated with increased mortality, death isften not sudden or due to AV block but rather is due to thenderlying heart disease itself and nonarrhythmic cardiacauses (102,103,108,109,111,114–117).

Atrial pacing at electrophysiological study in asymptomaticatients as a means of identifying patients at increased risk ofuture high- or third-degree AV block is controversial. Therobability of inducing block distal to the AV node (i.e., intra-r infra-His) with rapid atrial pacing is low (102,110,111,118–21). Failure to induce distal block cannot be taken as evidencehat the patient will not develop third-degree AV block in theuture. However, if atrial pacing induces nonphysiologicalnfra-His block, some consider this an indication for pacing118). Nevertheless, infra-His block that occurs during eitherapid atrial pacing or programmed stimulation at short cou-ling intervals may be physiological and not pathological,imply reflecting disparity between refractoriness of the AV
ode and His-Purkinje systems (122). a
ecommendations for Permanent Pacing in Chronicifascicular Block

LASS I

. Permanent pacemaker implantation is indicated for advancedsecond-degree AV block or intermittent third-degree AV block.(Level of Evidence: B) (63–68,101)

. Permanent pacemaker implantation is indicated for type IIsecond-degree AV block. (Level of Evidence: B) (73,75,79,123)

. Permanent pacemaker implantation is indicated for alternatingbundle-branch block. (Level of Evidence: C) (124)

LASS IIa

. Permanent pacemaker implantation is reasonable for syncopenot demonstrated to be due to AV block when other likely causeshave been excluded, specifically ventricular tachycardia (VT).(Level of Evidence: B) (102–111,113–119,123,125)

. Permanent pacemaker implantation is reasonable for an inciden-tal finding at electrophysiological study of a markedly prolongedHV interval (greater than or equal to 100 milliseconds) inasymptomatic patients. (Level of Evidence: B) (109)

. Permanent pacemaker implantation is reasonable for an inciden-tal finding at electrophysiological study of pacing-induced infra-His block that is not physiological. (Level of Evidence: B) (118)

LASS IIb

. Permanent pacemaker implantation may be considered in thesetting of neuromuscular diseases such as myotonic musculardystrophy, Erb dystrophy (limb-girdle muscular dystrophy), andperoneal muscular atrophy with bifascicular block or any fascicularblock, with or without symptoms. (Level of Evidence: C) (91–97)

LASS III

. Permanent pacemaker implantation is not indicated for fascicu-lar block without AV block or symptoms. (Level of Evidence: B)(103,107,109,116)

. Permanent pacemaker implantation is not indicated for fascicu-lar block with first-degree AV block without symptoms. (Level ofEvidence: B) (103,107,109,116)

.1.4. Pacing for Atrioventricular Block Associatedith Acute Myocardial Infarction

ndications for permanent pacing after myocardial infarc-ion (MI) in patients experiencing AV block are related inarge measure to the presence of intraventricular conductionefects. The criteria for patients with MI and AV block doot necessarily depend on the presence of symptoms.urthermore, the requirement for temporary pacing in AMIoes not by itself constitute an indication for permanentacing (see “ACC/AHA Guidelines for the Management ofatients With ST-Elevation Myocardial Infarction” [6]).he long-term prognosis for survivors of AMI who havead AV block is related primarily to the extent of myocar-ial injury and the character of intraventricular conductionisturbances rather than the AV block itself (66,126–130).atients with AMI who have intraventricular conductionefects, with the exception of isolated left anterior fascicularlock, have an unfavorable short- and long-term prognosis
nd an increased risk of sudden death (66,79,126,128,130).

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his unfavorable prognosis is not necessarily due to devel-pment of high-grade AV block, although the incidence ofuch block is higher in postinfarction patients with abnor-al intraventricular conduction (126,131,132).When AV or intraventricular conduction block compli-

ates AMI, the type of conduction disturbance, location ofnfarction, and relation of electrical disturbance to infarction

ust be considered if permanent pacing is contemplated.ven with data available, the decision is not always straight-

orward, because the reported incidence and significance ofarious conduction disturbances vary widely (133). Despitehe use of thrombolytic therapy and primary angioplasty,hich have decreased the incidence of AV block in AMI,ortality remains high if AV block occurs (130,134–137).Although more severe disturbances in conduction have

enerally been associated with greater arrhythmic and non-rrhythmic mortality (126–129,131,133), the impact ofreexisting bundle-branch block on mortality after AMI isontroversial (112,133). A particularly ominous prognosis isssociated with left bundle-branch block combined withdvanced second- or third-degree AV block and with rightundle-branch block combined with left anterior or leftosterior fascicular block (105,112,127,129). Regardless ofhether the infarction is anterior or inferior, the develop-ent of an intraventricular conduction delay reflects exten-

ive myocardial damage rather than an electrical problem insolation (129). Although AV block that occurs duringnferior MI can be associated with a favorable long-termlinical outcome, in-hospital survival is impaired irrespectivef temporary or permanent pacing in this situation134,135,138,139). Pacemakers generally should not bemplanted with inferior MI if the peri-infarctional AV blocks expected to resolve or is not expected to negatively affectong-term prognosis (136). When symptomatic high-degreer third-degree heart block complicates inferior MI, evenhen the QRS is narrow, permanent pacing may be

onsidered if the block does not resolve. For the patient withecent MI with a left ventricular ejection fraction (LVEF)ess than or equal to 35% and an indication for permanentacing, consideration may be given to use of an ICD, aRT device that provides pacing but not defibrillation

apability (CRT-P), or a CRT device that incorporates bothacing and defibrillation capabilities (CRT-D) when im-rovement in LVEF is not anticipated.

ecommendations for Permanent Pacing After thecute Phase of Myocardial Infarction*

LASS I

. Permanent ventricular pacing is indicated for persistent second-degree AV block in the His-Purkinje system with alternatingbundle-branch block or third-degree AV block within or below theHis-Purkinje system after ST-segment elevation MI. (Level ofEvidence: B) (79,126–129,131)

pThese recommendations are consistent with the “ACC/AHA Guidelines for the

anagement of Patients With ST-Elevation Myocardial Infarction” (6).

. Permanent ventricular pacing is indicated for transient advancedsecond- or third-degree infranodal AV block and associatedbundle-branch block. If the site of block is uncertain, an electro-physiological study may be necessary. (Level of Evidence: B)(126,127)

. Permanent ventricular pacing is indicated for persistent andsymptomatic second- or third-degree AV block. (Level of Evi-dence: C)

LASS IIb

. Permanent ventricular pacing may be considered for persistentsecond- or third-degree AV block at the AV node level, even in theabsence of symptoms. (Level of Evidence: B) (58)

LASS III

. Permanent ventricular pacing is not indicated for transient AVblock in the absence of intraventricular conduction defects.(Level of Evidence: B) (126)

. Permanent ventricular pacing is not indicated for transient AVblock in the presence of isolated left anterior fascicular block.(Level of Evidence: B) (128)

. Permanent ventricular pacing is not indicated for new bundle-branch block or fascicular block in the absence of AV block.(Level of Evidence: B) (66, 126)

. Permanent ventricular pacing is not indicated for persistentasymptomatic first-degree AV block in the presence of bundle-branch or fascicular block. (Level of Evidence: B) (126)

.1.5. Hypersensitive Carotid Sinus Syndrome andeurocardiogenic Syncope

he hypersensitive carotid sinus syndrome is defined asyncope or presyncope resulting from an extreme reflexesponse to carotid sinus stimulation. There are 2 compo-ents of the reflex:

Cardioinhibitory, which results from increased parasym-pathetic tone and is manifested by slowing of the sinusrate or prolongation of the PR interval and advancedAV block, alone or in combination.

Vasodepressor, which is secondary to a reduction insympathetic activity that results in loss of vasculartone and hypotension. This effect is independent ofheart rate changes.

Before concluding that permanent pacing is clinicallyndicated, the physician should determine the relative con-ribution of the 2 components of carotid sinus stimulation tohe individual patient’s symptom complex. Hyperactiveesponse to carotid sinus stimulation is defined as asystoleue to either sinus arrest or AV block of more than 3econds, a substantial symptomatic decrease in systoliclood pressure, or both (140). Pauses up to 3 seconds duringarotid sinus massage are considered to be within normalimits. Such heart rate and hemodynamic responses mayccur in normal subjects and patients with coronary arteryisease. The cause-and-effect relation between the hyper-ensitive carotid sinus and the patient’s symptoms must berawn with great caution (141). Spontaneous syncope re-
roduced by carotid sinus stimulation should alert the

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hysician to the presence of this syndrome. Minimal pres-ure on the carotid sinus in elderly patients may result inarked changes in heart rate and blood pressure yet may not

e of clinical significance. Permanent pacing for patientsith an excessive cardioinhibitory response to carotid stim-lation is effective in relieving symptoms (142,143). Because0% to 20% of patients with this syndrome may have anmportant vasodepressive component of their reflex re-ponse, it is desirable that this component be defined beforene concludes that all symptoms are related to asystolelone. Among patients whose reflex response includes bothardioinhibitory and vasodepressive components, attentiono the latter is essential for effective therapy in patientsndergoing pacing.Carotid sinus hypersensitivity should be considered in

lderly patients who have had otherwise unexplained falls.n 1 study, 175 elderly patients who had fallen without lossf consciousness and who had pauses of more than 3econds during carotid sinus massage (thus fulfilling theiagnosis of carotid sinus hypersensitivity) were randomizedo pacing or nonpacing therapy. The paced group had aignificantly lower likelihood of subsequent falling episodesuring follow-up (144).Neurocardiogenic syncope and neurocardiogenic syn-

romes refer to a variety of clinical scenarios in whichriggering of a neural reflex results in a usually self-limitedpisode of systemic hypotension characterized by bothradycardia and peripheral vasodilation (145,146). Neuro-ardiogenic syncope accounts for an estimated 10% to 40%f syncope episodes. Vasovagal syncope is a term used toenote one of the most common clinical scenarios withinhe category of neurocardiogenic syncopal syndromes. Pa-ients classically have a prodrome of nausea and diaphoresisoften absent in the elderly), and there may be a positiveamily history of the condition. Spells may be consideredituational (e.g., they may be triggered by pain, anxiety,tress, specific bodily functions, or crowded conditions).ypically, no evidence of structural heart disease is present.ther causes of syncope such as LV outflow obstruction,

radyarrhythmias, and tachyarrhythmias should be ex-luded. Head-up tilt-table testing may be diagnostic.

The role of permanent pacing in refractory neurocar-iogenic syncope associated with significant bradycardiar asystole remains controversial. Approximately 25% ofatients have a predominant vasodepressor reaction with-ut significant bradycardia. Many patients will have aixed vasodepressive/cardioinhibitory cause of their

ymptoms. It has been estimated that approximately onehird of patients will have substantial bradycardia orsystole during head-up tilt testing or during observednd recorded spontaneous episodes of syncope. Outcomesrom clinical trials have not been consistent. Results fromrandomized controlled trial (147) in highly symptom-

tic patients with bradycardia demonstrated that perma-ent pacing increased the time to the first syncopal event.
nother study demonstrated that DDD (a dual-chamber
acemaker that senses/paces in the atrium/ventricle ands inhibited/triggered by intrinsic rhythm) pacing with audden bradycardia response function was more effectivehan beta blockade in preventing recurrent syncope inighly symptomatic patients with vasovagal syncope andelative bradycardia during tilt-table testing (148). InPS (Vasovagal Pacemaker Study) (149), the actuarial

ate of recurrent syncope at 1 year was 18.5% foracemaker patients and 59.7% for control patients. How-ver, in VPS-II (Vasovagal Pacemaker Study II) (150), aouble-blind randomized trial, pacing therapy did noteduce the risk of recurrent syncopal events. In VPS-II,ll patients received a permanent pacemaker and wereandomized to therapy versus no therapy in contrast toPS, in which patients were randomized to pacemaker

mplantation versus no pacemaker. On the basis ofPS-II and prevailing expert opinion (145), pacing

herapy is not considered first-line therapy for mostatients with neurocardiogenic syncope. However, pacingherapy does have a role for some patients, specificallyhose with little or no prodrome before their syncopalvent, those with profound bradycardia or asystole duringdocumented event, and those in whom other therapiesave failed. Dual-chamber pacing, carefully prescribed onhe basis of tilt-table test results with consideration oflternative medical therapy, may be effective in reducingymptoms if the patient has a significant cardioinhibitoryomponent to the cause of their symptoms. Althoughpontaneous or provoked prolonged pauses are a concernn this population, the prognosis without pacing isxcellent (151).

The evaluation of patients with syncope of undeterminedrigin should take into account clinical status and shouldot overlook other, more serious causes of syncope, such asentricular tachyarrhythmias.

ecommendations for Permanent Pacing inypersensitive Carotid Sinus Syndrome andeurocardiogenic Syncope

LASS I

. Permanent pacing is indicated for recurrent syncope caused byspontaneously occurring carotid sinus stimulation and carotidsinus pressure that induces ventricular asystole of more than 3seconds. (Level of Evidence: C) (142,152)

LASS IIa

. Permanent pacing is reasonable for syncope without clear,provocative events and with a hypersensitive cardioinhibitoryresponse of 3 seconds or longer. (Level of Evidence: C) (142)

LASS IIb

. Permanent pacing may be considered for significantly symptom-atic neurocardiogenic syncope associated with bradycardia doc-umented spontaneously or at the time of tilt-table testing. (Level
of Evidence: B) (147,148,150,153)

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. Permanent pacing is not indicated for a hypersensitivecardioinhibitory response to carotid sinus stimulation withoutsymptoms or with vague symptoms. (Level of Evidence: C)

. Permanent pacing is not indicated for situational vasovagalsyncope in which avoidance behavior is effective and preferred.(Level of Evidence: C)

.2. Pacing for Specific Conditions

he following sections on cardiac transplantation, neuro-uscular diseases, sleep apnea syndromes, and infiltrative

nd inflammatory diseases are provided to recognize devel-pments in these specific areas and new information thatas been obtained since publication of prior guidelines.ome of the information has been addressed in priorections but herein is explored in more detail.

.2.1. Cardiac Transplantation

he incidence of bradyarrhythmias after cardiac transplan-ation varies from 8% to 23% (154–156). Most brady-rrhythmias are associated with SND and are more ominousfter transplantation, when the basal heart rate should beigh. Significant bradyarrhythmias and asystole have beenssociated with reported cases of sudden death (157).ttempts to treat the bradycardia temporarily with measures

uch as theophylline (158) may minimize the need foracing. To accelerate rehabilitation, some transplant pro-rams recommend more liberal use of cardiac pacing forersistent postoperative bradycardia, although approxi-ately 50% of patients show resolution of the bradyarrhyth-ia within 6 to 12 months (159–161). The role of prophy-

actic pacemaker implantation is unknown for patients whoevelop bradycardia and syncope in the setting of rejection,hich may be associated with localized inflammation of the

onduction system. Posttransplant patients who have irre-ersible SND or AV block with previously stated Class Indications should have permanent pacemaker implanta-ion, as the benefits of the atrial rate contribution to cardiacutput and to chronotropic competence may optimize theatient’s functional status. When recurrent syncope devel-ps late after transplantation, pacemaker implantation maye considered despite repeated negative evaluations, asudden episodes of bradycardia are often eventually docu-ented and may be a sign of transplant vasculopathy.

ecommendations for Pacing After Cardiacransplantation

LASS I

. Permanent pacing is indicated for persistent inappropriate orsymptomatic bradycardia not expected to resolve and for otherClass I indications for permanent pacing. (Level of Evidence: C)

LASS IIb

. Permanent pacing may be considered when relative bradycardiais prolonged or recurrent, which limits rehabilitation or dischargeafter postoperative recovery from cardiac transplantation. (Level
of Evidence: C) c
. Permanent pacing may be considered for syncope after cardiactransplantation even when bradyarrhythmia has not been docu-mented. (Level of Evidence: C)

.2.2. Neuromuscular Diseases

onduction system disease with progression to completeV block is a well-recognized complication of severaleuromuscular disorders, including myotonic dystrophy andmery-Dreifuss muscular dystrophy. Supraventricular and

entricular arrhythmias may also be observed. Implantationf a permanent pacemaker has been found useful even insymptomatic patients with an abnormal resting ECG orith HV interval prolongation during electrophysiological

tudy (162). Indications for pacing have been addressed inrevious sections on AV block.

.2.3. Sleep Apnea Syndrome

variety of heart rhythm disturbances may occur inbstructive sleep apnea. Most commonly, these includeinus bradycardia or pauses during hypopneic episodes.trial tachyarrhythmias may also be observed, particularlyuring the arousal phase that follows the offset of apnea. Amall retrospective trial of atrial overdrive pacing in thereatment of sleep apnea demonstrated a decrease “inpisodes of central or obstructive sleep apnea withouteducing the total sleep time” (163). Subsequent random-zed clinical trials have not validated a role for atrialverdrive pacing in obstructive sleep apnea (164,165). Fur-hermore, nasal continuous positive airway pressure therapyas been shown to be highly effective for obstructive sleeppnea, whereas atrial overdrive pacing has not (166,167).

hether cardiac pacing is indicated among patients withbstructive sleep apnea and persistent episodes of bradycar-ia despite nasal continuous positive airway pressure has noteen established.Central sleep apnea and Cheyne-Stokes sleep-disordered

reathing frequently accompany systolic heart failure andre associated with increased mortality (168). CRT has beenhown to reduce central sleep apnea and increase sleepuality in heart failure patients with ventricular conductionelay (169). This improvement in sleep-disordered breath-ng may be due to the beneficial effects of CRT on LVunction and central hemodynamics, which favorably mod-fies the neuroendocrine reflex cascade in central sleep apnea.

.2.4. Cardiac Sarcoidosis

ardiac sarcoidosis usually affects individuals aged 20 to 40ears and is associated with noncaseating granulomas withn affinity for involvement of the AV conduction system,hich results in various degrees of AV conduction block.yocardial involvement occurs in 25% of patients with

arcoidosis, as many as 30% of whom develop completeeart block. Owing to the possibility of disease progression,acemaker implantation is recommended even if high-grade or
omplete AV conduction block reverses transiently (170–172).

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Cardiac sarcoidosis can also be a cause of life-threateningentricular arrhythmias with sustained monomorphic VTue to myocardial involvement (173–175). Sudden cardiacrrest may be the initial manifestation of the condition, andatients may have few if any manifestations of dysfunctionn organ systems other than the heart (173,174). Althoughhere are no large randomized trials or prospective registriesf patients with cardiac sarcoidosis, the available literaturendicates that cardiac sarcoidosis with heart block, ventric-lar arrhythmias, or LV dysfunction is associated with aoor prognosis. Therapy with steroids or other immuno-uppressant agents may prevent progression of the cardiacnvolvement. Bradyarrhythmias warrant pacemaker therapy,ut they are not effective in preventing or treating life-hreatening ventricular arrhythmias. Sufficient clinical datare not available to stratify risk of SCD among patients withardiac sarcoidosis. Accordingly, clinicians must use thevailable literature along with their own clinical experiencend judgment in making management decisions regardingCD therapy. Consideration should be given to symptomsuch as syncope, heart failure status, LV function, andpontaneous or induced ventricular arrhythmias at electro-hysiological study to make individualized decisions regard-ng use of the ICD for primary prevention of SCD.

.3. Prevention and Termination of Arrhythmiasy Pacing

nder certain circumstances, an implanted pacemaker maye useful to treat or prevent recurrent ventricular and SVTs176–185). Re-entrant rhythms including atrial flutter,aroxysmal re-entrant SVT, and VT may be terminated byvariety of pacing techniques, including programmed stim-lation and short bursts of rapid pacing (186,187). Al-hough rarely used in contemporary practice after tachycar-ia detection, these antitachyarrhythmia devices mayutomatically activate a pacing sequence or respond to anxternal instruction (e.g., application of a magnet).

Prevention of arrhythmias by pacing has been demon-trated in certain situations. In some patients with long-QTyndrome, recurrent pause-dependent VT may be preventedy continuous pacing (188). A combination of pacing andeta blockade has been reported to shorten the QT intervalnd help prevent SCD (189,190). ICD therapy in combi-ation with overdrive suppression pacing should be consid-red in high-risk patients.

Although this technique is rarely used today given thevailability of catheter ablation and antiarrhythmic drugs,trial synchronous ventricular pacing may prevent recur-ences of reentrant SVT (191). Furthermore, althoughentricular ectopic activity may be suppressed by pacing inther conditions, serious or symptomatic arrhythmias arearely prevented (192).

Potential recipients of antitachyarrhythmia devices thatnterrupt arrhythmias should undergo extensive testing be-ore implantation to ensure that the devices safely and
eliably terminate the tachyarrhythmias without accelerating i
he tachycardia or causing proarrhythmia. Patients forhom an antitachycardia pacemaker has been prescribedave usually been unresponsive to antiarrhythmic drugs orere receiving agents that could not control their cardiac

rrhythmias. When permanent antitachycardia pacemakersetect and interrupt SVT, all pacing should be done in thetrium because of the risk of ventricular pacing–inducedroarrhythmia (176,193). Permanent antitachycardia pacingATP) as monotherapy for VT is not appropriate given thatTP algorithms are available in tiered-therapy ICDs thatave the capability for cardioversion and defibrillation inases when ATP is ineffective or causes acceleration of thereated tachycardia.

ecommendations for Permanent Pacemakers Thatutomatically Detect and Pace to Terminateachycardias

LASS IIa

. Permanent pacing is reasonable for symptomatic recurrent SVTthat is reproducibly terminated by pacing when catheter ablationand/or drugs fail to control the arrhythmia or produce intolerableside effects. (Level of Evidence: C) (177–179,181,182)

LASS III

. Permanent pacing is not indicated in the presence of an acces-sory pathway that has the capacity for rapid anterograde con-duction. (Level of Evidence: C)

.3.1. Pacing to Prevent Atrial Arrhythmias

any patients with indications for pacemaker or ICDherapy have atrial tachyarrhythmias that are recognizedefore or after device implantation (194). Re-entrant atrialachyarrhythmias are susceptible to termination with ATP.dditionally, some atrial tachyarrhythmias that are due to

ocal automaticity may respond to overdrive suppression.ccordingly, some dual-chamber pacemakers and ICDs

ncorporate suites of atrial therapies that are automaticallypplied upon detection of atrial tachyarrhythmias.

The efficacy of atrial ATP is difficult to measure, primar-ly because atrial tachyarrhythmias tend to initiate anderminate spontaneously with a very high frequency. Withevice-classified efficacy criteria, approximately 30% to 60%f atrial tachyarrhythmias may be terminated with atrialTP in patients who receive pacemakers for symptomaticradycardia (195–197). Although this has been associatedith a reduction in atrial tachyarrhythmia burden over time

n selected patients (195,196), the success of this approachas not been duplicated reliably in randomized clinical trials197). Similar efficacy has been demonstrated in ICDatients (194,198,199) without compromising detection ofT, ventricular fibrillation (VF), or ventricular proarrhyth-ia (200). In either situation, automatic atrial therapies

hould not be activated until the atrial lead is chronicallytable, because dislodgement into the ventricle could result
n the induction of VT/VF.

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.3.2. Long-QT Syndrome

he use of cardiac pacing with beta blockade for preventionf symptoms in patients with the congenital long-QTyndrome is supported by observational studies (189,201,202).he primary benefit of pacemaker therapy may be inatients with pause-dependent initiation of ventricularachyarrhythmias (203) or those with sinus bradycardia ordvanced AV block in association with the congenitalong-QT syndrome (204,205), which is most commonlyssociated with a sodium channelopathy. Benson et al. (206)iscuss sinus bradycardia due to a (sodium) channelopathy.lthough pacemaker implantation may reduce the inci-ence of symptoms in these patients, the long-term survivalenefit remains to be determined (189,201,204).

ecommendations for Pacing to Prevent Tachycardia

LASS I

. Permanent pacing is indicated for sustained pause-dependentVT, with or without QT prolongation. (Level of Evidence: C)(188,189)

LASS IIa

. Permanent pacing is reasonable for high-risk patients with con-genital long-QT syndrome. (Level of Evidence: C) (188,189)

LASS IIb

. Permanent pacing may be considered for prevention of symptom-atic, drug-refractory, recurrent AF in patients with coexistingSND. (Level of Evidence: B) (31,184,207)

LASS III

. Permanent pacing is not indicated for frequent or complexventricular ectopic activity without sustained VT in the absenceof the long-QT syndrome. (Level of Evidence: C) (192)

. Permanent pacing is not indicated for torsade de pointes VT dueto reversible causes. (Level of Evidence: A) (190,203)

.3.3. Atrial Fibrillation (Dual-Site, Dual-Chamber,lternative Pacing Sites)

n some patients with bradycardia-dependent AF, atrialacing may be effective in reducing the frequency ofecurrences (208). In MOST, 2010 patients with SND wereandomized between DDDR and VVIR pacing. After aean follow-up of 33 months, there was a 21% lower risk ofF (p�0.008) in the DDDR group than in the VVIR

roup (209). Other trials are under way to assess the efficacyf atrial overdrive pacing algorithms and algorithms thateact to premature atrial complexes in preventing AF, butata to date are sparse and inconsistent (197,210). Dual-siteight atrial pacing or alternate single-site atrial pacing fromnconventional sites (e.g., atrial septum or Bachmann’sundle) may offer additional benefits to single-site righttrial pacing from the appendage in patients with symptom-tic drug-refractory AF and concomitant bradyarrhythmias;owever, results from these studies are also contradictorynd inconclusive (211,212). Additionally, analysis of the
fficacy of pacing prevention algorithms and alternative l
acing sites is limited by short-term follow-up (213). Inatients with sick sinus syndrome and intra-atrial block (Pave more than 180 milliseconds), biatrial pacing may lower

ecurrence rates of AF (214).

ecommendation for Pacing to Prevent Atrialibrillation

LASS III

. Permanent pacing is not indicated for the prevention of AF inpatients without any other indication for pacemaker implanta-tion. (Level of Evidence: B) (215)

.4. Pacing for Hemodynamic Indications

lthough most commonly used to treat or prevent abnormalhythms, pacing can alter the activation sequence in theaced chambers, influencing regional contractility and cen-ral hemodynamics. These changes are frequently insignif-cant clinically but can be beneficial or harmful in someonditions. Pacing to decrease symptoms for patients withbstructive hypertrophic cardiomyopathy (HCM) is dis-ussed separately in Section 2.4.2, “Obstructive Hypertro-hic Cardiomyopathy.”

.4.1. Cardiac Resynchronization Therapy

rogression of LV dysfunction to heart failure with lowVEF is frequently accompanied by impaired electro-echanical coupling, which may further diminish effective

entricular systolic function. The most common disruptionsre prolonged AV conduction (first-degree AV block) androlonged ventricular conduction, most commonly leftundle-branch block. Prolonged ventricular conductionauses regional mechanical delay within the LV that canesult in reduced ventricular systolic function with increasedetabolic costs, functional mitral regurgitation, and adverse

emodeling with increased ventricular dilatation. Prolonga-ion of the QRS interval occurs in approximately one thirdf patients with advanced heart failure (216) and has beenssociated with ventricular electromechanical delay (“dys-ynchrony”) as identified by multiple sophisticated echocar-iographic indices. QRS duration and dyssynchrony haveoth been identified as predictors of worsening heart failure,CD, and total mortality (217).Modification of ventricular electromechanical delay withultisite ventricular pacing (“biventricular pacing andRT”) can improve ventricular systolic function with re-uced metabolic costs, ameliorate functional mitral regur-itation, and, in some patients, induce favorable remodelingith reduction of cardiac chamber dimensions (218,219).unctional improvement has been demonstrated for exerciseapacity with peak oxygen consumption in the range of 1 tomilliliters per kilogram per minute and a 50- to 70-meter

ncrease in 6-minute walk distance, with a 10-point orreater reduction of heart failure symptoms on the 105-oint Minnesota scale (220–222).Meta-analyses of initial clinical experiences and then

arger subsequent trials confirmed an approximately 30%

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ecrease in hospitalizations and, more recently, a mortalityenefit of 24% to 36% (223). Resynchronization therapy inhe COMPANION (Comparison of Medical Therapy,acing, and Defibrillation in Heart Failure) trial directlyompared pacing with (CRT-D) and without (CRT-P)efibrillation capability with optimal medical therapy (224).RT-D reduced mortality by 36% compared with medical

herapy, but there was insufficient evidence to conclude thatRT-P was inferior to CRT-D. The CARE-HF (Cardiacesynchronization in Heart Failure) trial limited subjects toQRS greater than 150 milliseconds (89% of patients) orRS 120 to 150 milliseconds with echocardiographic evi-

ence of dyssynchrony (11% of patients). It was the firsttudy to show a significant (36%) reduction in death foresynchronization therapy unaccompanied by backup defi-rillation compared with optimal medical therapy (225).In 1 clinical trial, approximately two thirds of patients

ho were randomized to CRT showed a clinical responseompared with approximately one third of patients in theontrol arm (222). It remains difficult to predict and explainhe disparity of clinical response. The prevalence of dyssyn-hrony has been documented in more than 40% of patientsith dilated cardiomyopathy (DCM) and QRS greater than20 milliseconds and is higher among patients with QRSreater than 150 milliseconds. The aggregate clinical expe-ience has consistently demonstrated that a significantlinical response to CRT is greatest among patients withRS duration greater than 150 milliseconds, but intraven-

ricular mechanical delay, as identified by several echocar-iographic techniques, may exist even when the QRSuration is less than 120 milliseconds. No large trial has yetemonstrated clinical benefit among patients without QRSrolongation, even when they have been selected for echo-ardiographic measures of dyssynchrony (226). The ob-erved heterogeneity of response also may result from factorsuch as suboptimal lead placement and inexcitable areas ofbrosis in the paced segments. These factors may contributeo the finding of worsening clinical function in someatients after addition of LV stimulation.Clinical trials of resynchronization almost exclusively

ncluded patients in sinus rhythm with a left bundle-branchattern of prolonged ventricular conduction. Limited pro-pective experience among patients with permanent AFuggests that benefit may result from biventricular pacinghen the QRS is prolonged, although it may be most

vident in those patients in whom AV nodal ablation haseen performed, such that right ventricular (RV) pacing isbligate (227,228).There is not sufficient evidence yet to provide specific

ecommendations for patients with right bundle-branchlock, other conduction abnormalities, or QRS prolonga-ion due to frequent RVA pacing. Furthermore, there arensufficient data to make specific recommendations regard-ng CRT in patients with congenital heart disease (229). Inddition, patients receiving prophylactic pacemaker-
efibrillators often evolve silently to dominant ventricular i
acing, due both to intrinsic chronotropic incompetence and tohe aggressive uptitration of beta-adrenergic blocking agents.

The major experience with resynchronization derivesrom patients with New York Heart Association (NYHA)lass III symptoms of heart failure and LVEF less than or

qual to 35%. Heart failure symptom status should bessessed after medical therapy has been optimized for ateast 3 months, including titration of diuretic therapy to

aintain normal volume status. Patients with Class IVymptoms of heart failure have accounted for only 10% of allatients in clinical trials of resynchronization therapy. Theseatients were highly selected, ambulatory outpatients whoere taking oral medications and had no history of recentospitalization (230). Although a benefit has occasionallyeen described in patients with more severe acute decom-ensation that required brief intravenous inotropic therapyo aid diuresis, resynchronization is not generally used as arescue therapy” for such patients. Patients with dependencen intravenous inotropic therapy, refractory fluid retention,r progressive renal dysfunction represent the highest-riskopulation for complications of any procedure and for earlyortality after discharge, and they are also unlikely to

eceive a meaningful mortality benefit from concomitantefibrillator therapy.Those patients with NYHA Class IV symptoms of heart

ailure who derive functional benefit from resynchronizationherapy may return to Class III status, in which preventionf sudden death becomes a relevant goal. Even among theelected Class IV patients identified within the COMPAN-ON trial (224), there was no difference in 2-year survivaletween the CRT patients with and without backup defi-rillation, although more of the deaths in the CRT-P groupere classified as sudden deaths (230).Indications for resynchronization therapy have not been

stablished for patients who have marked dyssynchrony andlass I to II symptoms of heart failure in whom devicelacement is indicated for other reasons. Ongoing studiesre examining the hypothesis that early use of CRT, beforehe development of Class III symptoms that limit dailyctivity, may prevent or reverse remodeling caused byrolonged ventricular conduction. However, it is not knownhen or whether CRT should be considered at the time of

nitial ICD implantation for patients without intrinsic QRSrolongation even if frequent ventricular pacing is antici-ated. Finally, a randomized prospective trial by Beshai etl. did not confirm the utility of dyssynchrony evaluation bychocardiography to guide CRT implantation, especiallyhen the QRS is not prolonged (226).Optimal outcomes with CRT require effective placement

f ventricular leads, ongoing heart failure management witheurohormonal antagonists and diuretic therapy, and, inome cases, later reprogramming of device intervals. Theivotal trials demonstrating the efficacy of CRT took placen centers that provided this expertise both at implantationnd during long-term follow-up. The effectiveness of CRT
n improving clinical function and survival would be antic-

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ecommendations for Cardiac Resynchronizationherapy in Patients With Severe Systolic Heart Failure

LASS I

. For patients who have LVEF less than or equal to 35%, a QRSduration greater than or equal to 0.12 seconds, and sinusrhythm, CRT with or without an ICD is indicated for the treatmentof NYHA functional Class III or ambulatory Class IV heart failuresymptoms with optimal recommended medical therapy. (Level ofEvidence: A) (222,224,225,231)

LASS IIa

. For patients who have LVEF less than or equal to 35%, a QRSduration greater than or equal to 0.12 seconds, and AF, CRT withor without an ICD is reasonable for the treatment of NYHAfunctional Class III or ambulatory Class IV heart failure symp-toms on optimal recommended medical therapy. (Level of Evi-dence: B) (220,231)

. For patients with LVEF less than or equal to 35% with NYHAfunctional Class III or ambulatory Class IV symptoms who arereceiving optimal recommended medical therapy and who havefrequent dependence on ventricular pacing, CRT is reasonable.(Level of Evidence: C) (231)

LASS IIb

. For patients with LVEF less than or equal to 35% with NYHAfunctional Class I or II symptoms who are receiving optimalrecommended medical therapy and who are undergoing implan-tation of a permanent pacemaker and/or ICD with anticipatedfrequent ventricular pacing, CRT may be considered. (Level ofEvidence: C) (231)

LASS III

. CRT is not indicated for asymptomatic patients with reducedLVEF in the absence of other indications for pacing. (Level ofEvidence: B) (222,224,225,231)

. CRT is not indicated for patients whose functional status and lifeexpectancy are limited predominantly by chronic noncardiacconditions. (Level of Evidence: C) (231)

.4.2. Obstructive Hypertrophic Cardiomyopathy

arly nonrandomized studies demonstrated a fall in the LVutflow gradient with dual-chamber pacing and a short AVelay and symptomatic improvement in some patients withbstructive HCM (232–235). One long-term study (236) inpatients supported the long-term benefit of dual-chamberacing in this group of patients. The outflow gradient waseduced even after cessation of pacing, which suggests thatome ventricular remodeling had occurred as a consequencef pacing. Two randomized trials (235,237) demonstratedubjective improvement in approximately 50% of studyarticipants, but there was no correlation with gradienteduction, and a significant placebo effect was present. Ahird randomized, double-blinded trial (238) failed to dem-nstrate any overall improvement in QOL with pacing,lthough there was a suggestion that elderly patients (more
han 65 years of age) may derive more benefit from pacing. s
In a small group of patients with symptomatic, hyperten-ive cardiac hypertrophy with cavity obliteration, VDDacing with premature excitation statistically improved ex-rcise capacity, cardiac reserve, and clinical symptoms (239).ual-chamber pacing may improve symptoms and LV

utflow gradient in pediatric patients. However, rapid atrialates, rapid AV conduction, and congenital mitral valve abnor-alities may preclude effective pacing in some patients (240).There are currently no data available to support the

ontention that pacing alters the clinical course of theisease or improves survival or long-term QOL in HCM.herefore, routine implantation of dual-chamber pacemak-

rs should not be advocated in all patients with symptomaticbstructive HCM. Patients who may benefit the most arehose with significant gradients (more than 30 mm Hg atest or more than 50 mm Hg provoked) (235,241–243).omplete heart block can develop after transcoronary alco-ol ablation of septal hypertrophy in patients with HCMnd should be treated with permanent pacing (244).

For the patient with obstructive HCM who is at high riskor sudden death and who has an indication for pacemakermplantation, consideration should be given to completionf risk stratification of the patient for SCD and to implan-ation of an ICD for primary prevention of sudden death. Aingle risk marker of high risk for sudden cardiac arrest maye sufficient to justify consideration for prophylactic ICDmplantation in selected patients with HCM (245).

ecommendations for Pacing in Patients Withypertrophic Cardiomyopathy

LASS I

. Permanent pacing is indicated for SND or AV block in patientswith HCM as described previously (see Section 2.1.1, “SinusNode Dysfunction,” and Section 2.1.2, “Acquired Atrioventricu-lar Block in Adults”). (Level of Evidence: C)

LASS IIb

. Permanent pacing may be considered in medically refractorysymptomatic patients with HCM and significant resting or pro-voked LV outflow tract obstruction. (Level of Evidence: A) As forClass I indications, when risk factors for SCD are present,consider a DDD ICD (see Section 3, “Indications for ImplantableCardioverter-Defibrillator Therapy”). (233,235,237,238,246,247)

LASS III

. Permanent pacemaker implantation is not indicated for patientswho are asymptomatic or whose symptoms are medically con-trolled. (Level of Evidence: C)

. Permanent pacemaker implantation is not indicated for symp-tomatic patients without evidence of LV outflow tract obstruc-tion. (Level of Evidence: C)

.5. Pacing in Children, Adolescents, and Patientsith Congenital Heart Disease

he most common indications for permanent pacemakermplantation in children, adolescents, and patients withongenital heart disease may be classified as 1) symptomatic
inus bradycardia, 2) the bradycardia-tachycardia syn-

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romes, and 3) advanced second- or third-degree AV block,ither congenital or postsurgical. Although the generalndications for pacemaker implantation in children anddolescents (defined as less than 19 years of age) (248) areimilar to those in adults, there are several importantonsiderations in young patients. First, an increasing num-er of young patients are long-term survivors of complexurgical procedures for congenital heart defects that result inalliation rather than correction of circulatory physiology.he residua of impaired ventricular function and abnormalhysiology may result in symptoms due to sinus bradycardiar loss of AV synchrony at heart rates that do not produceymptoms in individuals with normal cardiovascular physi-logy (249,250). Hence, the indications for pacemakermplantation in these patients need to be based on theorrelation of symptoms with relative bradycardia ratherhan absolute heart rate criteria. Second, the clinical signif-cance of bradycardia is age dependent; whereas a heart ratef 45 bpm may be a normal finding in an adolescent, theame rate in a newborn or infant indicates profoundradycardia. Third, significant technical challenges mayomplicate device and transvenous lead implantation in verymall patients or those with abnormalities of venous orntracardiac anatomy. Epicardial pacemaker lead implanta-ion represents an alternative technique for these patients;owever, the risks associated with sternotomy or thoracot-my and the somewhat higher incidence of lead failure muste considered when epicardial pacing systems are required251). Fourth, because there are no randomized clinicalrials of cardiac pacing in pediatric or congenital heartisease patients, the level of evidence for most recommen-ations is consensus based (Level of Evidence: C). Diagnoseshat require pacing in both children and adults, such asong-QT syndrome or neuromuscular diseases, are discussedn specific sections on these topics in this document.

Bradycardia and associated symptoms in children areften transient (e.g., sinus arrest or paroxysmal AV block)nd difficult to document (252). Although SND (sick sinusyndrome) is recognized in pediatric patients and may bessociated with specific genetic channelopathies (206), it isot itself an indication for pacemaker implantation. In theoung patient with sinus bradycardia, the primary criterionor pacemaker implantation is the concurrent observation ofsymptom (e.g., syncope) with bradycardia (e.g., heart rate

ess than 40 bpm or asystole more than 3 seconds)53,86,253). In general, correlation of symptoms with bra-ycardia is determined by ambulatory ECG or an implant-ble loop recorder (254). Symptomatic bradycardia is anndication for pacemaker implantation provided that otherauses have been excluded. Alternative causes to be consid-red include apnea, seizures, medication effects, and neuro-ardiogenic mechanisms (255,256). In carefully selectedases, cardiac pacing has been effective in the prevention ofecurrent seizures and syncope in infants with recurrentallid breath-holding spells associated with profound bra-
ycardia or asystole (257). a
A variant of the bradycardia-tachycardia syndrome, sinusradycardia that alternates with intra-atrial re-entrantachycardia, is a significant problem after surgery for con-enital heart disease. Substantial morbidity and mortalityave been observed in patients with recurrent or chronic

ntra-atrial re-entrant tachycardia, with the loss of sinushythm an independent risk factor for the subsequentevelopment of this arrhythmia (258,259). Thus, both

ong-term atrial pacing at physiological rates and atrial ATPave been reported as potential treatments for sinus brady-ardia and the prevention or termination of recurrentpisodes of intra-atrial re-entrant tachycardia (260,261).he results of either mode of pacing for this arrhythmiaave been equivocal and remain a topic of considerableontroversy (262,263). In other patients, pharmacologicalherapy (e.g., sotalol or amiodarone) may be effective in theontrol of intra-atrial re-entrant tachycardia but also resultn symptomatic bradycardia (264). In these patients, radio-requency catheter ablation of the intra-atrial re-entrantachycardia circuit should be considered as an alternative toombined pharmacological and pacemaker therapies (265).urgical resection of atrial tissue with concomitant atrialacing has also been advocated for congenital heart diseaseatients with intra-atrial re-entrant tachycardia refractory tother therapies (266).The indications for permanent pacing in patients with

ongenital complete AV block continue to evolve on theasis of improved definition of the natural history of theisease and advances in pacemaker technology and diagnos-ic methods. Pacemaker implantation is a Class I indicationn the symptomatic individual with congenital complete AVlock or the infant with a resting heart rate less than 55pm, or less than 70 bpm when associated with structuraleart disease (267,268). In the asymptomatic child ordolescent with congenital complete AV block, severalriteria (average heart rate, pauses in the intrinsic rate,ssociated structural heart disease, QT interval, and exerciseolerance) must be considered (208,269). Several studiesave demonstrated that pacemaker implantation is associ-ted with both improved long-term survival and preventionf syncopal episodes in asymptomatic patients with congen-tal complete AV block (270,271). However, periodic eval-ation of ventricular function is required in patients withongenital AV block after pacemaker implantation, becauseentricular dysfunction may occur as a consequence ofyocardial autoimmune disease at a young age or

acemaker-associated dyssynchrony years or decades afteracemaker implantation (272,273). The actual incidence ofentricular dysfunction due to pacemaker-related chronicentricular dyssynchrony remains undefined.

A very poor prognosis has been established for congenitaleart disease patients with permanent postsurgical AVlock who do not receive permanent pacemakers (209).herefore, advanced second- or third-degree AV block thatersists for at least 7 days and that is not expected to resolve
fter cardiac surgery is considered a Class I indication for

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acemaker implantation (274). Conversely, patients inhom AV conduction returns to normal generally have a

avorable prognosis (275). Recent reports have emphasizedhat there is a small but definite risk of late-onset completeV block years or decades after surgery for congenital heartisease in patients with transient postoperative AV block276,277). Limited data suggest that residual bifascicularonduction block and progressive PR prolongation mayredict late-onset AV block (278). Because of the possibilityf intermittent complete AV block, unexplained syncope isClass IIa indication for pacing in individuals with a historyf temporary postoperative complete AV block and residualifascicular conduction block after a careful evaluation foroth cardiac and noncardiac causes.Additional details that need to be considered in pace-aker implantation in young patients include risk of para-

oxical embolism due to thrombus formation on an endo-ardial lead system in the presence of residual intracardiacefects and the lifelong need for permanent cardiac pacing279). Decisions about pacemaker implantation must alsoake into account the implantation technique (transvenousersus epicardial), with preservation of vascular access at aoung age a primary objective (280).

ecommendations for Permanent Pacing in Children,dolescents, and Patients With Congenitaleart Disease

LASS I

. Permanent pacemaker implantation is indicated for advancedsecond- or third-degree AV block associated with symptomaticbradycardia, ventricular dysfunction, or low cardiac output.(Level of Evidence: C)

. Permanent pacemaker implantation is indicated for SND withcorrelation of symptoms during age-inappropriate bradycardia.The definition of bradycardia varies with the patient’s age andexpected heart rate. (Level of Evidence: B) (53,86,253,257)

. Permanent pacemaker implantation is indicated for postopera-tive advanced second- or third-degree AV block that is notexpected to resolve or that persists at least 7 days after cardiacsurgery. (Level of Evidence: B) (74,209)

. Permanent pacemaker implantation is indicated for congenitalthird-degree AV block with a wide QRS escape rhythm, complexventricular ectopy, or ventricular dysfunction. (Level of Evidence: B)(271–273)

. Permanent pacemaker implantation is indicated for congenitalthird-degree AV block in the infant with a ventricular rate lessthan 55 bpm or with congenital heart disease and a ventricularrate less than 70 bpm. (Level of Evidence: C) (267,268)

LASS IIa

. Permanent pacemaker implantation is reasonable for patientswith congenital heart disease and sinus bradycardia for theprevention of recurrent episodes of intra-atrial reentrant tachy-cardia; SND may be intrinsic or secondary to antiarrhythmictreatment. (Level of Evidence: C) (260,261,264)

. Permanent pacemaker implantation is reasonable for congenitalthird-degree AV block beyond the first year of life with an average
heart rate less than 50 bpm, abrupt pauses in ventricular rate c
that are 2 or 3 times the basic cycle length, or associated withsymptoms due to chronotropic incompetence. (Level of Evi-dence: B) (208,270)

. Permanent pacemaker implantation is reasonable for sinus bra-dycardia with complex congenital heart disease with a restingheart rate less than 40 bpm or pauses in ventricular rate longerthan 3 seconds. (Level of Evidence: C)

. Permanent pacemaker implantation is reasonable for patients withcongenital heart disease and impaired hemodynamics due to sinusbradycardia or loss of AV synchrony. (Level of Evidence: C) (250)

. Permanent pacemaker implantation is reasonable for unex-plained syncope in the patient with prior congenital heart surgerycomplicated by transient complete heart block with residualfascicular block after a careful evaluation to exclude othercauses of syncope. (Level of Evidence: B) (273,276–278)

LASS IIb

. Permanent pacemaker implantation may be considered for tran-sient postoperative third-degree AV block that reverts to sinusrhythm with residual bifascicular block. (Level of Evidence: C) (275)

. Permanent pacemaker implantation may be considered for con-genital third-degree AV block in asymptomatic children or ado-lescents with an acceptable rate, a narrow QRS complex, andnormal ventricular function. (Level of Evidence: B) (270,271)

. Permanent pacemaker implantation may be considered forasymptomatic sinus bradycardia after biventricular repair ofcongenital heart disease with a resting heart rate less than 40bpm or pauses in ventricular rate longer than 3 seconds. (Level ofEvidence: C)

LASS III

. Permanent pacemaker implantation is not indicated for transientpostoperative AV block with return of normal AV conduction inthe otherwise asymptomatic patient. (Level of Evidence: B)(274,275)

. Permanent pacemaker implantation is not indicated for asymp-tomatic bifascicular block with or without first-degree AV blockafter surgery for congenital heart disease in the absence of priortransient complete AV block. (Level of Evidence: C)

. Permanent pacemaker implantation is not indicated for asymp-tomatic type I second-degree AV block. (Level of Evidence: C)

. Permanent pacemaker implantation is not indicated for asymp-tomatic sinus bradycardia with the longest relative risk intervalless than 3 seconds and a minimum heart rate more than 40bpm. (Level of Evidence: C)

.6. Selection of Pacemaker Device

nce the decision has been made to implant a pacemaker ingiven patient, the clinician must decide among a large

umber of available pacemaker generators and leads. Gen-rator choices include single- versus dual-chamber versusiventricular devices, unipolar versus bipolar pacing/sensingonfiguration, presence and type of sensor for rate response,dvanced features such as automatic capture verification,trial therapies, size, and battery capacity. Lead choicesnclude diameter, polarity, type of insulation material, andxation mechanism (active versus passive). Other factorshat importantly influence the choice of pacemaker system
omponents include the capabilities of the pacemaker pro-

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rammer, local availability of technical support, and remoteonitoring capabilities.Even after selecting and implanting the pacing system,

he physician has a number of options for programming theevice. In modern single-chamber pacemakers, programma-le features include pacing mode, lower rate, pulse widthnd amplitude, sensitivity, and refractory period. Dual-hamber pacemakers have the same programmable features,s well as maximum tracking rate, AV delay, mode-witching algorithms for atrial arrhythmias, and others.ate-responsive pacemakers require programmable features

o regulate the relation between sensor output and pacingate and to limit the maximum sensor-driven pacing rate.iventricular pacemakers require the LV pacing output toe programmed, and often the delay between LV and RVacing must also be programmed. With the advent of moreophisticated pacemaker generators, optimal programmingf pacemakers has become increasingly complex and device-pecific and requires specialized knowledge on the part ofhe physician.

Many of these considerations are beyond the scope of thisocument. Later discussion focuses primarily on the choiceegarding the pacemaker prescription that has the greatestmpact on procedural time and complexity, follow-up,atient outcome, and cost: the choice among single-hamber ventricular pacing, single-chamber atrial pacing,nd dual-chamber pacing.

Table 2 summarizes the appropriateness of differentacemakers for the most commonly encountered indicationsor pacing. Figure 1 is a decision tree for selecting a pacingystem for patients with AV block. Figure 2 is a decisionree for selecting a pacing system for patients with SND.

An important challenge for the physician in selecting aacemaker system for a given patient is to anticipaterogression of abnormalities of that patient’s cardiacutomaticity and conduction and then to select a system

able 2. Choice of Pacemaker Generator in Selected Indication

Pacemaker Generator Sinus Node Dysfunction

ingle-chamber atrial pacemaker No suspected abnormality of atrioventrconduction and not at increased riskfuture atrioventricular block

Maintenance of atrioventricular synchrduring pacing desired

ingle-chamber ventricularpacemaker

Maintenance of atrioventricular synchrduring pacing not necessary

Rate response available if desired

ual-chamber pacemaker Atrioventricular synchrony during pacindesired

Suspected abnormality of atrioventricuconduction or increased risk for futuatrioventricular block


ingle-lead, atrial-sensing ventricularpacemaker

Not appropriate

hat will best accommodate these developments. Thus, its reasonable to select a pacemaker with more extensiveapabilities than needed at the time of implantation buthat may prove useful in the future. Some patients withND and paroxysmal AF, for example, may develop AVlock in the future (as a result of natural progression ofisease, drug therapy, or catheter ablation) and mayltimately benefit from a dual-chamber pacemaker withode-switching capability.Similarly, when pacemaker implantation is indicated,

onsideration should be given to implantation of a moreapable device (CRT, CRT-P, or CRT-D) if it ishought likely that the patient will qualify for the latterithin a short time period. For example, a patient who

equires a pacemaker for heart block that occurs in theetting of MI who also has an extremely low LVEF maye best served by initial implantation of an ICD ratherhan a pacemaker. In such cases, the advantage ofvoiding a second upgrade procedure should be balancedgainst the uncertainty regarding the ultimate need forhe more capable device.

.6.1. Major Trials Comparing Atrial or Dual-Chamberacing With Ventricular Pacing

ver the past decade, the principal debate with respect tohoice of pacemaker systems has concerned the relativeerits of dual-chamber pacing, single-chamber ventricular

acing, and single-chamber atrial pacing. The physiologicalationale for atrial and dual-chamber pacing is preservationf AV synchrony; therefore, trials comparing these modesave often combined patients with atrial or dual-chamberacemakers in a single treatment arm. There have been 5ajor randomized trials comparing atrial or dual-chamber

acing with ventricular pacing; they are summarized inable 3. Of the 5 studies, 2 were limited to patients paced

or SND, 1 was limited to patients paced for AV block, and

Pacing

Atrioventricular BlockNeurally Mediated Syncope orCarotid Sinus Hypersensitivity

Not appropriate Not appropriate

Chronic atrial fibrillation or other atrialtachyarrhythmia or maintenance ofatrioventricular synchrony duringpacing not necessary


Chronic atrial fibrillation orother atrial tachyarrhythmia

Rate response available ifdesired

Rate response available if desiredAtrioventricular synchrony during

pacing desiredAtrial pacing desired

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included patients paced for either indication. Only theanish study (281) included a true atrial pacing arm; among

atients in the AAI/DDD arm in CTOPP (Canadian Trialf Physiologic Pacing), only 5.2% had an atrial pacemaker282). A significant limitation of all of these studies is theercentage of patients (up to 37.6%) who crossed over fromtreatment arm to another or otherwise dropped out of

heir assigned pacing mode.An important consideration in the assessment of trials

hat compare pacing modes is the percent of pacing amonghe study patients. For example, a patient who is paced onlyor very infrequent sinus pauses or infrequent AV block willrobably have a similar outcome with ventricular pacing asith dual-chamber pacing, regardless of any differential

ffects between the 2 pacing configurations. With thexception of the MOST study (31) and limited data in theK-PACE trial (United Kingdom Pacing and Cardiovas-

ular Events) (283), the trials included in Table 3 do notnclude information about the percent of atrial or ventricularacing in the study patients.

.6.2. Quality of Life and Functional Status End Points

umerous studies have shown significant improvement in

igure 1. Selection of Pacemaker Systems for Patients With Atrio

ecisions are illustrated by diamonds. Shaded boxes indicate type of pacemaker. AV

eported QOL and functional status after pacemaker im- a

lantation (22,23,285,286), but there is also a well-ocumented placebo effect after device implantation (222).his section will focus on differences between pacing modesith respect to these outcomes.In the subset of patients in the PASE (Pacemaker

election in the Elderly) study who received implants forND, dual-chamber pacing was associated with greater

mprovement than was ventricular pacing with regard to ainority of QOL and functional status measures, but thereere no such differences among patients paced for AV block

23). In the MOST patients, all of whom received implantsor SND, dual-chamber–paced patients had superior out-omes in some but not all QOL and functional statuseasures (22,286). CTOPP, which included patients who

eceived implants for both SND and AV block, failed toetect any difference between pacing modes with respect toOL or functional status in a subset of 269 patients who

nderwent this evaluation; a breakdown by pacing indica-ion was not reported (284).

Older cross-over studies of dual-chamber versus ventric-lar pacing, which allowed for intrapatient comparisonsetween the 2 modes, indicate improved functional status

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tance, Sulke et al. (288) studied 22 patients who receivedual-chamber rate-responsive pacemakers for high-gradeV block and found improved exercise time, functional

tatus, and symptoms with DDDR compared with VVIRacing, as well as vastly greater patient preference forDDR pacing.

igure 2. Selection of Pacemaker Systems for Patients With S

ecisions are illustrated by diamonds. Shaded boxes indicate type of pacemaker. AV

able 3. Randomized Trials Comparing Atrium-Based Pacing W

CharacteristicsDanish Study

(281)PASE(23)

acing indication SND SND and AVB

o. of patients randomized 225 407

ean follow-up (years) 5.5 1.5

acing modes AAI vs. VVI DDDR* vs. VVIR*

trium-based pacing superiorwith respect to:

Quality of life or functionalstatus

NA SND patients: yesAVB patients: no

Heart failure Yes No

Atrial fibrillation Yes No

Stroke orthromboembolism

Yes No

Mortality Yes No

ross-over or pacing dropout VVI to AAI/DDD: 4%AAI to DDD: 5%AAI to VVI: 10%

VVIR* to DDDR*: 26%

R*added to pacing mode designation indicates rate-responsive pacemakers implanted in all paatients.
AAI indicates atrial demand; AVB, atrioventricular block; CTOPP, Canadian Trial of Physiologic Pacing
ND, sinus node dysfunction; UK-PACE, United Kingdom Pacing and Cardiovascular Events; and VVI, ve

.6.3. Heart Failure End Points

Danish study showed an improvement in heart failuretatus among atrially-paced patients compared with ven-ricularly paced patients, as measured by NYHA functionallass and diuretic use (281). MOST showed a marginal

Node Dysfunction

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entricular Pacing

CTOPP(282,284,285)

MOST(22,31,48,49,286,287)

UK-PACE(283)

SND and AVB SND AVB

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DDD/AAI vs. VVI(R) DDDR vs. VVIR* DDD(R) vs. VVI(R)

No Yes NA

No Marginal No

Yes Yes No

No No No

No No No

VI(R) dropout: 7%DD/AAI dropout: 25%

VVIR* to DDDR*: 37.6% VVI(R) to DDD(R): 3.1%DDD(R) dropout: 8.3%

(R) added to pacing mode designation indicates rate-responsive pacemakers implanted in some

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mprovement in a similar heart failure score with dual-hamber versus ventricular pacing, as well as a weak asso-iation between dual-chamber pacing and fewer heart fail-re hospitalizations (22). None of the other studies listed inable 3 detected a difference between pacing modes with

espect to new-onset heart failure, worsening of heartailure, or heart failure hospitalization. A meta-analysis ofhe 5 studies listed in Table 3 did not show a significantifference between atrially paced- or dual-chamber–pacedatients compared with ventricularly paced patients withespect to heart failure hospitalization (289).

.6.4. Atrial Fibrillation End Points

he Danish study, MOST, and CTOPP showed signifi-antly less AF among the atrially paced or dual-chamber–aced patients than the ventricularly paced patients22,281,282). In MOST, the divergence in AF incidenceecame apparent at 6 months, whereas in CTOPP, theivergence was apparent only at 2 years. PASE, a muchmaller study, did not detect any difference in AF betweents 2 groups (23). The UK-PACE trial did not demonstratesignificant difference in AF between its 2 treatment arms;owever, a trend toward less AF with dual-chamber pacingegan to appear at the end of the scheduled 3-yearollow-up period (28). The meta-analysis of the 5 studiesisted in Table 3 showed a significant decrease in AF withtrial or dual-chamber pacing compared with ventricularacing, with a hazard ratio (HR) of 0.80 (289).

.6.5. Stroke or Thromboembolism End Points

f the 5 studies listed in Table 3, only the Danish studyetected a difference between pacing modes with respect totroke or thromboembolism (281). However, the meta-nalysis of the 5 studies in Table 3 showed a decrease oforderline statistical significance in stroke with atrial orual-chamber pacing compared with ventricular pacing,ith an HR of 0.81 (289).

.6.6. Mortality End Points

he Danish study showed significant improvement in bothverall mortality and cardiovascular mortality among thetrially paced patients compared with the ventricularlyaced patients (281). None of the other studies showed aignificant difference between pacing modes in either overallr cardiovascular mortality. The meta-analysis of the 5tudies in Table 3 did not show a significant differenceetween atrially paced or dual-chamber–paced patientsompared with ventricularly paced patients with respect toverall mortality (289).Taken together, the evidence from the 5 studies most

trongly supports the conclusion that dual-chamber or atrialacing reduces the incidence of AF compared with ventric-lar pacing in patients paced for either SND or AV block.here may also be a benefit of dual-chamber or atrial pacingith respect to stroke. The evidence also supports a modest

mprovement in QOL and functional status with dual- s

hamber pacing compared with ventricular pacing in pa-ients with SND. The preponderance of evidence fromhese trials regarding heart failure and mortality arguesgainst any advantage of atrial or dual-chamber pacing forhese 2 end points.

.6.7. Importance of Minimizing Unnecessary Ventricularacing

n the past 5 years, there has been increasing recognition ofhe deleterious clinical effects of RVA pacing, both inatients with pacemakers (48,49,215) and in those withCDs (50,51,290). Among the patients in MOST with aormal native QRS duration, the percent of ventricularacing was correlated with heart failure hospitalization andew onset of AF (48). It has been speculated that the morerequent ventricular pacing in patients randomized toDDR pacing (90%) compared with patients randomized

o VVIR pacing (58%) may have negated whatever positiveffects may have accrued from the AV synchrony afforded byual-chamber pacing in this study. A possible explanationor the striking benefits of AAI pacing found in the Danishtudy (281) described above is the obvious absence ofentricular pacing in patients with single-chamber atrialacemakers (281).In a subsequent Danish study, patients with SND were

andomized between AAIR pacing, DDDR pacing with aong AV delay (300 milliseconds), and DDDR pacing with

short AV delay (less than or equal to 150 milliseconds)45). The prevalence of ventricular pacing was 17% in theDDR–long-AV-delay patients and 90% in the DDDR–

hort-AV-delay patients. At 2.9 years of follow-up, thencidence of AF was 7.4% in the AAIR group, 17.5% in the

DDR–long-AV-delay group, and 23.3% in the DDDR–hort-AV-delay group. There were also increases in lefttrial and LV dimensions seen in both DDDR groups butot the AAIR group. This study supports the superiority oftrial over dual-chamber pacing and indicates that thereay be deleterious effects from even the modest amount of

entricular pacing that typically occurs with maximallyrogrammed AV delays in the DDD mode.Patients included in studies showing deleterious effects of

V pacing were either specified as having their RV leadositioned at the RV apex (40,43,280) or can be presumedn most cases to have had the lead positioned there based onrevailing practices of pacemaker and defibrillator implan-ation (45,46,277). Therefore, conclusions about deleteriousffects of RV pacing at this time should be limited toatients with RVA pacing. Studies are currently under wayhat compare the effects of pacing at alternative RV sitesseptum, outflow tract) with RVA pacing.

Despite the appeal of atrium-only pacing, there remainsoncern about implanting single-chamber atrial pacemakersn patients with SND because of the risk of subsequent AVlock. Also, in the subsequent Danish study comparingtrial with dual-chamber pacing, the incidence of progres-
ion to symptomatic AV block, including syncope, was 1.9%

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er year, even with rigorous screening for risk of AV blockt the time of implantation (45). Programming a dual-hamber device to the conventional DDD mode with aaximally programmable AV delay or with AV search

ysteresis does not eliminate frequent ventricular pacing insignificant fraction of patients (291,292). Accordingly,

everal pacing algorithms that avoid ventricular pacingxcept during periods of high-grade AV block have beenntroduced recently (293). These new modes dramaticallyecrease the prevalence of ventricular pacing in both pace-aker and defibrillator patients (294–296). A recent trial

howed the frequency of RV pacing was 9% with one ofhese new algorithms compared with 99% with conventionalual-chamber pacing, and this decrease in RV pacing wasssociated with a 40% relative reduction in the incidence ofersistent AF (296). Additional trials are under way tossess the clinical benefits of these new pacing modes (297).

.6.8. Role of Biventricular Pacemakers

s discussed in Section 2.4.1, “Cardiac Resynchronizationherapy,” multiple controlled trials have shown biventricu-

ar pacing to improve both functional capacity and QOLnd decrease hospitalizations and mortality for selectedatients with Class III to IV symptoms of heart failure.lthough patients with a conventional indication for pace-aker implantation were excluded from these trials, it is

easonable to assume that patients who otherwise meet theirnclusion criteria but have QRS prolongation due to ven-ricular pacing might also benefit from biventricular pacing.

Regardless of the duration of the native QRS complex,atients with LV dysfunction who have a conventionalndication for pacing and in whom ventricular pacing isxpected to predominate may benefit from biventricularacing. A prospective randomized trial published in 2006oncerning patients with LV enlargement, LVEF less thanr equal to 40%, and conventional indications for pacinghowed that biventricular pacing was associated with im-roved functional class, exercise capacity, LVEF, and serumrain natriuretic peptide levels compared with RV pacing298). It has also been demonstrated that LV dysfunction inhe setting of chronic RV pacing, and possibly as a result ofV pacing, can be improved with an upgrade to biventricu-

ar pacing (299).Among patients undergoing AV junction ablation for

hronic AF, the PAVE (Left Ventricular-Based Cardiactimulation Post AV Nodal Ablation Evaluation) trialrospectively randomized patients between RVA pacingnd biventricular pacing (300). The patients with RVAacing had deterioration in LVEF that was avoided by theatients with biventricular pacing. The group with biven-ricular pacing also had improved exercise capacity com-ared with the group with right apical pacing. The advan-ages of biventricular pacing were seen predominantlymong patients with reduced LVEF or heart failure ataseline. Other studies have shown that among AF patients
ho experience heart failure after AV junction ablation and y
V pacing, an upgrade to biventricular pacing results inmproved symptomatology and improved LV function301,302).

These findings raise the question of whether patientsith preserved LV function requiring ventricular pacingould benefit from initial implantation with a biventricularevice (or one with RV pacing at a site with more synchro-ous ventricular activation than at the RV apex, such asacing at the RV septum, the RV outflow tract (303,304),r the area of the His bundle) (305). Some patients withormal baseline LV function experience deterioration inVEF after chronic RV pacing (47,306). The concern over

he effects of long-term RV pacing is naturally greatestmong younger patients who could be exposed to ventricularacing for many decades. Studies have suggested thathronic RVA pacing in young patients, primarily those withongenital complete heart block, can lead to adverse histo-ogical changes, LV dilation, and LV dysfunction41,306,307).

There is a role for CRT-P in some patients, especiallyhose who wish to enhance their QOL without defibrilla-ion backup. Elderly patients with important comorbiditiesre such individuals. Notably, there is an important survivalenefit from CRT-P alone (224,225).

.7. Optimizing Pacemaker Technology and Cost

he cost of a pacemaker system increases with its degreef complexity and sophistication. For example, the cost of

dual-chamber pacemaker system exceeds that of aingle-chamber system with respect to the cost of theenerator and the second lead (increased by approxi-ately $2500 [287]), additional implantation time and

upplies (approximately $160 [287]), and additionalollow-up costs (approximately $550 per year [287]). Aiventricular pacemaker entails even greater costs, withhe hardware alone adding $5000 to $10 000 to theystem cost. With respect to battery life, that of aual-chamber generator is shorter than that of a single-hamber generator (287,308) and that of a biventricularevice is shorter still. There are also QOL concernsssociated with the more complex systems, includingncreased device size and increased frequency of follow-p. Against these additional costs are the potentialenefits of the more sophisticated systems with respect toOL, morbidity, and mortality. Furthermore, when a

ingle-chamber system requires upgrading to a dual-hamber system, the costs are significant; one studystimated the cost of such an upgrade to be $14 451 (287).

An analysis of MOST found that the cost-effectiveness ofual-chamber pacemaker implantation compared with ven-ricular pacemaker implantation (287) was approximately53 000 per quality-adjusted year of life gained over 4 yearsf follow-up. Extended over the expected lifetime of aypical patient, the calculated cost-effectiveness of dual-hamber pacing improved to $6800 per quality-adjusted
ear of life gained.

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It has been estimated that 16% to 24% of pacemakermplantations are for replacement of generators; of those,6% are replaced because their batteries have reached theirlective replacement time (309,310). Hardware and soft-are (i.e., programming) features of pacemaker systems thatrolong useful battery longevity may improve the cost-ffectiveness of pacing. Leads with steroid elution and/origh pacing impedance allow for less current drain. Optimalrogramming of output voltages, pulse widths, and AVelays can markedly decrease battery drain; one studyhowed that expert programming of pacemaker generatorsan have a major impact on longevity, prolonging it by anverage of 4.2 years compared with nominal settings (311).enerators that automatically determine whether a pacing

mpulse results in capture allow for pacing outputs closer tohreshold values than conventional generators. Althoughhese and other features arguably should prolong generatorife, there are other constraints on the useful life of aacemaker generator, including battery drain not directlyelated to pulse generation and the limited life expectancy ofany pacemaker recipients; rigorous studies supporting the

verall cost-effectiveness of these advanced pacing featuresre lacking.

.8. Pacemaker Follow-Up

fter implantation of a pacemaker, careful follow-up andontinuity of care are required. The writing committeeonsidered the advisability of extending the scope of theseuidelines to include recommendations for follow-up andevice replacement but deferred this decision given otherublished statements and guidelines on this topic. These areddressed below as a matter of information; however, nondorsement is implied. The HRS has published a series ofeports on antibradycardia pacemaker follow-up (312,13). The Canadian Working Group in Cardiac Pacing haslso published a consensus statement on pacemaker follow-up314). In addition, the Centers for Medicare and Medicaidervices has established guidelines for monitoring of patientsovered by Medicare who have antibradycardia pacemakers,lthough these have not been updated for some time (315).

Many of the same considerations are relevant toollow-up of pacemakers, ICDs, and CRT systems. Pro-ramming undertaken at implantation should be reviewedefore discharge and changed accordingly at subsequentollow-up visits as indicated by interrogation, testing, andatient needs. With careful attention to programmingacing amplitude, pulse width, and diagnostic functions,attery life can be enhanced significantly without compro-ising patient safety. Taking advantage of programmable

ptions also allows optimization of pacemaker function forhe individual patient.

The frequency and method of follow-up are dictated byultiple factors, including other cardiovascular or medical

roblems managed by the physician involved, the age of theacemaker, and geographic accessibility of the patient to
edical care. Some centers may prefer to use remote t
onitoring with intermittent clinic evaluations, whereasthers may prefer to do the majority or all of the patientollow-up in a clinic.

For many years, the only “remote” follow-up was trans-elephonic monitoring (TTM). Available for many years,TM provides information regarding capture of the cham-er(s) being paced and battery status. TTM may alsorovide the caregiver with information regarding appropri-te sensing. However, in recent years, the term “remoteonitoring” has evolved to indicate a technology that is

apable of providing a great deal of additional information.utomatic features, such as automatic threshold assessment,ave been incorporated increasingly into newer devices andacilitate follow-up for patients who live far from follow-uplinics (316). However, these automatic functions are notniversal and need not and cannot supplant the benefits ofirect patient contact, particularly with regard to historyaking and physical examination.

A more extensive clinic follow-up usually includes assess-ent of the clinical status of the patient, battery status,

acing threshold and pulse width, sensing function, and leadntegrity, as well as optimization of sensor-driven rateesponse and evaluation of recorded events, such as modewitching for AF detection and surveillance and ventricularachyarrhythmia events. The schedule for clinic follow-uphould be at the discretion of the caregivers who areroviding pacemaker follow-up. As a guideline, the 1984ealth Care Financing Administration document suggests

he following: for single-chamber pacemakers, twice in therst 6 months after implantation and then once every 12onths; for dual-chamber pacemakers, twice in the first 6onths, then once every 6 months (315).Regulations regarding TTM have not been revised since

984 (315). Guidelines that truly encompass remote mon-toring of devices have not yet been endorsed by any of the

ajor professional societies. The Centers for Medicare andedicaid Services have not provided regulations regarding

he use of this technology but have provided limitedirection regarding reimbursement. The Centers for Medi-are and Medicaid Services have published a statement thathysicians should use the existing current procedural termi-ology codes for in-office pacemaker and ICD interrogationodes for remote monitoring of cardiac devices (317).learly stated guidelines from professional societies areecessary and should be written in such a way as to permitemote monitoring that achieves specific clinical goals.uidelines are currently in development given the rapid

dvancement in remote monitoring technology.Appropriate clinical goals of remote monitoring should

e identified and guidelines developed to give caregivers thebility to optimize the amount of clinical information thatan be derived from this technology. Appropriate clinicaloals of TTM should be divided into those pieces ofnformation obtainable during nonmagnet (i.e., free-unning) ECG assessment and assessment of the ECG
racing obtained during magnet application. The same goals

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hould be achieved whether the service is being provided bycommercial or noncommercial monitoring service.Goals of TTM nonmagnet ECG assessment are as

ollows:

Determine whether the patient displays intrinsic rhythmor is being intermittently or continuously paced at theprogrammed settings.Characterize the patient’s underlying atrial mechanism,for example, sinus versus AF, atrial tachycardia, etc.If intrinsic rhythm is displayed, determine that normal(appropriate) sensing is present for 1 or both chambersdepending on whether it is a single- or dual-chamberpacemaker and programmed pacing mode.

Goals of TTM ECG assessment during magnet applica-ion are as follows:

Verify effective capture of the appropriate chamber(s)depending on whether it is a single- or dual-chamberpacemaker and verify the programmed pacing mode.Assess magnet rate. Once magnet rate is determined, thevalue should be compared with values obtained onprevious transmissions to determine whether any changehas occurred. The person assessing the TTM should alsobe aware of the magnet rate that represents electivereplacement indicators for that pacemaker.If the pacemaker is one in which pulse width is 1 of theelective replacement indicators, the pulse width shouldalso be assessed and compared with previous values.If the pacemaker has some mechanism to allow transtele-phonic assessment of threshold (i.e., Threshold MarginTest [TMT™]) and that function is programmed “on,”the results of this test should be demonstrated andanalyzed.If a dual-chamber pacemaker is being assessed andmagnet application results in a change in AV intervalduring magnet application, that change should be dem-onstrated and verified.

.8.1. Length of Electrocardiographic Samples for Storage

t is important that the caregiver(s) providing TTM assess-ent be able to refer to a paper copy or computer-archived

opy of the transtelephonic assessment for subsequent care.he length of the ECG sample saved should be based on

he clinical information that is required (e.g., the pointsisted above). It is the experience of personnel trained inTM that a carefully selected ECG sample of 6 to 9

econds can demonstrate all of the points for each of theategories listed above (i.e., a 6- to 9-second strip ofonmagnet and 6- to 9-second strip of magnet-appliedCG tracing).

.8.2. Frequency of Transtelephonic Monitoring

he follow-up schedule for TTM varies among centers, andhere is no absolute schedule that need be mandated.
egardless of the schedule to which the center may adhere, M
TM may be necessary at unscheduled times if, for exam-le, the patient experiences symptoms that potentially re-ect an alteration in rhythm or device function.The majority of centers with TTM services follow the

chedule established by the Health Care Financing Admin-stration (now the Centers for Medicare and Medicaidervices). In the 1984 Health Care Financing Administra-ion guidelines, there are 2 broad categories for follow-upas shown in Table 4): Guideline I, which was thought topply to the majority of pacemakers in use at that time, anduideline II, which would apply to pacemaker systems forhich sufficient long-term clinical information exists to

nsure that they meet the standards of the Inter-Societyommission for Heart Disease Resources for longevity and

nd-of-life decay. The standards to which they referred are0% cumulative survival at 5 years after implantation and annd-of-life decay of less than a 50% drop in output voltagend less than a 20% deviation in magnet rate, or a drop ofbpm or less, over a period of 3 months or more. As of

000, it appears that most pacemakers would meet thepecifications in Guideline II.

Note that there is no federal or clinical mandate thathese TTM guidelines be followed. The ACC, AHA, and

RS have not officially endorsed the Health Care Financ-ng Administration guidelines. Nevertheless, they may beseful as a framework for TTM. An experienced center mayhoose to do less frequent TTM and supplement it withn-clinic evaluations as stated previously.

able 4. Device Monitoring Times Postimplantation: Healthare Financing Administration 1984 Guidelines forranstelephonic Monitoring

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uideline I

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1st month Every 2 weeks

2nd to 36th month Every 8 weeks

37th month to failure Every 4 weeks

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7th to 36th month Every 8 weeks


uideline II

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Dual chamber



31st to 48th month Every 8 weeks


odified from the U.S. Department of Health and Human Services (315). In the public domain.

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Review all programmed parametersReview stored events (e.g., counters, histograms, andelectrograms)If review of programmed parameters or stored eventssuggests a need for reprogramming or a change intherapy, arrange a focused in-clinic appointment.

. Indications for Implantable Cardioverter-efibrillator Therapy

ndications for ICDs have evolved considerably from initialmplantation exclusively in patients who had survived 1 or

ore cardiac arrests and failed pharmacological therapy318). Multiple clinical trials have established that ICD useesults in improved survival compared with antiarrhythmicgents for secondary prevention of SCD (16,319–326).arge prospective, randomized, multicenter studies havelso established that ICD therapy is effective for primaryrevention of sudden death and improves total survival inelected patient populations who have not previously had aardiac arrest or sustained VT (16–19,327–331).

We acknowledge that the “ACC/AHA/ESC 2006uidelines for Management of Patients With Ventricularrrhythmias and the Prevention of Sudden Cardiac Death”

16) used an LVEF of less than 40% as a critical point toustify ICD implantation for primary prevention of SCD.he LVEF used in clinical trials assessing the ICD for primaryrevention of SCD ranged from less than or equal to 40% inUSTT (Multicenter Unsustained Ventricular Tachycardia

rial) to less than or equal to 30% in MADIT II (Multicenterutomatic Defibrillator Implantation Trial II) (329,332). Two

rials, MADIT I (Multicenter Automatic Defibrillator Im-lantation Trial I) (327) and SCD-HeFT (Sudden Cardiaceath in Heart Failure Trial) (333), used LVEFs of less than

r equal to 35% as entry criteria. The present writing commit-ee reached the consensus that it would be best to have ICDsffered to patients with clinical profiles as similar to thosencluded in the trials as possible. Having given careful consid-ration to the issues related to LVEF for these updated ICDuidelines, we have written these indications for ICDs basedn the specific inclusion criteria for LVEF in the trials. Becausef this, there may be some variation from previously publisheduidelines (16).

We also acknowledge that the determination of LVEFacks a “gold standard” and that there may be variationmong the commonly used clinical techniques of LVEFetermination. All clinical methods of LVEF determination

ack precision, and the accuracy of techniques varies amongstaboratories and institutions. Given these considerations, theresent writing committee recommends that the clinician usehe LVEF determination that they believe is the most clinicallyccurate and appropriate in their institution.

Patient selection, device and lead implantation, follow-
p, and replacement are parts of a complex process that y
equires familiarity with device capabilities, adequate caseolume, continuing education, and skill in the managementf ventricular arrhythmias, thus mandating appropriateraining and credentialing. Training program requirementsor certification programs in clinical cardiac electrophysiol-gy that include ICD implantation have been established byhe American Board of Internal Medicine and the Americansteopathic Board of Internal Medicine. Individuals with

asic certification in pediatric cardiology and cardiac surgeryay receive similar training in ICD implantation. In 2004,

equirements for an “alternate training pathway” for thoseith substantial prior experience in pacemaker implantationere proposed by the HRS with a scheduled expiration for

his alternate pathway in 2008 (11,12). Fifteen percent ofhysicians who implanted ICDs in 2006 reported in theational ICD registry that they had no formal trainingelectrophysiology fellowship, cardiac surgical training, orompletion of the alternate pathway recommendation)11,12,334).

The options for management of patients with ventricularrrhythmias include antiarrhythmic agents, catheter abla-ion, and surgery. The “ACC/AHA/ESC 2006 Guidelinesor Management of Patients With Ventricular Arrhythmiasnd the Prevention of Sudden Cardiac Death” have beenublished with a comprehensive review of managementptions, including antiarrhythmic agents, catheter ablation,urgery, and ICD therapy (16).

.1. Secondary Prevention of Suddenardiac Death

.1.1. Implantable Cardioverter-Defibrillator Therapyor Secondary Prevention of Cardiac Arrest andustained Ventricular Tachycardia

econdary prevention refers to prevention of SCD in thoseatients who have survived a prior sudden cardiac arrest orustained VT (16). Evidence from multiple randomizedontrolled trials supports the use of ICDs for secondaryrevention of sudden cardiac arrest regardless of the type ofnderlying structural heart disease. In patients resuscitatedrom cardiac arrest, the ICD is associated with clinically andtatistically significant reductions in sudden death and totalortality compared with antiarrhythmic drug therapy in

rospective randomized controlled trials (16,319–326).Trials of the ICD in patients who have been resuscitated

rom cardiac arrest demonstrate survival benefits with ICDherapy compared with electrophysiologically guided drugherapy with Class I agents, sotalol, and empirical amioda-one therapy (320,323). A large prospective, randomizedecondary prevention trial comparing ICD therapy withlass III antiarrhythmic drug therapy (predominantly em-irical amiodarone) demonstrated improved survival withCD therapy (319). Unadjusted survival estimates for theCD group and the antiarrhythmic drug group, respectively,ere 89.3% versus 82.3% at 1 year, 81.6% versus 74.7% at 2
ears, and 75.4% versus 64.1% at 3 years (p�0.02). Esti-

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ated relative risk reduction with ICD therapy was 39%95% CI 19% to 59%) at 1 year, 27% (95% CI 6% to 48%)t 2 years, and 31% (95% CI 10% to 52%) at 3 years. Twother reports of large prospective trials in similar patientroups have shown similar results (322,323).

The effectiveness of ICDs on outcomes in the recentarge, prospective secondary prevention trials—AVID (An-iarrhythmics Versus Implantable Defibrillators) (319),ASH (Cardiac Arrest Study Hamburg) (321), and CIDS

Canadian Implantable Defibrillator Study) (322)—wereonsistent with prior investigations (320). Specifically, theCD was associated with a 50% relative risk reduction forrrhythmic death and a 25% relative risk reduction forll-cause mortality (324). Thus, the secondary preventionrials have been robust and have shown a consistent effect ofmproved survival with ICD therapy compared with antiar-hythmic drug therapy across studies (324).

Some individuals are resuscitated from cardiac arrest dueo possible transient reversible causes. In such patients,yocardial revascularization may be performed when ap-

ropriate to reduce the risk of recurrent sudden death, withndividualized decisions made with regard to the need forCD therapy (16). Sustained monomorphic VT with prior

I is unlikely to be affected by revascularization (16).yocardial revascularization may be sufficient therapy in

atients surviving VF in association with myocardial isch-mia when ventricular function is normal and there is noistory of an MI (16).Unless electrolyte abnormalities are proven to be the sole

ause of cardiac arrest, survivors of cardiac arrest in whomlectrolyte abnormalities are discovered in general should bereated in a manner similar to that of cardiac arrest survivorsithout electrolyte abnormalities (16). Patients who expe-

ience sustained monomorphic VT in the presence ofntiarrhythmic drugs or electrolyte abnormalities shouldlso be evaluated and treated in a manner similar to patientsith VT or VF without electrolyte abnormalities or antiar-

hythmic drugs (16).

.1.2. Specific Disease States and Secondary Preventionf Cardiac Arrest or Sustained Ventricular Tachycardia

he majority of patients included in prior prospectiveandomized trials of patients resuscitated from cardiac arrestave had coronary artery disease with impaired ventricularunction (320,322,323,325,326). Patients with other typesf structural heart disease constitute a minority of patientsn the secondary prevention trials. However, supplementalbservational and registry data support the ICD as thereferred strategy over antiarrhythmic drug therapy forecondary prevention for patients resuscitated from cardiacrrest due to VT or fibrillation with coronary artery diseasend other underlying structural heart disease.

.1.3. Coronary Artery Disease

atients with coronary artery disease represent the majority
f patients receiving devices in prior reports of patients i
urviving cardiac arrest. Evidence strongly supports a sur-ival benefit in such patients with an ICD compared withther therapy options (319,322,323). Between 73% and3% of patients enrolled in the AVID, CASH, and CIDSrials had underlying coronary artery disease (319,321,322).he mean LVEF ranged from 32% to 45% in these trials,hich indicates prior MI in the majority of patients

319,322,323). Multiple analyses have supported the notionhat patients with reduced LV function may experiencereater benefit with ICD therapy than with drug therapy320,335–338). All patients undergoing evaluation for ICDherapy should be given optimum medical treatment forheir underlying cardiovascular condition (16).

Patients experiencing cardiac arrest due to VF that occursore than 48 hours after an MI may be at risk for recurrent

ardiac arrest (16). It is recommended that such patients bevaluated and optimally treated for ischemia (16). If there isvidence that directly and clearly implicates ischemia im-ediately preceding the onset of VF without evidence of a

rior MI, the primary therapy should be complete coronaryevascularization (16). If coronary revascularization is notossible and there is evidence of significant LV dysfunction,he primary therapy for patients resuscitated from VFhould be the ICD (16).

Patients with coronary artery disease who present withustained monomorphic VT or VF and low-level elevationsf cardiac biomarkers of myocyte injury/necrosis should bereated similarly to patients who have sustained VT and noocumented rise in biomarkers (16). Prolonged episodes ofustained monomorphic VT or VF may be associated withrise in cardiac troponin and creatine phosphokinase levelsue to myocardial metabolic demands that exceed supply inatients with coronary artery disease. Evaluation for isch-mia should be undertaken in such patients (16). However,hen sustained VT or VF is accompanied by modest

levations of cardiac enzymes, it should not be assumed thatnew MI was the cause of the sustained VT (16). Withoutther clinical data to support the occurrence of a new MI, its reasonable to consider that such patients are at risk forecurrent sustained VT or VF (16). With these consider-tions in mind, these patients should be treated for thisrrhythmia in the same manner as patients without biomar-er release accompanying VT (16).

.1.4. Nonischemic Dilated Cardiomyopathy

atients with nonischemic DCM and prior episodes ofF or sustained VT are at high risk for recurrent cardiac

rrest. Empirical antiarrhythmic therapy or drug therapyuided by electrophysiological testing has not been dem-nstrated to improve survival in these patients. The ICDas been shown to be superior to amiodarone for second-ry prevention of VT and VF in studies in which the majorityf patients had coronary artery disease (322,323,336), but theubgroups with nonischemic DCM in these studies bene-ted similarly (319,322,323) or more than the group with

schemic heart failure (324). On the basis of these data, the

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.1.5. Hypertrophic Cardiomyopathy

CM is an inherited heart muscle disease that affectspproximately 1 of every 500 persons in the general popu-ation and is the most common cause of cardiac arrest inndividuals younger than 40 years of age (339). HCMhould be suspected as the cause of cardiac arrest in youngndividuals during exertion, because exercise increases theisk of life-threatening ventricular arrhythmias with thisondition (339). Sudden death may also be the first mani-estation of the disease in a previously asymptomatic indi-idual. A history of prior cardiac arrest indicates a substan-ial risk of future VT or VF with this condition (339).rospective randomized trials of ICD versus pharmacolog-

cal therapy for patients with prior cardiac arrest and HCMave not been performed; however, registry data and obser-ational trials are available (339,340).

In those patients with HCM resuscitated from priorardiac arrest, there is a high frequency of subsequent ICDherapy for life-threatening ventricular arrhythmias (339).n the basis of these data, the ICD is the preferred therapy

or such patients with HCM resuscitated from prior cardiacrrest (339,340).

.1.6. Arrhythmogenic Right Ventricular Dysplasia/ardiomyopathy

rrhythmogenic RV dysplasia/cardiomyopathy (ARVD/C) isgenetic condition characterized by fibrofatty infiltration of

he RV and less commonly the LV. It usually manifestslinically with sustained monomorphic VT with left bundleorphology in young individuals during exercise. There are

o prospective randomized trials of pharmacological therapyersus ICD therapy in patients with ARVD/C for second-ry prevention of SCD; however, observational reports fromultiple centers consistently demonstrate a high frequency

f appropriate ICD use for life-threatening ventricularrrhythmias and a very low rate of arrhythmic death inatients with ARVD/C treated with an ICD (341–348).

.1.7. Genetic Arrhythmia Syndromes

enetic syndromes that predispose to sustained VT or VFnclude the long- and short-QT syndromes, Brugada syn-rome, idiopathic VF, and catecholaminergic polymorphicT (338,349–356). These primary electrical conditions

ypically exist in the absence of any underlying structuraleart disease and predispose to cardiac arrest. Althoughontroversy still exists with regard to risk factors for suddeneath with these conditions, there is consensus that thoseith prior cardiac arrest or syncope are at very high risk for

ecurrent arrhythmic events. On the basis of the absence ofny clear or consistent survival benefit of pharmacologicalherapy for those individuals with these genetic arrhythmia
yndromes, the ICD is the preferred therapy for those with c
rior episodes of sustained VT or VF and may also beonsidered for primary prevention for some patients with aery strong family history of early mortality (see Sections.2.4, “Hypertrophic Cardiomyopathy,” and 3.2.7, “Primarylectrical Disease”).

.1.8. Syncope With Inducible Sustained Ventricularachycardia

atients with syncope of undetermined origin in whomlinically relevant VT/VF is induced at electrophysiologicaltudy should be considered candidates for ICD therapy. Inhese patients, the induced arrhythmia is presumed to be theause of syncope (341,357–366). In patients with hemody-amically significant and symptomatic inducible sustainedT, ICD therapy can be a primary treatment option.ppropriate ICD therapy of VT and VF documented by

tored electrograms lends support to ICD therapy as arimary treatment for DCM patients with syncope341,367).

.2. Primary Prevention of Sudden Cardiac Death

rimary prevention of SCD refers to the use of ICDs inndividuals who are at risk for but have not yet had anpisode of sustained VT, VF, or resuscitated cardiac arrest.linical trials have evaluated the risks and benefits of the

CD in prevention of sudden death and have improvedurvival in multiple patient populations, including thoseith prior MI and heart failure due to either coronary arteryisease or nonischemic DCM. Prospective registry data are

ess robust but still useful for risk stratification and recom-endations for ICD implantation in selected other patient

opulations, such as those with HCM, ARVD/C, and theong-QT syndrome. In less common conditions (e.g., Bru-ada syndrome, catecholaminergic polymorphic VT, cardiacarcoidosis, and LV noncompaction), clinical reports andetrospectively analyzed series provide less rigorous evidence inupport of current recommendations for ICD use, but thisonstitutes the best available evidence for these conditions.

.2.1. Coronary Artery Disease

here now exists a substantial body of clinical trial data thatupport the use of ICDs in patients with chronic ischemiceart disease. A variety of risk factors have been used to

dentify a high-risk population for these studies. MADIT I327) and MUSTT (329) required a history of MI, spon-aneous nonsustained VT, inducible VT at electrophysio-ogical study, and a depressed LVEF (less than or equal to5% or less than or equal to 40%, respectively) to enter thetudy. MADIT I showed a major relative risk reduction of4% with the ICD. MUSTT was not specifically a trial ofCD therapy, because it compared no therapy with electro-hysiologically guided therapy, but in the group randomizedo electrophysiologically guided therapy, benefit was seennly among those who received an ICD.MADIT II (332) enrolled 1232 patients with ischemic

ardiomyopathy and an LVEF less than or equal to 30%.

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o spontaneous or induced arrhythmia was required fornrollment. All-cause mortality was 20% in the controlroup and 14.2% in the ICD group (relative risk 31%;�0.016). SCD-HeFT included patients with both isch-mic and nonischemic cardiomyopathies, an LVEF lesshan or equal to 35%, and NYHA Class II or III congestiveeart failure (333). Among the 1486 patients with ischemiceart disease randomized to either placebo or ICD therapy,he 5-year event rates were 0.432 and 0.359, respectivelyHR 0.79; p�0.05). Two recent meta-analyses of theserials have supported the overall conclusion that ICDherapy in high-risk individuals with coronary artery diseaseesults in a net risk reduction for total mortality of between0% and 30% (325,368).Two trials, however, have failed to show improved

urvival with ICD therapy in patients either at the time ofurgical revascularization or within 40 days of an acute MI.n the CABG-Patch (Coronary Artery Bypass Graft-Patch)rial (328), routine ICD insertion did not improve survivaln patients with coronary artery disease undergoing bypassurgery who were believed to be at high risk of sudden deathn the basis of an abnormal signal-averaged ECG andevere LV dysfunction (LVEF less than or equal to 35%).imilar data about the effects of percutaneous revasculariza-ion are not available. In DINAMIT (Defibrillator in Acute

yocardial Infarction Trial) (331), 674 patients with aecent MI (within 6 to 40 days), reduced LV functionLVEF less than or equal to 35%), and impaired cardiacutonomic function (depressed heart rate variability orlevated average heart rate) were randomized to either ICDherapy or no ICD therapy. Although arrhythmic death waseduced in the ICD group, there was no difference in totalortality (18.7% versus 17.0%; HR for death in the ICD

roup 1.08; p�0.66). See Table 5 for further information.

able 5. Major Implantable Cardioverter-Defibrillator Trials for P

Trial YearPatients

(n)

Inclusion Criterion:LVEF % Less Than or

Equal to

ADIT I (327) 1996 196 35

ADIT II (332) 2002 1232 30

ABG-Patch (328) 1997 900 36

EFINITE (369) 2004 485 35

INAMIT (331) 2004 674 35

CD-HeFT (333) 2005 1676 35

VID (319) 1997 1016 40

ASH† (323) 2000 191 M: 45�18 at baseline

IDS (322) 2000 659 35

Hazard ratios for death due to any cause in the implantable cardioverter-defibrillator groardioverter-defibrillator and amiodarone patients from CASH. ‡Upper bound of 97.5% confidenAVID indicates Antiarrhythmics Versus Implantable Defibrillators; CABG, coronary artery bypas

EFINITE, Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation; DINAMIT, Defibrilleft ventricular dysfunction; LVEF, left ventricular ejection fraction; MADIT I, Multicenter Automati
yocardial infarction; NA, not applicable; NICM, nonischemic cardiomyopathy; NS, not statistically sigAECG, signal-averaged electrocardiogram; and SCD-HeFT, Sudden Cardiac Death in Heart Failure Tria
.2.2. Nonischemic Dilated Cardiomyopathy

ultiple randomized prospective trials now supplement thevailable observational studies that have reported on the rolef the ICD in primary prevention of SCD in patients withonischemic DCM (16,224,333,369–379). Observationaltudies suggest that up to 30% of deaths in patients withCM are sudden (380). Mortality in medically treated

atients with DCM and a prior history of syncope mayxceed 30% at 2 years, whereas those treated with an ICDxperience a high frequency of appropriate ICD therapy16,372,373).

CAT (Cardiomyopathy Trial) enrolled patients withecently diagnosed DCM with randomization to medicalherapy versus medical therapy with an ICD (377). Thetudy was terminated before the primary end point waseached because of a lower-than-expected incidence ofll-cause mortality (377). There was no statistical probabil-ty of finding a significant survival advantage with eithertrategy. With 50 patients in the ICD arm and 54 in theontrol group, the study was underpowered to find aifference in survival with ICD therapy. At the time of-year follow-up, there were fewer deaths in the ICD grouphan in the control group (13 versus 17, respectively) (377).

Another inconclusive trial was the AMIOVIRT (Amio-arone Versus Implantable Defibrillator in Patients withonischemic Cardiomyopathy and Asymptomatic Nonsus-

ained Ventricular Tachycardia) study (378). The trialandomized 103 patients with DCM, LVEF less than orqual to 35%, and nonsustained VT to amiodarone or ICD.he study was stopped prematurely due to statistical futility

n reaching the primary end point of reduced total mortality378). The DEFINITE (Defibrillators in Nonischemicardiomyopathy Treatment Evaluation) trial randomized

ntion of Sudden Cardiac Death

Other InclusionCriteria

HazardRatio*

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NSVT and positive EP 0.46 0.26 to 0.82 0.009

Prior MI 0.69 0.51 to 0.93 0.016

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NICM, PVCs, or NSVT 0.65 0.40 to 1.06 0.08

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1.08 0.76 to 1.55 0.66

Prior MI or NICM 0.77 0.62 to 0.96 0.007

Prior cardiac arrest 0.62 0.43 to 0.82 �0.02

Prior cardiac arrest 0.77 1.112‡ 0.081§

Prior cardiac arrest,syncope

0.82 0.60 to 1.10 NS

pared with the non-implantable cardioverter-defibrillator group. †Includes only implantableval. §One-tailed.surgery; CASH, Cardiac Arrest Study Hamburg; CIDS, Canadian Implantable Defibrillator Study;Acute Myocardial Infarction Trial; EP, electrophysiological study; HRV, heart rate variability; LVD,rillator Implantation Trial I; MADIT II, Multicenter Automatic Defibrillator Implantation Trial II; MI,

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58 patients with nonischemic cardiomyopathy, NYHAlass I to III heart failure, LVEF less than or equal to 35%,

nd more than 10 premature ventricular complexes per hourr nonsustained VT to optimal medical therapy with orithout an ICD (369). With a primary end point of

ll-cause mortality, statistical significance was not reached,ut there was a strong trend toward reduction of mortalityith ICD therapy (p�0.08). After 2 years, mortality was4.1% in the standard therapy group versus 7.9% amonghose receiving an ICD, which resulted in a 6.2% absoluteeduction and a 35% relative risk reduction with ICDmplantation (369). The results were consistent and com-arable to those of other similar trials (16,333,379).SCD-HeFT compared amiodarone, ICD, and optimaledical therapy in 2521 patients with coronary artery

isease or nonischemic cardiomyopathy with NYHA func-ional Class II or III heart failure and LVEF less than orqual to 35% (333). The amiodarone treatment groupeceived the drug by way of a double-blinded, placebo-ontrolled design (333). The median follow-up was 45.5onths. The absolute mortality decrease in the medical

roup was 7.2% after 5 years in the overall population. TheCD group experienced a decreased risk of death of 23%ompared with the placebo group (HR 0.77, 97.5% CI 0.62o 0.96), and total mortality in the medical group was 7.2%er year, with a risk reduction of 23% in the ICD groupersus placebo (95% CI 0.62 to 0.96; p�0.007). Relativeisk reduction was comparable for the group with LVysfunction due to prior MI and the nonischemic group,ut absolute mortality was lower in the nonischemic group.his resulted in a greater number needed to treat per life

aved among ischemic patients. There was no mortalityifference between the amiodarone and placebo groups.urther risk stratification may decrease the number of

ndividuals needed to undergo ICD implantation to save aife in this population.

With the exception of DEFINITE (25% in the ICDrm), trials assessing ICD therapy in primary prophylaxis ofCM have not generally included asymptomatic patients inYHA functional Class I; therefore, the efficacy of ICDs in

his population is not fully known. Because mortality may beow in this subgroup, the benefit of ICD therapy is

oderate at best (369).The COMPANION trial randomized patients with

lass III or IV heart failure, ischemic or nonischemicCM, and QRS duration greater than 120 milliseconds in1:2:2 ratio to receive optimal pharmacological therapy

lone or in combination with CRT with either a pacemakerr a pacemaker-defibrillator (224). Of the 1520 patientsandomized in the trial, 903 were allocated to either theedical therapy or defibrillator arms; of this subset, 397

44%) had DCM. Cardiac resynchronization with an ICDignificantly reduced all-cause mortality compared withharmacological therapy alone in patients with DCM (HR
or all-cause death 0.50, 95% CI 0.29 to 0.88; p�0.015) (224). s
Two studies have evaluated the time dependence of riskor sudden death relative to the time of diagnosis ofonischemic DCM (369,381). An analysis of the DEFI-ITE study demonstrated that those who have a recent

ardiomyopathy diagnosis do not benefit less from use of anCD than those with a remote diagnosis (369). On the basisf these data, ICD therapy should be considered in suchatients provided that a reversible cause of transient LVunction has been excluded and their response to optimaledical therapy has been assessed. The optimal time re-

uired for this assessment is uncertain; however, anothernalysis determined that patients with nonischemic DCMxperienced equivalent occurrences of treated and poten-ially lethal arrhythmias irrespective of diagnosis duration381). These findings suggest that use of a time qualifierelative to the time since diagnosis of a nonischemic DCMay not reliably discriminate patients at high risk for SCD

n this selected population (381). Given these consider-tions, physicians should consider the timing of defibrillatormplantation carefully.

.2.3. Long-QT Syndrome

he long-QT syndromes represent a complex spectrum oflectrophysiological disorders characterized by a propensityor development of malignant ventricular arrhythmias, es-ecially polymorphic VT (382,383). Because this is arimary electrical disorder, with most patients having novidence of structural heart disease or LV dysfunction, theong-term prognosis is excellent if arrhythmia is controlled.ong-term treatment with beta blockers, permanent pacing,r left cervicothoracic sympathectomy may be helpful (384–86). ICD implantation is recommended for selected pa-ients with recurrent syncope despite drug therapy, sus-ained ventricular arrhythmias, or sudden cardiac arrest349,351,352,387,388). Furthermore, use of the ICD forrimary prevention of SCD may be considered when theres a strong family history of SCD or when compliance orntolerance to drugs is a concern (349,351,352,387,388).

The clinical manifestations of a long-QT mutation maye influenced by the specific gene involved and the func-ional consequences of the mutation in that gene. Risktratification of patients with long-QT syndrome continueso evolve, with data from genetic analysis becoming increas-ngly useful for clinical decision making (389–394).


ost individuals with HCM are asymptomatic, and therst manifestation of the condition may be SCD (245,395–00). SCD in patients with HCM is generally related toentricular arrhythmia thought to be triggered by factorsuch as ischemia, outflow obstruction, or AF (339). SCD isess frequently due to bradycardia (16,339). Among selectedigh-risk patients, the annual mortality from HCM haseen estimated to be as high as 6% in reports from tertiaryenters (245,395–398). However, community-based studies
uggest a more benign disease in the majority of individuals,

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ith an annual mortality rate in the range of 1% or less16,401–403).

Risk factors for SCD have been derived from multiplebservational studies and registries (339,404–408). A con-ensus document on HCM from the ACC and the Euro-ean Society of Cardiology categorized known risk factorsor SCD as “major” and “possible” in individual patients395). The major risk factors include prior cardiac arrest,pontaneous sustained VT, spontaneous nonsustained VT,amily history of SCD, syncope, LV thickness greater thanr equal to 30 mm, and an abnormal blood pressureesponse to exercise (395). This consensus document alsooted possible risk factors, which included AF, myocardial

schemia, LV outflow obstruction, high-risk mutations, andntense (competitive) physical exertion (395). The severityf other symptoms, such as dyspnea, chest pain, and effortntolerance, has not been correlated with increased risk ofCD (16,395). A flat or hypotensive response to upright orupine exercise testing in patients younger than 40 years oldas been shown to be a risk factor for SCD, although theositive predictive value of this finding is low (395). Aormal blood pressure response identifies a low-risk group16,395). The presence of nonsustained VT on Holteronitoring has been associated with a higher risk of SCD,

lthough the positive predictive accuracy is relatively low395). Recent analyses indicate that in a high-risk HCMohort, ICD interventions were frequent and were highlyffective in restoring normal sinus rhythm (245). However,n important proportion of ICD discharges occur in pri-ary prevention patients who undergo implantation of the

CD for a single risk factor. Therefore, a single risk markerf high risk for sudden cardiac arrest may be sufficient toustify consideration for prophylactic ICD implantation inelected patients (245).

Although no randomized studies are available, the ICDas been used in patients with cardiac arrest, sustained VT,r VF, with a high percentage of patients receiving appro-riate ICD discharge during follow-up at a rate of 11% perear (245,339). In a nonrandomized study of ICD implan-ation in HCM, ICD implantation in a subgroup of patientsor primary prophylaxis on the basis of perceived high riskor SCD (syncope, family history of SCD, nonsustainedT, inducible VT, or septal thickness greater than or equal

o 30 mm) resulted in a lower rate of appropriate dischargef 5% per year (245,339). The ICD is not indicated in theajority of asymptomatic patients with HCM, who will

ave a relatively benign course. Its role is individualized inhe patient considered to be at high risk for SCD245,339,395). Although precise risk stratification has noteen validated, patients with multiple risk factors (especiallyevere septal hypertrophy, greater than or equal to 30 mm)nd those with SCD (especially multiple SCDs) in closeelatives appear to be at sufficiently high risk to merit
onsideration of ICD therapy (16,245). a
.2.5. Arrhythmogenic Right Ventricular Dysplasia/ardiomyopathy

elected patients with ARVD/C may be at risk for SCD.ecause clinical series have reported favorable outcomesith this therapy for primary prevention of SCD inRVD/C, the ICD has assumed a larger role in therapy

16,341,342,345–348,409,410). On the basis of the avail-ble clinical data from observational studies, it is reasonableo conclude that the ICD is a reasonable therapy forecondary prevention of sudden cardiac arrest in patientsith ARVD/C (16,341,342,345–348,409,410).When the ICD is being considered for primary preven-

ion, it should be kept in mind that predictive markers ofCD in patients with ARVD/C have not yet been definedn large prospective studies focusing on survival16,341,342,345–348,409,410). Risk factors that have clin-cal utility in identifying patients with ARVD/C who are atisk for life-threatening ventricular arrhythmias includenduction of VT during electrophysiological testing, detec-ion of nonsustained VT on noninvasive monitoring, maleender, severe RV dilation, and extensive RV involvement16,341,342,345–348,409,410). Young age at presentationless than 5 years), LV involvement, prior cardiac arrest, andnexplained syncope serve as markers of risk (341,342,346–48,411,412). Patients with genotypes of ARVD/C associ-ted with a high risk for SCD should be considered for ICDherapy (345).

Although the role of ICD therapy for primary preventionf sudden death in patients with ischemic heart disease andilated, nonischemic cardiomyopathy is well established onhe basis of multiple clinical trials with a consistent findingf benefit, the data supporting ICD use in patients withRVD/C are less extensive (16,341,342,345–348,409,410).ome authorities have proposed that an ICD should be

mplanted in patients with ARVD/C and an increased riskor SCD based on the presence of a previous cardiac arrest,yncope due to VT, evidence of extensive RV disease, LVnvolvement, or presentation with polymorphic VT andVA aneurysm, which is associated with a genetic locus on

hromosome 1q42-43 (16,341,342,345–348,409,410).It is evident that there is not yet clear consensus on the

pecific risk factors that identify those patients withRVD/C in whom the probability of SCD is sufficientlyigh to warrant an ICD for primary prevention. In theuture, the results of large prospective registries with rigor-us enrollment criteria for patients with ARVD/C in whomCDs have been placed for primary prevention will givensights into the optimal risk stratification techniques forrimary prevention. In the meantime, individualized deci-ions for primary prevention of SCD must be based onxperience, judgment, and the available data. In consideringhis decision, the clinician should be mindful that inatients with ARVD/C, the ICD has proved safe andeliable in sensing and terminating sustained ventricular
rrhythmias. Sudden death is rare in the available clinical

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eries, whereas appropriate ICD shocks are common (16,41,342,345–348,409,410).

.2.6. Noncompaction of the Left Ventricle

oncompaction of the LV is a rare congenital cardiomyop-thy characterized anatomically by excessive prominentrabeculae and deep intertrabecular recesses in the LVithout other major congenital cardiac malfunction

410,413–421). The origin of the anatomic abnormalities isikely due to an arrest of normal embryogenesis of thendocardium and epicardium of the ventricle during devel-pment. This leads to suspension of the normal compactionrocess of the loose myocardial meshwork. Diagnosis isifficult and is frequently missed or delayed owing to lack ofnowledge about this uncommon disease. Echocardio-raphy is considered by many to be the diagnostic proceduref choice, but some cases are detected by computed tomog-aphy or magnetic resonance imaging. Abnormalities in theesting ECG, including bundle-branch block or ST-egment depression, are found in most patients, but thendings do not have a high degree of sensitivity or speci-city (410,413–421).Ventricular arrhythmias and sudden death are among theajor complications of this disorder. Sudden death can

ccur at any age, and there are currently no techniqueslinically useful for risk stratification for life-threateningentricular arrhythmias with noncompaction. Althoughhere is no impairment of systolic function, ventricularrrhythmias are frequent in noncompaction. Approximately0% of children with noncompaction demonstrate complexentricular arrhythmias. Available clinical data indicate thatudden death is the most common cause of mortality.lthough there are no prospective trials or registry data,

here are sufficient observational data to indicate thatlacement of an ICD as a strategy to reduce the risk ofudden death is a reasonable clinical strategy (410,413–421).

.2.7. Primary Electrical Disease (Idiopathic Ventricularibrillation, Short-QT Syndrome, Brugada Syndrome,nd Catecholaminergic Polymorphic Ventricularachycardia)

he Brugada syndrome is characterized by ST-segmentlevation across the right precordial leads in association withhigh risk of SCD (16,422–425). Although the Brugada-attern ECG most commonly shows J-point segment ele-ation in leads V1 to V3 and right bundle-branch block, theCG pattern can be intermittent (16). Less commonly, the

-point elevation occurs in the inferior leads (16). Patientsith the Brugada syndrome have a structurally normal heartith a primary channelopathy (16,426). This is transmittedith an autosomal dominant pattern of inheritance, andore than 90% of those affected are male. The genetic basis

or the Brugada syndrome involves the cardiac sodiumhannel gene (SCN5A) (16,426).

Cardiac events such as syncope or cardiac arrest occur
redominantly in the third and fourth decades of life, a
lthough presentation with cardiac arrest in neonates orhildren has been reported (16,422,424). Fever can acutelyredispose to cardiac arrest in the Brugada syndrome16,422–424).

Risk stratification for SCD in patients with the Brugadayndrome is of clinical importance, because implantation ofn ICD is the only prophylactic measure able to preventCD (16,422–424). As with long-QT syndrome, there areo data showing that family history predicts cardiac eventsmong family members with the Brugada syndrome (16).ccordingly, asymptomatic individuals with the character-

stic ECG but with no family history are not necessarily atow risk (16). Additionally, family members of an individualith SCD due to Brugada syndrome should not be assumed

o be at increased risk of SCD (16). Patients with apontaneous Brugada pattern have a worse prognosis thanndividuals in whom the typical ECG is observed only afterharmacological drug challenge (16,422–424). Patientsith syncope and the ECG pattern of spontaneous ST-

egment elevation have a 6-fold higher risk of cardiac arresthan patients without syncope and the spontaneous ECGattern (16,422,424).The role of electrophysiological testing remains contro-

ersial in the Brugada syndrome. Although some investiga-ors suggest that electrophysiological testing has a usefulole in risk stratification, others have not confirmed thisbservation. Electrophysiological testing had a low positiveredictive value (23%), but over a 3-year follow-up, it had aery high negative predictive value (93%) (16,422,424). Byontrast, Priori et al. reported that electrophysiologicalesting has a low accuracy in predicting individuals who willxperience cardiac arrest (16,410). Priori et al. have pro-osed that noninvasive risk stratification based on the ECGnd symptoms provides an accurate alternative for risktratification (16,410).

Because only a single gene has been linked to the Brugadayndrome, there is still insufficient information about theontribution of genetic defects in predicting clinical out-ome (16,410,426). Specific mutations in the SCN5A geneo not identify a subset of patients at higher risk of cardiacvents (16,410,426). SCD is caused by rapid polymorphicT or VF that frequently occurs at rest or during sleep (16).atients with Brugada syndrome usually do not have ven-

ricular extrasystoles or nonsustained runs of VT at Holterecording. Therefore, the therapeutic approach for theseatients is centered on the prevention of cardiac arrest.Catecholaminergic polymorphic VT is characterized by

entricular tachyarrhythmias that develop in relation to phys-cal or emotional stress in the presence of a resting ECG thathows no diagnostic abnormalities at rest (16,428–431). Thenitial symptoms often manifest during childhood, althoughate-onset cases have been described (16,385,410,427–431).atecholaminergic polymorphic VT is transmitted by either

n autosomal dominant or recessive inheritance pattern.pproximately one-half of the autosomal dominant cases

re caused by mutations in the gene encoding the cardiac

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Risk stratification for SCD in catecholaminergic poly-orphic VT is not possible given the relatively small

umber of patients reported. Most clinical reports indicatehat beta blockers appear to be an effective treatment.atients who have had an episode of VF are considered atigher risk and are usually treated with an ICD in additiono beta-blocker therapy (16,385,410,431). The recurrence ofustained VT, hemodynamically untolerated VT, or syncopeor which causes other than VT are excluded while theatient is receiving a beta blocker are similarly consideredarkers of higher risk (16). In such patients, an ICD is a

ommonly used and reasonable approach (16). Further-ore, electrophysiological testing is not useful in the man-

gement of patients with catecholaminergic polymorphicT since the arrhythmia is usually not inducible withrogrammed ventricular stimulation (16,385,410,431).oth supraventricular and ventricular arrhythmias are usu-lly reproducibly induced by exercise stress test (16,385,10,431). Isolated premature ventricular complexes gener-lly precede runs of nonsustained VT (16). With continuedxercise, the runs of VT typically increase in duration, andT may become sustained (16). A beat-to-beat alternatingRS axis that changes by 180° (“bidirectional VT”) is a

ypical pattern of catecholaminergic polymorphic VT-elated arrhythmias (16). Catecholaminergic polymorphicT patients can also present with irregular polymorphic VTr VF (16). Beta blockers are generally effective in prevent-ng recurrences of syncope even when arrhythmias can stille elicited during an exercise stress test (16). If syncopeccurs in a patient taking a beta blocker, implantation of anCD is recommended (16).

VF has been reported in patients with abnormal repolar-zation due to ion channel mutations that result in a

arkedly shortened QT interval (432). Only a few smalleries of such patients have been described, and at present,vidence-based recommendations about management ofsymptomatic individuals with a short QT interval cannote made. Some patients who survive a clinical episode of VFave no identifiable structural heart disease, no documentedransient cause for arrhythmia, and no known ion channelefect. In such patients, VF is termed “idiopathic.” ICDherapy is appropriate for secondary prevention in patientsith the short-QT syndrome and idiopathic VF.

.2.8. Idiopathic Ventricular Tachycardias

onomorphic VT may be seen in individuals with struc-urally normal hearts who have no known ion channelopa-hies. The most common sites of origin are the RV outflow
ract, the fascicular region of the LV, structures in the LV w
utflow tract, and the mitral annular region. The risk forudden death related to these arrhythmias is low (433).

.2.9. Advanced Heart Failure and Cardiac Transplantation

atients with moderate to severe heart failure face the twinisks of terminal heart failure decompensation and deathue to unanticipated ventricular tachyarrhythmias. WhenCD or CRT-D implantation is discussed with theseatients, the likelihood of both life-saving and inappropriatehocks should be placed in the context of the overallnticipated mortality with heart failure, the expected dura-ion of life prolongation after effective therapies, and theikely evolution to limiting symptoms and ultimately deathue to pump failure (434). The relative contribution ofreventable sudden death to mortality decreases with re-eated hospitalizations and multiple comorbidities, partic-larly in the setting of kidney dysfunction or advanced age.hese factors, whether cardiac or noncardiac, also influence

he value that patients place on quality versus length of lifeemaining. However, individual preferences cannot be as-umed and should be explored with each patient.

Candidates for transplantation constitute a special case ofevere heart failure because of the likelihood of prolongedurvival after transplantation, with 50% of patients currentlyurviving at 10 years after transplantation. The high rate ofudden death on the transplant waiting list merits ICDmplantation in most candidates with heart failure who arewaiting transplantation out of the hospital. The ICD haseen highly effective as a bridge to transplantation for thesendividuals both with and without a prior history of life-hreatening arrhythmias.

Class IV status itself is a heterogenous and dynamic state435) in which the absolute incidence of sudden deathncreases but the proportion of sudden deaths prevented byCDs declines, and heart failure deaths account for a greaterroportion of overall mortality. Once patients have persis-ent or frequently recurrent Class IV symptoms despiteptimal management, life expectancy is less than 12onths, and ICD implantation is not indicated, regardless

f patient and family preferences. Occasionally, patientsannot be weaned from intravenous inotropic infusions andre discharged with chronic inotropic infusion therapy forymptom palliation, with the expectation that death due toeart failure will likely occur within the next 6 months.espite the proarrhythmic potential of inotropic agents,

hese patients receiving chronic infusions should not beiven an ICD (unless awaiting transplantation or otherefinitive therapy).Often, patients hospitalized with Class IV symptoms will

ndergo substantial improvement and can be discharged onral therapy with minimal or no symptoms at rest. For theseatients who can remain stable at 1 month after discharge,ithout evidence of recurrent congestion or worsening renal

unction, survival is similar to that of other Class III patients
ho have not been recently hospitalized. In this situation,

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Patients with Class IV symptoms of heart failure withrolonged QRS duration and optimal lead placement mayeturn to Class III status or better for both function andurvival, at which point prevention of sudden death againecomes a relevant goal. Information on this group isimited because only 10% of the almost 4000 patients inesynchronization trials have had Class IV symptoms. In theOMPANION trial (224), there were Class IV patients forhom resynchronization improved QOL and reduced re-ospitalization and mortality; however, these patients hadeen stable at home before study entry and may notepresent typical Class IV patients. Even in this selectedroup, there was no difference in 2-year survival betweenRT patients with and without the defibrillator feature

230). In patients with Class IV symptoms in whomesynchronization is inadequate to restore clinical stability,he presence of a defibrillator often complicates the impend-ng transition to end-of-life care.

ecommendations for Implantable Cardioverterefibrillators

econdary prevention refers to the prevention of SCD inhose patients who have survived a prior cardiac arrest orustained VT. Primary prevention refers to the preventionf SCD in individuals without a history of cardiac arrest orustained VT. Patients with cardiac conditions associatedith a high risk of sudden death who have unexplained

yncope that is likely to be due to ventricular arrhythmias areonsidered to have a secondary indication.

Recommendations for consideration of ICD therapy,articularly those for primary prevention, apply only toatients who are receiving optimal medical therapy and havereasonable expectation of survival with a good functional

tatus for more than 1 year. It is difficult to estimate survivalith heart failure in the general population, for whom

omorbidities and age differ from those in trial populationsrom which the predictive models have been derived. Pa-ients with repeated heart failure hospitalizations, particu-arly in the presence of reduced renal function, are at highisk for early death due to heart failure (436–438). Seebove for discussion regarding the use of LVEFs based onrial inclusion criteria.

We acknowledge that the “ACC/AHA/ESC 2006uidelines for Management of Patients With Ventricularrrhythmias and the Prevention of Sudden Cardiac Death”

16) used the LVEF of less than 40% as a critical point toustify ICD implantation for primary prevention of SCD.he LVEF used in clinical trials assessing the ICD forrimary prevention of SCD ranged from less than or equalo 40% in MUSTT to less than or equal to 30% in MADITI (329,332). Two trials, MADIT I (18) and SCD-HeFT19) used LVEFs of less than or equal to 35% as entryriteria for the trial. This writing committee reached con-
ensus that it would be best to have ICDs offered to patients
†f

ith clinical profiles as similar to those included in the trialss possible. Having given careful consideration to the issueselated to LVEF for these updated ICD guidelines, we haveritten these indications for ICDs on the basis of the

pecific inclusion criteria for LVEF in the trials. Because ofhis, there may be some variation from previously publisheduidelines (16).

We also acknowledge that the determination of LVEFacks a “gold standard” and that there may be variationmong the commonly used clinical techniques of LVEFetermination. All clinical methods of LVEF determination

ack precision and the accuracy of techniques varies amongstaboratories and institutions. Based on these considerations,his writing committee recommends that the clinician usehe LVEF determination that they feel is the most clinicallyccurate and appropriate in their institution.

LASS I

. ICD therapy is indicated in patients who are survivors of cardiacarrest due to VF or hemodynamically unstable sustained VT afterevaluation to define the cause of the event and to exclude anycompletely reversible causes. (Level of Evidence: A) (16,319–324)

. ICD therapy is indicated in patients with structural heart diseaseand spontaneous sustained VT, whether hemodynamically stableor unstable. (Level of Evidence: B) (16,319–324)

. ICD therapy is indicated in patients with syncope of undeter-mined origin with clinically relevant, hemodynamically signifi-cant sustained VT or VF induced at electrophysiological study.(Level of Evidence: B) (16,322)

. ICD therapy is indicated in patients with LVEF less than or equal to35% due to prior MI who are at least 40 days post-MI and are inNYHA functional Class II or III. (Level of Evidence: A) (16,333)

. ICD therapy is indicated in patients with nonischemic DCM whohave an LVEF less than or equal to 35% and who are in NYHAfunctional Class II or III. (Level of Evidence: B) (16,333,369,379)

. ICD therapy is indicated in patients with LV dysfunction due toprior MI who are at least 40 days post-MI, have an LVEF less thanor equal to 30%, and are in NYHA functional Class I. (Level ofEvidence: A) (16,332)

. ICD therapy is indicated in patients with nonsustained VT due toprior MI, LVEF less than or equal to 40%, and inducible VF orsustained VT at electrophysiological study. (Level of Evidence:B) (16,327,329)

LASS IIa

. ICD implantation is reasonable for patients with unexplainedsyncope, significant LV dysfunction, and nonischemic DCM.(Level of Evidence: C)

. ICD implantation is reasonable for patients with sustained VTand normal or near-normal ventricular function. (Level of Evi-dence: C)

. ICD implantation is reasonable for patients with HCM who have1 or more major† risk factors for SCD. (Level of Evidence: C)

. ICD implantation is reasonable for the prevention of SCD inpatients with ARVD/C who have 1 or more risk factors for SCD.(Level of Evidence: C)

See Section 3.2.4, “Hypertrophic Cardiomyopathy,” for definition of major riskactors.

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. ICD implantation is reasonable to reduce SCD in patients withlong-QT syndrome who are experiencing syncope and/or VT whilereceiving beta blockers. (Level of Evidence: B) (349–354)

. ICD implantation is reasonable for non hospitalized patientsawaiting transplantation. (Level of Evidence: C)

. ICD implantation is reasonable for patients with Brugada syn-drome who have had syncope. (Level of Evidence: C)

. ICD implantation is reasonable for patients with Brugada syn-drome who have documented VT that has not resulted in cardiacarrest. (Level of Evidence: C)

. ICD implantation is reasonable for patients with catecholamin-ergic polymorphic VT who have syncope and/or documentedsustained VT while receiving beta blockers. (Level of Evidence: C)

0. ICD implantation is reasonable for patients with cardiac sar-coidosis, giant cell myocarditis, or Chagas disease. (Level ofEvidence: C)

LASS IIb

. ICD therapy may be considered in patients with nonischemicheart disease who have an LVEF of less than or equal to 35% andwho are in NYHA functional Class I. (Level of Evidence: C)

. ICD therapy may be considered for patients with long-QT syn-drome and risk factors for SCD. (Level of Evidence: B) (16,349–354)

. ICD therapy may be considered in patients with syncope andadvanced structural heart disease in whom thorough invasiveand noninvasive investigations have failed to define a cause.(Level of Evidence: C)

. ICD therapy may be considered in patients with a familialcardiomyopathy associated with sudden death. (Level of Evi-dence: C)

. ICD therapy may be considered in patients with LV noncompac-tion. (Level of Evidence: C)

LASS III

. ICD therapy is not indicated for patients who do not have areasonable expectation of survival with an acceptable functionalstatus for at least 1 year, even if they meet ICD implantationcriteria specified in the Class I, IIa, and IIb recommendationsabove. (Level of Evidence: C)

. ICD therapy is not indicated for patients with incessant VT or VF.(Level of Evidence: C)

. ICD therapy is not indicated in patients with significant psychi-atric illnesses that may be aggravated by device implantation orthat may preclude systematic follow-up. (Level of Evidence: C)

. ICD therapy is not indicated for NYHA Class IV patients withdrug-refractory congestive heart failure who are not candidatesfor cardiac transplantation or CRT-D. (Level of Evidence: C)

. ICD therapy is not indicated for syncope of undetermined causein a patient without inducible ventricular tachyarrhythmias andwithout structural heart disease. (Level of Evidence: C)

. ICD therapy is not indicated when VF or VT is amenable tosurgical or catheter ablation (e.g., atrial arrhythmias associatedwith the Wolff-Parkinson-White syndrome, RV or LV outflow tractVT, idiopathic VT, or fascicular VT in the absence of structuralheart disease). (Level of Evidence: C)

. ICD therapy is not indicated for patients with ventricular tachy-arrhythmias due to a completely reversible disorder in theabsence of structural heart disease (e.g., electrolyte imbalance,
drugs, or trauma). (Level of Evidence: B) (16) (
.3. Implantable Cardioverter-Defibrillators inhildren, Adolescents, and Patients Withongenital Heart Disease

he indications for ICD implantation in young patients andhose with congenital heart disease have evolved over theast 15 years based on data derived primarily from adultandomized clinical trials. Similar to adults, ICD indica-ions have evolved from the secondary prevention of SCD tohe treatment of patients with sustained ventricular arrhyth-ias to the current use of ICDs for primary prevention in

atients with an increased risk of SCD. However, inontrast to adults, there are minimal prospective dataegarding ICD survival benefit, because fewer than 1% of allCDs are implanted in pediatric or congenital heart diseaseatients (439). Considerations such as the cumulative life-ime risk of SCD in high-risk patients and the need forecades of antiarrhythmic therapy make the ICD an im-ortant treatment option for young patients.SCD in childhood and adolescence is associated with 3

rincipal forms of cardiovascular disease: 1) congenital heartisease, 2) cardiomyopathies, and 3) genetic arrhythmiayndromes (440,441). Prospective identification and treat-ent of young patients at risk for sudden death is crucial

ecause compared with adults, a very low percentage ofhildren undergoing resuscitation survive to hospital dis-harge (442).

The indications for ICD therapy in pediatric patientsho have been resuscitated or who are at high risk for SCD

re similar to those for adults. Data from nonrandomizedtudies provide support for the Class I recommendation thatoung patients who have been resuscitated from SCDhould undergo ICD implantation after a careful evaluationo exclude any potentially reversible causes (440,443–445).pontaneous sustained VT or unexplained syncope with

nducible sustained hypotensive VT in patients with con-enital heart disease are also considered Class I ICDndications when other remediable causes (hemodynamic orrrhythmic) have been excluded (446). Catheter ablation orurgical therapies may provide an alternative to use of anCD in patients with congenital heart disease and recurrentT (447).Recommendations regarding ICD implantation for pri-ary prevention of SCD in young patients are based on

imited clinical experience and extrapolation of data fromdult studies. No randomized clinical trials have beenerformed to date, and given the relative infrequency ofCD in young patients, they are unlikely to be completed inhe near future. Because the risk of unexpected suddeneath is greater in young patients than in adults with geneticiseases such as HCM or the long-QT syndrome, a familyistory of sudden death, possibly with genetic confirmation,ay influence the decision to implant an ICD for primary

revention. Additional risk factors to be considered in theseiseases are discussed in specific sections in this document
354,382,448).

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With regard to primary prevention of SCD in patientsith congenital heart disease, the marked heterogeneity ofefects precludes generalization of risk stratification. Unex-ected sudden death is reported in 1.2% to 3.0% of patientser decade after surgical treatment of tetralogy of Fallot,ith risk factors including ventricular dysfunction, QRSuration, and atrial and ventricular arrhythmias (249). Aignificantly greater risk of SCD has been identified foratients with transposition of the great arteries or aortictenosis, with most cases presumed to be due to a malignantentricular arrhythmia associated with ischemia, ventricularysfunction, or a rapid ventricular response to atrial flutterr fibrillation (449–451).The risk of SCD associated with systemic ventricular

ysfunction in congenital heart disease patients remainsontroversial (452,453). The ability to define the riskssociated with impaired function is complicated by the facthat right (pulmonary) ventricular dysfunction is moreommon than left (systemic) ventricular dysfunction andhat a variety of atrial arrhythmias and conduction blocksay independently predispose these patients to arrhythmias

r syncope. The lack of prospective and randomized clinicalrials precludes exact recommendations regarding risk strat-fication and indications for ICD implantation for primaryrevention of SCD in patients with postoperative congenitaleart disease and ventricular dysfunction. One other poten-ial ICD indication in young patients, which is similar todults, is the patient with congenital coronary anomalies ororonary aneurysms or stenoses after Kawasaki disease, inhich an ischemic substrate for malignant arrhythmias maye present (441).Because of concern about drug-induced proarrhythmia

nd myocardial depression, an ICD (with or without CRT)ay be preferable to antiarrhythmic drugs in young patientsith DCM or other causes of impaired ventricular functionho experience syncope or sustained ventricular arrhyth-ias. ICDs may also be considered as a bridge to orthotopic

eart transplantation in pediatric patients, particularly givenhe longer times to donor procurement in younger patients454,455).

ecommendations for Implantable Cardioverter-efibrillators in Pediatric Patients and Patients Withongenital Heart Disease

LASS I

. ICD implantation is indicated in the survivor of cardiac arrestafter evaluation to define the cause of the event and to excludeany reversible causes. (Level of Evidence: B) (440,443–445)

. ICD implantation is indicated for patients with symptomaticsustained VT in association with congenital heart disease whohave undergone hemodynamic and electrophysiological evalua-tion. Catheter ablation or surgical repair may offer possible alterna-tives in carefully selected patients. (Level of Evidence: C) (447)

LASS IIa

. ICD implantation is reasonable for patients with congenital heart
disease with recurrent syncope of undetermined origin in the m
presence of either ventricular dysfunction or inducible ventriculararrhythmias at electrophysiological study. (Level of Evidence: B)(18,446)

LASS IIb

. ICD implantation may be considered for patients with recurrentsyncope associated with complex congenital heart disease andadvanced systemic ventricular dysfunction when thorough inva-sive and noninvasive investigations have failed to define a cause.(Level of Evidence: C) (451,454)

LASS III

. All Class III recommendations found in Section 3, “Indications forImplantable Cardioverter-Defibrillator Therapy,” apply to pediat-ric patients and patients with congenital heart disease, and ICDimplantation is not indicated in these patient populations. (Levelof Evidence: C)


rior studies of ICD therapy for primary and secondaryrevention of SCD in HCM are discussed in Sections 3.1.5nd 3.2.4; most of these studies have included both pediatricnd adult patients. The indications for ICDs in pediatricatients with HCM for primary and secondary preventionf sudden cardiac arrest are the same as those for adults.linical decisions should be based on risks and benefits thatay be unique to pediatric patients. In the pediatric

opulation, recommendations for ICD therapy should beade with careful consideration of the risks of device

mplantation, which may be increased on the basis of bodyize. Additionally, consideration should be given to thedditional years of benefit that could potentially result fromrevention of SCD in this population.

.4. Limitations and Other Considerations

.4.1. Impact on Quality of Life (Inappropriate Shocks)

espite its life-saving potential, the use of ICD therapyarries a risk for psychological consequences and may lead todecrement in QOL, particularly among patients who have

xperienced shocks (456). Reports of significant behavioralisorders, including anxiety, device dependence, or socialithdrawal, have been described with ICD implantation

457–459). However, QOL substudies from large, random-zed clinical trials of ICD therapy demonstrated that overall,

OL was no different or was somewhat better amongatients randomized to ICD therapy than among those inhe control groups, with decreases in physical, emotional,nd psychological measures of health-related QOL concen-rated among patients who experienced ICD shocks328,367,460). Given the broader indication for and markedncrease in implantation of ICDs for primary preventionhat is being driven by the results of the SCD-HeFT and

ADIT II trials (332,333), understanding the frequencynd causes of inappropriate shocks and devising manage-
ent strategies to mitigate both inappropriate therapies and

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heir psychological and QOL consequences will be impor-ant for an increasingly large segment of the population.

A systematic review summarized the frequency of inap-ropriate ICD therapies reported in randomized clinicalrials of primary and secondary prevention (461). In theserials, during follow-up that ranged from 20 to 45 months,nappropriate ICD therapy was delivered in 10% to 24% ofatients. In the PainFREE Rx II (Pacing Fast VT Reduceshock Therapies II) trial, in which patients were random-

zed to either ATP or shocks as first therapy for fast VT, ateast 1 inappropriate detection occurred in 15% of patientsuring approximately 11 months of follow-up (294). Theroportion of detections that were inappropriate was mod-stly but not significantly higher among primary preventionatients than among secondary prevention patients (46%ersus 34%; p�0.09). Both older and more recent registryeports suggest similar rates of inappropriate therapy innselected populations (462,463).By far, the leading cause of inappropriate therapy is theisclassification of SVT, most commonly AF (294,358,

62,463). But ICD lead malfunction and other causes, suchs oversensing of T waves, double counting of prolongedRS, and electromagnetic interference, may account for

% to 30% of inappropriate therapy (305,367,462,464).atients with multiple ICD shocks should be evaluated

mmediately to determine the cause of the shocks and toirect urgent management. Short-term therapy with anxi-lytic drugs may be instituted early for patients afterecurrent device firings to minimize acute and delayednxiety reactions.

A variety of approaches to reduce the occurrence ofnappropriate shocks are currently available, and selectionepends on the cause of the shocks and the type of device

mplanted. Although there has been debate as to the utilityf dual-chamber versus single-chamber devices in reducingates of inappropriate ICD therapy, a recently publishedandomized trial suggests that optimal programming ofual-chamber devices can reduce the rate of inappropriateetections and therapies due to SVTs (465). In the multi-enter Detect Supraventricular Tachycardia Study, 400atients with a clinical indication for an ICD receivedual-chamber devices and were randomized in a single-lind fashion to optimal single- or dual-chamber detectionrogramming. SVT occurred in 34% of subjects (31% in theingle-chamber arm and 37% in the dual-chamber arm).ates of inappropriate detection of SVT were substantial inoth arms (39.5% in the single-chamber arm and 30.9% inhe dual-chamber arm), but the adjusted odds ratio ofnappropriate detection of SVT in the dual-chamber armompared with the single-chamber arm was 0.53 (95% CI.30 to 0.94; p�0.03). This reduction in inappropriateetection translated to a similar reduction in inappropriateherapy, with no compromise of VT detection, which makeshis trial the first to show superiority of dual-chamberevices when optimally programmed. Other areas of active
esearch include the development of enhanced mathemati- m
ally modeled detection protocols for evaluation of internallectrograms to improve discrimination of SVT from VTnd to increase the ability to detect lead failures (466–468).egardless of the cause of or solution for inappropriate ICD

herapy (particularly shocks), careful attention to a team-ased approach that includes the patient and family inmotional and psychological support is also recommended456,469).

.4.2. Surgical Needs

urgically placed epicardial pacing leads are indicated inelected instances when standard transvenous lead place-ent is either not feasible or contraindicated. Examples of

uch circumstances include: 1) inability or failure to place andequate LV lead in patients requiring biventricular pacing,) indications for permanent pacing in certain pediatricatients and in pediatric or adult patients with tricuspidalve prostheses or recurrent or prolonged bacteremia, and) congenital acquired venous anomalies that precluderansvenous access to the heart.

The reported success rate of coronary venous lead im-lantation for biventricular pacing ranges from 81% to 99%470,471). Causes of failed percutaneous lead placementay be anatomic (superior vena cava or coronary sinus

bstruction or inadequate coronary venous anatomy) orechnical (failure to cannulate the coronary sinus, coronaryinus dissection, inadequately high pacing thresholds withntermittent capture, diaphragmatic pacing due to proximityf the phrenic nerve to the target coronary sinus branch, oread dislodgement) (470,472,473). When coronary sinusead implantation fails, several nonrandomized studies haveemonstrated that surgical LV lead placement is almostlways successful (470–473). In this setting, the key advan-age of surgical lead placement is access to the entireosterior and lateral walls of the LV, which enables thehoice of the best pacing site (471,474). The combination ofchocardiography with tissue Doppler imaging and electro-hysiological measurements may facilitate the choice of aransthoracically directed LV epicardial pacing site (473).mplantation of 2 epicardial leads may be considered torovide backup capability if 1 lead should fail or becomeislodged (475). Steroid-eluting epicardial leads may bereferable to screw-on leads (473).The choice of surgical procedure appears to influence

ospital morbidity. Surgical approaches for placement ofV epicardial leads include left thoracotomy, left thoracos-opy, and robotically assisted port-based placement. Tho-acotomy in fragile patients with heart failure has beenssociated with bleeding, stroke, hypotension, and arrhyth-ias (470,476). In contrast, thoracoscopic and robotic

pproaches have been reported to be associated with mini-al morbidity and may be preferred (472,473,475). These

ess invasive procedures generally require 60 to 90 minutesf operative time and a mean hospital stay of 4 to 5 days472). However, not all patients are candidates for mini-
ally invasive or robotic procedures. Subjects who have

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ndergone prior thoracotomy or sternotomy operations mayave limited pericardial/epicardial accessibility.In certain instances, it may be advisable to place an LV

picardial lead at the time of concomitant cardiac surgery. Inatients who are currently or in the future may be candidatesor CRT who require coronary artery bypass grafting oritral valve surgery and have medically refractory, symp-

omatic heart failure, ischemic cardiomyopathy or DCM,rolonged QRS interval, LV end-diastolic diameter greaterhan or equal to 55 mm, and LVEF less than or equal to5%, the surgeon may elect to place an LV epicardial lead477). The lead is tunneled to a prepectoral pocket forntraoperative or postoperative attachment to an appropriateacing generator. This approach is probably not indicatedor the patient who is expected to have substantial improve-ent in LVEF after cardiac surgery (e.g., the patient with

xtensive viable myocardium who is undergoing revascular-zation). There are limited data documenting outcomes ofhis “preemptive” strategy.

Epicardial leads may be necessary in some pediatric patients.he most common indications for permanent pacemaker

mplantation in the pediatric population are SND or AV blockfter surgery for congenital heart disease and congenital AVlock (478). In most instances, such pacing systems can belaced by standard transvenous techniques (479). However,picardial leads may be needed in children as a result of theirmall size, the presence of congenital heart defects with aight-to-left shunt, or an inability to pace the chamber desiredecause of anatomic barriers (e.g., after a Fontan procedure)478–480). In such instances, steroid-eluting leads providexcellent durability (479).

Epicardial leads are suggested in some pediatric or adultatients who need pacing and who have recurrent orrolonged bacteremia (481). For a single episode of device-elated bacteremia, extraction of all hardware followed byeimplantation by the transvenous route at a later date isppropriate.

Implantation of permanent epicardial pacing leads isndicated in the pacemaker-dependent patient undergoing

echanical tricuspid valve replacement. A prosthetic me-hanical tricuspid valve represents an absolute contraindica-ion to placement of transvenous RV leads, because sucheads will cross the valve and may interfere with valveunction. This scenario occurs commonly in patients withricuspid valve endocarditis and a transvenous pacemaker.t surgery, all hardware should be removed. If the tricuspid

alve is repairable, standard transvenous pacing leads can belaced postoperatively. However, if tricuspid valve replace-ent is necessary, epicardial ventricular leads should be

mplanted at the time of surgery.

.4.3. Patient Longevity and Comorbidities

hysicians, patients, and their families increasingly will beaced with decisions about device-based therapies (ICD andRT) in elderly patients who meet conventional criteria for

mplantation. These decisions require not only evidence of f

linical benefit demonstrated in randomized clinical trialsut also estimates of life expectancy, consideration ofomorbidities and procedural risk, and patient preferences.lthough these factors are important when device implan-

ation is considered in any age group, they assume greatereight in clinical decision-making among the elderly.Unfortunately, few clinical trials of device-based therapy

ave enrolled enough elderly patients (age greater than 75ears) to reliably estimate the benefits of device-basedherapy in this group. Indeed, patients in device trials haveenerally had an average age less than 65 years and littleomorbidity. In contrast, the average patient hospitalizedith heart failure and low LVEF is 75 years old with 2

omorbidities. The 1-year mortality rate for this populations in the range of 30% to 50%, with a 2-fold higher risk ofeath in patients with estimated creatinine clearance lesshan 60 ml per minute (326,482). The presence of chroniculmonary disease and dementia further increases the riskor death. Fewer than 10% of deaths in this populationould be attributed to presumed SCD in patients livingndependently (482). After 3 hospitalizations for heartailure in a community population, median survival declineso 1 year and would be prolonged by only 0.3 years even ifll presumed SCDs were prevented (5). For all patients, theikelihood of meaningful prolongation of life by preventionf SCD must be assessed against the background of otheractors that limit patient function and survival.

Among 204 elderly patients with prior MI and LVEFess than or equal to 30% enrolled in MADIT II (total�1223), a trial of primary prevention of SCD with ICDherapy, the HR for mortality with ICD therapy was 0.5695% CI 0.29 to 1.08; p�0.08), which was similar to thator younger patients (HR 0.63, 95% CI 0.45 to 0.88;�0.01) (482a). Furthermore, QOL scores were similarmong older and younger patients. Subgroup analyses byge (less than or equal to 65 versus greater than 65 years)rom COMPANION and SCD-HeFT showed some ero-ion of benefit among the older group, but there were noignificant treatment interactions with age (224,333).

In a study of 107 consecutive patients greater than 80ears old (82% with ischemic cardiomyopathy) and 241onsecutive patients 60 to 70 years of age (80% withschemic cardiomyopathy), life expectancy after device im-lantation (predominantly ICD alone) among the octoge-arians was 4.2 years compared with 7 years among those 60o 70 years old (483). Thus, although survival after implan-ation is shorter among the elderly than among youngerroups, survival is substantial, and age itself should not behe predominant consideration in the use of device-basedherapy among the elderly.

The presence and number of noncardiac comorbiditiesre another important consideration in the decision toroceed with device-based therapy in the elderly. In oneegistry, although age greater than 75 years and heart failureere important predictors of death at 1 and 2 years of

ollow-up, after adjustment for age, heart failure, and

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atient sex, the number of noncardiac comorbidities wastatistically significantly associated with survival among467 patients who received ICD therapy (484). The pres-nce of 3 or more noncardiac comorbidities was associatedith a nearly 3-fold increase in the hazard for mortality (HR.98, 95% CI 1.74 to 5.10). Therefore, as much as age, theresence and number of noncardiac comorbidities are crit-cal considerations in the decision to use device-basedherapy.

A meta-analysis of secondary prevention trials (AVID,ASH, and CIDS) revealed that although ICD therapy

educed all-cause and arrhythmic death among patients lesshan 75 years old, among 252 patients older than 75 years,he HR for all-cause mortality (predominantly due torogressive heart failure) was 1.06 (95% CI 0.69 to 1.64;�0.79), and for arrhythmic death, it was 0.90 (95% CI.42 to 1.95; p�0.79) (485). The interaction p value was.09, which suggests that the elderly may derive less benefitrom ICD therapy in secondary prevention than youngeratients.In summary, these data suggest that although age is an

mportant predictor of outcome after ICD therapy, meanurvival of more than 4 years may be expected even amongctogenarians, and age alone should not be used as a soleriterion to withhold device-based therapy. However, im-ortant considerations in the decision to use device-basedherapy should include the indication for device implanta-ion (for ICDs, primary versus secondary prevention), theumber of comorbidities, and patient preferences.Considerations specific to elderly patients are also rele-

ant to pacing, CRT, and ICD therapies. Similar tonrollment in ICD trials, few patients older than 75 yearsave been enrolled in trials of CRT. However, subgroupnalyses from CARE-HF (age less than 66.4 versus greaterhan or equal to 66.4 years) and COMPANION (age lesshan or equal to 65 versus greater than 65 years) suggest thatlder patients derive similar benefit from CRT as youngeratients (224,225).The “ACC/AHA/ESC 2006 Guidelines for Manage-ent of Patients With Ventricular Arrhythmias and therevention of Sudden Cardiac Death” addressed ICD

mplantation in the elderly (16). Many of those consider-tions are relevant to other types of device implantation.ecause of underrepresentation of the elderly in clinical

rials, much of the rationale for implanting devices in theseatients rests on subgroup analyses that were not prespeci-ed and is therefore relatively weak. Furthermore, not onlyelative efficacy but also procedural complication rates inlder versus younger patients are largely unexplored. Thesenknowns must be balanced against the fact that manylderly patients remain functional until shortly before deathnd reasonably deserve similar treatment options as youngeratients in many cases. The ethical principles of autonomy,eneficence (“do good and avoid evil”), and nonmaleficence
“do no harm”) must always prevail.
.4.4. Terminal Care

n the United States, the withholding and withdrawal ofife-sustaining treatments (e.g., cardiopulmonary resuscita-ion, mechanical ventilation, or hemodialysis) from termi-ally ill patients who do not want the treatments is ethicalnd legal (486). Honoring these requests is an integralspect of patient-centered care and should not be regardeds physician-assisted suicide or euthanasia.

When terminally ill patients (or their surrogates) requestacemaker, ICD, or CRT deactivation, questions related tohe ethics of device deactivation may arise. Questionsommonly asked include: Are implantable devices life-ustaining treatments? Is deactivation the same ashysician-assisted suicide or euthanasia? Is deactivationthical? Is it legal? Under what conditions (e.g., code status)hould deactivation be performed? Who should carry outeactivation? What documentation should exist?The prevalence of implantable devices in patients dying of

oncardiac diseases makes this an increasingly encounteredlinical issue. Patients and families fear that devices willrolong the dying process, and some dying patients withCDs fear uncomfortable defibrillations. In fact, investiga-ors have found that some patients with ICDs experiencencomfortable defibrillations throughout the dying process,ncluding moments before death. Cardiologists who im-lant devices do not commonly have discussions withatients about end-of-life issues and device deactivation.urthermore, published experience with deactivation ofevices is limited (487).There is general consensus regarding the ethical and legal

ermissibility of deactivating ICDs in dying patients whoequest deactivation (488). However, caregivers involved inevice management generally make a distinction betweeneactivating a pacemaker and deactivating an ICD or CRTevice. Given the clinical context, all 3 can be considered

ife-sustaining treatments. Notably, all of these devices maye refused by patients, and to impose them on patients whoo not want them is unethical and illegal (battery). Further-ore, ethics and law make no distinction between with-

olding and withdrawing treatments.An approach to dying patients who request pacemaker,

CD, or CRT deactivation should include the following:

A dying patient (or, if the patient lacks decision-makingcapacity, the patient’s surrogate decision maker) whorequests device deactivation should be fully informed ofthe consequences and alternatives to device deactivation,and a summary of the conversation should be recorded inthe medical record.An order for device deactivation should be accompaniedby a do-not-resuscitate (DNR) order; these orders shouldbe recorded in the patient’s medical record.Psychiatric consultation should be sought in any situationin which a dying patient who requests device deactivation
is thought to have impaired decision-making capacity.

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Ethics consultation should be sought in any situation inwhich the clinician or clinicians disagree, based on theirclinical judgment, with a request for device deactivation.If the clinician asked to deactivate a device has personalbeliefs that prohibit him or her from carrying out devicedeactivation (conscientious objection), then the patientshould be referred to another clinician.If the patient is remote from the implanting medicalcenter, the clinician who is responsible for the patient’scare at the local site should document the informationnoted above in the medical record, and someone capableof programming the device to “inactive” status should berecruited to reprogram the device under the direction ofthe local physician.

Clinicians involved in device education at the time ofmplantation may need to provide more comprehensivenformation with regard to end-of-life issues. For example,linicians should encourage patients undergoing device im-lantation to complete advanced directives and specificallyddress the matter of device management and deactivationf the patient is terminally ill.

.5. Cost-Effectiveness of Implantableardioverter-Defibrillator Therapy

ong-term follow-up studies have consistently demon-trated that cumulative medical costs are increased substan-ially among patients receiving an ICD (17–19,489–491).everal studies have attempted to weigh whether thesedded costs are worthwhile in light of the potential formproved survival among patients receiving ICD therapy492). These studies calculate a cost-effectiveness ratio thats defined as the difference in the total cost of patientseceiving an ICD and patients receiving alternative therapy,ivided by the additional life-years of survival provided byn ICD compared with alternative therapy. A benchmarkor comparison is provided by renal dialysis, which costspproximately $50 000 to add 1 life-year of survival. Cost-ffectiveness, like other outcome measures in clinical re-earch studies, must be interpreted in light of the charac-eristics of the study populations and the length ofollow-up available.

The early studies of ICD cost-effectiveness were based onathematical models and relied on nonrandomized studies

o estimate clinical efficacy and cost. These studies foundost-effectiveness ratios of $17 000 (493), $18 100 (494),nd $29 200 per year of life saved (495). Another modelncorporated costs of nonthoracotomy ICDs and efficacystimates based on randomized trials and found ICDost-effectiveness was between $27 300 and $54 000 perife-year gained, which corresponded to risk reductions of0% and 20%, respectively (496).Several randomized clinical trials have measured both

ost and clinical outcomes and thus can directly estimate c

CD cost-effectiveness. MADIT found a 54% reduction inotal mortality and a cost-effectiveness ratio of $27 000 perife-year added (18). In contrast, CIDS found a 20%eduction in total mortality and a cost-effectiveness ratiof $139 000 per life-year added (322,490). The cost-ffectiveness ratio from the AVID trial was $66 677 perife-year added (491). MADIT II found a 32% reduction inotal mortality and $39 200 higher costs among ICD-ssigned patients than among those treated with conven-ional therapy (17). The cost-effectiveness ratio in MADITI was measured as $235 000 per year of life added at 2 yearsf follow-up but was projected to be between $78 600 and114 000 per year of life added by 12 years of follow-up.CD-HeFT reported that total mortality was reduced by3% and costs increased by $19 000 over 5 years ofollow-up in patients assigned to ICDs compared withatients assigned to placebo (19). SCD-HeFT estimatedhe lifetime cost-effectiveness ratio of the ICD strategy was38 400 per year of life added. This range of results fromandomized studies is primarily due to different estimates ofhe effectiveness of the ICD in reducing mortality, becausell showed similar increases in the cost of care among ICDecipients. When the results of all clinical trials were used inmodel that used a consistent framework to project the fullain in life expectancy and lifetime costs in each trial (497),he cost-effectiveness of the ICD ranged from $25 300 to50 700 per life-year added in the randomized trials inhich the ICD reduced mortality. In the CABG-Patch trial

nd DINAMIT, however, patients assigned to an ICD hadower survival and higher costs than patients assigned toonventional therapy, and the ICD strategy was not cost-ffective. The evidence suggests that proper patient selections necessary for ICD implantation to be cost-effective; whenCD implantation is restricted to appropriately selectedatients, it has a cost-effectiveness ratio similar to otherccepted cardiovascular therapies and compares well to thetandard benchmark of renal dialysis ($30 000 to $50 000er year of life saved). In principle, ICD implantation wille more cost-effective when used for patients at high risk ofrrhythmic death and at low risk of other causes of death.dditional risk stratification of patients with a reducedVEF may improve patient selection for the ICD and

hereby enhance its cost-effectiveness (498). Cost-ffectiveness of the ICD would also be improved by lower-ng the cost of the device itself and further improving itseliability and longevity.

The cost-effectiveness of CRT has not been evaluatedxtensively. A CRT-P device reduces hospitalization foreart failure patients, and these cost savings partially offsethe initial cost of device implantation. CRT-P devices arelso effective in improving QOL and may improve survival.he cost-effectiveness of CRT-P devices versus medical

herapy appears to be favorable. There are few data on the
ost-effectiveness of CRT-D compared with CRT-P devices.

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.6. Selection of Implantable Cardioverter-efibrillator Generators

single RV lead for sensing and defibrillation is mandatoryor all currently available ICD systems. Single-chamberCD systems are capable of bradycardia support in theentricle and ATP. Dual-chamber ICD systems (right atrialnd RV leads) are additionally capable of AV sequentialacing. Triple-chamber ICD systems (right atrial, RV, andV leads) are capable of CRT (CRT-D). Despite these

ncreasing complexities, the optimal hardware system forCD indications derived from mortality studies has not beenully evaluated. There is increasing evidence that choice ofardware may affect important outcomes in ICD patients.his relates primarily to 2 considerations: 1) management of

entricular pacing and 2) pain associated with high-voltagehocks. Conventional ICD therapy in any form may bessociated with worsening heart failure, VT, VF, andoncardiac death that can be related to the adverse effects ofVA pacing (50,51). This is consistent with the increased

isks of AF and heart failure attributable to RVA pacing inacemaker trials (45,48). The issue of QOL in the ICDatient population has been evaluated extensively (460,499–02). Although ICD therapy is generally well tolerated byost patients, approximately 30% to 50% experience some

egree of psychological distress after implantation (503).ne of the principal limitations of ICD therapy is the

iscomfort associated with high-voltage shocks. Severaltudies have noted a direct correlation between poor QOLcores and the experience of ICD shocks (460,499–501).

Any hardware system that increases unnecessary ventric-lar pacing from any site may increase the risk of heartailure, particularly in patients with poor cardiac ventricularystolic function (293). The risk of heart failure is increasedven in hearts with initially normal ventricular systolicunction and with part-time ventricular pacing. RVA pacingreates abnormal contraction, reduced ventricular systolicunction, hypertrophy, and ultrastructural abnormalities.he magnitude of the effect relates to the frequency of

entricular pacing and the degree of pacing-induced me-hanical dyssynchrony rather than the hardware system49). Although these effects have been demonstrated mostlearly during RVA pacing, biventricular or LV pacing maylso induce dyssynchrony in hearts with normal ventricularonduction (504) and can reduce LV systolic function inatients with no baseline dyssynchrony (505).In patients with no AV block and no intraventricular

onduction abnormalities, ventricular pacing should bevoided as much as possible. For many ICD patients whoo not have an indication for bradycardia support, this cane achieved by programming a very low backup ventricularacing rate (i.e., 30 to 40 bpm). The optimal managementf cardiac pacing in ICD patients in whom bradycardiaupport is required, desired, or emerges is unknown. For
CD patients with SND in whom bradycardia support is f
equired or desired, ventricular pacing may be minimized byse of newer techniques specifically designed to promotentrinsic conduction (292,506). In patients with AV block,lternate single-site RV or LV pacing or biventricularacing (CRT-P/CRT-D) may be superior to RVA pacing.fforts to optimize pacing mode or site should be greater inatients with longer expected duration of pacing, poorerardiac function, and larger mechanical asynchrony. Aware-ess of the problem of dyssynchrony should also lead toore regular monitoring of cardiac ventricular systolic

unction and mechanical asynchrony in any patient withentricular pacing.

ATP refers to the use of pacing stimulation techniquesor termination of tachyarrhythmias. Tachycardias thatequire reentry to persist are susceptible to termination withacing. The most common mechanism of VT in ICDatients is scar-related reentry. The sine qua non of ae-entrant arrhythmia is the ability to reproducibly initiatend terminate the tachycardia by critically timed extra-timuli (124). Therefore, the possibility of successful termi-ation of tachycardias with pacing can be anticipated on theasis of the mechanism. Such techniques can be appliedutomatically with ICDs and offer the potential for painlessermination of VT.

Adjudicated analysis of stored electrograms has revealedhat the majority (approximately 85% to 90%) of spontane-us ventricular tachyarrhythmias in ICD patients are due toT and fast VT, whereas only approximately 10% are due toF (507,508). Numerous older studies have consistentlyemonstrated that ATP can reliably terminate approxi-ately 85% to 90% of slow VTs (cycle lengths less than 300illiseconds to 320 milliseconds) with a low risk of accel-

ration (1% to 5%) (509–511). More recently, similarly highates of success and low acceleration and syncope rates forast VTs (average cycle length 240 milliseconds to 320illiseconds) have been demonstrated (507,508). These

bservations have repositioned the ICD as primarily anTP device with defibrillation backup only as needed.eduction in painful shocks may improve patient QOL

508) and extend ICD pulse-generator longevity. It is notet clear whether important differences in optimal applica-ion of ATP exist in different ICD patient populations. Ineneral, secondary prevention patients have a greater fre-uency of spontaneous ventricular arrhythmia than primaryrevention patients. However, differences in the incidencef specific ventricular rhythms (VT, fast VT, and VF),esponse to therapy (ATP or shocks), and susceptibility topurious therapies due to SVT are incompletely character-zed (294,512). Differences in substrate may be important asell. Monomorphic VT associated with chronic ischemiceart disease is most commonly due to classic reentry and isherefore susceptible to termination by ATP. MonomorphicT is less commonly due to reentry and occurs with lower

requency in nonischemic DCM.

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.7. Implantable Cardioverter-Defibrillator Follow-Up

ll patients with ICDs require periodic and meticulousollow-up to ensure safety and optimal device performance, asell as to monitor a patient’s clinical status (513). The goals of

CD follow-up include monitoring of device system function;ptimization of performance for maximal clinical effectivenessnd system longevity; minimization of complications; antici-ation of replacement of system components and trackingevices under advisory; ensuring timely intervention for clinicalroblems; patient tracking, education, and support; and main-enance of ICD system records. The importance of deviceurveillance and management should be discussed with patientsefore ICD implantation. Compliance with device follow-up isn important element in the evaluation of appropriate candidatesor device therapy and to obtain the best long-term result.

ICD follow-up is best achieved in an organized programnalogous to pacemaker follow-up at outpatient clinics312). Physicians and institutions performing implantationf these devices should maintain follow-up facilities fornpatient and outpatient use. Such facilities should obtainnd maintain implantation and follow-up support devicesor all ICDs used at that facility. The facility should betaffed or supported by a cardiologist and/or electrophysi-logist, who may work in conjunction with trained associ-ted professionals (312,514,515). Continuous access tohese services should be available as much as feasible on both

regularly scheduled and more emergent basis. The im-lantation and/or follow-up facility should be able to locatend track patients who have received ICDs or who haventered the follow-up program.

.7.1. Elements of Implantable Cardioverter-Defibrillatorollow-Up

he follow-up of an ICD patient must be individualized inccordance with the patient’s clinical status and conducted by ahysician fully trained in ICD follow-up (12); if this is not ahysician fully trained in all aspects of ICD implantation andollow-up, then such an individual should be available for anyroblems that may develop. Direct patient contact is ideal,llowing for interval history taking, physical examination of themplantation site, and device programming changes that maye warranted. Six-month intervals for device follow-up appearo be safe (516), but more frequent evaluations may be requiredepending on the device characteristics and the patient’slinical status. Manufacturers’ guidelines for device follow-upay vary with individual models and should be available.evice automaticity has facilitated follow-up (316), as has the

mplementation of remote monitoring techniques (513,517).epending on the manufacturer, remote device interrogation

s achieved through Internet-based systems or via radiofre-uency transmissions from the ICD via a phone device to aentral monitoring center; remote reprogramming of devices isot available currently. Remote monitoring may lessen theependence on clinic visits, particularly in patients who live at
considerable distance from the follow-up clinic, and may d
llow for the earlier detection of real or potential problemsssociated with the device. Guidelines for remote monitoringave yet to be established. It should be recognized, further-ore, that remote monitoring is an adjunct to follow-up and

annot entirely supplant clinic visits (518,519).In general, device programming is initiated at implantation

nd may be reviewed periodically. It is often necessary toeprogram the initially selected parameters either in the out-atient clinic or during electrophysiological testing. Whenevice function or concomitant antiarrhythmic therapy isodified, electrophysiological testing may be warranted to

valuate sensing, pacing, or defibrillation functions of theevice. Particular attention should be given to review of sensingarameters, programmed defibrillation and pacing therapies,evice activation, and event logs. Technical elements thatequire review include battery status, lead system parameters,nd elective replacement indicators. Intervening evaluation ofevice function is often necessary. In general, when ICDherapy is delivered, the device should be interrogated.

After implantation of a device, its performance should beeviewed, limitations on the patient’s specific physical activitiesstablished, and registration accomplished. Current policies onriving advise patients with an ICD implanted for secondaryrevention to avoid operating a motor vehicle for 6 monthsfter the last arrhythmic event if it was associated with loss orear loss of consciousness to determine the pattern of recurrentT/VF (520,521). For patients with ICDs implanted forrimary prevention, avoidance of driving for at least 7 days tollow healing has been recommended (522). Interactions withlectromagnetic interference sources potentially affect employ-ent. Sports involvement (523) and recommendations regard-

ng safeguards for future surgical procedures (524) should beiscussed. There are currently not enough data to makeecommendations regarding antibiotic prophylaxis for proce-ures or operations required in the first 6 months after ICD

mplantation; physicians must weigh the risks and benefits ofntibiotic prophylaxis and use their judgment in each case.CD recipients should be encouraged to carry proper identifi-ation and information about their device at all times. Patientseceiving these devices can experience transient or sustainedevice-related anxiety. Education and psychological supportefore, during, and after ICD insertion are highly desirable andan improve the patient’s QOL (457,458).

Increasing attention has been paid to the safety and efficacyf implantable devices. It is incumbent upon the follow-uphysician to be aware of advisories issued in relation tootential device malfunction (2). Specific recommendations forlinicians managing such advisories are to consider lead/deviceeplacement if death is a likely result of device malfunction; theechanism of device/lead failure is known, potentially recur-

ent, and possibly life-threatening; the patient is pacemaker-ependent; the risk of replacement is substantially lower thanhe risk of device malfunction; or the device is approaching itslective replacement indicator (3). Complications related toeplacement of ICD generators under advisory have been well
ocumented, including infection, the need for reoperation, and

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ssociated with device replacement. In general, for pacemaker-ependent patients, advisory device failure rates in excess of.3% warrant consideration of device replacement; in patientsith ICD generators under advisory, an estimated failure ratef 3% favors replacement in the majority of cases, decreasing to% when procedural mortality rates are 0.1% or less and/or riskf fatal arrhythmias increases to 20% per year (526). It isnticipated that the above general recommendations and esti-ates will vary as a function of the specific nature of the

dvisory, how the malfunction presents, whether early detec-ion and/or reprogramming may be employed in addressinghe potential device failure, and whether the lead (versus theenerator) is affected. This has been demonstrated, for exam-le, in the case of a recent lead advisory associated withpurious shocks attributable to lead fracture, oversensing, andigh impedance; reprogramming to minimize overdetection ofoise, enabling of alert features to detect changes in imped-nce, and increasing utilization of remote monitoring to followuch leads may have an effect on future rates of invasive leadeplacement and/or extraction (527).

.7.2. Focus on Heart Failure After First Appropriatemplantable Cardioverter-Defibrillator Therapy

n patients with heart failure who have not previously had aife-threatening arrhythmia, the first event identifies them aseing at higher risk than before for both sudden death andeath due to heart failure, with the majority of patientsurviving less than 2 years (17,19). It is not known to whatxtent these herald events serve as markers or as contributors torogression of disease. They should trigger reevaluation ofreatable causes of heart failure and of the medical regimen. Inddition, the treatment regimen should be evaluated for inter-entions that may decrease the risk of arrhythmia recurrence.articular care should be paid to the titration of beta-drenergic blockers. These agents have been shown to decreaseisease progression and improve outcomes, but uptitration can

ead to heart failure exacerbation and must be attemptedradually in small dose increments. Many patients with symp-omatic heart failure cannot tolerate “target doses” of beta-drenergic blockers, whether used primarily for the indicationf heart failure or to prevent recurrent arrhythmias. Althoughatients with heart failure who have had device therapy woulddeally be followed up by specialists in both arrhythmia

anagement and heart failure management, most patients doot have routine access to such settings. To maximize theenefit after a sudden death has been prevented, it is crucialhat the management team evaluate the heart failure profile,eview the medical regimen, and plan for ongoing care.

. Areas in Need of Further Research

he ACC/AHA Task Force on Practice Guidelines has
harged writing committees to suggest areas in need of L
urther research. To this end, the present writing committeeffers the following suggestions. They are presented inabular form for ease of readability. Their order does notmply any order of priority.

. Optimal access to device therapy should be provided toall eligible populations irrespective of sex and ethnicity.

. Risk stratification of patients meeting current clinicalindications for primary prevention ICD implantationshould be improved to better target therapy to thosemost likely to benefit from it.

. Identification of patients most likely to benefit from/respond to CRT must be improved.

. Identify patients without current pacemaker or ICDindications among those who may benefit from suchtherapies.

. Indicators should be identified that provide directionabout when it is safe to not replace an ICD that hasreached the end of its effective battery life.

. The cost-effectiveness of device therapy should be ex-plored further.

. Guidelines for remote monitoring should be developed.

. Ways to improve reliability and longevity of leads andgenerators must be found, as well as methods to ensurediscovery of performance issues when they arise.

. Representation of the elderly in clinical trials should beincreased.

0. The influence of age on procedural complication ratesand the risk/benefit ratio for device implantation shouldbe defined.

1. The effect (positive, negative, or neutral) of biventricu-lar or LV stimulation in patients with normal ventric-ular function should be determined.

2. The need for pacing after MI in the current era shouldbe determined.

3. Long-term outcomes and risk factors for patients re-ceiving ICDs in general practice compared with trialpopulations and at academic centers should be identi-fied and described.

4. Guidelines for device management in patients withterminal illness or other requests to terminate devicetherapy should be developed.

5. The role of ICDs in primary prevention for childrenwith genetic channelopathies, cardiomyopathies, and con-genital heart defects should be defined more precisely.

6. The efficacy of biventricular pacing in children withcongenital heart disease and dilated cardiomyopathyshould be determined.

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merican College of Cardiology Foundationohn C. Lewin, MD, Chief Executive Officerharlene May, Director, Clinical Policy and Guidelines
isa Bradfield, Associate Director, Practice Guidelines

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ark D. Stewart, MPH, Associate Director, Evidence-ased Medicineristen N. Fobbs, MS, Senior Specialist, Practice Guidelinesrin A. Barrett, Senior Specialist, Clinical Policy anduidelines

merican Heart Association. Cass Wheeler, Chief Executive Officerayle R. Whitman, RN, PhD, FAAN, FAHA, Viceresident, Office of Science Operationsathryn A. Taubert, PhD, FAHA, Senior Science Advisor

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43. Hamilton RM, Dorian P, Gow RM, Williams WG. Five-yearexperience with implantable defibrillators in children. Am J Cardiol.1996;77:524–6.

44. Alexander ME, Cecchin F, Walsh EP, Triedman JK, BevilacquaLM, Berul CI. Implications of implantable cardioverter defibrillatortherapy in congenital heart disease and pediatrics. J CardiovascElectrophysiol. 2004;15:72–6.

45. Choi GR, Porter CB, Ackerman MJ. Sudden cardiac death andchannelopathies: a review of implantable defibrillator therapy. PediatrClin North Am. 2004;51:1289–303.

46. Khairy P, Landzberg MJ, Gatzoulis MA, et al. Value of programmedventricular stimulation after tetralogy of fallot repair: a multicenterstudy. Circulation. 2004;109:1994–2000.

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55. Evans RW, Manninen DL, Dong FB, Frist WH, Kirklin JK. Themedical and surgical determinants of heart transplantation outcomes:the results of a consensus survey in the United States. J Heart LungTransplant. 1993;12:42–5.

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57. Vlay SC, Olson LC, Fricchione GL, Friedman R. Anxiety and angerin patients with ventricular tachyarrhythmias. Responses after auto-matic internal cardioverter defibrillator implantation. Pacing ClinElectrophysiol. 1989;12:366–73.

58. Luderitz B, Jung W, Deister A, Marneros A, Manz M. Patientacceptance of the implantable cardioverter defibrillator in ventriculartachyarrhythmias. Pacing Clin Electrophysiol. 1993;16:1815–21.

59. Thomas SA, Friedmann E, Kao CW, et al. Quality of life andpsychological status of patients with implantable cardioverter defi-brillators. Am J Crit Care. 2006;15:389–98.

60. Irvine J, Dorian P, Baker B, et al. Quality of life in the CanadianImplantable Defibrillator Study (CIDS). Am Heart J. 2002;144:282–9.

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62. Alter P, Waldhans S, Plachta E, Moosdorf R, Grimm W. Compli-cations of implantable cardioverter defibrillator therapy in 440 con-secutive patients. Pacing Clin Electrophysiol. 2005;28:926–32.

63. Rosenqvist M, Beyer T, Block M, Den DK, Minten J, Lindemans F.Adverse events with transvenous implantable cardioverter-defibrillators: a prospective multicenter study. European 7219 JewelICD investigators. Circulation. 1998;98:663–70.

64. Al-Ahmad A, Wang PJ, Homoud MK, Estes NA III, Link MS.Frequent ICD shocks due to double sensing in patients withbi-ventricular implantable cardioverter defibrillators. J Interv CardElectrophysiol. 2003;9:377–81.

65. Friedman PA, McClelland RL, Bamlet WR, et al. Dual-chamberversus single-chamber detection enhancements for implantable defi-brillator rhythm diagnosis: the detect supraventricular tachycardiastudy. Circulation. 2006;113:2871–9.

66. Williams JL, Shusterman V, Saba S. A pilot study examining theperformance of polynomial-modeled ventricular shock electrogramsfor rhythm discrimination in implantable devices. Pacing Clin Elec-trophysiol. 2006;29:930–9.

67. Gunderson BD, Gillberg JM, Wood MA, Vijayaraman P, ShepardRK, Ellenbogen KA. Development and testing of an algorithm todetect implantable cardioverter-defibrillator lead failure. HeartRhythm. 2006;3:155–62.

68. Gunderson BD, Patel AS, Bounds CA, Shepard RK, Wood MA,Ellenbogen KA. An algorithm to predict implantable cardioverter-defibrillator lead failure. J Am Coll Cardiol. 2004;44:1898–902.

69. Sears SF Jr., Shea JB, Conti JB. Cardiology patient page. How torespond to an implantable cardioverter-defibrillator shock. Circula-tion. 2005;111:e380–e382.

70. Shah RV, Lewis EF, Givertz MM. Epicardial left ventricular leadplacement for cardiac resynchronization therapy following failedcoronary sinus approach. Congest Heart Fail. 2006;12:312–6.

71. Koos R, Sinha AM, Markus K, et al. Comparison of left ventricularlead placement via the coronary venous approach versus lateralthoracotomy in patients receiving cardiac resynchronization therapy.
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http://www.seattleheartfailuremodel.org

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72. Gabor S, Prenner G, Wasler A, Schweiger M, Tscheliessnigg KH,Smolle-Juttner FM. A simplified technique for implantation of leftventricular epicardial leads for biventricular re-synchronization usingvideo-assisted thoracoscopy (VATS). Eur J Cardiothorac Surg. 2005;28:797–800.

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74. Mair H, Sachweh J, Meuris B, et al. Surgical epicardial leftventricular lead versus coronary sinus lead placement in biventricularpacing. Eur J Cardiothorac Surg. 2005;27:235–42.

75. DeRose JJ, Ashton RC, Belsley S, et al. Robotically assisted leftventricular epicardial lead implantation for biventricular pacing. J AmColl Cardiol. 2003;41:1414–9.

76. Jansens JL, Jottrand M, Preumont N, Stoupel E, de Cannier̀e D.Robotic-enhanced biventricular resynchronization: an alternative toendovenous cardiac resynchronization therapy in chronic heart fail-ure. Ann Thorac Surg. 2003;76:413–7.

77. Mizuno T, Tanaka H, Makita S, Tabuchi N, Arai H, Sunamori M.Biventricular pacing with coronary bypass and Dor’s ventriculoplasty.Ann Thorac Surg. 2003;75:998–9.

78. Sachweh JS, Vazquez-Jimenez JF, Schondube FA, et al. Twentyyears experience with pediatric pacing: epicardial and transvenousstimulation. Eur J Cardiothorac Surg. 2000;17:455–61.

79. Walsh EP, Cecchin F. Recent advances in pacemaker and implant-able defibrillator therapy for young patients. Curr Opin Cardiol.2004;19:91–6.

80. Cohen MI, Rhodes LA, Spray TL, Gaynor JW. Efficacy of prophy-lactic epicardial pacing leads in children and young adults. AnnThorac Surg. 2004;78:197–202.

81. Vogt PR, Sagdic K, Lachat M, Candinas R, von Segesser LK, TurinaMI. Surgical management of infected permanent transvenous pace-maker systems: ten year experience. J Card Surg. 1996;11:180–6.

82. Setoguchi S, Stevenson LW, Schneeweiss S. Repeated hospitaliza-tions predict mortality in the community population with heartfailure. Am Heart J. 2007;154:260–6.

82a.Huang DT, Sesselberg HW, McNitt S, et al. Improved survivalassociated with prophylactic implantable defibrillators in elderlypatients with prior myocardial infarction and depressed ventricularfunction: a MADIT-II substudy. J Cardio Electro. 2007;18:833–8.

83. Koplan BA, Epstein LM, Albert CM, Stevenson WG. Survival inoctogenarians receiving implantable defibrillators. Am Heart J. 2006;152:714–9.

84. Lee DS, Tu JV, Austin PC, et al. Effect of cardiac and noncardiacconditions on survival after defibrillator implantation. J Am CollCardiol. 2007;49:2408–15.

85. Healey JS, Hallstrom AP, Kuck KH, et al. Role of the implantabledefibrillator among elderly patients with a history of life-threateningventricular arrhythmias. Eur Heart J. 2007;28:1746–9.

86. Mueller PS, Hook CC, Hayes DL. Ethical analysis of withdrawal ofpacemaker or implantable cardioverter-defibrillator support at theend of life. Mayo Clin Proc. 2003;78:959–63.

87. Lewis WR, Luebke DL, Johnson NJ, Harrington MD, CostantiniO, Aulisio MP. Withdrawing implantable defibrillator shock therapyin terminally ill patients. Am J Med. 2006;119:892–6.

88. Gostin LO. Law and medicine. JAMA. 1997;277:1866–7.89. Weiss JP, Saynina O, McDonald KM, McClellan MB, Hlatky MA.

Effectiveness and cost-effectiveness of implantable cardioverter defi-brillators in the treatment of ventricular arrhythmias among Medicarebeneficiaries. Am J Med. 2002;112:519–27.

90. O’Brien BJ, Connolly SJ, Goeree R, et al. Cost-effectiveness of theimplantable cardioverter-defibrillator: results from the CanadianImplantable Defibrillator Study (CIDS). Circulation. 2001;103:1416–21.

91. Larsen G, Hallstrom A, McAnulty J, et al. Cost-effectiveness of theimplantable cardioverter-defibrillator versus antiarrhythmic drugs insurvivors of serious ventricular tachyarrhythmias: results of theAntiarrhythmics Versus Implantable Defibrillators (AVID) eco-nomic analysis substudy. Circulation. 2002;105:2049–57.

92. Hlatky MA, Sanders GD, Owens DK. Evidence-based medicine andpolicy: the case of the implantable cardioverter defibrillator. Health
Aff (Millwood ). 2005;24:42–51.
93. Saksena S, Madan N, Lewis C. Implanted cardioverter-defibrillatorsare preferable to drugs as primary therapy in sustained ventriculartachyarrhythmias. Prog Cardiovasc Dis. 1996;38:445–54.

94. Kupersmith J, Hogan A, Guerrero P, et al. Evaluating and improvingthe cost-effectiveness of the implantable cardioverter-defibrillator.Am Heart J. 1995;130:507–15.

95. Larsen GC, Manolis AS, Sonnenberg FA, Beshansky JR, Estes NA,Pauker SG. Cost-effectiveness of the implantable cardioverter-defibrillator: effect of improved battery life and comparison withamiodarone therapy. J Am Coll Cardiol. 1992;19:1323–34.

96. Owens DK, Sanders GD, Harris RA, et al. Cost-effectiveness ofimplantable cardioverter defibrillators relative to amiodarone for preven-tion of sudden cardiac death. Ann Intern Med. 1997;126:1–12.

97. Sanders GD, Hlatky MA, Owens DK. Cost-effectiveness of implant-able cardioverter-defibrillators. N Engl J Med. 2005;353:1471–80.

98. Owens DK, Sanders GD, Heidenreich PA, McDonald KM, HlatkyMA. Effect of risk stratification on cost-effectiveness of the implant-able cardioverter defibrillator. Am Heart J. 2002;144:440–8.

99. Sears SE Jr., Conti JB. Understanding implantable cardioverterdefibrillator shocks and storms: medical and psychosocial consider-ations for research and clinical care. Clin Cardiol. 2003;26:107–11.

00. Schron EB, Exner DV, Yao Q, et al. Quality of life in theantiarrhythmics versus implantable defibrillators trial: impact oftherapy and influence of adverse symptoms and defibrillator shocks.Circulation. 2002;105:589–94.

01. Namerow PB, Firth BR, Heywood GM, Windle JR, Parides MK.Quality-of-life six months after CABG surgery in patients random-ized to ICD versus no ICD therapy: findings from the CABG PatchTrial. Pacing Clin Electrophysiol. 1999;22:1305–13.

02. Exner DV. Quality of life in patients with life-threatening arrhyth-mias: does choice of therapy make a difference? Am Heart J.2002;144:208–11.

03. Sears SF, Todaro JF, Urizar G, et al. Assessing the psychosocialimpact of the ICD: a national survey of implantable cardioverterdefibrillator health care providers. Pacing Clin Electrophysiol. 2000;23:939–45.

04. Wyman BT, Hunter WC, Prinzen FW, Faris OP, McVeigh ER.Effects of single- and biventricular pacing on temporal and spatialdynamics of ventricular contraction. Am J Physiol Heart CircPhysiol. 2002;282:H372–H379.

05. Yu Y, Kramer A, Spinelli J, Ding J, Hoersch W, Auricchio A.Biventricular mechanical asynchrony predicts hemodynamic effect ofuni- and biventricular pacing. Am J Physiol Heart Circ Physiol.2003;285:H2788–H2796.

06. Sweeney MO. The nature of the game. J Cardiovasc Electrophysiol.2005;16:483–5.

07. Wathen MS, Sweeney MO, DeGroot PJ, et al. Shock reductionusing antitachycardia pacing for spontaneous rapid ventricular tachy-cardia in patients with coronary artery disease. Circulation. 2001;104:796–801.

08. Wathen MS, DeGroot PJ, Sweeney MO, et al. Prospective random-ized multicenter trial of empirical antitachycardia pacing versusshocks for spontaneous rapid ventricular tachycardia in patients withimplantable cardioverter-defibrillators: Pacing Fast VentricularTachycardia Reduces Shock Therapies (PainFREE Rx II) trialresults. Circulation. 2004;110:2591–6.

09. Fisher JD, Mehra R, Furman S. Termination of ventricular tachy-cardia with bursts of rapid ventricular pacing. Am J Cardiol. 1978;41:94–102.

10. Gillis AM, Leitch JW, Sheldon RS, et al. A prospective randomizedcomparison of autodecremental pacing to burst pacing in devicetherapy for chronic ventricular tachycardia secondary to coronaryartery disease. Am J Cardiol. 1993;72:1146–51.

11. Schaumann A, von zur Mühlen F, Herse B, Gonska BD, Kreuzer H.Empirical versus tested antitachycardia pacing in implantable cardio-verter defibrillators: a prospective study including 200 patients.Circulation. 1998;97:66–74.

12. Wilkoff BL, Hess M, Young J, Abraham WT. Differences intachyarrhythmia detection and implantable cardioverter defibrillatortherapy by primary or secondary prevention indication in cardiacresynchronization therapy patients. J Cardiovasc Electrophysiol.
2004;15:1002–9.

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13. Schoenfeld MH. Contemporary pacemaker and defibrillator devicetherapy: challenges confronting the general cardiologist. Circulation.2007;115:638–53.

14. Scheinman M, Akhtar M, Brugada P, et al. Teaching objectives forfellowship programs in clinical electrophysiology. J Am Coll Cardiol.1988;12:255–61.

15. Faust M, Fraser J, Schurig L, et al. Educational guidelines for theclinically associated professional in cardiac pacing and electrophysi-ology. Pacing Clin Electrophysiol. 1990;13:1448–55.

16. Senges-Becker JC, Klostermann M, Becker R, et al. What is the“optimal” follow-up schedule for ICD patients? Europace. 2005;7:319–26.

17. Schoenfeld MH, Compton SJ, Mead RH, et al. Remote monitoringof implantable cardioverter defibrillators: a prospective analysis.Pacing Clin Electrophysiol. 2004;27:757–63.

18. Fetter JG, Stanton MS, Benditt DG, Trusty J, Collins J. Transtele-phonic monitoring and transmission of stored arrhythmia detectionand therapy data from an implantable cardioverter defibrillator.Pacing Clin Electrophysiol. 1995;18:1531–9.

19. Winters SL, Packer DL, Marchlinski FE, et al. Consensus statementon indications, guidelines for use, and recommendations forfollow-up of implantable cardioverter defibrillators. North AmericanSociety of Electrophysiology and Pacing. Pacing Clin Electrophysiol.2001;24:262–9.

20. Epstein AE, Miles WM, Benditt DG, et al. Personal and publicsafety issues related to arrhythmias that may affect consciousness:implications for regulation and physician recommendations. A med-ical/scientific statement from the American Heart Association andthe North American Society of Pacing and Electrophysiology. Cir-culation. 1996;94:1147–66.

21. Jung W, Luderitz B. European policy on driving for patients withimplantable cardioverter defibrillators. Pacing Clin Electrophysiol.
1996;19:981–4. a
22. Epstein AE, Baessler CA, Curtis AB, et al. Addendum to “Personaland public safety issues related to arrhythmias that may affectconsciousness: implications for regulation and physician recommen-dations: a medical/scientific statement from the American HeartAssociation and the North American Society of Pacing and Electro-physiology”: public safety issues in patients with implantable defi-brillators: a scientific statement from the American Heart Asso-ciation and the Heart Rhythm Society. Circulation. 2007;115:1170–6.

23. Maron BJ, Zipes DP. Introduction: eligibility recommendations forcompetitive athletes with cardiovascular abnormalities-general con-siderations. J Am Coll Cardiol. 2005;45:1318–21.

24. Practice advisory for the perioperative management of patients withcardiac rhythm management devices: pacemakers and implantablecardioverter-defibrillators: a report by the American Society ofAnesthesiologists Task Force on Perioperative Management of Pa-tients with Cardiac Rhythm Management Devices. Anesthesiology.2005;103:186–98.

25. Gould PA, Krahn AD. Complications associated with implantablecardioverter-defibrillator replacement in response to device adviso-ries. JAMA. 2006;295:1907–11.

26. Amin MS, Matchar DB, Wood MA, Ellenbogen KA. Managementof recalled pacemakers and implantable cardioverter-defibrillators: adecision analysis model. JAMA. 2006;296:412–20.

27. Hauser RG, Kallinen LM, Almquist AK, Gornick CC, KatsiyiannisWT. Early failure of a small-diameter high-voltage implantablecardioverter-defibrillator lead. Heart Rhythm. 2007;4:892–6.

ey Words: ACC/AHA practice guideline y device-based therapy ymplantable cardioverter-defibrillator y implantable coronary device y
rrhythmia y pacemaker y pacing y cardiomyopathy.
PPENDIX 1. AUTHOR RELATIONSHIPS WITH INDUSTRY—ACC/AHA/HRS GUIDELINES FOR DEVICE-BASEDHERAPY OF CARDIAC RHYTHM ABNORMALITIES

Committee MemberConsulting Fees/

Honoraria Speakers’ Bureau

Ownership/Partnership/

Principal Research GrantsInstitutional or Other

Financial Benefit

r. Andrew E.Epstein*

● Boston Scientific● CryoCath● Medtronic● Sanofi-Aventis● St. Jude†

● Boston Scientific● Medtronic● Reliant Pharmaceuticals● Sanofi-Aventis● St. Jude

None ● Biotronik†● Boston Scientific†● C. R. Bard/

Electrophysiology Division†● Irving Biomedical†● Medtronic†● St. Jude†

Electrophysiologyfellowship support from:

● Medtronic†● St. Jude†

r. John P. DiMarco* ● Boston Scientific†● CV Therapeutics†● Daiichi Sankyo● Medtronic†● Novartis†● Sanofi-Aventis● Solvay● St. Jude

None None ● Boston Scientific†● CV Therapeutics†● Medtronic● Sanofi-Aventis● St. Jude

None

r. Kenneth A.Ellenbogen*

● Ablation Frontiers● Atricure● Biosense Webster● Biotronik● Boston Scientific● Medtronic● Sorin/ELA● St. Jude

● Reliant Pharmaceuticals● Sanofi-Aventis

None ● Biosense Webster● Boston Scientific†● Cameron Medical● Impulse Dynamics● Medtronic†● St. Jude

None

r. N.A. MarkEstes III

● Medtronic ● Boston Scientific● Medtronic● St. Jude

None None None

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T

c

i

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Committee MemberConsulting Fees/



Principal Research GrantsInstitutional or Other

Financial Benefit

r. Roger A.Freedman*

● Boston Scientific● Medtronic● Sorin/ELA● St. Jude

● Boston Scientific● St. Jude

● St. Jude ● Boston Scientific†● Medtronic†● St. Jude†

University of Utah Divisionof Cardiology receiveselectrophysiologyfellowship support grantsfrom:

● Boston Scientific†● Medtronic†● St. Jude†

r. Leonard S.Gettes

None None None None None

r. A. Marc Gillinov* ● AtriCure● Edwards†● Medtronic

● Guidant● St. Jude

● Viacor† None None

r. GabrielGregoratos


r. Stephen C.Hammill

● Biosense Webster ● Boston Scientific None ● Medtronic None

r. David L. Hayes* ● AI Semi● Blackwell/Futura†● Boston Scientific†● Medtronic†● Sorin/ELA● St. Jude

None None ● Boston Scientific†● Medtronic†● St. Jude

● Biotronik● Boston Scientific†● Medtronic†● Sorin/ELA● St. Jude

r. Mark A. Hlatky ● Blue Cross/Blue ShieldTechnology EvaluationCenter

None None None None

r. L. Kristin Newby ● AstraZeneca/Atherogenics● Biosite● CV Therapeutics● Johnson & Johnson● Novartis● Procter & Gamble● Roche Diagnostics

None None ● Adolor● American Heart

Association†● BG Medicine● Bristol-Myers

Squibb/Sanofi†● Inverness Medical†● Medicure†● Schering-Plough†

None

r. Richard L. Page ● Astellas● Berlex● Pfizer● Sanofi-Aventis†

None None ● Procter & Gamble ● Boston Scientific†● Medtronic†● St. Jude†

r. Mark H.Schoenfeld


r. Michael J. Silka None None None None None

r. Lynne WarnerStevenson

● Biosense Webster‡● Boston Scientific‡● CardioMEMS● Medtronic● Medtronic‡● Scios

None None ● Biosense Webster‡● Medtronic

None

r. Michael O.Sweeney*

● Medtronic† ● Boston Scientific● Medtronic†

None None None

his table represents the relationships of committee members with industry that were reported orally at the initial writing committee meeting and updated in conjunction with all meetings and conference

alls of the writing committee during the document development process (last revision, January 16, 2008). It does not necessarily reflect relationships with industry at the time of publication. A person

s deemed to have a significant interest in a business if the interest represents ownership of 5% or more of the voting stock or share of the business entity, or ownership of $10 000 or more of the

air market value of the business entity, or if funds received by the person from the business entity exceed 5% of the person’s gross income for the previous year. A relationship is considered to be

odest if it is less than significant under the preceding definition. Relationships noted in this table are modest unless otherwise noted.

*Recused from voting on guideline recommendations. †Indicates significant-level relationship (more than $10 000). ‡Indicates spousal relationship.

AD

D

D

D

D

D

D

D

D


PPENDIX 2. PEER REVIEWER RELATIONSHIPS WITH INDUSTRY—ACC/AHA/HRS GUIDELINES FOREVICE-BASED THERAPY OF CARDIAC RHYTHM ABNORMALITIES

Peer Reviewer* RepresentationConsulting Fees/



Principal Research Grant

Institutional orOther Financial

Benefit

r. Mina K. Chung Official—Heart RhythmSociety

● American Collegeof CardiologyFoundation

● Boston MedicalCenter

● Boston Scientific(honorariadonated)

● Elsevier● Medtronic

(honorariadonated)

● Nexcura (nohonorariareceived)

● University of TexasHealth ScienceCenter

● WebMD Health(for CryoCathTechnologies, Inc.)

None None ● Biotronik† (researchgrants toelectrophysiologysection, ClevelandClinic)

● Boston Scientific†(research grants toelectrophysiologysection, ClevelandClinic)

● Medtronic†(research grants toelectrophysiologysection, ClevelandClinic)

● ReliantPharmaceuticals†(research grants toelectrophysiologysection, ClevelandClinic)

● St. Jude Medical†(research grants toelectrophysiologysection, ClevelandClinic)

None

r. Fred Kusumoto Official—Heart RhythmSociety

● Boston Scientific● Medtronic

None None None None

r. Bruce Lindsay Official—AmericanCollege of CardiologyBoard of Trustees


r. Samir Saba Official—American HeartAssociation

None None None ● Boston Scientific● Medtronic● St. Jude Medical

None

r. Paul Wang Official—American HeartAssociation;

Content—American HeartAssociationElectrocardiography andArrhythmias Committee

● Boston Scientific†● Lifewatch†● Medtronic● St. Jude

● Boston Scientific†● Medtronic● St. Jude

● HansenMedical†

● Boston Scientific†● Medtronic● St. Jude

None

r. Stuart Winston Official—AmericanCollege of CardiologyBoard of Governors

● Boston Scientific None None None None

r. Patrick McCarthy Organizational—Society ofThoracic Surgeons

● CV Therapeutics†● Medtronic

None None None None

r. Mandeep Mehra Organizational—HeartFailure Society ofAmerica

● Astellas● Boston Scientific● Cordis● Debiopharma● Medtronic● Novartis● Roche Diagnostics● Scios● Solvay● St. Jude

None None ● Maryland IndustrialPartnerships†

● National Institutes ofHealth†

● Other Tobacco-Related Diseases†

● University ofMaryland†(salary);

● Legalconsultant

D

D

D

D

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(


Peer Reviewer* RepresentationConsulting Fees/



Principal Research Grant

Institutional orOther Financial

Benefit

r. JenniferCummings

Content—AmericanCollege of CardiologyFoundation ClinicalElectrophysiologyCommittee

● Corazon● Medtronic● Reliant● Signalife● St. Jude● Zin

None None None None

r. ChristopherFellows

Content—AmericanCollege of CardiologyFoundation ClinicalElectrophysiologyCommittee

● Boston Scientific● St. Jude

None None None None

r. NoraGoldschlager

Content—Individual ● St. Jude None None None None

r. Peter Kowey Content—AmericanCollege of CardiologyFoundation ClinicalElectrophysiologyCommittee

None ● Medtronic† ● CardioNet† None None

r. Rachel Lampert Content—Heart RhythmSociety Scientific andClinical DocumentsCommittee

None None None ● Boston Scientific†● Medtronic†● St. Jude†

None

r. J. Philip Saul Content—Pediatric Expertand American Collegeof CardiologyFoundation ClinicalElectrophysiologyCommittee


r. George Van Hare Content—Individual ● St. Jude None None ● Medtronic†(fellowship funding)

None

r. Edward P. Walsh Content—IndividualPediatric Expert


r. Clyde Yancy Content—AmericanCollege of Cardiology/American HeartAssociation Lead TaskForce Reviewer and2005 Chronic HeartFailure GuidelineWriting Committee

● AstraZeneca● GlaxoSmithKline● Medtronic● NitroMed● Otsuka● Scios

● GlaxoSmithKline● Novartis

None ● GlaxoSmithKline● Medtronic● NitroMed● Scios

None

his table represents the relationships of reviewers with industry that were reported at peer review. It does not necessarily reflect relationships with industry at the time of publication. A person is deemedo have a significant interest in a business if the interest represents ownership of 5% or more of the voting stock or share of the business entity, or ownership of $10 000 or more of the fair marketalue of the business entity, or if funds received by the person from the business entity exceed 5% of the person’s gross income for the previous year. A relationship is considered to be modest if its less than significant under the preceding definition. Relationships noted in this table are modest unless otherwise noted.

*Names are listed in alphabetical order within each category of review. Participation in the peer review process does not imply endorsement of this document. †Indicates significant-level relationshipmore than $10 000).

AA

A

A

A

A

A

A

A

A

A

C

C

C

C

C

C

C

C

C

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D

E

H

H

H

I

L

L

M

M

M

M

M

N

P

P

P

Q

R

R

S

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S

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PPENDIX 3. ABBREVIATIONS LISTCC � American College of Cardiology

CCF � American College of Cardiology Foundation

F � Atrial fibrillation

HA � American Heart Association

MI � Acute myocardial infarction

MIOVIRT � Amiodarone Versus Implantable Defibrillator in Patients with Nonischemic Cardiomyopathy and Asymptomatic Nonsustained Ventricular Tachycardia

RVD/C � Arrhythmogenic right ventricular dysplasia/cardiomyopathy

TP � Antitachycardia pacing

V � Atrioventricular

VID � Antiarrhythmics Versus Implantable Defibrillators

ABG-Patch � Coronary Artery Bypass Graft-Patch

ARE-HF � Cardiac Resynchronization in Heart Failure

ASH � Cardiac Arrest Study Hamburg

AT � Cardiomyopathy Trial

IDS � Canadian Implantable Defibrillator Study

OMPANION � Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure Trial

RT � Cardiac resynchronization therapy

RT-D � Cardiac resynchronization therapy device incorporating both pacing and defibrillation capabilities

RT-P � Cardiac resynchronization device providing pacing but not defibrillation capability

TOPP � Canadian Trial of Physiologic Pacing

CM � Dilated cardiomyopathy

DD � Dual-chamber pacemaker that senses/paces in the atrium/ventricle and is inhibited/triggered by intrinsic rhythm

EFINITE � Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation

INAMIT � Defibrillator in Acute Myocardial Infarction Trial

CG � Electrocardiograph

CM � Hypertrophic cardiomyopathy

R � Hazard ratio

RS � Heart Rhythm Society

CD � Implantable cardioverter-defibrillator

V � Left ventricular/left ventricle

VEF � Left ventricular ejection fraction

ADIT I � Multicenter Automatic Defibrillator Implantation Trial I

ADIT II � Multicenter Automatic Defibrillator Implantation Trial II

I � Myocardial infarction

OST � Mode Selection Trial

USTT � Antiarrhythmic Drug Therapy in the Multicenter UnSustained Tachycardia Trial

YHA � New York Heart Association

ainFREE Rx II � Pacing Fast VT Reduces Shock Therapies Trial II

ASE � Pacemaker Selection in the Elderly

AVE � Left Ventricular-Based Cardiac Stimulation Post AV Nodal Ablation Evaluation Study

OL � Quality of life

V � Right ventricular/right ventricle

VA � Right ventricular apical

CD � Sudden cardiac death

CD-HeFT � Sudden Cardiac Death in Heart Failure Trial

ND � Sinus node dysfunction

VT � Supraventricular tachycardia

TM � Transtelephonic monitoring

K-PACE � United Kingdom Pacing and Cardiovascular Events

F � Ventricular fibrillation

PS � Vasovagal Pacemaker Study I

PS-II � Vasovagal Pacemaker Study II

T � Ventricular tachycardia