Embed Size (px)
Citation preview
1
TITLE: Cryoballoon Ablation for Atrial Fibrillation
AUTHOR: Judith Walsh, MD, MPH Professor of Medicine
Division of General Internal Medicine Department of Medicine University of California San Francisco PUBLISHER: California Technology Assessment Forum DATE OF PUBLICATION: June 29, 2011 PLACE OF PUBLICATION: San Francisco, CA
2
CRYOBALLOON ABLATION FOR ATRIAL FIBRILATION A Technology Assessment
INTRODUCTION
The California Technology Assessment Forum (CTAF) was asked to assess the evidence for
cryoballoon catheter ablation for the treatment of atrial fibrillation. This topic is being reviewed
now because of its potential as a new nonpharmacologic ablative procedure for the treatment of
atrial fibrillation (AF).
BACKGROUND
AF, the most common sustained atrial arrhythmia, is more common in men where the prevalence
increases with increasing age1. AF can be paroxysmal (episodes terminate in less than seven
days), persistent (more than seven days) or chronic (more than a year). AF can cause significant
symptoms including palpitations, shortness of breath and fatigue. In addition, AF is associated with
a fivefold increased risk of stroke as well as an increased risk of mortality.
The two goals of therapy of AF are risk reduction of stroke and alleviation of symptoms. Stroke
reduction requires anticoagulation with warfarin for most individuals. Treatment of the symptoms of
AF include strategies to convert the patient back to normal sinus rhythm or strategies to control the
rate of AF. Although there was no overall mortality difference, some randomized trials of rate
versus rhythm control have suggested a trend toward reduced mortality in patients who are treated
with rate control2-4. There were no differences in functional status of quality of life.
Maintenance of sinus rhythm has typically been achieved with electrical cardioversion or with
antiarrhythmic drugs. Antiarrhythmic drugs can sometimes have limited efficacy and can also have
significant side effects which limit their long term use.
Because of the limitations of antiarrhythmic drugs, nonpharmacologic approaches to the
maintenance of sinus rhythm have been explored. These nonpharmacologic approaches include
surgery or ablation procedures, such as radiofrequency ablation (RFA) or cryoballoon ablation.
3
The initiation of AF requires both a trigger either within or near the atria and a susceptible substrate
within the atria5. Ablation procedures for preventing recurrent AF are directed towards 1)
elimination of the triggers of AF which is done by disrupting the conduction of electrical activity
between the tissues that contain the arrhythmogenic triggers (usually the pulmonary veins (PV))
and the atrial myocardium or 2) modifying the atrial substrate responsible for maintaining AF.
The triggers in paroxysmal AF and chronic or persistent AF appear to be different, which makes
paroxysmal AF a better potential target for ablation procedures. In paroxysmal AF, ectopic beats
commonly come from muscle fibers that extend from the left atrium (LA) to the pulmonary veins
(PV). These ectopic foci can be localized to the PV in about 90% of people with paroxysmal AF.
Most patients only have one or two foci, making them easier targets for ablation. The majority of
the foci are from 2-4 cm inside the PV and the remaining foci are usually in the right or LA.
Ablation attempts have typically targeted the foci in the PV6-8.
In contrast, in chronic AF, there tend to be multiple ectopic sites throughout the atria. Since
ablation procedures often focus on isolation of the PV, these procedures are potentially less
efficacious in patients with chronic AF9. The goal of most ablation procedures is to achieve
complete electrical isolation of the PV from the left atrium. Many studies evaluate PV isolation as
an intermediate outcome when evaluating cryoballoon ablation efficacy.
Although RFA has been successful in eliminating some ectopic foci, and in reducing symptomatic
AF at one year follow-up10, challenges with RFA have included difficulties in isolating the ectopic
focus and PV stenosis. Isolation of the PV ectopic foci using RFA is complicated and requires
complex imaging and mapping techniques. Because of difficulties in isolating the ectopic foci in the
PV, some newer approaches have aimed to isolate all four PVs from the body of the atrium6.
Cryoballoon ablation has the theoretical advantage of allowing PV isolation with a single
application, whereas with conventional RFA technology, multiple applications around the PVs are
4
required to isolate the PVs at the level of the antrum. In addition, cryoablation is potentially simpler
and less dependent on the operator.
In conclusion, cryoballoon ablation has been proposed as a treatment alternative for AF, and may
be particularly useful in AF refractory to antiarrhythmic drug therapy (ADT). Similar to other ablation
procedures, it has the potential advantage of avoiding long term drug side effects. In comparison
with RFA, it has the theoretic advantage of simpler isolation of the pulmonary veins. Thus, the
question is how does it compare to other treatment options for the treatment of drug refractory AF.
TA Criterion 1: The technology must have final approval from the appropriate government
regulatory bodies
Cryoablation for atrial fibrillation is a procedure and not subject to FDA approval. However,
devices used for this procedure may be subject to FDA approval. The Arctic Front® Cardiac Cryo-
Ablation Catheter system by Medtronic which received FDA PMA status in August 2007 is the only
device approved for use for this procedure. Some studies have indicated the use of the CryoCor
device for atrial fibrillation. However, the CryoCor device has FDA clearance for use in only atrial
flutter and therefore any use for atrial fibrilation would be considered off label.
TA criterion 1 is met.
TA Criterion 2: The scientific evidence must permit conclusions concerning the
effectiveness of the technology regarding health outcomes.
The Medline database, Cochrane clinical trials database, Cochrane reviews database and
Database of Abstracts of Reviews of Effects (DARE) were searched using the search terms atrial
fibrillation or paroxysmal atrial fibrillation and also with the term cryotherapy or cryosurgery or
cryoballoon or cryoablation or cryo-Maze or cryotherm and catheter ablation and argon or cool or
cooled or cooling. The search was performed for the period from 1966 to April, 2011. The
5
bibliographies of systematic reviews and key articles were manually searched for additional
references and references were requested form the device manufacturer. The abstracts of
citations were reviewed for relevance and all potentially relevant articles were reviewed in full.
Inclusion criteria:
Study had to evaluate cryoballoon ablation in patients with AF
Study had to measure clinical outcomes
Included only humans
Published in English as a peer reviewed article
Studies were excluded if they only focused on non-clinical outcomes. They were also excluded if
they were retrospective. We also excluded studies that only evaluated cryoablation techniques as
part of a surgical procedure.
A total of 590 potentially relevant articles were identified. 535 were excluded for not addressing the
research question. A total of 55 abstracts were evaluated. 43 were excluded. Reasons for
exclusion included not reporting clinical outcomes, not being prospective, or evaluating
cryoablation as part of a surgical procedure. Of these, twelve published prospective studies are
included in this evaluation.
Details of the twelve prospective studies and the outcomes measured are described in Table 1.
There were ten prospective observational studies and two nonrandomized comparison studies. To
date, no randomized controlled trials (RCT) evaluating clinical outcomes comparing cryoablation
with other atrial fibrillation treatments have been published.
Although the outcomes varied among the studies, typical outcomes included the percentage of
individuals remaining free from atrial arrhythmias or the time to recurrence of atrial
tachyarrhythmia. No studies have assessed the impact of cryoballoon ablation on the important
outcomes of mortality, stroke, heart failure or progression of paroxysmal AF to more persistent
forms, although typically the main goal of catheter ablation is to decrease the symptoms associated
with AF.
6
Table 1: Study Characteristics of Prospective studies of Cryoballoon Ablation for the Treatment of
Atrial Fibrillation
Study N Inclusion Criteria
Intervention Outcomes
Neumann, 200811 346 Symptomatic and drug refractory paroxysmal or persistent AF
Cryoablation (Arctic Front CryoCath)
First recurrence of AF
Hoyt, 200512 32 Drug refractory paroxysmal AF
Cryoablation (CryoCor)
First recurrence of AF
Defaye, 201113 117 Paroxysmal or persistent AF resistant to or intolerant of drugs
Cryoablation (Arctic Front CryoCath)
Freedom from symptomatic or documented AF
Moreira, 200814 70 Recent onset parosysmal AF
Cryothermic ostial PV isolation (CryoCor)
Complete success; recurrences
Klein, 200815 21 Highly symptomatic paroxysmal AF and at least one unsuccessful try of anti arrhythmic therapy
Cryoablation (Arctic Front CryoCath)
Recurrence of symptomatic AF
Chun, 200916 27 Highly symptomatic AF despite drug treatment
Cryoablation (Arctic Front CryoCath)
Acute PVI Complications AF recurrence
Chierchia, 201017 21 Symptomatic drug resistant paroxysmal AF
Cryoablation (Arctic Front CryoCath)
Recurrence of atrial arrhythmias
Mansour, 201018 22 Drug refractory persistent AF
Cryoablation (Arctic Front CryoCath) and RFA
% AF free without antiarrhythmic drugs
Tang, 201019 23 Symptomatic medically refractory paroxysmal AF
Cryoablation (Arctic Front CryoCath)
% free from AF
Kuhne, 201020 14 Symptomatic Cryoablation % free from AF
7
persistent, paroxysmal AF
(Arctic Front CryoCath)
Nonrandomized comparisons
Hofmann, 201021 79 Symptomatic drug refractory paroxysmal AF “Anatomically suitable Pulmonary Veins (PV)”
Mesh Ablator catheter (MESH) (n=43) vs cryoballoon (n=36) (manufacturer not stated) (sequential patients)
Clinical success freedom from AF off drugs
Kojodjojo, 201022 177 Symptomatic medically refractory persistent or paroxysmal AF
Cryoablation (Arctic Front ) (n=124)or RFA (n=53) (nonrandomized)
% free from AF
Completed, not yet published
STOP-AF, 2010 abstract
245 At least 2 episodes of documented AF in previous 2 months or treatment failure with at least one anti-arrhythmic drug
Cryoablation (Arctic Front CryoCath) vs anti-arrhythmic drug therapy
Freedom from combined outcome of detectable AF, use of non-study drugs and other AF interventions
Ongoing
FREEZE-AF [Luik, 2010]
Goal 244 At least two episodes of PAF in past 3 months; failure of at least on ADT
RFA vs Cryoablation (Arctic Front CryoCath)
Freedom from AF without antiarrhythmic drugs and without persistent complications at 6 and 12 months
Table Legend: AF Atrial fibrillation PVI Pulmonary vein isolation MESH Mesh ablator catheter ADT Anti-arrhythmic drug therapy RFA Radiofrequency catheter ablation Level of Evidence: 3,4,5
8
TA Criterion 2 is met.
TA Criteria 3: The technology must improve net health outcomes
A total of 693 patients were included in 10 prospective studies of cryoballoon ablation. Two
additional nonrandomized studies compared cryoablation with RFA. The study characteristics are
described in Table 1 and the study results are described in Table 2. The majority of the
noncomparative studies had less than 50 patients each; two of the studies were larger and
accounted for 463 of the 693 patients. Follow-up ranged from six months to one year. Some of the
studies only included patients with paroxysmal AF, but many included patients with either
paroxysmal or persistent AF.
9
Table 2: Results of Prospective Studies of Cryoballoon Ablation in the Treatment of Atrial
Fibrillation
Study Mean age Average length of
follow-up
Results
Neumann, 200811 59 12 months Maintenance of sinus rhythm in 74% of patients with paroxysmal AF and 42% of those with persistent AF
Hoyt, 200512 Not reported 6 months Of 29 with immediately successful ablation, 7 had recurrence within 3 months. Among 22 with single cryoablation, 18 (82%) free of symptomatic AF and 55% off anti-arrhythmic drugs
Defaye, 201113 55 9.6 months Paroxysmal AF: at 6 months 79% recurrence free and 69% recurrence free at 12 months
Moreira, 200814 40 33 months 49% complete success (no AF and no drugs) 22% had no recurrence with anti-arrhythmic drugs
Klein, 200815 56 6 month 86% of patients free of AF at 6 months
Chun, 200916 56 271 days 39% with AF recurrence
Chierchia, 201017 73 11.5 months 62% with no arrhythmia symptoms at follow up
Mansour, 201018 22 6 months 86.4% AF free and not on ADT
Tang, 201019 Not reported 7.4 months 74% free form AF at 7.4 months
Kuhne, 201020 59 1 year 71% free from AF at
10
one year follow up
Nonrandomized comparisons
Hofmann, 201021 56/59 6 months Clinical success 44% in MESH and 69% in cryo (p,0.05)
Kojodjojo, 201022 57/61 13.1 months 77% of PAF treated with cryo free of AF at 12 months (vs 72% for RFA) 48% of persistent AF treated with cryo free of AF at 12 month follow-up (too few to calculate for RFA)
Completed, not yet published
STOP-AF 2010 abstract
57 12 months 69.9% free of AF and did not require administration of a non-study drug or interventional procedure for treatment of AF
Table legend: AF Atrial fibrillation ADT Antiarrhythmic drug therapy MESH Mesh Ablator catheter PAF Paroxysmal atrial fibrillation RFA Radiofrequency catheter ablation
In the single center French study done by Defaye et al., 117 consecutive patients with paroxysmal
(n=92) or persistent (n=25) AF were followed for an average of 9.6 months after undergoing
cryoablation. At nine months, 79% of patients with Paroxysmal atrial fibrillation (PAF) were AF
free, whereas at nine months 59% with persistent AF were AF free. Phrenic nerve palsy was the
most frequent complication.
In the largest prospective study, 346 patients in three centers with drug refractory PAF (n=293) or
persistent AF (n=53) underwent cryoablation11. Similar to the results seen in the French study,
11
more patients with PAF than with persistent AF remained in sinus rhythm at 12 month follow up
(74% vs 42%). Phrenic nerve palsy was the most frequent complication. Other complications
included those related to the catheter (femoral AV fistula, femoral arterial pseudoaneurysm). Two
patients had transient ST elevation that resolved within two minutes. There were no cases of PV
stenosis, although this complication has been reported in other studies of this procedure.
Potential Benefits
In all ten of the observational noncomparative studies, as well as in the two nonrandomized
comparative studies, cryoballoon ablation was associated with a significant percentage of patients
being free of AF and/or being off ADT at follow-up. Many of the studies included patients with both
PAF and persistent AF and, in general, the benefits seemed to be greater in those with PAF, but
these groups were not analyzed separately.
In a recent meta-analysis of cryoballoon ablation studies, among studies reporting a three month
blanking period (time frame during which transient arrhythmias were not considered recurrences) ,
at one year follow-up, 72.83% were free from recurrent AF23. Again, these were mostly
observational studies with no comparison group.
Overall, the follow-up of these observational studies were relatively short (longest was one year)
and there were no comparison groups, but many patients were free of AF at follow-up.
Potential Harms
The most common complication of cryoballoon ablation is phrenic nerve palsy, with an incidence of
6.38% in a recent meta-analysis23. The incidence went down to 4.73% after the ablation period.
The vast majority of patients recovered with time, with only 0.37% having phrenic nerve palsy that
lasted more than a year.
PV stenosis is a common complication of ablation procedures although it is often asymptomatic.
Among studies that systematically screened for PV stenosis, the incidence of radiographic PV
12
stenosis was 0.89%23. However, in a recent study presented in abstract form (STOP-AF) , PV
stenosis occurred in 3% of patients24. Overall the incidence of significant PV stenosis resulting in
symptoms or requiring intervention was 0.17% in the recent meta-analysis23.
The incidence of thromboembolic complications, including periprocedural stroke, transient ischemic
attacks (TIA) or myocardial infarction (MI), was 0.57%, and pericardial effusion or tamponade
occurred in 1.46% of cases23. Overall, when comparing the complications seen with cryoablation
with those seen with RFA, the complication rates seem to be relatively similar.
Summary
In summary, AF cryoballoon ablation leads to a significant number of patients being free from AF at
follow up and off ADT, although the longest duration of follow up for which outcomes have been
measured is 12 months. Phrenic nerve palsy is the most common complication although it usually
spontaneously resolves over time. PV stenosis is a potentially serious complication and its exact
incidence remains controversial, in part based on differing definitions of how to define the outcome.
Despite this, the incidence of symptomatic PV requiring intervention appears to be relatively low.
What remains unknown are the long term effects- both positive and negative- of cryoballoon
ablation..
TA Criterion 3 is met.
TA Criterion 4: The technology must be as beneficial as any of the established alternatives.
The main potential alternatives to cryoballoon ablation are ADT or RFA. Among patients with PAF,
without prior exposure to ADT, approximately 20-40% of patients treated with either class I drugs
or sotolol and 60-70% of patients treated with amiodarone will have no recurrence of AF at one
year2,25,26. Many patients cannot be maintained in sinus rhythm with ADT. Amiodarone, although
commonly used for the treatment of AF, is not FDA approved for this indication.
13
Since ADT as the established alternative for rhythm control is not ideal, other options are needed.
The main nonpharmacologic approach to AF is RFA. Several RCTs have compared RFA with ADT
although the duration of follow-up was short10,27-31. In the short term, RFA has been shown to be
more beneficial than ADT at preventing recurrent symptomatic AF, and for individuals for whom
ADTs have failed or not tolerated, RFA has emerged as a nonpharmacologic alternative. CTAF
reviewed the use of RFA as a treatment for PAF refractory to drug therapy in June, 2010, and
concluded that RFA for this use met CTAF criteria 1 through 5 for safety, effectiveness and
improvement in health outcomes. Thus cryoballoon ablation must be compared to either ADT or
RFA.
To date, two nonrandomized studies have compared cryoballoon ablation with RFA. In an Austrian
study, 79 patients whose anatomy was deemed suitable underwent RFA or cryoablation. The first
43 patients received RFA and the subsequent 36 patients were treated with cryoablation. The
clinical success rate was defined as absence of AF without ADT. As is typical in these studies, the
first two months were a “blanking” period, and AF recurrences during this time period were not
considered as failures. At six month follow-up, the clinical success rate was 69% in the
cryoballoon ablation group and 44% in the RFA group (p<0.05)21. Although the clinical success at
six months was superior with cryoballoon ablation, the generalizability of these results obtained in a
nonrandomized group of patients is minimal.
In the other nonrandomized study, 124 consecutive patients with paroxysmal or persistent AF
underwent cryoballoon ablation, and during the same time period, 53 consecutive patients
underwent RFA. Investigators reported results separately for patients with paroxysmal and
persistent AF at 12 month follow-up. At 12 months, 77% of patients with PAF undergoing
cryoballoon ablation were free of AF compared with 72% of those undergoing RFA (p=NS).
Among those with persistent AF, at 12 months, 48% of those with persistent AF who were treated
with cryoballoon ablation were free of AF at follow-up. There were too few patients with persistent
AF treated with RFA to allow a meaningful comparison. In a nonrandomized study that combined
14
patients with PAF and persistent AF, the comparative efficacy of RFA and cryoablation cannot be
evaluated.
In May of 2010, the results of the STOP-AF (sustained treatment of paroxysmal AF) trial were
reported at the American College of Cardiology Annual Scientific session24: Cryoballoon Ablation
of Pulmonary Veins for Paroxysmal Atrial Fibrillation: First Results of the North American Arctic
Front STOP-AF Pivotal Trial24. The STOP-AF trial included 245 patients with PAF who were
refractory to at least one anti-arrhythmic drug. Patients were randomized to receive either ADT or
cryoballoon ablation using the Arctic Front Cryoablation catheter system. There was a 90 day
blanking period during which AF recurrences were not considered failures. Patients were followed
up at one, three, six, nine and 12 months. A total of 163 patients were treated with cryoablation
and 82 received ADT. Patient mean age was 57 and 77% were men. Less than 10% were New
York Heart Association (NYHA) class II or greater and the mean left ventricular ejection fraction
(LVEF) was 60%. Nineteen percent of patients required a repeat ablation during the blanking
period. At one year follow-up, 69.9% of the patients treated with cryoablation were free of PAF, in
contrast to only 8.3% of patients treated with ADT. About 3% of individuals treated with
cryoablation had a serious complication requiring an intervention. PV stenosis occurred in 3.1% of
patients in the cryoablation arm compared with 2.4% of patients in the drug treatment arm. One
patient with PV stenosis required surgical intervention. Phrenic nerve palsy was common and
occurred in about 11% of patients, although the vast majority resolved at 12 month follow-up.
There was a high rate of crossover from the ADT arm to the cryoblation arm. Among patients
treated with cryoablation for AF, less than 1% were hospitalized with an AF recurrence, compared
with 6% of those treated with ADT.
The STOP-AF trial compares cryoablation with ADT. Another important question is how
cryoballoon ablation compares with RFA, since often these ablation procedures are considered in
patients who are refractory to or unable to tolerate ADT. The FREEZE-AF trial is an ongoing trial
which aims to recruit 244 patients with PAF and randomize them to RFA vs. cryoablation. Study
outcomes will include freedom from AF without antiarrhythmic drugs and without persistent
15
complications measured at about both six and 12 months. The results of this study will provide
important information about the comparative efficacy of RFA and cryoablation for the treatment of
paroxysmal AF.
Thus to date, two non-randomized studies have compared cryoablation to RFA. Although the
results suggest that cryoablation may be potentially beneficial, definitive conclusions cannot be
drawn from nonrandomized studies. The results of the STOP-AF trial, reported in abstract form,
suggest that cryoablation is effective at one year follow-up in treating many patients with drug
refractory AF, although some patients did develop pulmonic stenosis. However, the results of the
STOP-AF trial cannot be considered definitive until published in a peer reviewed journal. In the
future, the FREEZE-AF trial will provide important information about the comparative efficacy of
RFA and cryoballoon ablation.
TA Criterion 4 is not met.
TA Criterion 5: The improvement must be attainable outside the investigational settings.
Since an improvement has not yet been shown in the investigational setting, it is not possible to
demonstrate an improvement outside the investigational setting.
TA Criterion 5 is not met.
Summary
Cryoballon ablation is proposed as an alternative treatment for atrial fibrillation, and could
potentially be most useful in individuals with PAF refractory to drug treatment. Although many
prospective observational studies have suggested that cryoballoon ablation can reduce AF and
ADT use at one year follow-up, to date, no published RCTs have compared cryoablation with either
16
ADT or RFA catheter ablation. In addition, evidence comparing long term benefits and harms to
other treatments is also lacking.
RECOMMENDATION
It is recommended that cryoablation as a treatment for atrial fibrillation does not meet meets CTAF
TA criteria 4 or 5 for improvement in health outcomes.
The California Technology Assessment Forum panel voted to accept the recommendation as
written.
June 29, 2011
This is the first time CTAF has reviewed this technology.
17
RECOMMENDATIONS OF OTHERS
Blue Cross Blue Shield Association (BCBSA)
A search of the BCBSA Technology Evaluation Center website did not find any assessment on
cryoablation for atrial fibrillation.
Centers for Medicare and Medicaid Services (CMS)
No CMS National Coverage Determination (NCD) was found for cryoablation for atrial fibrillation.
California Chapter of the American College of Cardiology (CA ACC)
The CA ACC was invited to provide an opinion on this technology and to provide testimony at the
public meeting on June 29, 2011. CA ACC did not provide an opinion nor did a representative
attend the meeting to provide testimony.
Heart Rhythm Society (HRS)
The HRS provided an opinion supporting the use of this technology. HRS provided a written
opinion and a representative attended the meeting and provided testimony on behalf of HRS .
Agency for Healthcare Research and Quality (AHRQ)
No specific guideline was found for cryoablation for atrial fibrillation.
National Institute for Health and Clinical Excellence (NICE)
The Interventional Procedures Advisory Committee (IPAC) of NICE will be considering the
development of a guideline for percutaneous balloon cryoablation for atrial fibrillation over the
summer of 2011 and expects a provisional publication date of a guideline by autumn of 2011.
ACC/AHA
In 2011, the American College of Cardiology Foundation and the American Heart Association Task
Force on Practice Guidelines updated their 2006 Guidelines for the Management of Patients with
18
Atrial Fibrillation. These updated guidelines were developed in collaboration with the Heart
Rhythm Society. The guideline is available at:http://circ.ahajournals.org/cgi/content/full/123/1/104.
ESC
The Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology
(ESC) also released their guideline for the management of atrial fibrillation.
The guideline is available at:
http://www.escardio.org/guidelines-surveys/esc-guidelines/Pages/atrial-fibrillation.aspx
19
ABBREVIATIONS USED IN THIS REPORT
CTAF California Technology Assessment Forum
RFA Radiofrequency catheter ablation
AF Atrial fibrillation
PV Pulmonary veins
LA Left atrium
ADT Antiarrhythmic drug therapy
DARE Database of Abstracts of Reviews of Effects
PAF Paroxysmal atrial fibrillation
RCT Randomized controlled trials
MI Myocardial infarction
TIA Transient ischemic attacks
PVI Pulmonary vein isolation
MESH Mesh ablator catheter
NYHA New York Heart Association
LVEF Left ventricular ejection fraction
STOP-AF Sustained treatment of paroxysmal AF
20
REFERENCES
1. Go AS, Hylek EM, Phillips KA, et al. Prevalence of diagnosed atrial fibrillation
in adults: national implications for rhythm management and stroke prevention: the
AnTicoagulation and Risk Factors in Atrial Fibrillation (ATRIA) Study. Jama.
May 9 2001;285(18):2370-2375.
2. Maintenance of sinus rhythm in patients with atrial fibrillation: an AFFIRM
substudy of the first antiarrhythmic drug. Journal of the American College of
Cardiology. Jul 2 2003;42(1):20-29.
3. Van Gelder IC, Hagens VE, Bosker HA, et al. A comparison of rate control and
rhythm control in patients with recurrent persistent atrial fibrillation. The New
England journal of medicine. Dec 5 2002;347(23):1834-1840.
4. Wyse DG, Waldo AL, DiMarco JP, et al. A comparison of rate control and
rhythm control in patients with atrial fibrillation. The New England journal of
medicine. Dec 5 2002;347(23):1825-1833.
5. Calkins H, Brugada J, Packer DL, et al. HRS/EHRA/ECAS expert Consensus
Statement on catheter and surgical ablation of atrial fibrillation: recommendations
for personnel, policy, procedures and follow-up. A report of the Heart Rhythm
Society (HRS) Task Force on catheter and surgical ablation of atrial fibrillation.
Heart Rhythm. Jun 2007;4(6):816-861.
6. Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation
by ectopic beats originating in the pulmonary veins. The New England journal of
medicine. Sep 3 1998;339(10):659-666.
7. Chen SA, Hsieh MH, Tai CT, et al. Initiation of atrial fibrillation by ectopic beats
originating from the pulmonary veins: electrophysiological characteristics,
pharmacological responses, and effects of radiofrequency ablation. Circulation.
Nov 2 1999;100(18):1879-1886.
8. Tsai CF, Tai CT, Hsieh MH, et al. Initiation of atrial fibrillation by ectopic beats
originating from the superior vena cava: electrophysiological characteristics and
results of radiofrequency ablation. Circulation. Jul 4 2000;102(1):67-74.
9. Cheema A, Dong J, Dalal D, et al. Circumferential ablation with pulmonary vein
isolation in permanent atrial fibrillation. The American journal of cardiology.
May 15 2007;99(10):1425-1428.
10. Wilber DJ, Pappone C, Neuzil P, et al. Comparison of antiarrhythmic drug
therapy and radiofrequency catheter ablation in patients with paroxysmal atrial
fibrillation: a randomized controlled trial. Jama. Jan 27 2010
303(4):333-340.
11. Neumann T, Vogt J, Schumacher B, et al. Circumferential pulmonary vein
isolation with the cryoballoon technique results from a prospective 3-center study.
J Am Coll Cardiol. Jul 22 2008;52(4):273-278.
12. Hoyt RH, Wood M, Daoud E, et al. Transvenous catheter cryoablation for
treatment of atrial fibrillation: results of a feasibility study. Pacing Clin
Electrophysiol. Jan 2005;28 Suppl 1:S78-82.
21
13. Defaye P, Kane A, Chaib A, Jacon P. Efficacy and safety of pulmonary veins
isolation by cryoablation for the treatment of paroxysmal and persistent atrial
fibrillation. Europace. Mar 31 2011.
14. Moreira W, Manusama R, Timmermans C, et al. Long-term follow-up after
cryothermic ostial pulmonary vein isolation in paroxysmal atrial fibrillation. J Am
Coll Cardiol. Feb 26 2008;51(8):850-855.
15. Klein G, Oswald H, Gardiwal A, et al. Efficacy of pulmonary vein isolation by
cryoballoon ablation in patients with paroxysmal atrial fibrillation. Heart Rhythm.
Jun 2008;5(6):802-806.
16. Chun KR, Schmidt B, Metzner A, et al. The 'single big cryoballoon' technique for
acute pulmonary vein isolation in patients with paroxysmal atrial fibrillation: a
prospective observational single centre study. Eur Heart J. Mar 2009;30(6):699-
709.
17. Chierchia GB, Capulzini L, de Asmundis C, et al. Cryoballoon ablation for
paroxysmal atrial fibrillation in septuagenarians: a prospective study. Indian
Pacing Electrophysiol J. 2010;10(9):393-399.
18. Mansour M, Forleo GB, Pappalardo A, et al. Combined use of cryoballoon and
focal open-irrigation radiofrequency ablation for treatment of persistent atrial
fibrillation: results from a pilot study. Heart Rhythm. Apr 2010;7(4):452-458.
19. Tang M, Kriatselis C, Nedios S, et al. A novel cryoballoon technique for mapping
and isolating pulmonary veins: a feasibility and efficacy study. J Cardiovasc
Electrophysiol. Jun 1 2010;21(6):626-631.
20. Kuhne M, Schaer B, Ammann P, Suter Y, Osswald S, Sticherling C. Cryoballoon
ablation for pulmonary vein isolation in patients with paroxysmal atrial
fibrillation. Swiss Med Wkly. Apr 17 2010;140(15-16):214-221.
21. Hofmann R, Honig S, Leisch F, Steinwender C. Pulmonary vein isolation with
Mesh Ablator versus cryoballoon catheters: 6-month outcomes. J Interv Card
Electrophysiol. Dec 2010;29(3):179-185.
22. Kojodjojo P, O'Neill MD, Lim PB, et al. Pulmonary venous isolation by antral
ablation with a large cryoballoon for treatment of paroxysmal and persistent atrial
fibrillation: medium-term outcomes and non-randomised comparison with
pulmonary venous isolation by radiofrequency ablation. Heart. Sep
2010;96(17):1379-1384.
23. Andrade JG, Khairy P, Guerra PG, et al. Efficacy and Safety of Cryoballoon
Ablation for Atrial Fibrillation - A Systematic Review of Published Studies.
Heart Rhythm. Mar 29 2011.
24. Packer D, Irwin JM, J C, al. e. Cryoballoon ablation of pulmonary veins for
paroxysmal atrial fibrillation: first results of the North American Arctic Front ST
OP-AF pivotal trial. J Am Coll Cardiol. 2010;55:E3015–3016.
25. Roy D, Talajic M, Dorian P, et al. Amiodarone to prevent recurrence of atrial
fibrillation. Canadian Trial of Atrial Fibrillation Investigators. The New England
journal of medicine. Mar 30 2000;342(13):913-920.
22
26. Singh BN, Singh SN, Reda DJ, et al. Amiodarone versus sotalol for atrial
fibrillation. The New England journal of medicine. May 5 2005;352(18):1861-
1872.
27. Jais P, Cauchemez B, Macle L, et al. Catheter ablation versus antiarrhythmic
drugs for atrial fibrillation: the A4 study. Circulation. Dec 9 2008;118(24):2498-
2505.
28. Krittayaphong R, Raungrattanaamporn O, Bhuripanyo K, et al. A randomized
clinical trial of the efficacy of radiofrequency catheter ablation and amiodarone in
the treatment of symptomatic atrial fibrillation. Journal of the Medical
Association of Thailand = Chotmaihet thangphaet. May 2003;86 Suppl 1:S8-16.
29. Pappone C, Augello G, Sala S, et al. A randomized trial of circumferential
pulmonary vein ablation versus antiarrhythmic drug therapy in paroxysmal atrial
fibrillation: the APAF Study. Journal of the American College of Cardiology. Dec
5 2006;48(11):2340-2347.
30. Stabile G, Bertaglia E, Senatore G, et al. Catheter ablation treatment in patients
with drug-refractory atrial fibrillation: a prospective, multi-centre, randomized,
controlled study (Catheter Ablation For The Cure Of Atrial Fibrillation Study).
European heart journal. Jan 2006;27(2):216-221.
31. Wazni OM, Marrouche NF, Martin DO, et al. Radiofrequency ablation vs
antiarrhythmic drugs as first-line treatment of symptomatic atrial fibrillation: a
randomized trial. Jama. Jun 1 2005;293(21):2634-2640.
