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DITORIAL COMMENTARY

ad lead? Good lead? What should we believe?eff S. Healey, MD, Andrew D. Krahn, MD

rom McMaster University, Hamilton, Ontario, Canada, and University of Western Ontario, London, Ontario, Canada.

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Now that randomized trials have established that im-lantable cardioverter-defibrillators (ICDs) prolong survivaln appropriately selected patients,1–3 there has been an ap-ropriate increase in research aimed at measuring and min-mizing device-related complications. Although much re-ent attention has been focused on the chronic performancef ICD generators4 and leads,5 periprocedural complicationsemain common and important problems. Underreporting ofardware failures and the lack of a mandate to collectnformation on other device-related complications, such aserforation and dislodgment, greatly limit the extent tohich physicians can rely on existing reporting mechanisms

s their sole source of information.6 This is particularly thease for lead performance, as there is greater interactionith the implanting physician’s technical skill and the fact

hat most malfunctioning leads are abandoned or revisedithout necessarily notifying the manufacturer or regula-

ors.In this issue of Heart Rhythm, Epstein et al7 estimate the

isk of lead perforation and dislodgment for the St. Judeiata family of leads using a large pooled dataset from

everal clinical registries. In nearly 7,500 patients, theyound a rate of perforation of only 0.31% and dislodgmentf 0.88%, rates that are low and in keeping with industryenchmarks.2,8 Although their findings appear at odds withn earlier, single-center report suggesting rates of 3.8% and.7%, respectively,9 the discrepancy likely is the result ofifferences in study design and sample size that serve toighlight many of the difficulties in evaluating lead perfor-ance.Several cases of late ICD lead perforation involving

mall-diameter, active-fixation right ventricular leads haveeen reported in the past few years.10,11 Such cases mayerve as an early warning of problems with new technolo-ies, such as small-diameter ICD leads, and may highlightotentially novel issues such as “late” perforation. How-ver, they lack an appropriate denominator to place thesevents in context and thus cannot provide a useful estimatef the risk of such problems. Case reports are highly sus-eptible to publication bias, so this type of research may

ddress reprint requests and correspondence: Dr. Jeff S. Healey, De-artment of Medicine, McMaster University, 237 Barton St. East, Hamil-

pon, Ontario L8L2X2, Canada. E-mail address: healeyj@hhsc.ca.

547-5271/$ -see front matter © 2009 Heart Rhythm Society. All rights reserved

ead clinicians to significantly overestimate the risk of rareomplications.

Consecutive case series are a better method for capturingead-related problems because they provide proper contexto the complication of interest; however, they have theirwn limitations. In 2008, Danik et al9 reported a single-enter, retrospective series showing an increased risk oferforations with St. Jude Riata leads compared withedtronic Sprint Fidelis leads. However, like many single-

enter series, the actual number of complications was smallin this case, five perforations). Thus, if even one lesserforation had been seen with the Riata leads, the increasedisk seen in this series would have failed to meet nominaltatistical significance. The more uncommon a complica-ion, the less likely even the largest clinical centers will haveufficient numbers to detect anything but massive differ-nces in complication rates.6 For example, if the true rate ofCD lead perforations is, in fact, 0.3%,7 then 17,000 patientsould have to be randomized to a standard or new lead toave even 80% power to detect a doubling of this risk.nother problem with estimating the risk of uncommon

omplications using single-center case series is that thempetus for conducting such research is often the observa-ion of one or two these complications.4 Because thesendex cases are inherently part of the numerator for thevent rate, the resulting estimate is biased, having beennflated by these cases.

Another limitation of single-center case series is theifficulty in extrapolating the results of one center to allenters because of possibly important differences in patientopulation, surgical technique, and ascertainment of com-lications. This is particularly relevant for lead dislodgmentnd perforation because all of the factors may influence theisk of these complications.12 Every ICD lead has its par-icular handling characteristics,12 so the risk of complicationepends not only on the overall experience of a particularroup of operators but also on their experience with the leadn question. On the other hand, an advantage of single-enter retrospective registries is that investigators have thebility to collect highly detailed implant information, whichay permit the identification of lead–technique interactions

hat influence complications rates, such as the lower risk ofead failure seen with Fidelis leads implanted by the ce-

halic route.13 However; the ability to make such observa-

. doi:10.1016/j.hrthm.2008.11.016

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211Healey and Krahn Editorial Commentary

ions again is limited by the need for a large numbers ofatients.

Industry- or government-sponsored multicenter registriesermit the acquisition of data from large numbers of pa-ients.7,8,14 To further increase numbers, data from severalf these sources can be pooled7; however, the methods forelecting individual registries should be transparent to reas-ure the reader that selection bias has not occurred. Al-hough such registries provide more broadly applicablendings and may allow the evaluation of device–patient

nteractions, depending on the initial objectives of the reg-stry, the collection of patient and implant characteristicsnd even the outcomes may be limited. In fact, one weak-ess of the analysis of Epstein et al7 is their retrospectivescertainment of complications. Although the registries inheir analysis were prospective, patients may have beennrolled after implantation, and the decision to collect dis-odgment and perforation data was retrospective. Perfora-ions were captured only if they required reintervention.lthough this approach is reasonable, it is prone to missing

ome reinterventions, and it would not capture clinicallyelevant perforations that resulted in pericardial effusions orericarditis that were managed medically. A systematicvaluation of implanted ICD leads using computed tomo-raphic scanning suggests that up to 14% of right ventric-lar leads actually perforate15; thus, the risk of clinicalerforation depends heavily on the criteria used for diagno-is and the rigor with which this complication is sought.herefore, it is imperative that a consensus be reached

egarding the definition of common device-related compli-ations to permit valid comparisons between studies.

One thing that is clear from the literature on device-elated complications is that we are very early adopters ofew technology.4,5,7,9 Although this approach has its advan-ages, it behooves us to implement a rigorous, well-de-igned, well-funded system to track device-related compli-ations so that clinicians can be proactive with regard tossues of device reliability. Several such projects are under-ay and have already provided clinicians with importantenchmark information on complication rates.8,14 However,one of these projects is as comprehensive as we wouldish, and the long-term sustainability of some of therojects remains in question.

It is clear that we must consider all relevant device-relatedomplications together. Both Danik et al9 and Epstein et al7

ppropriately presented data for both lead perforation and dis-odgment. Not only are both of these device-related complica-

ions clinically important, but changes in technique and lead

esign aimed at minimizing one complication actually couldncrease the other. Furthermore, the “superior” lead in thetudy by Danik et al9 subsequently has been withdrawn fromhe market due to a higher-than-anticipated rate of postimplantailure.5,6 This irony further highlights the importance of eval-ating all aspects of chronic lead performance.

In the case of Riata leads, what can we conclude? Al-hough the true rates of perforation and dislodgment likelyre higher than reported by Epstein et al,7 they almostertainly are not as high as suggested in earlier reports.9

his is crucial in the context of a definite clinical need formaller leads, particularly in the pediatric population. Basedn our current ability to discriminate, we can conclude thathe performance of Riata leads falls within the range of whats considered the acceptable standard. However, it is sober-ng to realize how limited is our ability to conclude other-ise.

eferences1. Connolly SJ, Hallstrom AP, Cappato R, et al. Meta-analysis of the implantable

cardioverter defibrillator secondary prevention trials. Eur Heart J 2000;21:2071–2078.

2. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillatorin patients with myocardial infarction and reduced ejection fraction. N EnglJ Med 2002;346:877–883.

3. Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med 2005;352:225–237.

4. Gould PA, Krahn AD, Canadian Heart Rhythm Society Working Group onDevice Advisories. Complications associated with implantable cardioverter-defibrillator replacement in response to device advisories. JAMA 2006;295:1907–1911.

5. Krahn AD, Champagne J, Healey JS, et al. Outcome of the Fidelis implantablecardioverter-defibrillator lead advisory: a report from the Canadian HeartRhythm Society Working Group on Device Advisories. Heart Rhythm 2008;5:639–642.

6. Maisel WH. Semper Fidelis: consumer protection for patients with implantedmedical devices. N Engl J Med 2008;358:985–987.

7. Epstein AE, Baker II JH, Beau SL, et al. Performance of the St. Jude MedicalRiata leads. Heart Rhythm 2009;6:204–209.

8. Lee DS, Birinie D, Cameron D, et al. Design and implementation of a popula-tion-based registry of implantable cardioverter defibrillators (ICDs) in Ontario.Heart Rhythm 2008;5:1250–1256.

9. Danik SB, Mansour M, Singh J, et al. Increased incidence of subacute leadperforation noted with one implantable cardioverter-defibrillator. Heart Rhythm2007;4:439–442.

0. Khan MH, Joseph G, Khaykin Y, et al. Delayed lead perforation: a disturbingtrend. Pacing Clin Electrophysiol 2005;28:251–253.

1. Satpahty R, Hee T, Esterbrooks D, et al. Delayed defibrillator lead perforation:an increasing phenomenon. Pacing Clin Electrophysiol 2008;31:10–12.

2. Maisel WH. Transvenous implantable cardioverter-defibrillator leads: the weak-est link. Circulation 2007;115:2461–2463.

3. Farwell D, Green MS, Lemery R, et al. Accelerating risk of Fidelis lead fracture.Heart Rhythm 2008;5:1375–1379.

4. Hammill SC, Stevenson LW, Kadish AH, et al. Review of the registry’s firstyear, data collected and future plans. Heart Rhythm 2007;4:1260–1263.

5. Hirschl DA, Jain VR, Spindola-Franco J, et al. Prevalence and characterization

of asymptomatic pacemaker and ICD lead perforation on CT. Pacing ClinElectrophysiol 2007;30:28–32.