Author + information
- Published online November 29, 2017.
- Evan Adelstein, MD and
- Samir Saba, MD∗ ()
- ↵∗Address for correspondence:
Dr. Samir Saba, Heart and Vascular Institute, University of Pittsburgh Medical Center, 200 Lothrop Street, PUH B535, Pittsburgh, Pennsylvania 15213.
The wearable cardioverter-defibrillator (WCD) was developed as a noninvasive means of protecting patients at high risk for sudden cardiac death (SCD) without a permanent implantable cardioverter-defibrillator (ICD). It was intended as a bridge for patients who were unable to receive an ICD for various reasons (e.g., active infection, temporary but reversible acute illness) or to minimize SCD risk during a temporally limited period of additional risk stratification or clinical observation.
Prescription of the WCD has shifted from a niche tool to a matter of routine in patients with newly diagnosed cardiomyopathy. Spurring its expanded use are limitations on ICD use, heightened fear of SCD risk, and corporate marketing. What have not contributed to routine WCD use are randomized clinical trial data, because there are currently zero such trials to support its use. All published WCD data are from retrospective studies or registries (1–5), and even fewer included patients whose primary medical records were inspected (6). The Zoll corporation (Pittsburgh, Pennsylvania) is the sole manufacturer of the WCD (LifeVest), and the company has actively promoted its use not just as a means of preventing SCD but also as a cardiac monitor.
In this issue of JACC: Clinical Electrophysiology, Leyton-Mange et al. (7) describe the WCD experience at 2 academic medical centers. Patients were not randomized, but primary source medical records were analyzed for the study. The population comprised 147 patients, of whom 23 had a prior history of sustained ventricular tachycardia or ventricular fibrillation, 31 had new ischemic cardiomyopathy, and 37 had new nonischemic cardiomyopathy. With a median wear time of 21 hours per day, there were 6 shocks for ventricular tachyarrhythmias in 3 patients. One was status post–heart transplant with active rejection on inotrope therapy, and the patient succumbed to repeated ventricular arrhythmias despite WCD therapies. The second patient had prior ventricular tachyarrhythmias and was amid active infection; despite 2 successful WCD defibrillations, the patient expired soon thereafter. The third patient had a new ischemic cardiomyopathy and was treated by the WCD but ultimately required external rescue by emergency medical services. The authors therefore concluded that the WCD did not save any lives during 7,888 patient-days of wear time.
Most of the published prospective and retrospective WCD experiences have not confirmed indications with inspection of the primary medical record and have largely focused on patients with recent revascularization in the setting of ischemic cardiomyopathy (1,2,4). Similar to Leyton-Mange et al. (7), our center has also published retrospective WCD data demonstrating a low incidence of appropriate WCD therapy and consequently a small number of possible lives saved. There were no WCD therapies for ventricular tachyarrhythmias in patients with newly diagnosed nonischemic cardiomyopathy in either study. Despite such published data, the WCD has become part of the standard regimen in patients with newly diagnosed heart failure at many institutions, because it is assumed that the WCD is risk-free and that it saves lives, despite the dearth of data to support these assumptions.
Proponents of the WCD offer evidence of its effectiveness in terminating ventricular tachyarrhythmias as proof that it saves and prolongs life (8). It is also deemed risk-free because no surgery is required, although there is a small but significant risk of inappropriate shocks. However, experience teaches that expanding indications for medical interventions based on what should work is not necessarily appropriate. Suppressing premature ventricular complexes, known to be associated with SCD post–myocardial infarction (MI), with flecainide and encainide seemed a logical intervention until CAST (Cardiac Arrhythmia Suppression Trial) demonstrated that successfully suppressing premature ventricular complexes with class IC antiarrhythmic drugs increased mortality. Implanting ICDs in patients with recent MI and left ventricular dysfunction seemed a logical intervention, given the known high mortality in post-MI patients with reduced left ventricular function (9). Yet, DINAMIT (Defibrillator in Acute Myocardial Infarction Trial) found that reduced arrhythmic mortality associated with an ICD was equally offset by other causes of death and therefore was mortality-neutral (10). The findings were so counterintuitive that the IRIS (Immediate Risk Stratification Improves Survival) trial was performed in a similar population and yielded similar results (11). Now the WCD fills this temporal vacuum post-MI, again in the absence of any clinical data proving mortality benefit. It is naive to think that because the WCD is noninvasive, it should provide mortality benefit any more than a permanent ICD, yet the device is Food and Drug Administration–approved for such an indication.
The authors of the present study should be commended for publishing their data. Their 2 most striking findings are the low risk of appropriate shocks, despite including patients with prior sustained ventricular tachyarrhythmias; and the poor outcomes of those who did receive appropriate shocks, such that the WCD did not directly save any lives. Both findings bear striking similarity to those from our center’s 10-year experience, particularly the negligible risk of appropriate shocks in patients with newly diagnosed nonischemic cardiomyopathy.
VEST (Vest Prevention of Early Death Trial) remains the hope for providing randomized data supporting WCD use in patients with acute MI and reduced left ventricular function. However, enrollment has been slow, largely because of the availability of the WCD for clinical use, as Leyton-Mange et al. (7) astutely discuss. Approval of an intervention before randomized data supporting its use generates a vicious cycle in which acquiring conclusive data becomes progressively more difficult. It also seems evident that there will be no randomized data in patients newly diagnosed with nonischemic cardiomyopathy. We are therefore relegated to report real-life experience with the WCD, which, in the absence of randomized trials, represent the most reliable source of information.
Given the financial and emotional costs of the WCD, and the lack of randomized trial data supporting its use, studies such as those authored by Leyton-Mange et al. (7) are vital in informing clinical decisions in patients who may meet current approved indications for the WCD. Such studies are a call to action for a randomized trial evaluating its use in patients with a host of indications, including newly diagnosed nonischemic cardiomyopathy, newly recognized ischemic cardiomyopathy, and even explanted ICD patients with no prior history of ventricular arrhythmias awaiting ICD reimplantation. It is incumbent on the electrophysiology community to organize randomized trials to prove or disprove the utility of the WCD in fulfilling its mission of preventing SCD. Until then, the use of the WCD should be primarily reserved to patients with prior documented sustained arrhythmias who are temporarily unable to receive a permanent ICD.
↵∗ Editorials published in JACC: Clinical Electrophysiology reflect the views of the authors and do not necessarily represent the views of JACC: Clinical Electrophysiology or the American College of Cardiology.
Dr. Saba has received research support from National Heart, Lung Blood Institute, Boston Scientific, and Medtronic. Dr. Adelstein has received research support from Medtronic.
All authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Clinical Electrophysiology author instructions page.
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