Wearable Cardioverter Defibrillator in High-Risk Cardiac Patients

Study Questions:

How safe and effective is the wearable cardioverter defibrillator (WCD) in patients at high risk of sudden cardiac death?


WEARIT-II (The Prospective Registry of Patients Using the Wearable Defibrillator Registry) is the first prospective, observational registry of the WCD. The data set includes clinical data, arrhythmia events, ejection fraction (EF) improvements, and eventual implantable cardioverter-defibrillator (ICD) placement.


There were 2,000 patients with ischemic cardiomyopathy (n = 805), nonischemic cardiomyopathy (n = 927), and congenital/inherited heart disease (n = 268). Median age was 62 years; median EF was 25%. During a median WCD wear-time of 90 days, 41 patients experienced a total of 120 sustained episodes of ventricular tachycardia or ventricular fibrillation (VT/VF). Most sustained VTs were not treated by the WCD because the patient used the response button to delay therapy and subsequently the VTs self-terminated. The rate of sustained VT/VF by 3 months was 3% among patients with ischemic cardiomyopathy and congenital/inherited heart disease, and 1% among nonischemic patients (p = 0.02). Only 10 patients (0.5%) received inappropriate WCD therapy. Compliance was good with median daily use of 22.5 hours. Three patients died while wearing the WCD, all due to asystole. At the end of WCD use, 840 patients (42%) were implanted with ICDs. The most frequent reason not to implant ICDs following WCD use was improvement in EF.


WCD is safe and effective and its use is associated with relatively high appropriate and low inappropriate therapy rates.


I wish we knew more about the baseline characteristics of the patients in this cohort. The authors indicate that it included patients with “low ejection fraction and a high risk for sudden cardiac death after myocardial infarction, following coronary revascularization, with a new-onset dilated non-cardiomyopathy, with high risk for sudden cardiac death until stabilization, or with inherited or congenital heart disease.” They break it down by the etiology of cardiomyopathy, but it would be helpful to have more granular data. For example, what constituted high risk for sudden cardiac death after myocardial infarction? Was it just EF <30%? Syncope? Nonsustained VT? A large vascular territory? Or any body after myocardial infarction with low EF? …Same applies to other patient categories. It is unclear how to apply this study to patients we see.

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