Wearable Cardioverter-Defibrillator in Patients at Transient Risk of Sudden Cardiac Death: State of the Art and Contemporary Clinical Evidence.

Sudden cardiac death remains a major mode of cardiovascular mortality, yet the risk is neither constant over time nor adequately represented by left ventricular ejection fraction alone. The weeks after myocardial infarction and the early months after a new diagnosis of cardiomyopathy or acute myocarditis create arrhythmic vulnerability, and recovery with revascularization, guideline-directed medical therapy, rhythm control, or resolution of inflammation may render immediate implantable cardioverter-defibrillator implantation unnecessary or inappropriate. The wearable cardioverter-defibrillator (WCD) was developed to bridge this interval by providing non-invasive, continuously available detection and shock therapy for sustained ventricular tachyarrhythmias. The only randomized trial, VEST, did not significantly reduce arrhythmic death in the intention-to-treat analysis, and therefore does not support indiscriminate WCD prescription after myocardial infarction. Conversely, large registries and contemporary meta-analyses consistently document successful termination of malignant ventricular arrhythmias, clustering of events during the first weeks, and frequent subsequent recovery of systolic function. Economic models from several healthcare systems suggest that WCD use may be cost-effective in selected settings, although estimates are highly dependent on assumptions regarding baseline arrhythmic risk, treatment effectiveness, adherence, and healthcare-system costs, and several analyses have incorporated exposure-based VEST estimates or manufacturer involvement. Overall, current evidence supports the technical efficacy of the WCD for terminating sustained ventricular tachyarrhythmias, but observational shock rates do not establish a population-level survival benefit. The most defensible contemporary role of the WCD is therefore as a selective bridge-to-decision strategy in patients with transient or evolving arrhythmic risk, integrating not only LVEF but also substrate, arrhythmic triggers, timing, and clinical trajectory.