OBJECTIVES - This study sought to synthesize the available evidence on the use of the wearable cardioverter-defibrillator (WCD).

BACKGROUND - Observational WCD studies for the prevention of sudden cardiac death have provided conflicting data. The VEST (Vest Prevention of Early Sudden Death) trial was the first randomized controlled trial (RCT) showing no reduction in sudden cardiac death as compared to medical therapy only.

METHODS - We searched PubMed, EMBASE, and Google Scholar for studies reporting on the outcomes of patients wearing WCDs from January 1, 2001, through March 20, 2018. Rates of appropriate and inappropriate WCD therapies were pooled. Estimates were derived using DerSimonian and Laird’s method.

RESULTS - Twenty-eight studies were included (N = 33,242; 27 observational, 1 RCT-WCD arm). The incidence of appropriate WCD therapy was 5 per 100 persons over 3 months (95% confidence interval [CI]: 3.0 to 6.0, I2 = 93%). In studies on ischemic cardiomyopathy, the appropriate WCD therapy incidence was lower in the VEST trial (1 per 100 persons over 3 months; 95% CI: 1.0 to 2.0) as compared with observational studies (11 per 100 persons over 3 months; 95% CI: 11.0 to 20.0; I2 = 93%). The incidence of inappropriate therapy was 2 per 100 persons over 3 months (95% CI: 1.0 to 3.0; I2 = 93%). Mortality while wearing WCD was rare at 0.7 per 100 persons over 3 months (95% CI: 0.3 to 1.7; I2 = 94%).

CONCLUSIONS - The rate of appropriately treated WCD patients over 3 months of follow-up was substantial; higher in-observational studies as compared with the VEST trial. There was significant heterogeneity. More RCTs are needed to justify continued use of WCD in primary prevention.