Effectiveness, efficacy, and safety of wearable cardioverter-defibrillators in the treatment of sudden cardiac arrest - Results from a health technology assessment.

Objectives: To assess the effectiveness, efficacy, and safety of a wearable cardioverter-defibrillator (WCD) in adult persons with high risk for sudden cardiac arrest and for which an implantable cardioverter is currently not applicable.

Methods: We performed a systematic literature search in Medline, Embase, Cochrane Library, and CRD-databases. Study selection was performed by two reviewers independently. Data were presented quantitatively; due to heterogeneity of studies no meta-analysis was performed.

Results: One randomized-controlled trial (RCT), one non-randomized comparative trial, and forty-four non-comparative trials were included. The RCT reported an overall mortality of 3.1 percent in the WCD group versus 4.9 percent in controls (relative risk [RR]: .64; 95 percent confidence interval [CI], .43-.98, p = .04), but no significant effect on arrhythmia-related mortality. The RR for arrhythmia-related mortality amounted to .67 (95 percent CI, .37-1.21, p = .18) as assessed in the RCT. Appropriate shocks were observed in 1.3 percent of patients in both comparative studies, and inappropriate shocks in .6 percent of patients in the RCT. Termination of ventricular tachycardia (VT) or ventricular fibrillation (VF) was successful in 75 to 100 percent of appropriate shocks in all studies. Adverse events assessed in the RCT showed a lower incidence of shortness of breath (38.8 percent vs. 45.3 percent; p = .004), higher incidence of rash at any location (15.3 percent vs. 7.1 percent; p < .001), and higher incidence of itching at any location (17.2 percent vs. 6.4 percent; p < .001) for WCD.

Conclusions: Available evidence demonstrates that the WCD detects and terminates VT/VF events reliably and shows a high rate of appropriate shocks in mixed patient populations. Data of large registries confirm that the WCD is a safe intervention.