Wearable defibrillators may prevent sudden cardiac death

Wearable cardioverter-defibrillators (WCD) help protect newly diagnosed heart failure patients from sudden cardiac death (SCD), according to a recent study.

“The findings speak against a mortality shift from SCD to other causes of death and support the use of the WCD for temporary protection from SCD. Patients who did not receive an implantable CD (ICD) after the WCD period neither died of SCD nor suffered from ventricular arrhythmias during extended follow-up,” the researchers said.

The study included 357 patients (mean age 56±15 years, 69 percent men) who had been diagnosed with heart failure with reduced ejection fraction (HFrEF) and had received a WCD. Study endpoints included total mortality, left ventricular ejection fraction (LVEF), device implantations, and ventricular tachyarrhythmias. Information was collected at baseline, at the 3-month follow-up, and at the last available visit. Device data were obtained through the accompanying remote monitoring platform.

Over an average total wear time of 104±76 days, WCDs delivered 15 appropriate shocks to 14 patients (4 percent) for ventricular fibrillation or haemodynamically unstable fast ventricular tachycardia. Most patients (75 percent) were given WCD to be worn for 3 months, which was subsequently prolonged for 88 patients (25 percent). [ESC Heart Fail 2021;doi:10.1002/ehf2.13586]

Mean LVEF at the 3-month follow-up was 34±10 percent, and 113 patients (32 percent) were eligible and scheduled for ICD implantation, which was performed a mean of 105±54 days after WCD prescription. Among those who had prolonged WCD use (>3 months), 35 percent met ICD indication criteria and received the implants a mean of 241±99 days after WCD prescription.

Two deaths occurred during the WCD period (0.6 percent), both of which were due to noncardiac reasons and occurred 40 and 53 days after prescription, respectively. Neither mortality had received WCD shocks.

Survival data during the extended follow-up were available for 333 patients, corresponding to a cumulative observation period of 931 patient-years. Mean follow-up was 2.8±1.5 years. During this time, 30 patients died (9 percent), resulting in a mean estimated survival time of 6.2±0.1 years after WCD prescription.

Cause of death was cardiac in five patients (17 percent), one of whom had autopsy-confirmed acute myocardial infarction; this patient had refused ICD implantation for primary prophylaxis. Seventeen deaths were due to noncardiac causes, while eight patient had unknown causes.

By the end of the study, two of the 14 patients who had received WCD shocks died. WCD shock was not a significant predictor for mortality.

“This real-world cohort of patients wearing the WCD after diagnosis of HFrEF showed a favourable survival during extended follow-up, including patients who received appropriate WCD shocks for early haemodynamically unstable ventricular arrhythmias,” the researchers said.

“Thorough uptitration of heart failure medication and risk stratification should be performed before considering ICD implantation,” they added.