The Wearable Cardioverter-Defibrillator: Is It Now the Standard of Care?

Wearable Cardioverter Defibrillator - Initial Experience in the Outpatient Setting in Japan

Background: The wearable cardioverter defibrillator (WCD) has been available since 2014 in Japan, and its benefit in the in-hospital acute phase at high risk of ventricular tachyarrhythmia (VTA) has been established, but its clinical use in the outpatient setting remains unclear, especially in Japan.

Methods and Results: The subjects consisted of 43 consecutive patients with WCD use in the outpatient setting from April 2014 to October 2019 at the present institute. Event alerts and wearing compliance were checked via the remote monitoring system, and a dedicated WCD training team contacted the patients if necessary. The median observation period was 51 days (IQR, 37–68 days) and the median daily wearing time was 23.1 h/day (IQR, 22.0–23.6 h/day). WCD was prescribed for primary prevention of VTA in 7 patients (16%), and for secondary prevention in 36 (84%). The common reason for WCD use was preventive therapy and/or clinical observation. Two appropriate and one inappropriate shock were observed. Eleven patients were not indicated for ICD because of successful catheter ablation optimal medical therapy, VTA in early onset of heart disease and refusal. The remaining 32 patients, however, underwent ICD implantation.

Conclusions: In the present real-world study, the WCD wearing compliance was well-maintained in the outpatient setting. WCD is useful for patients at high risk of VTA.

Wearable Cardioverter-Defibrillator after Myocardial Infarction

BACKGROUND

Despite the high rate of sudden death after myocardial infarction among patients with a low ejection fraction, implantable cardioverter-defibrillators are contraindicated until 40 to 90 days after myocardial infarction. Whether a wearable cardioverter-defibrillator would reduce the incidence of sudden death during this high-risk period is unclear.

METHODS

We randomly assigned (in a 2:1 ratio) patients with acute myocardial infarction and an ejection fraction of 35% or less to receive a wearable cardioverter-defibrillator plus guideline-directed therapy (the device group) or to receive only guideline-directed therapy (the control group). The primary outcome was the composite of sudden death or death from ventricular tachyarrhythmia at 90 days (arrhythmic death). Secondary outcomes included death from any cause and nonarrhythmic death.

RESULTS

Of 2302 participants, 1524 were randomly assigned to the device group and 778 to the control group. Participants in the device group wore the device for a median of 18.0 hours per day (interquartile range, 3.8 to 22.7). Arrhythmic death occurred in 1.6% of the participants in the device group and in 2.4% of those in the control group (relative risk, 0.67; 95% confidence interval [CI], 0.37 to 1.21; P=0.18). Death from any cause occurred in 3.1% of the participants in the device group and in 4.9% of those in the control group (relative risk, 0.64; 95% CI, 0.43 to 0.98; uncorrected P=0.04), and nonarrhythmic death in 1.4% and 2.2%, respectively (relative risk, 0.63; 95% CI, 0.33 to 1.19; uncorrected P=0.15). Of the 48 participants in the device group who died, 12 were wearing the device at the time of death. A total of 20 participants in the device group (1.3%) received an appropriate shock, and 9 (0.6%) received an inappropriate shock.

CONCLUSIONS

Among patients with a recent myocardial infarction and an ejection fraction of 35% or less, the wearable cardioverter-defibrillator did not lead to a significantly lower rate of the primary outcome of arrhythmic death than control. (Funded by the National Institutes of Health and Zoll Medical; VEST ClinicalTrials.gov number, NCT01446965 .).

Use of the Wearable Cardioverter Defibrillator as a Bridge to Implantable Cardioverter Defibrillator

The wearable cardioverter defibrillator has been shown to be effective in terminating ventricular arrhythmias in patients at risk for sudden cardiac death. There are numerous scenarios in which implant of a permanent implantable cardioverter defibrillator is temporarily contraindicated or not advisable and a wearable cardioverter defibrillator may be beneficial. There are no prospective randomized studies published that provide conclusive guidance toward the use of the wearable cardioverter defibrillator, and thus, patient management needs to be individualized based on the available data.