A wearable cardioverter–defibrillator does not significantly reduce the risk of arrhythmic death after a myocardial infarction (MI), according to the results of the VEST study. Implantable cardioverter–defibrillators are contraindicated until 40–90 days after MI, so a wearable defibrillator might reduce the rate of sudden death during this high-risk period. A total of 2,302 patients with acute MI and an ejection fraction ≤35% were randomly assigned (2:1) to receive the wearable cardioverter–defibrillator LifeVest (ZOLL Medical) plus guideline-directed therapy or guideline-directed therapy alone. Participants in the device group wore the LifeVest for a median of 18 h per day. The rate of the primary end point (arrhythmic death) was 1.6% in the device group and 2.4% in the control group (relative risk (RR) 0.67, 95% CI 0.37–1.21, P = 0.18). All-cause mortality was 3.1% and 4.9% in each group, respectively (RR 0.64), and nonarrhythmic death occurred in 1.4% and 2.2% of patients in each group, respectively (RR 0.63). In the device group, 1.3% received an appropriate shock, 0.6% received an inappropriate shock, and 25% of the 48 patients who died were wearing the LifeVest at the time of death.