Despite the high rate of sudden death in the months following a heart attack, implantable cardioverter defibrillators (ICDs) placed in the chest aren't currently indicated for this patient population before 40-90 days for several reasons. First, large studies have failed to show that implanting an ICD during this period results in long-term reductions in mortality. Second, in many cases someone's ejection fraction will improve in the ensuing months post-heart attack. In VEST, for example, 60 percent of people with low ejection fraction in the first three months after heart attack recovered and no longer met the criteria for an ICD at 90 days. Lastly, there is competing risk of death from other causes not preventable with a defibrillator–for example, another heart attack or cardiac rupture.

According to Olgin, these new findings suggest WCDs could fill the gap in cardiac therapy until patients can be evaluated for an ICD. Current guidelines recommend the WCD as a potential tool that practitioners can use, but the researchers believe findings from this large randomized trial will add important data to further inform these guideline recommendations.


The LifeVest WCD is worn under clothing, directly against the skin and works by continuously monitoring a patient's heart and sounding alarms and/or giving verbal commands to encourage people to seek medical care, if needed. If a life-threatening heart rhythm is detected, the device delivers a shock to restore a normal heart rhythm.

"What's nice about the wearable defibrillator is that it's non-invasive and it's not permanent," Olgin said. "Based on our results, I think we'll see more widespread use of this device in these patients."

The trial enrolled 2,300 adult patients admitted to the hospital for heart attack with an ejection fraction of ≤ 35 percent across more than 100 trial sites in four countries. Upon discharge, patients were randomized 2 to 1 to either receive the WCD plus guideline-directed medical therapy or guideline-directed medical therapy alone for 90 days to determine the potential mortality benefit of the WCD.

Patients were advised and reminded to wear the WCD as much as possible and only take it off for bathing; participants who wore the WCD did so for an average of 21 hours a day. The primary outcome was sudden death at three months and secondary outcomes were total and cause-specific mortality, non-fatal ventricular arrhythmias and hospitalizations. Participants and sites were not blinded to the treatment arm, but they were blinded to any arrhythmia detections during the follow-up. Un-blinding could be requested if a participant had a shock, cardiac arrest or syncopal event. Outcomes were adjudicated by an independent, blinded panel.

Cardiology Homepage