Use of a wearable cardioverter-defibrillator (WCD) during the first 90 days after myocardial infarction (MI) did not lead to a reduction in sudden cardiac death (SCD) in the VEST study. The results were presented by Jeffrey Olgin, MD, FACC, on Saturday, March 10 in a Late-Breaking Clinical Trial session at ACC.18 in Orlando, FL. A significant 35 percent relative risk reduction in the secondary endpoint of total mortality was found in this first randomized trial of a WCD.

The VEST trial evaluated whether a WCD could reduce SCD occurrence in the immediate post-MI period (<90 days) in patients with reduced left ventricular ejection fraction (LVEF), as a bridge to evaluation for an implantable cardioverter-defibrillator (ICD). Participants and sites were blinded to any arrhythmia detections during follow-up. Unblinding could be requested if a participant had a shock, cardiac arrest or syncopal event. Outcomes were adjudicated by an independent, blinded panel.

A total of 2,302 patients with acute MI and LVEF ≤35 percent were randomized 2:1 at 108 sites in four countries to receive guideline-directed medical therapy (GDMT) plus a WCD (n=1,524) or GDMT alone (n=778) within seven days of hospital discharge. The primary outcome was SCD and death due to ventricular arrhythmias.

The mean follow-up was 84.3 days. Of the 1,524 patients assigned to WCD, 1,481 received a WCD and 19 percent of those never wore the WCD. Among patients in the control group, 20 received a WCD against protocol. About 80 percent of patients in the WCD group wore the device at the start of the study, but the percentage declined to about 45 percent by Day 90.

There was no significant difference in the primary endpoint rate between the WCD and control groups (1.6 vs. 2.4 percent). Total mortality was 3.1 percent in the WCD group and 4.9 percent in the control group. For the secondary endpoint of overall non-sudden death, there was no significant difference between groups. But stroke deaths were significantly lower in the WCD group than in the control group (0.0 vs 0.5 percent). Patients in the WCD group had significantly less shortness of breath versus controls (38.7 vs. 45.4 percent).

"It is possible that sudden deaths were misclassified as it's difficult to define sudden death with accuracy when a death is unwitnessed and there is little documentation," said Olgin. "But the cause of death is irrelevant if we can prevent it. This study found that the device was associated with fewer deaths among people recovering from a heart attack with low ejection fraction. It's also the first therapy associated with a mortality benefit above and beyond standard medical therapy immediately after heart attack."

Although the primary endpoint was not met, the investigators concluded that prescribing the WCD is reasonable to protect high-risk patients with a low LVEF post-MI until evaluation for an ICD at 40 to 90 days. These new findings suggest WCDs could fill the gap in cardiac therapy until patients can be evaluated for an ICD, suggest the researchers, and add important data to further inform guideline recommendations. Cost-effectiveness analyses also will be important.

Keywords: ACC18, ACC Annual Scientific Session, Arrhythmias, Cardiac, Defibrillators, Implantable, Stroke Volume, Intention to Treat Analysis, Electric Countershock, Myocardial Infarction, Patient Discharge, Death, Sudden, Edema, Intubation, Percutaneous Coronary Intervention, ACC Scientific Session Newspaper

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