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Published on: February 16, 2011
Wearable Cardioverter-Defibrillator after Myocardial Infarction
Jeffrey E Olgin1, Mark J Pletcher1, Eric Vittinghoff1
1From the Division of Cardiology, Department of Medicine, the UCSF Center for the Prevention of Sudden Death (J.E.O., C.M., B.K.L.) and the Department of Epidemiology and Biostatistics (M.J.P., E.V., T.F.H., F.L., J.A.S., S.H.), University of California, San Francisco, San Francisco; the Department of Electrocardiology, Medical University of Lodz, Lodz, Poland (J.W.); McLeod Regional Medical Center, Florence, SC (R.M.); Ochsner Medical Center and Ochsner Clinical School, University of Queensland School of Medicine, New Orleans (D.P.M.); Hartford Healthcare Heart and Vascular Institute and University of Connecticut School of Medicine, Hartford (S.Z.); Beth Israel Deaconess Medical Center, Harvard Medical School, Boston (A.E.B.); Gill Heart Institute, University of Kentucky, and Veterans Affairs Medical Center, Lexington (C.S.E.); the Department of Internal Medicine, University of Michigan, Michigan Medicine, Ann Arbor (E.H.C.); Stony Brook Medicine, Stony Brook, NY (E.R.); and First Department of Medicine-Cardiology, University Medical Center Mannheim, Mannheim, and DZHK (German Center for Cardiovascular Research), Heidelberg - both in Germany (M.B.).
Insights
A wearable cardioverter-defibrillator did not significantly reduce arrhythmic death in patients with low ejection fraction after myocardial infarction. This wearable device did not prove effective in preventing sudden cardiac death during the high-risk post-MI period.
Area of Science:
- Cardiology
- Medical Devices
- Clinical Trials
Background:
- Patients with low ejection fraction after myocardial infarction face a high risk of sudden death.
- Implantable cardioverter-defibrillators are typically contraindicated in the early post-myocardial infarction period.
- The efficacy of wearable cardioverter-defibrillators in this high-risk window was previously unclear.
Purpose of the Study:
- To evaluate the effectiveness of a wearable cardioverter-defibrillator in reducing sudden death and arrhythmic death in patients with acute myocardial infarction and low ejection fraction.
- To compare the incidence of arrhythmic death and all-cause mortality between patients using a wearable cardioverter-defibrillator and those receiving guideline-directed therapy alone.
Main Methods:
- A randomized controlled trial was conducted with 2302 participants.
- Patients with acute myocardial infarction and ejection fraction ≤35% were assigned 2:1 to receive a wearable cardioverter-defibrillator plus guideline-directed therapy or guideline-directed therapy alone.
- The primary outcome was a composite of sudden death or death from ventricular tachyarrhythmia at 90 days (arrhythmic death).
Main Results:
- Arrhythmic death occurred in 1.6% of the device group versus 2.4% of the control group (relative risk, 0.67; P=0.18).
- All-cause mortality was lower in the device group (3.1%) compared to the control group (4.9%; relative risk, 0.64; P=0.04).
- The wearable cardioverter-defibrillator delivered appropriate shocks to 1.3% of recipients and inappropriate shocks to 0.6%.
Conclusions:
- The wearable cardioverter-defibrillator did not significantly reduce the primary outcome of arrhythmic death at 90 days in patients with recent myocardial infarction and low ejection fraction.
- While all-cause mortality showed a trend towards reduction with the device, the primary endpoint was not met.
- Further research may be needed to define the role of wearable cardioverter-defibrillators in specific patient populations or timeframes.
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 .).
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