Vest Prevention of Early Sudden Death Trial and VEST Registry

Inclusion Criteria: * Patients identified in the hospital or within 7 days after discharge with a diagnosis of an acute MI (STEMI or Non-STEMI) * LV ejection fraction ≤35% determined at the following time point: 1. If no PCI within the first 8 hours following the MI: ≥ 8 hours after MI 2. If acute PCI occurs within 8 hours of MI: ≥8 hours after PCI 3. If CABG is planned (before or within 7 days of discharge), wait to enroll and then use the most recent assessment at least 48 hours post CABG * Age ≥ 18 years Exclusion Criteria: * Existing ICD or indication for an ICD at the time of screening * Existing unipolar pacemakers/leads * Chronic renal failure requiring hemodialysis after hospital discharge * Chest circumference too small or too large for LifeVest garment\* * Participants discharged to an institutional setting with an anticipated stay \> 7 days * Pregnancy * Inability to consent * Any other condition or circumstance that in the judgment of the clinician makes the participant unsuitable for the study.