Efficacy of Implantable Defibrillator Therapy After a Myocardial Infarction

Site investigators are responsible for screening. Subjects must meet all inclusion criteria. Subjects with any exclusion criteria will be excluded. Initial inclusion criteria (eligibility for Holter screening). * 18 - 80 years old at time of consent * History of MI ≥ 2 months prior to screening based on ESC/ACCF/AHA/WHF criteria (both STEMI and NSTEMI subjects are eligible) * Appropriate post-MI management including revascularization where indicated * No contra-indication for transvenous ICD placement (e.g., mechanical tricuspid valve, known vascular access problems, active sepsis, etc.) * LVEF 36% - 50% measured at least 40 days after a confirmed MI ≥ 3 months after coronary angioplasty or coronary bypass surgery and within the following time windows: * LVEF ≤ 7 months of screening visit if index MI was ≤ 1 year of enrolment * LVEF ≤ 13 months of screening visit if index MI was \> 1 \& \< 3 years of enrolment * LVEF ≤ 25 months of screening visit if index MI was ≥ 3 years of enrolment * Proven, necessary or appropriate medications (e.g. beta-blocker, ACE inhibitor / ARB, statin, and anti-platelet) * In normal sinus rhythm (ECG documented) ≤ 8 weeks prior to the screening Holter * Written informed consent * Able and willing to complete the screening Holter, including the six-minute hall walk Additional inclusion criterion (eligibility for randomization). * Abnormal HRT \& TWA (core lab interpretation) on Holter performed at least 2 months after the index MI and the specified time after coronary revascularization * In normal sinus rhythm (ECG documented) within 8 weeks prior to the screening Holter * In normal sinus rhythm for ≥ 18 hours of the 24 hr screening Holter as determined by the study Holter Core Lab Exclusion criteria (randomization or registry). * Use of antiarrhythmic drugs * Clinical indication for permanent pacemaker or a cardiac resynchronization device * Clinical indication for an ICD or cardiac resynchronization ICD * Prior implantation of a pacemaker, ICD, or Cardiac Resynchronization device * Any condition, in the investigator's judgment, that would limit life expectancy to \< 12 months * Chronic renal failure (hemodialysis or peritoneal dialysis) * Active ischemia that is amenable to revascularization if not previously revascularized * Participation in another trial that may interfere with the REFINE ICD results. * Pregnancy * Inability to comply with the follow-up schedule