BACKGROUND: In survivors of sudden cardiac arrest with obstructive coronary artery disease, it remains challenging to distinguish ischemia as a reversible cause from irreversible scar-related ventricular arrhythmias. We aimed to evaluate the value of implantable cardioverter-defibrillator (ICD) implantation in sudden cardiac arrest survivors with presumably reversible ischemia and complete revascularization. METHODS AND RESULTS: This multicenter retrospective cohort study included 276 patients (80% men, age 67±10 years) receiving ICD implantation for secondary prevention. Angiography was performed before ICD implantation. A subgroup of 166 (60%) patients underwent cardiac magnetic resonance imaging with late gadolinium enhancement before implantation. Patients were divided in 2 groups, (1) ICD-per-guideline, including 228 patients with incomplete revascularization or left ventricular ejection fraction ≤35%, and (2) ICD-off-label, including 48 patients with complete revascularization and left ventricular ejection fraction >35%. The primary outcome was time to appropriate device therapy (ADT). During 4.0 years (interquartile range, 3.5–4.6) of follow-up, ADT developed in 15% of the ICD-off-label group versus 43% of the ICD-per-guideline group. Time to ADT was comparable in the ICD-off-label and ICD-per-guideline groups (hazard ratio (HR), 0.46; P=0.08). No difference in mortality was observed (HR, 0.95; P=0.93). Independent predictors of ADT included age (HR, 1.03; P=0.01), left ventricular end-diastolic volume HR, (1.05 per 10 mL increase; P>0.01) and extent of transmural late gadolinium enhancement (HR, 1.12; P=0.04). CONCLUSIONS: This study demonstrates that sudden cardiac arrest survivors with coronary artery disease remain at high risk of recurrent ventricular arrhythmia, even after complete revascularization and with preserved left ventricular function. Late gadolinium enhancement–cardiac magnetic resonance imaging derived left ventricular volumes and extent of myocardial scar were independently associated with.