Table 1. Indications for ICD Placement for Primary and Secondary Prevention of SCD [4].

Primary prevention of SCD

MI within the past 40 days and LVEF ≤ 35%

Patients with NICM with LVEF ≤ 35% after 3 months of optimized GDMT

HF patients who are candidates for CRT with BVICDa

Patients with congenital long QT syndrome with recurrent symptoms despite medical therapy

High-risk patients with hypertrophic cardiomyopathy

High-risk patients with Brugada syndrome, polymorphic VT and other channelopathies

Secondary prevention of SCD

Prior episode of survived VF/VT or sustained hemodynamically unstable VT without an identifiable reversible cause

Patients with episodes of spontaneously sustained VT in the presence of heart disease

^aLVEF ≤ 35%, on maximal GDMT for at least 3 months and has intraventricular conduction delay of more than 120 ms. ICD: implantable cardioverter defibrillator; SCD: sudden cardiac death; MI: myocardial infarction; LVEF: left ventricular ejection fraction; NICM: non-ischemic cardiomyopathy; GDMT: goal-directed medical therapy; CRT: cardiac resynchronization therapy; BVICD: biventricular implantable cardioverter defibrillator; VT: ventricular tachycardia; VF: ventricular fibrillation.