Comparative Effectiveness of Prophylactic ICD Versus Non-ICD Therapy

Inclusion Criteria: * Age ≥ 18 years (no upper limit) * Class I or IIa indication for a primary prevention ICD15: Ischemic or non-ischemic cardiomyopathy and NYHA Class ≥ II if most recent LVEF is ≤ 35% OR ischemic cardiomyopathy with NYHA Class I if most recent LVEF is ≤ 30% * Most recent LVEF (%) obtained per cardiac imaging obtained at any time prior to enrollment after being stable on optimal GDMT\*\* for at least one month * Stable optimal GDMT at least one calendar month prior to last cardiac imaging test, prespecified as one of the following for at least 1 calendar month prior to study randomization: receiving all 4 therapy classes (beta-blockers, ARNI/ARB/ACE, MRA and SGLT2i) OR GDMT Score ≥ 6 (per Figure 7) • MADIT-ICD Benefit Score \< 50 (per Figure 4) Exclusion Criteria: * Existing ICD/CRT-D * • Planned CRT-P or CRT-D implant for any indications including Class I or IIa indication for CRT: Presence of left bundle branch block (LBBB) with QRS ≥ 120 msec OR QRS duration ≥ 150 msec regardless of QRS morphology OR decision for CRT implant by EP provider for other indications * Acute MI within the past 3 calendar months * Chronic renal failure requiring hemodialysis * Coronary revascularization within the past 3 calendar months * History of sustained VT or VF * Known genetic cause of cardiomyopathy * Life expectancy \< 1 year * Unable or unwilling to follow study protocol * Inability to consent