Efficacy and Safety of Implantable Cardioverter-Defibrillator (ICD) Implantation in the Elderly

The overall aim of this trial is to study the safety and efficacy of ICD implantation as a primary prevention strategy of sudden cardiac death (SCD) in patients 70 years and older. In particular, this study is designed to determine the comparative effectiveness of ICD, in addition to optimal medical therapy (OMT), in reducing all-cause mortality, versus OMT alone; OMT includes standard intervention for chronic heart failure patients, i.e. lifestyle modification, disease management, adoption of healthy diet and exercise practices, etcetera. One particularly important secondary objective is to assess treatment efficacy under the conditions of high versus low co-morbidity burden. Participants will be randomized (1:1 ratio) to ICD + OMT or OMT alone, and stratified by participating site and co-morbidity level (Charlson score \<3 versus 3+). Acute treatment visits will occur as clinically indicated and per local convention; follow-up will occur 1-4 months post-randomization (all participants), and not sooner than 30 days - and not later than 120 days post-implantation (ICD arm); regular follow-up will occur at 6 month intervals post-randomization until study close (all participants). All follow-up will be conducted centrally. Neither the participant nor treating clinician will be masked to treatment. Primary Objective: The primary objective of this study is to determine if a primary prevention strategy with ICD implantation in addition to optimal medical therapy (OMT) is effective in reducing all-cause mortality compared to OMT alone in patients 70 years of age and older who are eligible for ICD therapy according to current Centers for Medicare \& Medicaid Services (CMS) criteria. Primary Hypothesis: The primary hypothesis of this study is that implantation of an ICD plus optimal medical therapy will reduce all-cause mortality in patients 70 years of age and older versus optimal medical therapy alone. Secondary Objectives: 1. One secondary objective of this study is to ascertain whether age, co-morbidity burden, or age and burden together, are determinants in mortality outcomes in the OMT versus ICD + OMT group. 2. An additional secondary objective of the study is to determine the effect of ICD implantation plus optimal medical therapy on quality of life among elderly patients compared with optimal medical therapy alone.