Many patients with heart failure and a reduced ejection fraction (HFrEF) with an indication for cardiac resynchronization therapy (CRT) are also eligible for prophylactic implantation of an implantable cardioverter defibrillator (ICD) for the prevention of sudden cardiac death (SCD). However, it is unclear whether patients who are eligible for CRT should routinely receive an ICD. In addition, the risk of SCD has declined in patients with HFrEF, a finding that is consistent with a cumulative benefit of disease-modifying pharmacological therapies and CRT on this cause of death.