ACE and heart failure: The following inclusion criteria were chosen: (1) control trials only comparing ivabradine to any placebo, such as beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), diuretics, and aldosterone antagonists); (2) heart failure of any type, heart failure with reduced ejection fraction (HFrEF) or heart failure with preserved ejection fraction (HFpEF); (3) studies that must include echocardiographs (ECHOs) to measure ejection fraction; (4) studies with follow-up data (cardiovascular mortality, re-admission); and (5) must be in English.