ACE and heart failure: Renin–angiotensin system (RAS) inhibitors, comprising angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), are first-line therapy for essential hypertension and heart failure, and also used as interventions of secondary prevention in coronary heart disease, diabetes mellitus, and diabetic nephropathy.1, 2, 3, 4