ACE and heart failure: Introduction: Guideline-directed medical therapy (GDMT) for heart failure with reduced ejection fraction (HFrEF) includes a combination of angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB)/angiotensin receptor neprilysin inhibitors (ARNI), beta-blockers, mineralocorticoid receptor agonists (MRA), and sodium-glucose co-transporter 2 inhibitors (SGLT2i).