ACE Inhibitors and ARBs

The choice between an ACE inhibitor and an angiotensin receptor blocker is not a fixed “ACE inhibitor first, ARB second” sequence. In Canadian practice, both are first-line antihypertensive classes; the choice turns on the indication, adverse-effect history, kidney function, potassium, pregnancy status, and interacting medicines. For most adults who require pharmacologic treatment for hypertension, Hypertension Canada 2025 favours starting two complementary agents, preferably as a single-pill combination containing an ACE inhibitor or ARB plus a thiazide-type diuretic or dihydropyridine calcium channel blocker. The decision changes in heart failure with reduced ejection fraction (HFrEF), where sacubitril/valsartan is preferred when feasible. ACE inhibitors and ARBs remain important alternatives, but they are not interchangeable with an ARNI or with each other in every clinical situation. The same renal haemodynamic effect that lowers intraglomerular pressure can also cause acute kidney injury or hyperkalemia in a vulnerable patient, so selection and follow-up are inseparable.