Therapeutic trials comparing angiotensin converting enzyme inhibitors and angiotensin II receptor blockers

Two independent pharmacologic methods of specifically interfering with the renin-angiotensin-aldosterone system have been brought to the marketplace: angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs). These agents have the potential not only to be very widely used for a broad variety of clinical indications but also to compete against each other as treatments for hypertension, heart failure, renal impairment, and other conditions. Many short-term comparative studies of these two classes of drugs have now been completed. Most have focused on surrogate endpoints, such as blood pressure, renal function, or cough. These studies have generally concluded that ARBs are better tolerated but that the two drug classes otherwise have similar efficacy. The largest clinical trial comparing ARBs and ACE inhibitors thus far completed, Evaluation of Losartan in the Elderly (ELITE 2), failed to confirm the results of a smaller study; it did not demonstrate a significant improvement in outcomes (death or hospitalization for heart failure) with an ARB used alone, despite better tolerability. Many longer-term outcome studies with survival endpoints are under way, but most will compare the combination against an ACE inhibitor alone. These studies will define the optimal use of these agents in medicine for decades to come.