Angiotensin II receptor blockers and cardiovascular outcomes: what does the future hold?

The ability of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) to lower blood pressure (BP) is well established. ACE inhibitors (ACE-Is) have also been shown to improve the prognosis of a broad range of patients at high cardiovascular risk, including those with heart failure, post-myocardial infarction (MI), and nephropathy. These benefits suggest that interrupting the renin-angiotensin-aldosterone system (RAAS) with ACE-Is has a widespread vasculoprotective effect, provided that BP is also adequately controlled. Evidence that RAAS blockade by ARBs also improves long-term clinical outcomes in patients with cardiovascular disease has started to accumulate, and will be tested further during the coming years as a number of large-scale, prospective trials are completed. These trials are investigating the long-term protective effects of ARBs on morbidity and mortality in patients with hypertension, heart failure, diabetes mellitus, acute MI, or established vascular disease. The results should establish the extent to which ARBs exhibit the vasculoprotective properties demonstrated by ACE-Is in patients at high cardiovascular risk. If ARBs are found to provide benefits that are similar to, or even greater than ACE-Is, it may have important implications for drug selection, given the excellent tolerability of ARBs. Some studies are also investigating whether more extensive RAAS blockade using a combination of an ARB and an ACE-I will offer even greater protection than either agent alone.