Antihypertensive therapy and cardiovascular prevention. The role of angiotensin II receptor blockers

Angiotensin II receptor blockers (ARBs) are widely used in patients with hypertension, heart failure, diabetic nephropathy, and other conditions. Over-stimulation of AT2 receptor as a result of AT1 blockade may contribute to the beneficial effects of ARBs through vasodilation and inhibition of cardiac and vascular hypertrophy and fibrosis. Some experimental studies, however, suggested that AT2 receptor over-stimulation, in addition to beneficial effects, might trigger inhibition of angiogenesis and apoptosis. In a review, some authors suggested that ARBs may increase the risk of myocardial infarction. This position triggered a hot scientific debate and further analyses of existing data. We completed a meta-analysis of randomized clinical trials comparing ARBs with either placebo or active drugs different from ARBs. ARBs were not associated with an excess risk of myocardial infarction (odds ratio 1.03 in a random-effect model and 1.02 in a fixed-effect model). Cardiovascular mortality did not differ between ARBs and drugs different from ARBs (odds ratio 1.00 in a random-effect model and 0.99 in a fixed-effect model) and it was slightly lesser with ARBs than with placebo (odds ratio 0.91; 95% confidence interval 0.83-0.99; p = 0.042) in a prespecified subgroup analysis. Other meta-analyses confirmed these data. In conclusion, evidence from randomized trials does not support the hypothesis that AT2 receptor over-stimulation produces harmful clinical effects. Current indications and contraindications to the use of ARBs in patients with hypertension, heart failure, and diebetic nephropathy should be maintained and probably extended to the entire class of these drugs. © 2007 AIM Publishing Srl.