Long-term renin-angiotensin blocking therapy in hypertensive patients with normal aorta may attenuate the formation of abdominal aortic aneurysms

Renin-angiotensin system (RAS) has been implicated in the pathogenesis of abdominal aortic aneurysm (AAA). Angiotensin II type 1 receptor blocker (ARB), when given with angiotensin II prevents AAA formation in mice, but found ineffective in attenuating the progression of preexisting AAA. This study was designed to evaluate the effect of chronic RAS blockers on abdominal aortic diameter in hypertensive patients without known aortic aneurysm. Consecutive hypertensive outpatients (n = 122) were stratified according to antihypertensive therapy they received for 12 months or more, consisting of ARB (n = 45), angiotensin converting enzyme inhibitor (ACE-I; n = 45), or nonARB/nonACE-I (control therapy; n = 32). Abdominal ultrasonography was performed to measure maximal subrenal aortic diameter. Eighty-four patients were reexamined by ultrasonography 8 months later. The correlation between the different antihypertensive therapies and aortic diameter was examined. Aortic diameters were significantly smaller in ARB than in control patients in the baseline and follow-up measurements (P =.004; P =.0004, respectively). Risk factor adjusted covariance analysis showed significant differences between ARB or ACE-I treated groups and controls (P =.006 or P =.046, respectively). Ultrasound that was performed 8 months later showed smaller increases in mean aortic diameters of the ARB and ACE-I groups than in controls. Both ARB and ACE-I therapy attenuated expansion of nonaneurysmal abdominal aorta in humans. These results indicate that RAS blockade given before advancement of aortic medial remodeling may slow down the development of AAA.