Use of angiotensin converting enzyme inhibitors is associated with increased growth rate of abdominal aortic aneurysms

Objectives

To evaluate whether either angiotensin converting enzyme (ACE) inhibitors or other classes of antihypertensive drug attenuate or increase growth rates of small infrarenal abdominal aortic aneurysms.

Methods

Prospective cohort study of 1701 patients enrolled in the UK Small Aneurysm Trial or associated study at 93 hospitals between 1991 and 1995 and who had at least two ultrasound measurements of aneurysm diameter and baseline drug prescription data recorded. Abdominal aortic aneurysm diameter was measured in the anterior-posterior plane using ultrasound. The mean growth rate was estimated through a mixed-effects linear growth model.

Results

Mean aneurysm growth rate in 169 patients taking ACE inhibitors at baseline was 3.33 mm/y vs 2.77 mm/y in the remaining 1532 patients, P = .009. The significance of this finding did not alter after adjustment for known confounders. The prescription of any antihypertensive agent and other specific classes of antihypertensive drugs were not found to be associated with aneurysm growth rate.

Conclusion

These results show that patients taking ACE inhibitors have faster aneurysm growth and are in conflict with the observation from a large Canadian data-base that aneurysm patients taking ACE inhibitors are less likely to present with aneurysm rupture. There is an urgent need for a randomized trial to assess whether ACE inhibitors are beneficial or harmful to patients with aneurysms below the threshold size for surgical intervention.