ACE Inhibitors Show Protection Against Aneurysm Rupture

By Mark S. Lesney 

Patients with abdominal aortic aneurysms who take ACE inhibitors have a lower risk of rupture than do those not taking such drugs, according to a population-based case-control study of more than 15,000 patients, reported by Dr. Daniel G. Hackam and his colleagues.

In all, 15,326 patients with abdominal aortic aneurysm (AAA) in 231 hospitals in Ontario, Canada, were assessed in the retrospective study using data from 1992 through 2002 contained in four linked databases, reported Dr. Hackam, the Sunnybrook Health Sciences Centre, Toronto.

Patients receiving an ACE inhibitor showed a significant 17% decrease in their chance of having a ruptured aneurysm, even when adjusted for demographic characteristics, risk factors for rupture, other comorbidities, and measures of health care use and screening (Lancet 2006;368:659-65).

In this population, 22% of the patients (cases) presented with ruptured aneurysms, compared with 78% with intact aneurysms (controls). The overall mean patient age was 75 years and 78% were men. Health status--as measured by number of drugs prescribed, Charlson comorbidity index, and the number of previous admissions--was similar for both groups. Overall, the ACE inhibitor therapy rate before admission was 22% (20% of the cases; 23% of controls).

Patients on ACE inhibitors who discontinued before admission showed no protective effect. Other antihypertensive drugs--including alpha- and beta-blockers, angiotensin II receptor blockers, thiazide diuretics, and calcium channel blockers--showed no protective effect. Therefore, the blood pressure-lowering quality of the ACE inhibitors does not account for protection against aneurysm rupture, they concluded.

In addition, six common nonantihypertensive drug classes assessed showed no significant protective effect against AAA rupture--antidepressants, gastric acid suppressants, thyroid hormone replacements, sedative-hypnotics, lipid-lowering agents, and antiosteoporosis agents.

The main shortcoming of the study is the lack of data on patient smoking status of the patients, according to a companion commentary by Dr. Nicholas Diehm and Dr. Iris Baumgartner of the University Hospital Bern (Switzerland) (Lancet 2006;368:622-3). Cigarette smoking is the main avoidable risk for the development and progress of AAAs.

However, on the basis of animal models and the results of this first large study of ACE inhibitors compared with angiotensin II receptor blockers, after recommending patients to stop smoking first, "we also favor ACE inhibitor treatment," they concluded.