AARDVARK (Aortic Aneurysmal Regression of Dilation: Value of ACE-Inhibition on RisK)

Overview

Abdominal aortic aneurysms (AAA) are balloon-like swellings of the body's main blood vessel (aorta) as it courses through the abdomen. As a result of the National Aneurysm Screening programme many more of these will be detected. Small AAAs grow slowly and remain a benign condition until the diameter exceeds 2-3 times the diameter of the normal aorta (about 5.5cm in size), when operative repair of the aneurysm is recommended avoiding the potentially fatal event of bursting and bleeding (aneurysm rupture). It is therefore important to identify a strategy to prevent aneurysm growth. There is a suggestion that the use of a specific drug class, angiotensin converting enzyme (ACE) inhibitors, may reduce the risk of rupture of the larger aneurysms. This trial will assess whether an ACE inhibitor (perindopril) has aneurysm-related benefits, in patients with small AAAs at screening centres in the London area. The effects of perindopril versus a placebo(dummy) on AAA growth rates will be compared. In addition by comparing the effects of perindopril with the effects of equivalent blood pressure lowering with another non-ACE inhibitor class of drug (amlodipine) on aneurysm growth rate, we can see whether any benefits of perindopril are simply the result of lowering blood pressure. 225 Patients will be assigned to one of these 3 treatments by chance (randomisation).In addition to analysis of the effect of perindopril and blood pressure lowering,the effect of the treatments on quality of life will be assessed. Patients will return at 3-monthly intervals for an ultrasound scan and blood pressure measurements, with questionnaires regarding quality of life at the start and end of the 2-year research period. An ultrasound scan is a painless test that uses sound waves to create images of organs and structures inside your body.

This trial will investigate the idea that an ACE-inhibitor reduces abdominal aortic aneurysm (AAA) growth rate, in a pilot 3-arm randomised controlled trial (i.e. the study treatment is chosen by random for each patient). The three interventions are ACE-inhibition with perindopril; equivalent blood pressure reduction with amlodipine (a calcium channel blocker) and a placebo tablet. By comparing the effects in the perindopril and amlodipine arms, this design will permit an evaluation of any blood pressure independent effects of perindopril. Pending results of this pilot trial, we plan to work with the local and National Aneurysm Screening programme to conduct a larger, definitive trial, to investigate the hypothesis that blood pressure reduction with an ACE-inhibitor slows the rate of small AAA growth preferentially compared with other antihypertensive agents. Secondary research questions in this trial are the effects of perindopril therapy on aneurysm-related death rates, other diseases possibly caused by an AAA and quality of life compared to similar blood pressure lowering effects with amlodipine and placebo.