Objective: A genetic polymorphism in the angiotensin-converting enzyme (ACE) gene (ACE I/D polymorphism) has been associated with abdominal aortic aneurysm. A link between aortic aneurysm and aortic stiffness has been suggested. However, no study has previously investigated the relationship between ACE and abdominal aortic wall integrity. The aim of this study was to explore the links between ACE I/D polymorphism, circulating ACE, and abdominal aortic wall integrity determined by abdominal aortic wall stiffness.

Methods: The study population consisted of 406 subjects (212 men and 194 women), 70–88 years. Diastolic lumen diameter, pulsatile diameter change and intima-media thickness were measured and used to calculate the cross-sectional compliance (CC), distensibility coefficient (DC), stiffness β and wall stress. ACE genotype was determined by PCR followed by gel electrophoresis, and circulating ACE level was measured using ELISA.

Results: Male carriers of the ACE D allele had a lower distensibility coefficient than II carriers (ID/DD 8.09 vs. II 10.38, p=0.017). Multiple regression analyses adjusting for confounding factors showed significant associations between the ACE D-allele and increased stiffness β as well as reduced CC. No significant association between abdominal aortic stiffness and the ACE D-allele was found in women.

Conclusion: This study showed, for the first time, a gender-specific association between the ACE-D allele and abdominal aortic wall mechanics, with men carrying the ACE D-allele having stiffer abdominal aortas compared to II carriers. Increased abdominal aortic stiffness indicates impaired vessel wall integrity, which along with other local predisposing factors, may increase the risk of aneurysm formation.