The relationship between abdominal aortic aneurysm distensibility and serum markers of elastin and collagen metabolism

Background: abdominal aortic aneurysm (AAA) distensibility may be an independent predictor of growth and rupture, possibly because it reflects changes in aortic wall structure and composition. Aim: to determine whether AAA distensibility is related to circulating markers of elastin and collagen metabolism. Methods: sixty-two male patients of median age (IQR) 68 (65-72) years with asymptomatic AAA of median (IQR) diameter 42 (37-45) mm were prospectively studied. Pressure-strain elastic modulus (Epi and stiffness (beta) were measured using an ultrasonic echo-tracker (Diamove). Serum elastin peptides (SEP), plasma elastin-alpha (1)-antitrypsin complex (E-AT), procollagen III-N-terminal propeptide (PIIINP) were measured by enzyme-linked immunoassay. Results: age and smoking adjusted Ep and beta were significantly inversely related to SEP (r = -0.33 and r = -0.31 respectively, both p < 0.02) and E-AT (r = -0.27 and r = -0.27 respectively, both p<0.05) both of which indicate elastolysis. By contrast, there was a significant positive correlation between PIIINP, indicative of increased collagen turnover, and both Ep and beta (both r = 0.45, p<0.01 unadjusted correlations). Conclusion: increased elastolysis is associated with increased AAA wall distensibility; whereas increased collagen turnover is associated with reduced distensibility.