Influence of angiotensin converting enzyme insertion/deletion polymorphism on long-term total graft occlusion after coronary artery bypass surgery

Background: The renin-angiotensin system has a very important role in coronary thrombosis and restenosis. Plasma angiotensin converting enzyme ( ACE) activity is associated with an insertion/deletion polymorphism in the gene coding for ACE. It is known that there is a strong correlation between ACE DD and atherosclerosis. However, little has been documented about its role in venous graft failure. The objective of this study was to investigate the relationships among the ACE gen polymorphism and long-term vein graft occlusion. Methods: The study population consisted of 87 consecutive white patients with symptomatic coronary artery disease in the previous month, who had had aorto-coronary bypass surgery (ACBS) more than 5 years back and who underwent coronary angiography for diagnostic purposes. On the same day as angiography, 10 mL whole blood was taken for ACE gene insertion/deletion (I/D) polymorphism. Results: Mean age of the patients was 64.4 +/- 8.6 years, and 71 (82%) of the patients were men. The average ACBS time was 7.9 +/- 1.9 years. The ACE genotype was II in 15 patients (17.2%), ID in 47 patients (54.0%), and DD in 25 patients (28.7%). Thus, D allele frequency was .82. There was no significant difference between the cases with regard to age, body mass index, blood pressure status, plasma glucose level, plasma lipid profile, smoking status, average of ACBS time or family history of coronary heart disease. In ACE II group 5 patients had total venous graft occlusion, in ACE ID group 27 patients had total occlusion and in ACE DD group 20 patients had at least one graft total occlusion. The frequency of the venous graft occlusion about total venous grafts is 36% in the ACE II group, 49% in the ACE ID group, and 80% in the ACE DD group ( P =.01). Conclusion: The ACE I/D gene polymorphism is associated with long-term survival of venous conduit. The ACE DD genotype or D allele influences the angiographic outcome of patients post-ACBS. These data suggest that routine determination of the ACE genotype may help identify patients who are at higher risk of venous graft failure after ACBS.