Practice Update: Cardiology

CARDIAC PROCEDURES & SURGERIES 27

Influence of Diabetes on Long-TermCoronary Artery Bypass Graft Patency JACC: Journal of the American College of Cardiology

COMMENT By Benjamin Morgan Scirica MD T his retrospective analysis from the Cleveland Clinic evaluated bypass graft patency in almost 15,000 patients with and without diabe- tes. Overall, arterial grafts demonstrated excellent patency (>93% patency at 20 years) compared with vein grafts (~40% at 20 years). To the surprise of the inves- tigators, there was no difference in the rates of patency for either arterial or venous grafts between patients with and without diabetes. Given the under- lying biology of diabetes and vascular disease, and the higher overall mortality in patients with diabetes, this seemingly paradoxical result raises the possibility that there is an inherent bias in the way patients were included in analysis, or of residual confounding. For example, were a greater number of healthier, asympto- matic patients with diabetes referred for follow-up catheterization due to the concern of progression whereas only symptomatic patients without diabetes were referred for follow-up angiography? Due to these potential limitations, I remain somewhat skeptical about the conclusion that patients with and without diabetes have similar graft patency. The principal message is that single arterial conduits have remarkable patency, almost a “life- long warranty,” and therefore should be utilized for revascularization of the most critical area of risk.

Take-home message • This retrospective study looked into the impact of diabetes on graft patency fol- lowing coronary artery bypass grafting. The stability of internal thoracic artery (ITA) grafts was similar among patients with and without diabetes; there were no significant differences at 1, 5, 10, and 20 years of follow-up. Conversely, the patency of saphenous vein grafts at 1, 5, 10, and 20 years decreased in both patients with diabetes (78%, 70%, 57%, and 42%, respectively) and without diabetes (82%, 72%, 58%, and 41%, respectively). Following adjustment for patient characteristics, early ITA patency was significantly higher for patients with diabetes (OR, 0.63), although there were no significant differences in late patency. After adjustments, there were no significant differences in early or late saphenous vein grafts between patients with and without diabetes. • The authors concluded that, contrary to their expectations, the long-term patency of bypass grafts was not affected by diabetes, and the excellent long-term patency of ITA grafts indicates that their use should be maximized in coronary artery bypass patients, regardless of diabetes status.

RESULTS ITA graft patency was stable over time and similar in patients with and without diabe- tes: at 1, 5, 10, and 20 years, 97%, 97%, 96%, and 96% in patients with diabetes, and 96%, 96%, 95%, and 93% in patients without diabe- tes, respectively (early p = 0.20; late p = 0.30). In contrast, saphenous vein graft patency declined over time and similarly in patients with and with- out diabetes: at 1, 5, 10, and 20 years, 78%, 70%, 57%, and 42% in patients with diabetes, and 82%, 72%, 58%, and 41% in patients without diabetes, respectively (early p < 0.002; late p = 0.60). After adjusting for patient characteristics, diabetes was associated with higher early patency of ITA grafts (odds ratio: 0.63; 95% confidence limits: 0.43 to 0.91; p = 0.013), but late patency of ITA grafts was similar in patients with and without diabetes (p = 0.80). Early and late patency of saphenous vein grafts were similar in patients with and without diabetes (early p = 0.90; late p = 0.80). CONCLUSIONS Contrary to our hypothesis, dia- betes did not influence long-term patency of bypass grafts. Use of ITA grafts should be

Abstract BACKGROUND Nearly 50% of patients undergoing coronary artery bypass grafting have diabetes. However, little is known about the influence of diabetes on long-term patency of bypass grafts. Because patients with diabetes have more severe coronary artery stenosis, we hypothe- sized that graft patency is worse in patients with than without diabetes. OBJECTIVES This study sought to examine the influence of diabetes on long-term patency of bypass grafts. METHODS From 1972 to 2011, 57,961 patients underwent primary isolated coronary artery bypass grafting. Of these, 1,372 pharmacolog- ically treated patients with diabetes and 10,147 patients without diabetes had 15,887 postoper- ative angiograms; stenosis was quantified for 7,903 internal thoracic artery (ITA) grafts and 20,066 saphenous vein grafts. Status of graft patency across time was analyzed by longitudi- nal nonlinear mixed-effects modeling.

Dr Scirica is Cardiologist and Director, Inovation, Cardiovascular Division, Brigham and Women’s Hospital; Associate Professor of Medicine, Harvard Medical School; Senior Investigator, TIMI Study Group, Boston, Massachusetts.

maximized in patients undergoing coronary artery bypass grafting because they have excellent patency in patients with and without diabetes even after 20 years. Influence of diabetes on long-term coronary artery bypass graft patency. J Am Coll Cardiol 2017 Aug 01;70(5)515-524, S Raza, EH Black-

stone, PL Houghtaling, et al. www.practiceupdate.com/c/56306

VOL. 2 • NO. 2 • 2017