Diabetes did not influence long-term patency of coronary artery bypass grafts, according to a study published July 24 in the Journal of the American College of Cardiology. The study findings suggest that the internal thoracic artery (ITA) graft should be used more frequently because of the excellent patency in patients with and without diabetes even after 20 years.

Sajjad Raza, MD, et al., examined data from 57,961 patients who underwent primary isolated coronary artery bypass grafting between 1972 to 2011. Among these were 1,372 patients with diabetes treated with medication and 10,147 patients without diabetes. There were 15,887 postoperative angiograms.

The researchers compared patency of ITA and saphenous vein (SV) grafts in patients with vs. without diabetes. Stenosis was quantified for 7,903 ITA grafts and 20,066 SV grafts. Status of graft patency across time was analyzed by longitudinal nonlinear mixed-effects modeling.

The results of the analysis showed ITA graft patency was stable and similar in patients with and without diabetes: at 96-97 percent at 1, 5, 10 and 20 years in patients with diabetes and 93-96 percent in those without diabetes, respectively (early p= 0.20; late p= 0.30).

In contrast, SV graft patency declined and was similar in patients with and without diabetes: at 1, 5, 10 and 20 years, it was 78 percent, 70 percent, 57 percent and 42 percent in patients with diabetes, and 82 percent, 72 percent, 58 percent and 41 percent in patients without diabetes, respectively (early p= 0.002; late p= 0.60).

Diabetes was associated with higher early patency of ITA grafts (odds ratio: 0.63; p= 0.013). However, long-term patency of ITA grafts was similar in patients with and without diabetes (p= 0.80). Early and late patency of SV grafts were similar in patients with and without diabetes (early p = 0.90; late p = 0.80).

In an accompanying editorial, David P. Taggart, MD, PhD, and Umberto Benedetto, PhD, comment, "At first sight these results, reporting substantially worse survival in patients with diabetes, despite equivalent graft patency, seem counterintuitive and raise the possibility of a diabetic 'paradox'." They add, "In view of the number of patients, angiograms, and duration of follow-up the current study gives the most definitive resolution to date, to the conflicting evidence of the effects of diabetes on graft patency."

Keywords: Saphenous Vein, Mammary Arteries, Odds Ratio, Constriction, Pathologic, Research Personnel, Follow-Up Studies, Coronary Artery Bypass, Postoperative Period, Angiography, Diabetes Mellitus, Diabetes Collaborative Registry

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