Fate of Grafts Bypassing Nonischemic Versus Ischemic Inducing Coronary Stenosis

Abstract

There is a lack of evidence regarding the efficacy of ischemia-guided coronary artery bypass grafting. We compared the incidence of graft failure between grafts bypassing ischemia-inducing and nonischemia-inducing stenoses. Between 1997 and 2011, 2,304 patients for whom baseline coronary angiography and myocardial perfusion imaging were available were identified from a single-center coronary artery bypass grafting registry. According to baseline myocardial perfusion imaging, each graft was assigned to either graft bypassing ischemia-inducing or nonischemia-inducing stenoses (ischemia-related grafts, n = 4,904; ischemia-unrelated grafts, n = 2,709). Graft failure was defined as total occlusion on coronary computed tomography angiography, performed at the discretion of the treating physician. The incidence of graft failure was compared on a per-graft basis. At 5 years, the incidence of graft failure was significantly higher in the ischemia-unrelated grafts (4.2% vs 2.9% in ischemia-related grafts; p = 0.003). Ischemia-related graft was an independent determinant of graft patency (adjusted hazard ratio 0.61; 95% confidence interval 0.44 to 0.84; p = 0.002). Increased risk of graft failure associated with ischemia-unrelated graft was observed only in the internal thoracic artery (3.3% vs 2.0%, p = 0.021) and arterial grafts (6.5% vs 4.3%, p = 0.020), but not in the venous grafts (2.7% vs 2.7%; p = 0.99). In terms of major adverse cardiac and cerebrovascular events, 5-year incidences were comparable between the patients with and without ischemia-unrelated grafts (219, 19.3% vs 160, 18.0%; p = 0.61). In conclusion, ischemia-unrelated grafts became dysfunctional more frequently than ischemia-related grafts, and were not preventive of adverse events.