Should all moderate coronary lesions be grafted during primary coronary bypass surgery? An analysis of progression of native vessel disease during a randomized trial of conduits

ObjectiveWhether to graft a moderately stenosed coronary vessel remains debatable. We investigated whether grafting such vessels is warranted based on angiographic evidence of disease progression.MethodsOf 619 patients who underwent on-pump coronary artery bypass grafting in an ongoing, randomized radial artery trial, 405 have at least 1 follow-up angiogram at a mean of 6.2 ± 3.1 years (range, 0-14 years) after surgery. Percent diameter stenosis in each major native vessel was reported by 3 cardiac specialists and classified as either moderate (40%-69%) or severe (≥70%) stenosis. Progression of native vessel disease and graft patency were determined by comparison of pre- and postoperative angiography.ResultsA total of 3816 native vessels and 1242 bypass grafts were analyzed, of which 386 moderate preoperative lesions were identified, 323 of which were grafted. In all territories, grafted vessels had greater risk of disease progression than ungrafted equivalents (43.4% vs 10.5%, P < .001). Moderate lesions were more likely than severe lesions to remain unchanged on follow-up angiography (52.6% vs 31.1%, P < .001). Only 1 in 7 moderate lesions in the right coronary artery exhibited significant progression during follow-up if left ungrafted, whereas the likelihood of progression in left-sided counterparts approached 50%. Arterial and vein grafts to left-sided moderately stenosed vessels had excellent patency (83% and 77% at 8 years, respectively), which was not matched by right-sided grafts (P = .051). Placement of a graft for a moderate lesion was associated with significantly greater incidence of disease progression, most marked in the right coronary territory.ConclusionsThe greater risk of progression of left-sided moderate lesions, and high graft patency rates when bypassed, suggests that the balance of clinical judgment lies in favor of grafting moderate left-sided lesions. In the right coronary system, however, a lesion is likely to remain moderate if left ungrafted and, with a low risk of progression, it may be reasonable to leave these vessels undisturbed.