Coronary Artery Target Selection and Survival After Bilateral Internal Thoracic Artery Grafting

Background: The importance of a coronary artery, based on the myocardial mass it perfuses, is well documented, but little is known about the importance of a vessel that has been bypassed and its effect on survival in the context of bilateral internal thoracic artery (BITA) grafting. Objectives: This study determined the effect of a dominant left anterior descending (LAD) artery and important non-LAD targets on outcomes after BITA grafting. Methods: From January 1972 to January 2011, of 6,127 patients who underwent BITA grafting, 2,551 received 1 ITA grafted to the LAD and had an evaluable coronary angiogram. A dominant LAD was defined as one that was wrapped around the left ventricular apex. Non-LAD targets were graded based on their terminal reach toward the apex: important: >75% (n = 1,698); and less important: ≤75% (n = 853). Mean follow-up was 14 ± 8.7 years. Multivariable analysis was performed to identify risk factors for time-related mortality. Results: A dominant LAD was present more frequently in patients with less important additional targets (51% vs. 35%; p < 0.0001). A total of 179 patients (7.0%) received a second ITA to multiple targets, 77 (43%) of which were to multiple important target vessels. Unadjusted late survival was similar regardless of degree of importance of the second ITA target—77% at 15 years (p = 0.70) for the important and less important targets, respectively. In the multivariable model, grafting the second ITA to multiple important targets was associated with better long-term survival (p = 0.005). In patients with a nondominant LAD, a second ITA grafted to a less important artery was associated with higher risk of operative mortality (2.4% vs. 0.51%; p = 0.007). A saphenous vein graft to an important or less important target did not influence long-term survival. Conclusions: In BITA grafting, bypassing multiple important targets to maximize myocardium supplied by ITAs improved long-term survival. In patients with a nondominant LAD, selecting an important target for the second ITA lowered operative mortality.