Does grafting coronary arteries with only moderate stenosis affect long-term mortality?

Objective Stenting coronary arteries with non-ischemia-producing moderate stenosis leads to worse outcomes than leaving them unstented. We sought to determine whether grafting coronary arteries with angiographically moderate stenosis is associated with worse long-term survival than leaving them ungrafted. Methods From 1972 to 2011, 55,567 patients underwent primary isolated coronary artery bypass grafting (CABG); 8531 had a single coronary artery with moderate (50%-69%) stenosis, bypassed in 6598 (77%) and not bypassed in 1933 (23%). These arteries were grafted with internal thoracic arteries (ITAs) in 1806 patients (27%) and with saphenous veins (SVs) in 4625 (70%). Mean follow-up for all-cause mortality was 13.0 ± 9.7 years. Results Survival was similar for patients with and without a graft to the moderately stenosed coronary artery (P =.3): 97%, 76%, 43%, and 18% at 1, 10, 20, and 30 years among patients receiving no graft; 97%, 74%, 41%, and 18% among those receiving an SV graft; and 98%, 82%, 51%, and 23% among those receiving an ITA graft. After adjusting for patient characteristics, SV grafting versus nongrafting of moderately stenosed coronary arteries was associated with similar long-term mortality (P =.2), whereas ITA grafting was associated with 22% lower long-term mortality (hazard ratio 0.78; 68% confidence interval 0.75-0.82; P <.0001). Conclusions Grafting coronary arteries with angiographically moderate stenosis is not harmful. Instead, ITA grafting of such coronary arteries is associated with lower long-term mortality. Thus, after placing the first ITA to the left anterior descending, the second ITA should be placed to the second most important coronary artery, even if it is moderately stenosed.