Comparison of long-term clinical results of double versus single internal mammary artery bypass grafting

Background. The long-term benefits of double versus single internal mammary artery (IMA) coronary bypass grafting have not yet been established. Methods. Six hundred patients were studied retrospectively 10 years after coronary revascularization using saphenous vein grafts (SVGs) only or single or double IMA grafts. Results. Patients with double IMA grafts were younger and were more likely to have diabetes, left main coronary stenosis, and three-vessel coronary artery disease than patients with SVGs or single IMA grafts. Patients with SVGs and double IMA grafts had a greater number of diseased coronary vessels and a greater number of coronary bypass grafts per patient than patients with single IMA grafts (mean ± SEM, 2.8 ± 1.0, 2.8 ± 0.7, 2.1 ± 0.8 grafts per patient, respectively, p< 0.0001). Actuarial survival rates 10 years after placement of SVGs and single and double IMA grafts averaged 83% ± 6%, 90% ± 4%, and 87% ± 8%, respectively (p = 0.03). Cox regression analysis showed that diabetes (relative risk, 2.03; 95% confidence interval, 1.55 to 2.66) and chronic pulmonary obstructive disease (relative risk, 2.20; 95% confidence interval, 1.58 to 3.80) increased, whereas an IMA graft on the left anterior descending coronary artery significantly decreased, the risk of death after operation (relative risk, 0.45; 95% confidence interval, 0.36 to 0.57) throughout the follow-up period. Conclusions. Use of an IMA graft on the left anterior descending coronary artery improves survival compared with use of an SVG. Although patients with double IMA grafts had a greater number of poor prognosis risk factors before operation, their 10-year survival rate was similar to that of patients with a single IMA graft.