Right internal mammary artery for myocardial revascularization: Early results and indications

The right internal mammary artery (RIMA) was used for coronary artery bypass grafting in 258 patients from October 1985 to October 1991. The RIMA was inserted as the only graft in 8 patients and in combination with the left internal mammary artery (LIMA) in 231 patients, the right gastroepiploic artery in 19, and autologous vein in 184. The patients received a total of 1 to 8 distal anastomoses (mean number, 3.3). A total of 64% of the RIMAs were anastomosed to the left anterior descending coronary artery. The primary indication for use of the RIMA was small-vessel disease in 86 patients, repeat bypass grafting in 32, varicose or stripped saphenous veins in 61, and “selected routine case” in 79. The early (≤30 days postoperatively) mortality rate in these four groups was 8.1%, 6.3%, 0%, and 0%, respectively (p < 0.01). Independent risk factors (logistic regression analysis) for early mortality were small-vessel disease, insufficient grafting, repeat coronary artery bypass grafting, diabetes, history of smoking, age of 60 years or older, and family history of ischemic heart disease. Combined into a risk index, these risk factors identified six risk groups with early mortality of 0% in the four low-risk groups and 5.6% and 58.3% in groups V and VI, respectively (p < 0.0001). No RIMA-related variables were risk factors for significant postoperative myocardial enzyme release. Intraoperative electromagnetic flow measurements revealed no differences between the RIMA and LIMA. Early angiographic patency in 50 patients was 98% for the RIMA and 93% for the LIMA. The RIMA-related variables were risk factors for neither early mortality nor significant enzyme release. The RIMA can be used to revascularize any of the three coronary systems but is primarily suited for the left anterior descending coronary artery. Indications for use of the RIMA (in most instances with the LIMA) include any situation with exhausted venous reserves, small-vessel disease (an indication for primary arterial grafting), isolated right coronary artery disease in selected patients, and selected routine cases (with the LIMA).