Sequential Internal Mammary Artery Conduits in Coronary Artery Bypass Grafting

The results of sequential internal mammary artery (IMA) grafting in myocardial revascularization, with special emphasis on IMA-related morbidity, have been evaluated over a 2-year period. Between June 1,1991 and July 1,1993,638 patients underwent isolated coronary artery bypass grafting (CABG) at our institution, using the IMA as a conduit. In 541 patients, one or both IMAs were used as a single coronary artery bypass conduit (group 1) and, in the remaining 97 patients, sequential IMA grafting was performed (group 2). The mean age was 60.1 ± 9.2 years and 82% of the patients were male. There were 16.6% repeat CABG in group 1 compared to 3.1% in group 2 (p < 0.01). All patients had preoperative angina and 67% were in the Canadian Cardiovascular Society angina class 3 and 4. Other preoperative patient characteristics were similar in both groups. The overall perioperative mortality was 1.9% (12/638). Twelve patients died in group 1. There were no mortalities in group 2. Nonfatal perioperative myocardial infarction occurred in 10 patients in group 1 (1.6%) and in none in group 2. The incidence of re-exploration for bleeding, sternal wound infections, sternal dehiscence or other perioperative complications was low in both groups. Significant IMA spasm or insufficient IMA flow due to small-caliber vessels occurred in only 1.3% (8/638: 6 patients in group 1 and 2 patients in group 2) (n.s.). None of the patients with sequential IMA grafts in group 2 had early graft failure (within 30 days postoperatively). Twelve months postoperatively, 88% (83/94 survivors) of the patients who had received a sequential IMA graft were completely free of angina. Coronary revascularization with sequential IMA graft was found to be safe and effective. Specific IMA problems such as IMA spasm occurred rarely and not more frequently when the IMA was used as sequential graft.