Surgical treatment of unstable angina by saphenous vein and internal mammary artery bypass grafting

During a 3 year period, direct myocardial revascularization was performed on an urgent basis in 48 patients with intermittent resting chest pain which persisted more than 24 hours despite in hospital medical therapy and was accompanied by electrocardiographic changes representative of ischemia. Sixteen patients had saphenous vein (SV) grafts exclusively, and 32 patients each had one or two internal mammary artery (IMA) grafts with or without additional vein grafts. Follow up ranges from 5 to 41 months (mean, 22 months). Twelve patients had single grafts to the left anterior descending coronary artery (LAD), 18 had double grafts, 16 had triple grafts, and 2 had quadruple grafts. The LAD required grafting in every patient. There was one operative death (2 percent) and one late death from noncardiac causes. There were two (4 percent) early postoperative myocardial infarcts and no late infarcts. Actuarial analysis projects a survival rate of 96 percent 3 years postoperatively. Eighty one percent of the survivors are in Functional Class I, 17 percent are in Class II, and 2 percent in Class III. All patients had postoperative angiography 2 weeks after operation. Eighty six percent of the SV grafts and all IMA grafts were open. No significant differences were observed between mean preoperative and postoperative left ventricular end diastolic pressures or ejection fractions, but these parameters were noted to improve after operation in several patients. The remarkably high early and late survival rates, the low incidence of myocardial infarction, and the excellent functional results after rather long follow up indicate that emergency revascularization provides an effective therapy for unstable angina. The use of IMA grafts, when feasible, is a safe and possibly preferable approach in these patients.