Operation for unstable angina pectoris: Factors influencing adverse in-hospital outcome

Coronary artery bypass grafting for the treatment of unstable angina is still associated with increased operative risk and postoperative morbidity. The impact of the extended use of arterial grafts on early results is incompletely defined. In a 7-year period (1986 to 1993), 474 patients (average age, 65 years; range, 34 to 85 years) underwent coronary artery bypass grafting for the treatment of unstable angina. Sixty-eight patients were operated on emergently and 406 urgently. They received an average of 3.0 distal anastomoses (range, 1 to 6). Seventy-nine patients had exclusively venous grafts, 316 had one internal thoracic artery graft, 79 had bilateral internal thoracic artery grafts, and 20 had inferior epigastric artery grafts. Sequential internal thoracic artery grafting was performed in 70 patients. Redo operations were performed in 26 patients. Thirty-four patients (7.2%) experienced a new myocardial infarction. Eighty-nine patients (18.8%) had an intraaortic balloon pump inserted preoperatively, intraoperatively, or postoperatively. Eight patients (1.7%) died intraoperatively and 24 patients (5.1%) died postoperatively. Seventy-seven patients (16.2%) had an adverse outcome, as shown by the need for an intraaortic balloon pump (intraoperatively or postoperatively) or hospital death, or by both. Forty variables were examined by multivariate analysis for their influence on the occurrence of an adverse outcome. Aortic cross-clamp time ( p = 0.0004), transfer from the intensive care unit ( p = 0.0023), female sex ( p = 0.0023), operation performed in early years ( p = 0.0041), left ventricular aneurysm ( p = 0.0068), the number of diseased coronary vessels ( p = 0.0312), and reoperation ( p = 0.0318) were all found to be significant independent predictors of increased risk. Thus, aortic cross-clamp duration remains the main determining factor of postoperative hospital outcome, which suggests the need for improved myocardial protection techniques. Outcome was not found to be adversely affected by the extended use of arterial grafts.