Reoperative coronary artery bypass procedures: risk factors for early mortality and late survival.

Abstract

The number of coronary artery disease reoperations is increasing. The aim of this paper is to identify risk factors and evaluate the results of REDO coronary artery bypass grafting (CABG). Between January 1984 and October 1994, 594 patients underwent REDO-CABG and 3157 underwent primary-CABG. The mean age was 62 years with 84% men. Hypertension, hyperlipidemia, insulin dependent diabetes, smoking and renal insufficiency were all more frequent in the REDO-group. A significantly higher number of patients undergoing REDO-CABG were in the Canadian Cardiovascular Society (CCS) angina class 3 and 4, had instable angina, had left main stem stenosis of greater than 70% and 3-vessel disease compared to those undergoing primary-CABG. The mean preoperative left ventricular function (LVEF) was 49.8 (REDO) vs. 58.2%, with a P value of less than 0.001. The overall postoperative mortality rate for REDO-operations was 9.6 (57/594) vs. 2.8% for primary-CABG. Patients with a reoperative interval of more than 1 year had an 8.9% mortality rate, compared to those reoperated less than 1 year after the initial CABG, where the mortality was 21% with a P value of less than 0.05. Postoperative low cardiac output syndrome, intraaortic balloon pump support, prolonged ventilatory support (> 24 h), hemorrhage and gastrointestinal complications were prominent features of the REDO-group (all P < 0.01). Urgent operation, CCS class 3 and 4, LVEF of less than 40%, generalized arteriosclerotic disease and advanced age (> 80 years) were independent risk factors for postoperative death in both groups. Preoperative renal insufficiency, diabetes and short interval from primary-CABG were added risk factors in the REDO-group. The 5-years survival rate after REDO-CABG was 89%, while the cardiac event-free survival rate was 79% and at 7 years 84 and 62%, respectively. Reoperative CABG is effective, but has an increased operative mortality and morbidity. The long-term results are encouraging. Unstable angina, poor preoperative left ventricular function, renal insufficiency, insulin dependant diabetes and an interval shorter than 1 year of the initial operation were independent riskfactors for mortality.