Factors Influencing Late Survival After Coronary Bypass Surgery

In order to determine which factors most influence late survival after the coronary bypass procedure, a review was made of the initial experience of one surgeon who performed 792 operations between 1968 and 1972. The initial 250 patients were compared with the subsequent 542 patients. The two groups were of similar age and sex and had a similar distribution of coronary disease and impaired left ventricular function. Perioperative mortality fell from an initial 6.8% (17/250) to 4.8% (26/542). The number of grafts per patient was initially 1.5 but later was 1.8. Graft patency beyond five years in 105 patients was 88.6% (148/167), 96.2% of patients had at least one patent graft. Initially, crude five year survival was 78.0% (195/250) but was 87.8% (476/542) in the later group. Patients who had no residual unbypassed lesions after operation had a 91.4% (287/314) survival while those with two residual lesions had a 66.7% (14/21) survival. Those patients with a preoperative end-diastolic pressure of less than 15 mmHg and no localized abnormality of contraction had a five year crude survival of 92.1% (316/343) whereas the patients with poor ventricular function had a survival of 81.8% (108/132). Our conclusion is that the most important factors determining late survival are the quality of surgical result achieved as shown by: perioperative mortality and graft patency; the degree of revascularization established; and the preoperative status of left ventricular function. The number of vessels diseased preoperatively had a minimal influence on late survival. These findings emphasize the primary importance of good surgical results in obtaining superior late survival rates.