Multivariate risk factor analysis of clinical outcome 15 years after venous coronary artery bypass graft surgery.

Abstract

Knowledge is still lacking about pre-operative and postoperative factors which predict the long-term prognosis of patients who undergo venous coronary artery bypass graft surgery. Four hundred and twenty-eight consecutive patients who underwent isolated venous coronary artery bypass graft surgery with or without left ventricular aneurysm surgery between 1 April 1976 and 1 April 1977, were followed prospectively. Follow-up was 99.8% complete and averaged 15.4 years for the survivors. Two prognostic models were set up to illustrate the influence of 21 variables, present at and, 5 years after, surgery, on the occurrence of six different clinical events. Multivariate analysis was performed using the Cox regression model. Age, left ventricular function, pre-operative severity of angina and diabetes mellitus are continuous incremental risk factors for one or more events. Revascularization with sequential grafts only, and obesity at operation are incremental risk factors for acute myocardial infarction. From the 'classical' risk factors present 5 years after surgery hypertension is an incremental risk factor for both overall and cardiac mortality, diabetes mellitus for cardiac mortality, myocardial infarction, balloon angioplasty and smoking for all clinical events except mortality. Well-known pre-operative factors including 'classical' risk factors, present late after surgery, influence the occurrence of clinical events. Treatment of these factors may result in better long-term prognosis after venous bypass graft surgery.