Multivariate analysis of operative mortality and late outcome after coronary bypass surgery

A multivariate discriminant analysis was made to find out the variables that could offer the greatest amount of predictive power on the long term results after myocardial revascularization. A total of 202 consecutive patients who underwent CABG operation in 1981 were reviewed 5 years later. Most of the patients (76.5%) had 3-vessel disease, previous AMI (70.2%), hypertriglyceridemia (61.7%), positive family history of CAD (68.0%) elevated blood cholesterol level (48.1%), hypertension (41.9%) or were smokers (61.9%). In 48.1% of the cases IMA was used for revascularization and in the rest saphenous vein graft alone. The 5-year survival of the entire group was 87%. The late mortality was related to 3 independent variables in multivariate analysis: 1) positive family history of CAD (p less than 0.05), 2) preoperative ejection fraction less than 0.30 (p less than 0.01) and 3) revascularization without IMA (p less than 0.02). The vast majority of patients (70%) had a better NYHA class 5 years postoperatively (the 95% confidence interval was 65-77%). These patients had experienced an average improvement of 2.0 NYHA categories. Eight per cent of patients had an unaltered and 5% a worse NYHA class than preoperatively. When the patients were grouped into those having a better NYHA class and into those who had an unchanged or worse NYHA class or who had died from CAD the only variable which was associated with poorer outcome appeared to be positive family history of CAD (p less than 0.01). It can be concluded that hereditary factors, utilization of internal mammary artery in revascularization and preoperative ejection fraction are the major predictors of late outcome after CABG.