[Results of coronary artery bypass surgery. Surgical mortality, survival and follow-up functional state. Multivariate discriminant analysis of relative risk factors]

Clinical results of coronary artery bypass surgery, have been evaluated by analyzing operative mortality, late survival, late functional results and their related risk factors. Four hundred and thirty-seven consecutive patients who underwent coronary artery bypass surgery between January, 1979, and December, 1983, were the clinical material of this study. The gender of patients was male in 89% of the cases; age ranged from 34 to 78 years with a mean of 54.8 +/- 8.2 (SD). Patients with combined surgical procedures were excluded. Follow-up averaged 55.7 months; 404 survivors have been contacted (97% of the total study population, if operative and late deaths are added); 218 patients underwent a control exercise test; postoperative employment status was determined for 242 individuals. The operative mortality was 5.49% (24 patients). Death was due to cardiac causes in 75% of the cases. The overall actuarial survival rate was 85 +/- 1.9% after 5 years and 83.4 +/- 2.2% after 7 years. When non-cardiac related deaths were excluded the actuarial rates were 88 +/- 1.7% and 87.2 +/- 1.9% after 5 and 7 years respectively. Actuarial freedom from all ischemic events (cardiac related death, late myocardial infarction or recurrence of angina) was 66.1 after five years, and was 70.2% if operative deaths were excluded. Actuarial freedom from recurrence of angina for patients alive at follow-up was 78.7% after five years, actuarial freedom from myocardial infarction was 93.5%. The mortality hazard showed a diphasic response, being higher perioperatively and constant in the following 5 years of follow-up. All ischemic events, both singularly and together, showed an accelerated rate of occurrence at the first and after the fifth postoperative year, the slope of the curve being quite flat during the 1 to 5 year interval. The control exercise test was negative for 62.8% of the patients, positive for 33.5% and undeterminable in 3.7%. Employment status was postoperatively unaffected in 49.6% of the cases, while 27.3% of the patients retired: the remaining individuals had already retired before surgery. Statistical analysis (stepwise logistic regression) identified age (p = 0.002) and cross-clamp time (p = 0.016) as significant risk factors of operative mortality. The ejection fraction showed a value close to statistical significance (p = 0.06).(ABSTRACT TRUNCATED AT 400 WORDS)