Survival following coronary artery bypass grafting in patients with severe angina pectoris (CASS). An observational study

This observational study evaluates the effects of the severity of angina pectoris and the treatment method upon the survival of 4,209 patients in the Coronary Artery Surgery Study registry. In this nonrandomized study, these patients met the criteria used in the Coronary Artery Surgery Study randomized trial, except for the degree of angina pectoris and the method of selection of treatment. The 5 year survival rate was greater than or equal to 93% in patients with Class I and II angina pectoris and normal left ventricular function, regardless of the number of involved vessels or treatment received. Late survival of surgically treated patients with Class III and IV angina pectoris and normal left ventricular function was similar, regardless of the number of vessels involved (greater than or equal to 92% at 5 years). Nonoperatively treated patients with Class III and IV angina pectoris and normal left ventricular function had poorer 5 year survival rates, lowest (74%) in patients with three vessel disease (p less than 0.0001). This difference was also observed in patients with abnormal left ventricular function, three vessel disease, and Class III and IV angina pectoris; the 5 year survival rates were 82% for the operative group and 52% for the nonoperative group (p less than 0.0001). These data confirm the importance of clinical as well as anatomic factors in determining the prognosis of patients with ischemic heart disease and indicate that coronary artery bypass grafting can improve late survival in patients with triple vessel disease and severe angina pectoris.