Improved survival of surgically treated patients with triple vessel coronary artery disease and severe angina pectoris. A report from the Coronary Artery Surgery Study (CASS) registry

We examined survival rate during a 6-year follow-up of patients in the registry of the Coronary Artery Surgery Study who had three vessel coronary artery disease and Canadian Cardiovascular Society class III-IV angina pectoris. All patients had a stenosis of 70% or greater in either the mid or proximal segment of all three coronary arteries. There were 679 medically treated patients and 1921 surgically treated patients in this nonrandomized comparison. Patients were stratified by left ventricular wall motion score and number of proximal coronary artery stenoses; after adjustment for these variables, the estimated probability of being alive at 6 years was 82% for surgically treated patients and 59% for medically treated patients (p < 0.0001). Among patients with the most severe left ventricular dysfunction (left ventricular wall motion score of 16 to 30), the 6-year survival rate was 63% for surgically treated patients and 30% for medically treated patients (p < 0.0001). Those with three proximal lesions (all graduations of left ventricular score) had an 81% 6-year survival rate with surgical treatment and 40% with medical treatment (p < 0.0001). Ninety percent of surgically treated patients with normal ventricular function were living at 6 years and 78% of medically treated patients (p < 0.0001). Among these patients, the survival rate was significantly better after surgical treatment than after only medical treatment if two or three proximal stenoses were present. If no proximal lesions were present (all categories of left ventricular function), 84% of surgically treated patients and 67% of medically treated patients were alive at 6 years (p < 0.0001). In a multivariate (Cox) analysis of preoperative clinical, hemodynamic, and angiographic factors, early operation was a strong predictor of survival (estimated relative risk 0.38).