Eighteen-year follow-up in the veterans affairs cooperative study of coronary artery bypass surgery for stable angina

Abstract

Background. The 18-year effect of bypass surgery compared with medical therapy on survival, incidence of myocardial infarction, and relief of angina was evaluated in 686 randomized patients with stable angina in the Veterans Affairs Cooperative Study of Coronary Artery Bypass Surgery. Methods and Results. The primary treatment comparisons were made according to intent to treat; 44% of the entire medical cohort had bypass surgery during a median follow-up of 16.8 years. Overall 18-year survival rates were 33% for medicine compared with 30% for surgery (p=0.60). Survival rates for high-risk patients without left main disease, which had shown a significant advantage for surgical therapy up to 11 years, were 23% medicine versus 24% surgery for patients with three-vessel disease and impaired left ventricular function (p=0.49) and 22% versus 25% for those with multiple clinical risk factors (p=0.12). For patients with two-vessel disease, who had significantly better survival with medical therapy at 11 years, rates were similar at 18 years in the two treatment groups (34% medicine versus 30% surgery, p=0.09). Cumulative 18-year myocardial infarction rates (fatal plus nonfatal) were 41% in medical and 49% in surgical patients (13% perioperative infarction rate), p=0.15. Nonfatal infarction rates were lower with medical than with surgical therapy (32% versus 44%, p=0.015), but fatal infarction rates were similar (14% medicine versus 13% surgery, p=0.62). The combined rate of myocardial infarction or death was also lower with medical therapy (75% versus 82%, p=0.016). In contrast, surgery reduced mortality after myocardial infarction by 35% at 10 years (p<0.001) but only by 13% at 18 years (p=0.09). The percent of medical and surgical patients who were angina-free was 3% versus 22% (p<0.001) at 1 year and 4% versus 12% (p<0.001) at 5 years compared with rates of 6% versus 5% (p>0.50) at 10 years and 3% versus 4% (p>0.50) at 15 years. Conclusions. The benefits of coronary artery bypass surgery on survival, symptoms, and postinfarction mortality were transient and lasted fewer than 11 years. The benefits began to diminish after 5 years, when graft closure accelerated. Surgery was effective in reducing mortality only for patients with a poor natural history. Low-risk patients, who had a good prognosis with medical therapy, derived no survival benefit with surgical therapy at any time during the follow-up period. Regardless of risk, surgery also did not reduce the incidence of myocardial infarction or the combined incidence of infarction or death.