Five-Year Follow-Up of the Medicine, Angioplasty, or Surgery Study (MASS II): A Randomized Controlled Clinical Trial of 3 Therapeutic Strategies for Multivessel Coronary Artery Disease

Abstract

Background— Despite routine use of coronary artery bypass graft (CABG) and percutaneous coronary intervention (PCI), no conclusive evidence exists that either modality is superior to medical therapy (MT) alone for treating multivessel coronary artery disease with stable angina and preserved ventricular function. Methods and Results— The primary end points were total mortality, Q-wave myocardial infarction, or refractory angina requiring revascularization. The study comprised 611 patients randomly assigned to undergo CABG (n=203), PCI (n=205), or MT (n=203). At the 5-year follow-up, the primary end points occurred in 21.2% of patients who underwent CABG compared with 32.7% treated with PCI and 36% receiving MT alone ( P =0.0026). No statistical differences were observed in overall mortality among the 3 groups. In addition, 9.4% of MT and 11.2% of PCI patients underwent repeat revascularization procedures compared with 3.9% of CABG patients ( P =0.021). Moreover, 15.3%, 11.2%, and 8.3% of patients experienced nonfatal myocardial infarction in the MT, PCI, and CABG groups, respectively ( P <0.001). The pairwise treatment comparisons of the primary end points showed no difference between PCI and MT (relative risk, 0.93; 95% confidence interval, 0.67 to 1.30) and a significant protective effect of CABG compared with MT (relative risk, 0.53; 95% confidence interval, 0.36 to 0.77). Conclusions— All 3 treatment regimens yielded comparable, relatively low rates of death. MT was associated with an incidence of long-term events and rate of additional revascularization similar to those for PCI. CABG was superior to MT in terms of the primary end points, reaching a significant 44% reduction in primary end points at the 5-year follow-up of patients with stable multivessel coronary artery disease.