THE MEDICINE, ANGIOPLASTY OR SURGERY STUDY (MASS) - A PROSPECTIVE, RANDOMIZED TRIAL OF MEDICAL THERAPY, BALLOON ANGIOPLASTY OR BYPASS-SURGERY FOR SINGLE PROXIMAL LEFT ANTERIOR DESCENDING ARTERY STENOSES

Objectives. This study sought to evaluate, in a prospective and random ized trial, the relative efficacies of three possible therapeutic stra tegies for patients with a single severe proximal stenosis of the left anterior descending coronary artery and stable angina. Background. Al though percutaneous transluminal coronary angioplasty and coronary art ery bypass surgery are often per formed in patients with a single prox imal stenosis of the left anterior descending coronary artery, it is u nclear whether revascularization offers greater clinical benefit than medical therapy alone. Methods. At a single center, 214 patients with stable angina, normal ventricular function and a proximal stenosis of the left anterior descending coronary artery >80% were randomly as sig ned to undergo mammary bypass surgery (n = 70), balloon angioplasty (n = 72) or medical therapy alone (n = 72). Angioplasty had to be consid ered technically feasible in every case. The predefined primary study end point was the combined incidence of cardiac death, myocardial infa rction or refractory angina requiring revascularization. Results. At a n average follow-up period of 3 years, a primary end point had occurre d in only 2 patients (3%) assigned to bypass surgery compared with 17 assigned to angioplasty (24%) and 12 assigned to medical therapy (17%) (p = 0.0002, angioplasty vs. bypass surgery; p = 0.006, bypass surger y vs. medical treatment; p = 0.28, angioplasty vs. medical treatment, all by log-rank test). There was no difference in mortality or infarct ion rates among the groups, However, no patient allocated to bypass su rgery needed revascularization, compared with eight and seven patients as signed, respectively, to coronary angioplasty and medical treatmen t (p = 0.019). Both revascularization techniques resulted in greater s ymptomatic relief and a lower incidence of ischemia on the treadmill t est; however, all three strategies eventually resulted ir! the aboliti on of limiting angina. Conclusions. The more aggressive therapeutic ap proach with initial bypass surgery for patients with a single severe p roximal stenosis of the left anterior descending coronary artery is as sociated with a lower incidence of medium-term adverse events than cor onary angioplasty or medical treatment. However, all three strategies resulted in a similar incidence of death and infarction during an aver age follow-up period of 3 years. This information should be taken into consideration when physicians and patients make therapeutic choices i n this setting. (J Am Coll Cardiol 1995;26:1600-5)