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(Circulation. 1999;100:II-107.)
© 1999 American Heart Association, Inc.

Surgery for Coronary Artery Disease

Five-Year Follow-Up of 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 Coronary Artery Stenosis

Whady A. Hueb, MD; Paulo Rogério Soares, MD; Sérgio Almeida de Oliveira, MD; Shiguemituzo Ariê, MD; Rita Helena A. Cardoso, MSc; Dalia Ballas Wajsbrot, MSc; Luiz A. M. Cesar, MD; Adib D. Jatene, MD; José Antonio F. Ramires, MD

From the Heart Institute of the University of São Paulo, São Paulo, Brazil.

Correspondence to Dr Whady A. Hueb, Instituto do Coração–HC-FMUSP, Divisão Clinica, Av Dr Eneas de Carvalho Aguiar, 44, Cerqueira Cesar–São Paulo/SP, Brazil. E-mail mass{at}incor.usp.br

Background—Although coronary angioplasty and myocardial bypass surgery are routinely used, there is no conclusive evidence that these interventional methods offer greater benefit than medical therapy alone. This study is intended to evaluate, in a prospective, randomized, and comparative analysis, the benefit of the 3 current therapeutic strategies for patients with stable angina and single proximal left anterior descending coronary artery stenosis.

Methods and Results—In a single institution, 214 patients with stable angina, normal ventricular function, and severe proximal stenosis (>80%) on the left anterior descending artery were selected for the study. After random assignment, 70 patients were referred to surgical treatment, 72 to angioplasty, and 72 to medical treatment. The primary end points were the occurrence of acute myocardial infarction or death and presence of refractory angina. After a 5-year follow-up, these combined events were reported in only 6 patients referred to surgery as compared with 29 patients treated with angioplasty and 17 patients who only received medical treatment (P=0.001). However, no differences were noted in relation to the occurrence of cardiac-related death in the 3 treatment groups (P=0.622). No patient assigned to surgery needed repeat operation, whereas 8 patients assigned to angioplasty and 8 patients assigned to medical treatment required surgical bypass after the initial random assignment. Surgery and angioplasty reduced anginal symptoms and stress-induced ischemia considerably. However, all 3 treatments effectively improved limiting angina.

Conclusions—Bypass surgery for single-vessel coronary artery disease is associated with a lower incidence of medium-term and long-term events as well as fewer anginal symptoms than that found in the patients who underwent angioplasty or medical therapy. In this study, coronary angioplasty was only superior to medical strategies in relation to the anginal status. However, the 3 treatment regimens yielded a similar incidence of acute myocardial infarction and death. Such information should be useful when choosing the best therapeutic option for similar patients.

Key Words: coronary disease • angioplasty • bypass