Second Medicine, Angioplasty, or Surgery Study - MASS-II


The goal of the trial was to compare the effect of medical, angioplasty, or surgical treatment on patients with stable angina and multivessel disease.

Study Design

Study Design:

Patients Screened: 20,769
Patients Enrolled: 611
Mean Follow Up: One year
Mean Patient Age: 60
Female: 31
Mean Ejection Fraction: LV ejection fraction ≥50%

Patient Populations:

A total of 611 mostly male patients mean age 60 years with stable angina and preserved LV function, more than half were hypertensive and more than three-quarters were in angina class 2 or 3, total cholesterol among the three randomized groups ranged from 214 to 222 mg/dl, 86-89% had coronary obstruction ≥70%, 42% had two-vessel disease, and 58% had three-vessel disease.


Excluded were individuals with the following: one-vessel disease, severe congestive heart failure, LV ejection fraction <50%, acute MI or unstable angina in the last three months, stroke or transient ischemic attack in the last six months, previous thrombotic diseases, and liver or renal failure.

Primary Endpoints:

Combination of cardiac death, nonfatal acute MI, and unstable angina

Secondary Endpoints:

Evolution of the atherosclerosis (coronary artery disease), evolution of left ventricular (LV) function, and quality of life

Drug/Procedures Used:

Patients were randomized into three treatments arms: medical (n=203), angioplasty (n=205), and surgery (n=203). Medications administered after randomization or following initial treatment included aspirin, oral anticoagulants, nitrates, beta-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, HMG-CoA reductase inhibitors, insulin, or oral treatment for diabetes.

Principal Findings:

The average number of vessels treated by percutaneous transluminal coronary angioplasty (PTCA) was 2.1; 72% received stents. Complete revascularization was achieved in 41% of patients undergoing angioplasty. Surgical patients received an average of 3.3 grafts, and 74% attained complete revascularization.

After one year of follow-up, mortality was 1.5% for medically managed patients as compared to 4.0% in coronary artery bypass graft (CABG) patients and 4.5% in PTCA patients (p=0.23). Q-wave myocardial infarction (MI) occurred in 5.0% of medical patients, 2.0% of CABG patients, and 8.3% of PTCA patients (p=0.01).

Although none of the CABG patients required revascularization during the first year of follow-up, 8% of medical patients and 12% of PTCA patients underwent CABG or crossover or further angioplasty (p<0.001). For the primary composite endpoint of freedom from death, MI, and recurrent angina, CABG was associated with a significantly higher rate of freedom from major adverse cardiac events, as compared to medical therapy and PCI (p<0.0001); there more events in the PCI group (n=50) than the medical therapy group (n=29) or CABG group (n=13). During the first year, CABG was the better alternative to PTCA or medical management, according to the combined cardiac events.


Among patients with stable angina and multivessel disease, CABG was associated with a significantly higher rate of freedom from major adverse cardiac events, as compared to medical therapy and PCI at one year follow-up. The first MASS trial randomized 214 patients with a single severe proximal stenosis of the left anterior descending coronary artery and stable angina to medical therapy, PTCA, and CABG (Hueb WA, et al. J Am Coll Cardiol 1995;26:1600-5). While CABG was associated with a lower incidence of medium-term adverse events and no CABG patients required revascularization (as compared to eight PTCA and seven medical management patients), all three strategies produced a similar incidence of death and MI during the average three-year follow-up period. Similar results were seen at five-year follow-up (Hueb WA, et al. Circulation 1999;100:II107-13).

MASS-II expanded upon the first trial by including patients with multivessel disease and effectively tripled the patient base of MASS I. Over the nearly five-year MASS-II recruitment period, 20,769 patients were enrolled, but only 611 were eventually randomized. While Dr. Hueb suggested that the MASS-II results imply that good treatment options exist for patients who refuse CABG, the small number of patients involved in the study may make it difficult for some clinicians to agree with the assessment of the endpoints of death or MI.


Hueb W, Soares PR, Gersh BJ, et al. The medicine, angioplasty, or surgery study (MASS-II): a randomized, controlled clinical trial of three therapeutic strategies for multivessel coronary artery disease: one-year results. J Am Coll Cardiol 2004;43:1743-51.

ACC '01, Late Breaking Clinical Trials, presented by Whady A. Hueb, MD, PhD, University of São Paulo Medical School, Brazil

Keywords: Myocardial Infarction, Follow-Up Studies, Angina, Stable, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Constriction, Pathologic, Insulins, Calcium Channel Blockers, Stents, Percutaneous Coronary Intervention, Cholesterol, Nitrates, Coronary Vessels, Coronary Artery Bypass, Diabetes Mellitus

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