Effect of metoprolol on death and cardiac events during a 2-year period after coronary artery bypass grafting. The MACB Study Group.

PURPOSE

To evaluate the effect of long-term treatment with metoprolol after coronary bypass grafting on death and cardiac events.

METHODS

Patients in western Sweden on whom coronary artery bypass grafting was performed between June 1988 and June 1991 were evaluated for inclusion during the first 3 weeks after surgery. Major exclusion criteria were age > 75 years, concomitant valve surgery, traditional contraindications to beta-blockers and unwillingness to participate. Patients were randomized in a double-blind fashion to 100 mg of metoprolol/placebo daily for 2 weeks and thereafter 200 mg daily for 2 years.

RESULTS

Of 2365 patients who were operated on, 967 were randomized to either metoprolol (n = 480) or placebo (n = 487). Primary end points (death, non-fatal myocardial infarction, unstable angina pectoris, need for coronary artery bypass grafting or percutaneous transluminal angioplasty), were reached by 42 patients in the metoprolol group (8.8%), as compared with 39 in the placebo group (8.0%) (P = 0.73). Of all the patients randomized to metoprolol, 34% withdrew from blind treatment prematurely compared with 44% for placebo (P < 0.01).

CONCLUSION

Prophylactic treatment with metoprolol over a 2-year period after coronary artery bypass grafting did not reduce death or the development of cardiac events. However, the 95% confidence limits ranged from the possibility of a 30% reduction in events to a 68% increase in events if patients were treated with metoprolol as compared with placebo.