Secondary prevention of cardiac events following myocardial infarction: effects of atenolol and enalapril. Beijing Collaborative Study Group.

OBJECTIVE

To investigate the actions of beta-blocker (atenolol) and ACE inhibitor (enalapril) for the secondary prevention of the main cardiac complications after acute myocardial infarction (AMI).

METHODS

1106 cases of AMI from 7 hospitals in the Beijing area were collected and were divided randomly into three groups: control (group C), atenolol (group A), and enalapril (group E). Drugs for investigation were administered 2-4 weeks after the onset of AMI, and the subjects were followed up for a median period of 19 months. All patients were given aspirin 50 mg/day. The end points of observation were cardiac events and non-cardiac events. Cardiac events included sudden cardiac death (SCD), heart failure death, total cardiac deaths, and myocardial re-infarction.

RESULTS

The clinical conditions of the three groups were compatible. Sixty-six cardiac events (6.0%) occurred. Comparing with group C, the rate of SCD decreased significantly by 68% in group A after atenolol treatment for 28 months. Both atenolol and enalapril significantly increased left ventricular ejection fraction (LVEF), whereas in group C the LVEF did not change during the follow-up period. There was obvious decreasing tendency of the survival curve in group C, compared with the other two groups. Totally drugs decrease one cardiac death 0/00/month. But the rate of myocardial re-infarction was the same in the three groups. No serious side effects on blood pressure or heart rate were observed.

CONCLUSIONS

Both atenolol and enalapril (domestic products) are beneficial to the secondary prevention of SCD and heart failure death after AMI, but not to re-infarction. Both drugs should be continued for a prolonged period to be effective. Drugs given 2-4 weeks after acute stage are also effective, with no serious side effects.