Secondary prevention of acute myocardial infarction with beta-blocking agents and calcium antagonists

The discovery that beta blockers possess clinically useful hypotensive, antianginal and antiarrhythmic properties has attracted the interest of clinicians, researchers and the pharmaceutical community alike. In addition, minor differences in a variety of ancillary properties have led to speculation that specific classes of drugs might have advantages over other classes. The enthusiasm that greeted reports from the first small trials, which showed that beta blockers reduced the postmyocardial infarction mortality rate, attracted the commercial support necessary to evaluate different beta blockers in this clinical setting. The plethora of beta blockers that subsequently became available for study led to considerable improvement in both the design and implementation of large clinical trials. Despite apparent discrepancies in the results of various trials, meta-analysis indicates that most, if not all, beta blockers reduce postinfarction mortality. However, because meta-analysis cannot recommend a particular drug or specific dose for use in an individual patient, clinical practice must be based on the results of individual trials, not on the conclusions of meta-analysis. The clinical utility of beta blockers in the secondary prevention of myocardial infarction, coupled with experimental evidence that calcium antagonists reduce infarct size, led to a series of large studies designed to establish whether calcium antagonists have any effect on reducing mortality in patients with myocardial infarction. Lessons learned from the beta-blocker trials permitted a more rapid evaluation of the efficacy of calcium antagonists in this setting. It is clear that, unlike beta blockers, calcium antagonists are not effective in the secondary prevention of myocardial infarction.