Treatment for survivors of acute myocardial infarction: what have we learned from large intervention trials?

The current treatment of survivors of acute myocardial infarction is now largely based on sound scientific principles, supported by the results of large and well-designed clinical trials. These have demonstrated that aspirin, anticoagulants, beta-blockers, angiotensin converting enzyme inhibitors, and lipid-lowering agents reduce mortality and reinfarction in selected groups of patients. It remains uncertain whether these different treatments are additive and whether there are beneficial or undesirable interactions. In addition to informing us about the effectiveness or otherwise of these and other drugs, we have learned much about the conduct, analysis, and limitations of clinical trials in this context. The selection of patients for the various treatments is a matter of opinion because the results of the trials are open to a variety of interpretations. In assessing trials, one must be sure that they have been conducted on the intention to treat principle and that surrogate and composite end points have not been inappropriately used. In applying the results of trials to one's own practice, one must take into account the problems of extrapolation and subgroup analysis.