Treatment with beta-adrenergic blocking agents after myocardial infarction: From randomized trials to clinical practice

Abstract

Our aim was to determine the percent of patients with myocardial infarction who are treated with beta-adrenergic blocking agents in dosages proved to be effective in preventing death after a heart attack. In the prospective randomized trials showing that beta-blocker treatment improves survival rates after myocardial infarction, relatively high dosages of these agents were used. However, it is not known whether these dosages are used in current clinical practice. In a retrospective analysis of clinical data from 606 consecutive survivors of myocardial infarction at four university hospitals in three countries, we assessed the number of infarct survivors receiving prospectively defined "effective dosages" of beta-blockers. We defined these dosages as those that demonstrated improved survival rates of infarct survivors who received active drug in large, prospective, double-blind, placebo-controlled trials. Only 58% of infarct survivors with no contraindications to beta-blockers received these drugs at the time of hospital discharge, and only 11% received dosages equivalent to > 50% of the effective dosages. Independent predictors of failure to prescribe beta-blockers to infarct survivors without contraindications to these drugs were the use of diuretic agents, transient heart failure, impaired left ventricular function and increased patient age. Among patients receiving beta-blockers, only the use of propranolol predicted prescription of a low beta-blocker dosage. Failure to prescribe beta-blockers after myocardial infarction is common but in most cases is not due to clear contraindications. Many patients not receiving beta-blockers belong to subgroups that would derive the greatest benefit from such treatment. Finally, even when beta-blockers are prescribed, the dosages used are considerably lower than those proved to be effective in preventing death after myocardial infarction.