BETA-BLOCKER DOSAGES AND MORTALITY AFTER MYOCARDIAL-INFARCTION - DATAFROM A LARGE HEALTH MAINTENANCE ORGANIZATION

Background: Although long-term beta-blocker therapy has been found ben eficial in patients after an acute myocardial infarction, these drugs are greatly underused by clinicians. Moreover, the dosages of beta-blo ckers used in randomized controlled trials appear to be much larger th an those routinely prescribed. Objective: To determine whether an asso ciation exists between the dosage of beta-blockers prescribed after a myocardial infarction and cardiac mortality. Methods: We performed a r etrospective cohort study of 1165 patients who survived an acute myoca rdial infarction from January 1, 1990, through December 31, 1992. Thes e patients represent a subgroup of the 6851 patients hospitalized at n orthern California Kaiser Permanente hospitals. Results: Of the 37.7% of patients prescribed beta-blocker therapy, 48.1% were treated with d osages less than 50% of the dosage found to be effective in preventing cardiac death in large randomized clinical trials (lower-dosage thera py). Compared with patients not receiving beta-blockers, those treated with lower-dosage therapy appeared to have a greater reduction in car diovascular mortality (hazard ratio, 0.33; P = .009) than patients tre ated with a higher dosage (hazard ratio, 0.82; P = 0.51), after adjust ment for age, sex, race, disease severity, and comorbidities. Conclusi ons: The dosages of beta-blockers shown to be effective in randomized trials are not commonly used in clinical practice, and treatment with lower dosages of beta-blockers was associated with at least as great a reduction in mortality as treatment with higher dosages. This suggest s that physicians who are reluctant to prescribe beta-blockers because of the relatively large dosages used in the large prospective clinica l trials should be encouraged to prescribe smaller dosages.