Objective: To explore the reasons for underutilization of beta blocker treatment after acute myocardial infarction.
Design: A retrospective chart review.
Setting: Two large community hospitals in Milwaukee, Wisconsin.
Patients/participants: All subjects (n = 694) discharged alive from July 1, 1990, to June 30, 1991, who had a diagnosis of acute myocardial infarction were eligible. Of these, 250 had missing data, resulting in a final sample of 444.
Results: Twenty-nine percent of the 444 patients were prescribed beta blocker therapy on discharge. Characteristics of the patients and their treatment associated with receipt of beta blocker therapy were identified with a logistic regression model. The adjusted odds ratios were 0.52 for female gender, 0.34 for no health insurance, 0.21 for chronic obstructive pulmonary disease, 0.46 for congestive heart failure, 0.28 for atrioventricular block, 1.86 for hypertension, 1.93 for chest pain during acute myocardial infarction, and 4.65 for prehospital beta blocker use. Prescription of beta blocker therapy was also influenced by receipt of other treatment modalities. The adjusted odds ratios were 0.23 for receipt of beta blocker therapy associated with myocardial revascularization, 0.18 for prescription on discharge of calcium channel blockers, and 0.22 for receipt of angiotensin-converting enzyme inhibitors.
Conclusion: A minority of patients discharged after acute myocardial infarction receive beta blocker therapy, and women are only half as likely as men to receive it, after controlling for other factors. Though there are no data relating to whether calcium channel blockers or angiotensin-converting enzyme inhibitors lessen the protective effect of beta blocker therapy post-acute myocardial infarction, it would appear that these agents are frequently being used in lieu of beta blocker therapy for post-acute myocardial infarction patients.