Beta blockers are known to be useful for secondary prevention in patients who have had an acute myocardial infarction. However, studies suggest this class of medication is underutilized, especially in older patients. Krumholz and colleagues in the National Cooperative Cardiovascular Project evaluated prescribing patterns and the effects of beta blockers in elderly patients with myocardial infarction.
Patients at least 65 years of age who had a primary discharge diagnosis of acute myocardial infarction were included in the study. Exclusion criteria included bradycardia, hypotension, high-grade atrioventricular block, asthma, chronic lung disease, heart failure and documented intolerance to beta blockers.
Information was abstracted from medical records. The main outcomes measured included frequency of beta-blocker therapy and mortality within one year of hospital discharge. Demographic information, length of stay and clinical status were also recorded.
The records of 115,015 patients with a principle diagnosis of acute myocardial infarction were reviewed, and 45,308 of these patients were considered candidates for beta-blocker therapy. Only 50 percent of the candidates were prescribed this therapy. Those who were prescribed discharge medicines (particularly calcium channel blockers) were much less likely to be given beta blockers.
Physician specialty was also found to be a factor in whether a patient received beta blockers. Family physicians were less likely than cardiologists and internists to prescribe beta-blocker therapy. There were 36,795 patients who were not receiving beta-blocker therapy on admission to the hospital; 43.5 percent of these patients started this therapy before discharge.
The one-year mortality rate was significantly less in patients receiving beta blockers (7.7 percent) than in those not receiving beta-blocker therapy (12.6 percent). When adjustment was made for all variables, beta-blocker therapy was still associated with a 14 percent lower mortality risk. The adjusted relative risk was 0.83 for men and 0.89 for women.
The authors confirm that beta blockers are underutilized in the elderly population. They conclude that care of patients could be improved with more attention to prescribing beta blockers after myocardial infarction to elderly patients without contraindications to this treatment.