Comparative Effectiveness of β-Blocker Use Beyond 3 Years After Myocardial Infarction and Long-Term Outcomes Among Elderly Patients

Background: The benefit of beta-blocker use beyond 3 years after a myocardial infarction (MI) has not been clearly determined. Methods and Results: Using data from the CRUSADE Registry (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the American College of Cardiology/American Heart Association Guidelines) linked with Medicare claims, we studied patients >= 65 years of age with MI, discharged on beta-blocker therapy and alive 3 years later without a recurrent MI to evaluate beta-blocker use and dose (none, <50%, and >= 50% of the recommended target) at 3 years. Using inverse probability of treatment weighting, we then examined the adjusted association between beta-blocker use (and dose) at 3 years and the cardiovascular composite of all-cause mortality, hospitalization for recurrent MI, ischemic stroke, or heart failure over the subsequent 5 years. Of the 6893 patients >= 65 years age, beta-blocker use at 3 years was 72.2% (n=4980); 43% (n=2162) of these were treated with >= 50% of the target beta-blocker dose. beta-blocker use was not associated with a significant difference on the composite outcome (52.4% versus 55.4%, adjusted hazard ratio, 0.95; 95% CI, 0.88-1.03; P=0.23). Neither low dose (<50% target dose) nor high dose (>= 50% target dose) beta-blocker use was associated with a significant difference in risk when compared with no beta-blocker use. Results were also consistent in patients with and without heart failure or systolic dysfunction (P interaction =0.30). Conclusions: In this observational analysis, beta-blocker use beyond 3 years post-MI, regardless of the dose achieved, was not associated with improved outcomes. The role of prolonged beta-blocker use, particularly in older adults, needs further investigation.