The effectiveness of beta-blockers after myocardial infarction in patients with type 2 diabetes.

Abstract

Beta-blocker therapy has been proven to reduce mortality and reinfarction after myocardial infarction (MI), but the impact of beta-blockers on cardiac outcomes in patients with type 2 diabetes in routine practice is not clear. The purpose of this study was to determine the effectiveness of beta-blockers after MI in patients with type 2 diabetes. Using the Saskatchewan Health Databases, 12,272 patients with newly treated diabetes were identified between 1991 and 1996; 625 patients were subsequently admitted for MI. Beta-blocker exposure within 30 days of discharge was identified in 298 patients, and all were followed until death, coverage termination, or 31 December 1999. Multivariate proportional hazards models were used to assess differences in all-cause mortality, recurrent MI, and 30-day all-cause rehospitalization (the latter a proxy measure for drug safety). Patients were aged 69 +/- 11 years old, 66% were male, and mean follow-up was 2.7 +/- 2.1 years. Overall, beta-blockers were prescribed for 48% of patients. There were fewer deaths in the beta-blocker group versus control subjects (55 of 298 [18.5%] vs. 126 of 327 [38.5%], respectively, P < 0.001). However, beta-blockers were not associated with improved survival in multivariate analyses (hazard ratio [HR] 0.89 [95% CI 0.63-1.25]). There were no differences in rates of recurrent MI (adjusted HR 1.35 [0.93-1.95]) or rehospitalizations (adjusted odds ratio 1.40 [0.83-2.37]) between the groups. Beta-blocker therapy post-MI was not associated with reduced mortality or fewer recurrent events in people with type 2 diabetes in routine practice, although these medications were safe in this population.