Beta-blocker therapy beyond 1 year after MI fails to improve
Beta-blocker therapy did not improve survival beyond 1 year after an MI, although a dose-dependent effect was observed, according to findings from a landmark analysis of the OBTAIN registry.

Although beta-blockers are recommended following myocardial infarction (MI), the benefits of long-term treatment have not been established. The study's aim was to evaluate beta-blocker efficacy by dose in 1 year post-MI survivors.

The OBTAIN (Outcomes of Beta-Blocker Therapy After Myocardial Infarction) registry included 7057 patients with acute MI, with 6077 one-year survivors. For this landmark analysis, beta-blocker dose status was available in 3004 patients and analyzed by use (binary) and dose at 1 year after MI. Doses were classified as no beta-blocker and 0% to 12.5%, 12.5% to 25%, 25% to 50%, and more than 50% of target doses used in randomized clinical trials.

Age was 63 to 64 years, and approximately two thirds were men. Median follow-up duration was 1.05 years. When analyzed dichotomously, beta-blocker therapy was not associated with improved survival. When analyzed by dose, propensity score analysis showed significantly increased mortality in the no–beta-blocker group, the 0% to 12.5% group, and the 25% to 50% group, compared with the 12.5% to 25% dose group. The mortality in the full-dose group was not significantly higher. In subgroup analyses, only history of congestive heart failure demonstrated significant interaction with beta-blocker effects on survival.

Conclusively, this analysis suggests that patients treated with more than 12.5% to 25% of the target dose used in prior randomized clinical trials beyond 1 year after MI may have enhanced survival compared with no beta-blocker and other beta-blocker doses. A new paradigm for post-MI beta-blocker therapy is needed that addresses which patients should be treated, for how long, and at what dose.