Effect of β-Blockers Beyond 3 Years After Acute Myocardial Infarction.

BACKGROUND: The optimal duration of β-blocker therapy in patients with acute myocardial infarction (AMI) is unknown. We aimed to evaluate the late effect of β-blockers in patients with AMI.

METHODS AND RESULTS: We enrolled all consecutive patients who presented with AMI at Seoul National University Bundang Hospital, between June 3, 2003 and February 24, 2015. The primary end point was 5-year all-cause mortality, depending on the use of β-blockers at discharge, 1 year after AMI, and 3 years after AMI. Of 2592 patients, the prescription rates of β-blockers were 72%, 69%, 63%, and 60% at discharge and 1, 3, and 5 years after AMI, respectively. The patients who were receiving β-blocker therapy had more favorable clinical characteristics, such as younger age (62 versus 65 years; P <0.001). They received reperfusion therapy more often (92% versus 80%; P <0.001) than those without β-blocker prescription. In the univariate analysis, the patients with β-blocker prescription had lower 5-year mortality at all time points. In the Cox model after adjustment for significant covariates, β-blocker prescription at discharge was associated with a 29% reduced mortality risk (hazard ratio, 0.71; 95% confidence interval, 0.55-0.90; P =0.006); however, β-blocker prescriptions at 1 and 3 years after AMI were not associated with reduced mortality.

CONCLUSIONS: The beneficial effect of β-blocker therapy after AMI may be limited until 1 year after AMI. Whether late β-blocker therapy beyond 1 year after AMI offers clinical benefits should be confirmed in further clinical trials.