Although clinical guidelines recommend long-term β-blocker (BB) therapy to decrease mortality after acute myocardial infarction, these recommendations are based predominantly on evidence from before the reperfusion and thrombolytic eras. To investigate the effects of BB therapy for patients with acute myocardial infarctions on mortality in the percutaneous coronary intervention era, a total of 5,628 consecutive patients who were admitted <24 hours after the onset of ST-segment elevation myocardial infarction, treated with emergent percutaneous coronary intervention, and discharged alive were studied. During a median follow-up period of 1,430 days, mortality rates did not differ between patients with and without BB therapy (5.2% vs 6.2%, p = 0.786). Multivariate analysis revealed that BB treatment was not associated with a reduced risk for mortality (hazard ratio 0.935, 95% confidence interval 0.711 to 1.230, p = 0.534). The results of propensity score matching also indicated that the mortality rates did not differ between the 2 groups. However, subgroup analyses among matched populations revealed that BB treatment was associated with a significantly lower mortality risk for high-risk patients, who were defined as those with Global Registry of Acute Coronary Events (GRACE) risk scores ≥121 (hazard ratio 0.596, 95% confidence interval 0.416 to 0.854, p = 0.005) or those administered diuretics (hazard ratio 0.602, 95% confidence interval 0.398 to 0.910, p = 0.016), but not for lower risk patients. In conclusion, BB treatment was associated with reduced long-term mortality in patients after ST-segment elevation myocardial infarction at higher risk, but not in those at lower risk. Although randomized controlled studies are warranted to confirm these results, the implementation of BB therapy for discharged patients with ST-segment elevation myocardial infarction may need to be assessed on the basis of individual mortality risk in the percutaneous coronary intervention era.
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