Relationship Between β‐Blocker Therapy at Discharge and Clinical Outcomes in Patients With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

BACKGROUND: The evidence supporting the use of β‐blockers in patients with acute coronary syndrome after successful percutaneous coronary intervention has been inconsistent and scarce. METHODS AND RESULTS: Between March 1, 2009, and December 30, 2014, a total of 3180 eligible patients with acute coronary syndrome undergoing percutaneous coronary intervention were consecutively enrolled. The primary end point was all‐cause death and the secondary end point was a composite of all‐cause death, nonfatal myocardial infarction, heart failure readmission, and cardiogenic hospitalization. Patients were compared according to the use of β‐blockers at discharge. Compared with the no β‐blocker group, the risk of all‐cause death was significantly lower in the β‐blocker group (hazard ratio [HR], 0.33; 95% CI, 0.17–0.65 [P=0.001]). A consistent result was obtained in multiple adjusted model and propensity score–matched analysis. The use of β‐blockers was also associated with decreased risk of composite of adverse cardiovascular events (HR, 0.47; 95% CI, 0.28–0.81 [P=0.006]), although statistical significance disappeared after multivariable adjustment and propensity score matching. Furthermore, we performed post hoc analysis for the subsets of patients and the results revealed that patients with non–ST‐segment elevation myocardial infarction benefited the most from β‐blocker therapy at discharge (HR, 0.04; 95% CI, 0.00–0.27 [P=0.001]), and the use of <50% of target dose was significantly associated with better outcome compared with no β‐blocker use, rather than ≥50% of target dose. CONCLUSIONS: The administration of relatively low β‐blocker dose is associated with improved clinical outcomes among patients with acute coronary syndrome after successful percutaneous coronary intervention, especially for patients with non‐ST‐segment elevation myocardial infarction.