Admission Heart Rate Is a Determinant of Effectiveness of Beta-Blockers in Acute Myocardial Infarction Patients

Background: Beta-blockers are standard therapy for acute myocardial infarction (AMI). However, despite current advances in the management of AMI, it remains unclear whether all AMI patients benefit from beta-blockers. We investigated whether admission heart rate (HR) is a determinant of the effectiveness of beta-blockers for AMI patients. Methods and Results: We enrolled 3,283 consecutive AMI patients who were admitted to 28 participating institutions in the Japanese Registry of Acute Myocardial Infarction Diagnosed by Universal Definition (J-MINUET) study. According to admission HR, we divided patients into 3 groups: bradycardia (HR <60 beats/min, n=444), normocardia (HR 60 to <= 100 beats/min, n=2,013), and tachycardia (HR > 100 beats/min, n=342). The primary endpoint was major adverse cardiac events (MACE), including all-cause death, non-fatal MI, non-fatal stroke, heart failure (HF), and urgent revascularization for unstable angina, at 3-year follow-up. Beta-blocker at discharge was significantly associated with a lower risk of MACE in the tachycardia group (23.6% vs. 33.0%; P=0.033), but it did not affect rates of MACE in the normocardia group (17.8% vs. 18.4%; P=0.681). In the bradycardia group, beta-blocker use at discharge was significantly associated with a higher risk of MACE (21.6% vs. 12.7%; P=0.026). Results were consistent for multivariable regression and stepwise multivariable regression. Conclusions: Admission HR might determine the efficacy of beta-blockers for current AMI patients.