Background Although β-blockers increase survival in acute coronary syndrome (ACS) patients, the doses used in trials were higher than doses used in practice, and recent data do not support an advantage of higher doses. We hypothesized that rates of major adverse cardiac events (MACE), all-cause death, myocardial infarction, and stroke are equivalent for patients on low-dose and high-dose β-blocker. Methods Patients admitted to Intermountain Healthcare with ACS and diagnosed with ≥70% coronary stenosis between 1994 and 2013 were studied (N = 7,834). We classified low dose as ≤25% and high dose as ≥50% of an equivalent daily dose of 200 mg of metoprolol. Multivariate analyses were used to test association between low-dose versus high-dose β-blocker dosage and MACE at 0-6 months and 6-24 months. Results A total of 5,287 ACS subjects were discharged on β-blockers (87% low dose, 12% high dose, and 1% intermediate dose). The 6-month MACE outcomes rates for the β-blocker dosage (low versus high) were not equivalent (P = .18) (hazard ratio [HR] = 0.76; 95% CI, 0.52-1.10). However, subjects on low-dose β-blocker therapy did have a significantly decreased risk of myocardial infarction for 0-6 months (HR = 0.53; 95% CI, 0.33-0.86). The rates of MACE events during the 6-24 months after presentation with ACS were equivalent for the 2 doses (P = .009; HR = 1.03 [95% CI, 0.70-1.50]). Conclusions In ACS patients, rates of MACE for high-dose and low-dose β-blocker doses are similar. These findings question the importance of achieving a high dose of β-blocker in ACS patients and highlight the need for further investigation of this clinical question.
Bibliographical noteFunding Information:
We express our sincerest appreciation to the Dell Loy Hansen Foundation for their ongoing support of research at the Intermountain Heart Institute. We also thank Brianna S. Ronnow, MS, of the Intermountain Heart Institute Cardiovascular Research Program for her assistance in this project. Dr. Goldberger has received support by grant 5U01HL080416 from the National Heart, Lung, and Blood Institute of the National Institutes of Health .
This study was approved by the Intermountain Healthcare Institutional Review Board. Investigations were in accordance with the Declaration of Helsinki. The authors are solely responsible for the design and conduct of this study, all analyses, the drafting and editing of the paper, and its final contents. Funding for this study was provided in part by the Dell Loy Hansen Foundation .
© 2016 Elsevier, Inc.
Copyright 2017 Elsevier B.V., All rights reserved.