Abstract 18303: Clinical Outcomes With Beta-blockers in Patients With Myocardial Infarction and Coronary Artery Disease
Background: While the benefit of oral beta-blockers in patients with acute myocardial infarction (MI) is established, recent studies have cast doubt on the potential benefit of taking beta-blockers indefinitely after acute MI and in patients with coronary artery disease (CAD). Our objective was to complete a comprehensive evaluation of the long-term clinical effectiveness of beta- blockers in MI and CAD patients.
Methods: We conducted an observational study using linked “big data” administrative databases from Ontario, Canada of patients who were alive on January 1, 2008, based on constructing the following 2 cohorts: 1) patients with MI in the prior 10 years (n=88,067); or 2) patients with coronary artery disease (history of angina or history of revascularization [percutaneous coronary intervention or coronary artery bypass surgery]) but without prior MI (n=160,510). Exposure of interest was prescription of a beta-blocker within 100 days prior to January 1, 2008, the date of the cohort entry. The primary outcome was time to death or hospitalization for MI or angina, with subjects followed for at most 1 year. Potential confounders were accounted for with inverse probability of treatment weighting (IPTW) using the propensity score, with variance adjusted for weighting.
Results: Using IPTW, baseline characteristics were well balanced between treatment groups, with all standardized differences <0.1 in both the MI and CAD cohorts. In the MI cohort, 56,086 (63.7%) patients were taking beta-blockers. The median age was 77 years, with men comprising 58% of this cohort. Patients in the MI cohort receiving beta blockers had a significantly lower risk of the primary endpoint within 1 year [11.9% vs 12.5%; HR 0.95 (95% CI 0.92-0.97); p<0.001]. In the CAD cohort, 80,874 (50.4%) patients were taking beta-blockers. The median age was 77 years, with men comprising 56% of this cohort. In the CAD cohort, beta blockers were also associated with a significant reduction in the primary endpoint within 1 year [8.7% vs 9.1%; HR 0.96 (95% CI 0.94-0.98); p<0.001].
Conclusion: In this large, population based observational study of older patients, beta blockers were associated with a modest reduction in major cardiovascular events and mortality in those with prior MI and in those with CAD.
Author Disclosures: C.A. Jackevicius: Research Grant; Modest; CIHR Grant, HSF Grant. J. Tu: Research Grant; Modest; CIHR Grant. P. Austin: Research Grant; Modest; CIHR Grant. D. Lash: None. M. Koh: None. A. Chong: None. D. Ko: Research Grant; Modest; CIHR Grant, HSF Grant.
- © 2016 by American Heart Association, Inc.