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High, low doses of beta-blockers confer similar outcomes in patients with ACS
Patients with ACS experienced similar rates of major adverse CV events regardless of dosage of beta-blocker therapy, according to findings published in the American Heart Journal.
The findings call into question whether high-dose beta-blockers are needed in this population, the researchers wrote.
“Despite the inability to detect superiority in the composite outcomes, our data did suggest that low-dose beta-blockers may be associated with a reduction in MI and revascularization within the first 6 months following the ACS event,” Jason E. Allen, MD, of the Intermountain Medical Center Heart Institute in Murray, Utah, and the division of internal medicine at the University of Utah in Salt Lake City, and colleagues wrote.
The study included 7,834 patients (mean age, 61 years) evaluated for CAD between 1994 and 2013. Beta-blockers were assigned to 5,287 patients (67.5%) with ACS. From this group, 2,333 (44.1%) had previously taken beta-blockers, and 2,954 (55.9%) patients were naive to them.
Metoprolol was the beta-blocker most commonly assigned to patients (n = 4,273; 80.8%). Other beta-blockers administered included carvedilol (n = 529; 10%) and atenolol (n = 368; 7%). A low dose of beta-blocker was defined as 25% of metoprolol 200 mg per day, whereas a high dose was defined as 50% of metoprolol 200 mg per day. The dosage was determined at baseline, then revisited after 6 months.
During the next 2 years, patients were monitored to verify major adverse CV events, defined as stroke, MI and all-cause death. As a secondary endpoint, researchers also examined MI, death, cerebral vascular accident and the outcome of follow-up revascularization.
The researchers found no significant difference in major adverse CV events between the low-dose and high-dose groups at 6 months (HR = 0.76; 95% CI, 0.52-1.1) or between 6 and 24 months (HR = 1.03; 95% CI, 0.7-1.5). However, those given the low-dose beta-blocker had a substantially lower risk for MI during the first 6 months of the study (HR = 0.53; 95% CI, 0.33-0.86; absolute decrease in risk, 1.4%).
Also, compared with the high-dose group, the low-dose group had lower risk for revascularization (HR = 0.76; 95% CI, 0.6-0.96).
“In this study, no incremental benefit of higher doses of beta-blockers was found compared with lower doses of beta-blockers, and a secondary analysis raises the question of any important benefit of beta-blocker therapy, highlighting the importance of reexamining the role and dosing of beta-blockers in the current era of advanced therapies for CAD and ACS,” Allen and colleagues wrote. – by Darlene Dobkowski
Disclosure: The researchers report no relevant financial disclosures.