Early intravenous beta-blockers in patients with acute coronary syndrome-A meta-analysis of randomized trials

BackgroundIntravenous (IV) beta-blockade is currently a Class IIa recommendation in early management of patients with acute coronary syndromes (ACS) without obvious contraindications.MethodsWe searched the PubMed, EMBASE and the Cochrane Register for Controlled Clinical Trials for randomized clinical trials from 1965 through December, 2011, comparing intravenous beta-blockers administered within 12 hours of presentation of ACS with standard medical therapy and/or placebo. The primary outcome assessed was the risk of short-term (in-hospital mortality-with maximum follow up duration of 90 days) all-cause mortality in the intervention group versus the comparator group. The secondary outcomes assessed were ventricular tachyarrhythmias, myocardial reinfarction, cardiogenic shock, and stroke. Pooled treatment effects were estimated using relative risk with Mantel-Haenszel risk ratio, using a random-effects model.ResultsSixteen studies enrolling 73,396 participants met the inclusion ⁄ exclusion criteria. In- hospital mortality was reduced 8% with intravenous beta-blockers, RR = 0.92 (95% CI, 0.86-1.00; p = 0.04) when compared with controls. Moreover, intravenous beta-blockade reduced the risk of ventricular tachyarrhythmias (RR = 0.61; 95 % CI 0.47-0.79; p = 0.0003) and myocardial reinfarction (RR = 0.73, 95 % CI 0.59-0.91; p = 0.004) without increase in the risk of cardiogenic shock, (RR = 1.02; 95% CI 0.77-1.35; p = 0.91) or stroke (RR = 0.58; 95 % CI 0.17-1.98; p = 0.38).ConclusionsIntravenous beta-blockers early in the course of appropriate patients with ACS appears to be associated with significant reduction in the risk of short-term cardiovascular outcomes, including a reduction in the risk of all-cause mortality.