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Should We Use Intravenous Beta-Blockade Right After STEMI?

Insights from COMMIT

Data on the early (in-hospital) use of intravenous beta-blockade after ST-segment-elevation MI (STEMI) are inconclusive, despite proven benefits from long-term oral beta-blocker therapy that is initiated at hospital discharge.

Now, in COMMIT, a double-blind trial cofunded by metoprolol’s manufacturer, researchers in China randomized 45,852 patients (mean age, 61) with suspected acute MI to receive immediate metoprolol (up to 15 mg IV, then 50 mg orally every 6 hours for 1 day, then 200 mg controlled-release until hospital discharge or for up to 4 weeks) or matching placebo. About 54% of patients received fibrinolysis, mainly urokinase. (Because the subjects were also separately randomized to dual versus single antiplatelet therapy [see Journal Watch Cardiology Dec 16 2005], patients scheduled for PCI were excluded, as dual therapy is likely to be indicated in such patients.)

Nearly 90% of patients completed treatment (mean duration, 15 days). Metoprolol and placebo performed similarly on the primary composite endpoint of in-hospital death, reinfarction, or cardiac arrest (incidence, 9.4% and 9.9%, respectively) and on death alone (7.7% and 7.8%). Metoprolol recipients did have significantly fewer reinfarctions (2.0% vs. 2.5% with placebo), episodes of ventricular fibrillation (2.5% vs. 3.0%), and arrhythmia-related deaths (1.7% vs. 2.2%) -- but significantly more deaths from cardiogenic shock (2.2% vs. 1.7%), most dramatically within 1 day after admission. Notably, all excess deaths and most excess episodes of cardiogenic shock in the metoprolol group were among patients in Killip class III.

Comment: These results suggest that intravenous beta-blockade should not be used routinely as immediate therapy after STEMI. Early beta-blocker therapy reduced risks for fatal arrhythmias and reinfarction, but it increased the risk for cardiogenic shock, especially within 1 day after admission. However, a sizable proportion of the excess risk associated with metoprolol was in the 5% of study subjects who were in Killip class III, which is a contraindication for beta-blocker use. Nevertheless, in patients at high risk for cardiogenic shock, it would be reasonable to defer beta-blocker treatment until hemodynamic stability is reached or to uptitrate treatment cautiously.

— Beat J. Meyer, MD

Published in Journal Watch Cardiology December 16, 2005

Citation(s):

COMMIT (ClOpidogrel and Metoprolol in Myocardial Infarction Trial) collaborative group. Early intravenous then oral metoprolol in 45 852 patients with acute myocardial infarction: Randomised placebo-controlled trial. Lancet 2005 Nov 5; 366:1622-32.

• Medline abstract (Free)

Sabatine MS. Something old, something new: ß blockers and clopidogrel in acute myocardial infarction. Lancet 2005 Nov 5; 366:1587-9.

• Medline abstract (Free)

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