Key result
Early IV metoprolol fails to reduce 30-day infarct size vs. placebo in STEMI.
Why the study?
The impact of early intravenous beta-blockers before primary percutaneous coronary intervention on infarct size and clinical outcomes in a general STEMI population was not well established.
Does early intravenous metoprolol before primary percutaneous coronary intervention reduce 30-day myocardial infarct size in patients with ST-segment elevation myocardial infarction?
RCT (n=683)
Double-blind
1:1
Yes
Does early intravenous metoprolol before primary percutaneous coronary intervention reduce 30-day myocardial infarct size in patients with ST-segment elevation myocardial infarction?
In a general STEMI population undergoing primary PCI, early IV metoprolol did not reduce 30-day myocardial infarct size by CMR, though it reduced acute malignant arrhythmias without increasing adverse events.
Answers are grounded in this paper and cite their sources.
Early IV metoprolol before PPCI does not reduce infarct size in STEMI; challenges routine prehospital use and prior smaller studies.
Background The impact of intravenous (IV) beta-blockers before primary percutaneous coronary intervention (PPCI) on infarct size and clinical outcomes is not well established. Objectives This study sought to conduct the first double-blind, placebo-controlled international multicenter study testing the effect of early IV beta-blockers before PPCI in a general ST-segment elevation myocardial infarction (STEMI) population. Methods STEMI patients presenting <12 h from symptom onset in Killip class I to II without atrioventricular block were randomized 1:1 to IV metoprolol (2 × 5-mg bolus) or matched placebo before PPCI. Primary endpoint was myocardial infarct size as assessed by cardiac magnetic resonance imaging (CMR) at 30 days. Secondary endpoints were enzymatic infarct size and incidence of ventricular arrhythmias. Safety endpoints included symptomatic bradycardia, symptomatic hypotension, and cardiogenic shock. Results A total of 683 patients (mean age 62 ± 12 years; 75% male) were randomized to metoprolol (n = 336) or placebo (n = 346). CMR was performed in 342 patients (54.8%). Infarct size (percent of left ventricle [LV]) by CMR did not differ between the metoprolol (15.3 ± 11.0%) and placebo groups (14.9 ± 11.5%; p = 0.616). Peak and area under the creatine kinase curve did not differ between both groups. LV ejection fraction by CMR was 51.0 ± 10.9% in the metoprolol group and 51.6 ± 10.8% in the placebo group (p = 0.68). The incidence of malignant arrhythmias was 3.6% in the metoprolol group versus 6.9% in placebo (p = 0.050). The incidence of adverse events was not different between groups. Conclusions In a nonrestricted STEMI population, early intravenous metoprolol before PPCI was not associated with a reduction in infarct size. Metoprolol reduced the incidence of malignant arrhythmias in the acute phase and was not associated with an increase in adverse events. (Early-Beta blocker Administration before reperfusion primary PCI in patients with ST-elevation Myocardial Infarction [EARLY-BAMI]; EudraCT no: 2010-023394-19).
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Roolvink et al. (2016) conducted an RCT in ST-segment elevation myocardial infarction (STEMI) (n=683). Intravenous metoprolol vs. Matched placebo was evaluated on Myocardial infarct size (percent of left ventricle) as assessed by cardiac magnetic resonance imaging (CMR) at 30 days (p=0.616). Early IV metoprolol before primary PCI in STEMI patients did not reduce 30-day CMR infarct size compared with placebo (15.3% vs 14.9%; p=0.616).
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