Effect of early metoprolol on infarct size in ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention: The effect of metoprolol in cardioprotection during an acute myocardial infarction (METOCARD-CNIC) trial

Abstract

Background: The effect of beta-blockers on infarct size when used in conjunction with primary PCI is unknown. We hypothesize that metoprolol reduces infarct size when administered early (intravenously before reperfusion). Methods and results: Patients with Killip class II or less anterior STEMI undergoing PCI within 6 h of symptoms onset were randomized to receive intravenous metoprolol (n = 131) or not (control, n = 139) before reperfusion. All patients without contraindications received oral metoprolol within 24 h. The predefined primary end point was infarct size on MRI performed 5–7 days after STEMI. MRI was performed in 220 patients (81%). Mean ± SD infarct size by MRI was smaller after intravenous metoprolol compared with control (25.6 ± 15.3 vs 32.0 ± 22.2 g; adjusted difference, −6.52; 95% confidence interval, −11.39 to −1.78; p = 0.012). In patients with pre-PCI TIMI grade 0 to 1 flow, the adjusted treatment difference in infarct size was −8.13 (95% confidence interval, −13.10 to −3.16; p = 0.0024). Infarct size estimated by peak and area under the curve CK release was measured in all study populations and was significantly reduced by intravenous metoprolol. LVEF was higher in the intravenous metoprolol group (adjusted difference, 2.67%; 95% confidence interval, 0.09–5.21; p = 0.045). The composite of death, malignant ventricular arrhythmia, cardiogenic shock, AV block and re-infarction at 24 h in the intravenous metoprolol and control groups was 7.1% and 12.3%, respectively (p = 0.21). Conclusions: In patients with anterior Killip class II or less STEMI undergoing primary PCI, early intravenous metoprolol before reperfusion reduced infarct size and LVEF with no excess of adverse events during the first 24 h after STEMI.