Intravenous Metoprolol Before Primary Percutaneous Coronary Intervention

Using beta-blockers to reduce infarct size has a long, conflicted history. However, no recent studies have assessed beta-blocker use before primary percutaneous coronary intervention (PCI). Now, in a single-blind trial at seven hospitals in Spain, 270 patients with an anterior ST-segment-elevation myocardial infarction (STEMI) were randomized to receive intravenous metoprolol (up to three 5-mg boluses 2 minutes apart) or no metoprolol before primary PCI. Patients with Killip class III or IV status, hypotension, bradycardia, or atrioventricular block were excluded.

Mean infarct size was significantly smaller among intravenous metoprolol recipients than among nonrecipients, whether assessed by magnetic resonance imaging (MRI) 5 to 7 days after STEMI in a core lab blinded to treatment (25.6 g vs. 32.0 g) or according to the area under the curve of creatine-kinase release (49,427 IU/L vs. 62,953 IU/L). The difference in MRI-assessed infarct size between the two groups was even greater among patients with pre-PCI thrombolysis in myocardial infarction (TIMI) grade 0–1 flow (26.7 g vs. 34.4 g). Mean post-PCI left ventricular ejection fraction was also significantly higher in metoprolol recipients than in controls, both in the overall cohort (46.1% vs. 43.4%) and among patients with pre-TIMI 0–1 flow (45.1% vs. 41.0%). Rates of major adverse events (including heart block, heart failure, and cardiogenic shock) were similar between metoprolol recipients and controls.