Hemodynamic effects of metoprolol in acute myocardial infarction

The central hemodynamic effects of metoprolol in acute myocardial infarction have been studied in a multicenter, double-blind, randomized trial. One hundred and ninety patients with acute myocardial infarction not previously on β blockers with heart rate >65 beats/min and blood pressure >105 mm Hg and without clinical signs of serious heart failure were included. After insertion of a pulmonary artery catheter, patients were randomized to metoprolol, 15 mg intravenously, and 50 mg 4 times a day orally (n = 95) or placebo (n = 95) with a mean delay of 7.2 hours. Hemodynamic measurements were made at baseline and repeatedly during 24 hours. Heart rate, systolic blood pressure and cardiac index were all immediately reduced by 10 to 20% in the metoprolol group and the difference compared with placebo was maintained throughout the 24 hours (p