Göteborg Metoprolol Trial: clinical observations.

Heart rate, systolic blood pressure and rate-pressure product were analyzed during the first 18 hours and 4 days after intravenous metoprolol or placebo. On injection of metoprolol there was an immediate decrease in mean heart rate from 72.9 +/- 0.6 to 62.7 +/- 0.4 beats/min, but no change was found in the placebo group. The difference in heart rate remained during the first 4 days. Systolic blood pressure was reduced from 144.1 +/- 0.9 to 134.6 +/- 0.9 mm Hg after intravenous metoprolol and was lower than that in the placebo group during 4 days of follow-up. Indirect signs of congestive heart failure tended to be less severe in patients given metoprolol within 12 hours of the onset of symptoms than in those given placebo. The duration of hospitalization also tended to be shorter in patients given early metoprolol treatment than in those given placebo early.