Dosage of beta-adrenergic blockers after myocardial infarction

Dosages of beta-adrenergic blockers prescribed after myocardial infarction (MI) in a Veterans Affairs medical center were reviewed to determine if dosages were adjusted to target dosages used in clinical trials. The medical records of all patients with a discharge diagnosis of MI were reviewed. The target dosage, selected from major clinical trials, was atenolol 100 mg/day p.o., metoprolol tartrate 200 mg/day p.o., or propranolol 180-240 mg/day p.o. A systolic blood pressure of < or = 100 mm Hg and pulse rate of < or = 50 beats/min were defined as the clinical markers of the maximum tolerated beta-blocker dosage. A discharge diagnosis of MI was identified in 396 patients between January 1999 and December 2000, and 106 patients met the inclusion criteria. The patients had a mean +/- S.D. age of 66.3 +/- 10.7 years, 98% were men, and all received either atenolol or metoprolol. The mean +/- S.D. systolic and diastolic blood pressure and pulse rate on admission were 135 +/- 30 and 75 +/- 18 mm Hg and 80 +/- 20 beats/min, respectively. The mean +/- S.D. dosages for atenolol and metoprolol were 54 +/- 39 and 90 +/- 77 mg/day at the time of discharge, 54 +/- 38 and 95 +/- 81 mg/day at 6 months after discharge, and 53 +/- 40 and 82 +/- 80 mg/day at 12 months, respectively. Only 15% of the patients reached the target dosage, as defined in clinical trials, of a beta-blocker. No reason for maintaining the beta-blocker dosage was documented for 65% of the patients. Beta-blockers were prescribed frequently after MI but usually were not used at dosages that matched those in clinical trials.