A Comparative Study of Cardioselective β-Blockade and Diazepam in Patients with Acute Myocardial Infarction and Tachycardia

ABSTRACT. Eighty‐seven patients with an acute myocardial infarction and a pulse rate of ≥80/min on admission were randomly allotted to one group given cardioselective β‐blockade, a second group given diazepam, and a third group given placebo. The three groups were comparable in age, sex distribution, previous history of ischemic heart disease, initial pulse rate, blood pressure, pain index, enzyme values, and degree of ST elevation. The acute mortality (within 10 days) did not differ between the groups. The drug treatment elicited no reduction of infarct size, as judged from enzyme levels, degree of reduction of ST elevation, or physical exercise capacity. The reasons for this negative result are discussed. One possibility is that in routine clinical practice the therapeutic intervention starts too late after onset of symptoms. A beneficial effect on mortality among the patients whose treatment started early after onset of symptoms supports this conclusion.