Effects of betaxolol on heart rate in patients with a recent transmural myocardial infarction.

A randomized double-blind trial was performed with betaxolol, a beta 1-selective and long-acting beta-blocker, in patients with a recent first uncomplicated acute myocardial infarction (AMI). Patients were treated between the 3rd and 14th day after the onset of AMI with either a single oral dosage of 20 mg betaxolol or placebo. The effects on heart rate, ventricular and supraventricular arrhythmias were studied by continuous 24 hours ECG recordings on the 7th and between the 9th to 12th after the onset of AMI and by a submaximal exercise test on the 12th day. Hourly mean, peak and minimal heart rate were during the whole day significantly lower in the active treatment group. In betaxolol treated patients diurnal variations in heart rate were definitely changed. No differences in the occurrence of ventricular arrhythmias were found between both groups; auricular fibrillation was more common in placebo treated patients. Heart rate and pressure rate product were significantly higher during exercise in the placebo group. During exercise ventricular arrhythmias were infrequent in both groups. The clinical tolerance of betaxolol was excellent.