Metoprolol in the treatment of supraventricular tachyarrhythmias.

Twenty one patients with either paroxysmal supraventricular tachycardia (group A), atrial flutter (group B), or atrial fibrillation (group C) were treated with intravenous metoprolol in the dose range 2--20 mg. Sinus rhythm was restored in 3 out of 6 patients in group A, 3 out of 7 patients in group B and one out of 8 patients in group C. In patients who did not convert to sinus rhythm a remarkable decrease in ventricular rate occurred in 3 patients with atrial flutter and 4 patients with atrial fibrillation. In patients with systolic blood pressure greater than 100 mm Hg but without an acute myocardial infarction the risk of hypotension necessitating treatment was small. Metoprolol appears to be an effective and safe drug in the treatment of supraventricular tachycardia.