Clinical trial of intravenous dextro-alprenolol in cardiac arrhythmias

D-alprenolol, in doses of 50–170 mg, was given intravenously to 23 patients with various cardiac arrhythmias. Seven patients had acute myocardial infarction, ten patients had chronic ischemic heart disease with rhythm disturbances, three were in congestive failure and one had myocarditis. The ventricular arrhythmias were abolished in several patients. In some of the patients with compromised myocardial function, the blood pressure dropped markedly and heart rate slowed to a degree requiring treatment. These effects have been seen after other β-adrenergic blocking agents, and were considered to be due mainly to the cardiodepressive action of D-alprenolol in the doses used. Because of these potentially dangerous side effects, and because little benefit was apparent over other drugs, it was concluded that D-alprenolol should not be used for the treatment of arrhythmias in patients who have myocardial damage.