Failure of bretylium to suppress inducible ventricular tachycardia

Five patients with recurrent, life-threatening ventricular arrhythmias were given bretylium tosylate intravenously for a minimum of 4 days. Arrhythmias were not related to acute ischemia in any patient. Four patients had inducible ventricular tachycardia, and one patient had inducible ventricular fibrillation requiring cardioversion while taking no medications. Programmed electrical stimulation was then repeated to assess the ability of bretylium to suppress inducible ventricular tachycardia. Bretylium tosylate, at a mean dose of 2.3 mg intravenously per minute, did not suppress inducible ventricular arrhythmias in any patient. Rapid ventricular tachycardia was induced in all patients, and ventricular fibrillation was induced in one patient. Two patients required external cardioversion to terminate their arrhythmias. Bretylium tosylate, given in relatively large doses chronically, did not suppress inducible ventricular arrhythmias in these five otherwise drug-refractory patients with chronic recurrent ventricular tachycardia. This failure to suppress inducible ventricular arrhythmias cannot be attributed to the initial catecholamine release which occurs in the first hour or two after the drug is administered.