Tocainide for drug-resistant ventricular arrhythmias: Efficacy,side effects,and lidocaine responsiveness for predicting tocainide success

Tocainide therapy has been evaluated in 38 patients with ventricular arrhythmias. Thirty-one had recurrent sustained ventricular tachycardia and/or fibrillation and 29 required prior cardioversions. These arrhythmias could not be managed with quinidine, procainamide, disopyramide, or propranolol. Tocainide doses averaged 1,500 mg/day (range 600 to 2,400) and the majority of patients had plasma concentrations from 6 to 12 μg/ml. Twenty-two patients (61%) had their arrhythmias controlled with tocainide and 16 (39%) did not. Tocainide dose and plasma concentrations were similar for responders and nonresponders. Lidocaine was effective in 26 patients and 16 (63%) of these had their arrhythmias controlled with tocainide. Of 12 patients in whom lidocaine was known to be ineffective or who had not been previously treated, only two (17%) had arrhythmias controlled with tocainide (P < 0.02). Side effects occurred in approximately two thirds of patients but required discontinuation of long-term tocainide in only three patients.