Effect of tocainide on ventricular arrhythmias refractory to standard oral antiarrhythmic drugs but responsive to intravenous lidocaine

Twenty patients with life-threatening or symptomatic ventricular arrhythmias which were not responsive to standard oral antiarrhythmic drugs either because of lack of efficacy or because of adverse effects but which were responsive to intravenous lidocaine were subjects. The dose of tocainide was individually titrated for each patient according to efficacy and adverse effects. The mean daily tocainide dose was 1800 mg (range 1200-2400 mg). Three of 20 patients (15%) died of their underlying heart disease - one during the acute tocainide study and two during long-term tocainide treatment. Adverse effects from tocainide occurred in 11 of 20 patients (55%) and six (30%) had to discontinue tocainide because of major adverse effects - four during the acute tocainide study and two during long-term tocainide treatment. Fifteen patients on long-term tocainide were followed for a mean of 12 months (range 1-30 months). In the 13 patients able to tolerate long-term tocainide alone or in combination with other antiarrhythmic drugs, ventricular fibrillation occurred in none of four patients with prior ventricular fibrillation, short runs of ventricular tachycardia occurred in four of 11 patients (36%) with prior recurrent ventricular tachycardia, and couplets of PVCs occurred in eight of 12 patients (67%) with prior couplets. We conlcude that, in this selected group of patients at high-risk for sudden death, tocainide alone or in combination with other antiarrhythmic drugs prevented deterioration of life-threatening ventricular arrhythmias.