The effect of
flecainide acetate, a class 1c antiarrhythmic agent, was examined in 15 patients with recurrent
ventricular tachycardia. Intravenous
flecainide was administered in a dose of 2 mg/kg at the time of intracardiac stimulation and recording studies. Oral
flecainide was given to 10/15 patients and retesting was undertaken using an indwelling
electrode. Intravenous
flecainide terminated sustained stable
tachycardia in 8/11 patients and prevented reinitiation of
tachycardia in 5/10 patients. Oral
therapy prevented induction of
tachycardias in only 2/10 patients. Five patients had non-sustained
tachycardia and three had slower sustained
tachycardia. "New" non-clinical
tachycardias could be induced in six patients after
flecainide but five of these had had more than one type of induced
tachycardia. Four of 10 patients remained free of
tachycardias during follow-up. Withdrawal of oral treatment was necessary in three patients, one of whom had severe proarrhythmic effects. Two patients required additional antiarrhythmic
therapy. Long-term suppression could not be predicted from the results of oral
therapy, but testing after intravenous
drug seemed to be a more useful prognostic
indicator. In summary, intravenous
flecainide is effective for slowing and termination of stable
ventricular tachycardia. Oral
therapy is also effective but caution should be exerted in patients with multimorphic
tachycardias.