American heart journal
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American heart journal · May 1987
Case ReportsOccurrence of exercise-induced and spontaneous wide complex tachycardia during therapy with flecainide for complex ventricular arrhythmias: a probable proarrhythmic effect.
Flecainide acetate, a new antiarrhythmic agent, possesses favorable pharmacokinetic and hemodynamic properties and demonstrates highly favorable antiarrhythmic activity in patients with ventricular arrhythmias. However, the proarrhythmic potential of flecainide deserves further evaluation. In 7 (13%) of 55 consecutive patients treated with oral flecainide, 200 to 600 mg/day, for complex ventricular arrhythmias (including sustained ventricular tachycardia in 14), we observed the appearance of new or more sustained exercise-induced (five patients) or spontaneous (two patients) wide complex tachycardia. ⋯ In four patients, wide complex tachycardia did not recur during exercise testing during alternative antiarrhythmic therapy (three patients) or no antiarrhythmic therapy (one patient). These observations raise the possibility of flecainide-related proarrhythmia, manifested as an increased propensity to exercise (activity)-induced wide complex tachycardia, which was not reliably predicted by results of Holter recordings or programmed electrical stimulation. Patients with complex ventricular arrhythmias beginning long-term treatment with oral flecainide should be considered for treadmill exercise testing together with ambulatory monitoring as part of the initial assessment of drug efficacy.