Ventricular pacing failure after a single oral dose of pilsicainide in a patient with a permanent pacemaker and paroxysmal atrial fibrillation.

A single oral dose of pilsicainide, a Class Ic antiarrhythmic drug, is a widely used and highly effective therapy for termination of recent onset atrial fibrillation. We report on a patient in which ventricular pacing failure occurred immediately after a single oral dose of pilsicainide. It did not exhibit a parallel relationship between the change in the pacing threshold and plasma concentration of pilsicainide, and the recovery period for the ventricular pacing threshold was longer than that of the plasma concentration of pilsicainide in this patient. Careful attention should be paid when a single oral dose of pilsicainide for termination of recent onset atrial fibrillation is used in patients with permanent pacemakers.