A case of sinus pause due to the proarrhythmia of pilsicainide.

A 74-year-old man received oral administration of pilsicainide, a pure sodium channel blocker with slow recovery kinetics, to convert paroxysmal atrial fibrillation to sinus rhythm and developed loss of consciousness two days later. The ECG monitoring revealed sinus pause with markedly prolonged PQ interval and QRS width. Two days after the drug was discontinued, the duration of the QRS complex was normalized. This drug is rapidly absorbed from the gastrointestinal tract, most of which is excreted from the kidney. The plasma concentration of pilsicainide, although not measured, must have been very high, since his renal function was impaired. When pilsicainide is prescribed in patients with coronary artery disease or renal dysfunction, close attention must be paid to avoid life-threatening arrhythmias due to high plasma concentrations of the drug. This is an interesting case because the proarrhthmia of the drug was not tachyarrhythmia, such as ventricular tachycardia or torsades de pointes, but sinus pause.