PILOT EXPERIENCE IN INVESTIGATION OF ELEC TROPHYSIOLOGICAL AND ANTIARRHYTHMIC EFFECTS OF NIBENTAN IN PATIENTS WITH PAROXYSMAL TACHYARRHYTHMIAS

Electrophysiologic and antiarrhythmic effects of a new antiarrhythmic drug nibentan were studied in 9 patients with supraventricular and ven tricular arrhythmias. Intravenous bolus of 0.125 mg/kg of nibentan pro duced prolongation of QT and corrected QT intervals by 22% and 23%, re spectively. Nibentan significantly increased atrial and right ventricu lar effective refractory periods (by 25% and 16.8%, respectively). Fun ctional refractory period of the His-Purkinje system and retrograde ef fective refractory period of bundle of Kent were also increased (by 27 .7% and 35.6% respectively). No effects of nibentan on sinus node cond uction and automaticity were noted. The results showed that nibentan h as obvious electrophysiologic properties characteristic of class III a ntiarrhythmic drugs. Nibentan in highly effective against reproducible at endocardia pacing supraventricular and ventricular tachyarrhythmia s. No proarrhythmic action of nibentan was noted in this group of pati ents.