Abstract 18298: Niferidile, New Class III Antiarrhythmic Agent: Study of Electrophysiological Effects Aad Efficacy in Patients with Supraventricular Arrhythmias
Background. Niferidile (Nf) is a new potassium channel blocker that inhibits transient outward and delayed rectifier currents. Preclinical studies showed that Nf increases effective refractory periods (ERP) in atria more than in ventricles. High affinity of Nf to atrial myocardium should contribute to high efficacy in supraventricular arrhythmias and to low risk of ventricular proarrhythmia.
Objectives. To evaluate electrophysiological effects and antiarrhytmic efficacy of Nf in patients with paroxysmal supraventricular tachycardia (PSVT).
Materials and methods. Effects of Nf (administered 20µg/kg intravenously) were studied in 28 patients (16 males) with PSVT (14 orthodromic tachycardia in WPW syndrome, 10 AV-nodal reentrant tachycardia, 4 orthodromic tachycardia due to concealed bypass tract) during endocardial electrophysiological study. Termination of sustained paroxysms of PSVT by Nf could be investigated in 23 patients and prevention of reinduction of PSVT - in 25 patients.
Results. Nf terminated PSVT in 78.26% and prevented reinduction in 84% of patients. Nf increased ERP of right atrium (by 22.25%; p<0.01), left atrium (by 22.45%; p<0.01), right ventricle (by 12.03%; p<0.05) and accessory pathways (anterogradely by 23.64% [p<0.01]; retrogradely by 29.43% [p<0.001]). Nf did not affect sinus node and atrioventricular conduction. Nf significantly increased relative refractory period of His-Purkinje system (by 34.71%; p<0.01). Nf prolonged QT (by 24.5%; p<0.01) and QTc (by 20.11%; p<0.05) intervals. One patient developed short runs of torsade de pointes shortly after injection of drug.
Conclusion. Prolongation of ERP, predominantly in atria and accessory pathways, and RRP in His-Purkinje system are main electrophysiological effects of Nf. New drug demonstrated high antiarrhythmic efficacy and good safety profile in patients with PSVT.
- © 2012 by American Heart Association, Inc.