title: Effects of intravenous nifekalant, a class III antiarrhythmic drug, on atrial vulnerability parameters in patients with paroxysmal atrial fibrillation.
abstract: Nifekalant, a class III antiarrhythmic drug, has been shown to suppress ventricular tachyarrhythmias, but its effects on AF are unclear. The aim of this study was to clarify the effects of nifekalant on the atrial vulnerability parameters in patients with paroxysmal AF. The study included 18 patients with paroxysmal AF who underwent electrophysiological study before and after intravenous infusion of nifekalant. The atrial electrophysiological parameters including the atrial effective refractory period (AERP), maximum intraatrial conduction delay, and wavelength index, calculated as the ratio of AERP to the maximum conduction delay, were quantitatively measured at baseline and during nifekalant infusion. The mean AERP was significantly prolonged from 214 +/- 27 ms at baseline to 242 +/- 39 ms after nifekalant (P < 0.001). Although earlier studies have shown that nifekalant does not affect the atrial conduction time, the mean maximum conduction delay of the study patients was significantly prolonged from 59 +/- 19 ms at baseline to 72 +/- 28 ms after nifekalant (P = 0.015). There was no significant difference in the wavelength index at baseline (4.1 +/- 1.7) and after nifekalant (4.1 +/- 2.5). However, when the differences of AERP and wavelength index were defined as each parameter during nifekalant infusion minus that at baseline, the difference of AERP showed a direct positive correlation with that of the wavelength index (P = 0.013). In conclusion, nifekalant may be effective in the prevention of AF due to prolongation of the AERP. However, in those patients who have a lesser degree of prolongation of the AERP by nifekalant, the wavelength index tended to be decreased, suggesting that the drug might augment the propensity for AF.
authors.affiliation: Division of Cardiovascular Medicine, Department of Translational Medical Sciences, Course of Medical and Dental Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Minami
authors.forename: Shojiro
authors.initials: S
authors.lastname: Isomoto
authors.forename: Kojiro
authors.initials: K
authors.lastname: Nakao
authors.forename: Norihiro
authors.initials: N
authors.lastname: Komiya
authors.forename: Satoki
authors.initials: S
authors.lastname: Fukae
authors.forename: Osmar Antonio
authors.initials: OA
authors.lastname: Centurion
authors.forename: Katsusuke
authors.initials: K
authors.lastname: Yano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D020517:Atrial Appendage / Q000187:drug effects; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000503:physiopathology*; D016275:Atrial Function / Q000187:drug effects*; D002036:Bundle of His / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects; D004562:Electrocardiography / Q000187:drug effects; D004594:Electrophysiology; D005260:Female; D006352:Heart Ventricles / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D016014:Linear Models; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D011744:Pyrimidinones / Q000008:administration & dosage / Q000627:therapeutic use*; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D013997:Time Factors
chemical_list: D000889:Anti-Arrhythmia Agents; D011744:Pyrimidinones; C076259:nifekalant