EFFECTS OF PILSICAINIDE AND PROPAFENONE ON VAGALLY INDUCED ATRIAL-FIBRILLATION - ROLE OF SUPPRESSANT EFFECT IN CONDUCTIVITY

The effects of pilsicainide on vagally induced atrial fibrillation and on electrophysiological parameters were compared with those of propaf enone in alpha-chloralose-anesthetized dogs. Conduction velocity, effe ctive refractory period, wavelength, averaged atrial fibrillation cycl e length and activation sequence in the right atrial free wall were de termined before and after drug administration. Pilsicainide (2 mg/kg/5 min and 3 mg/kg/h)(n = 10) or propafenone (2 mg/kg/15 min and 3 mg/kg /h)(n = 10) was intravenously infused during stable atrial fibrillatio n sustaining > 30 min. Pilsicainide terminated atrial fibrillation in nine dogs, while propafenone did so in three (p < 0.01). After the dru g, conduction velocity was suppressed more in the pilsicainide than in the propafenone group (p < 0.01). There was no difference in effectiv e refractory period after drug between the two groups. Mean wavelength was prolonged from 46.0 to 70.4 mm in the pilsicainide group and from 45.0 to 110.8 mm in the propafenone(p < 0.01 vs. pilsicainide). Activ ation mapping during atrial fibrillation showed Type II or III atrial fibrillation as previously defined [Konings, K.T.S., Kirchhof, C.J.H.J ., Smeets, J.R.L.M., Wellens, H.J.J., Penn, O.C., Allessie, M.A., 1994 . High-density mapping of electrically induced atrial fibrillation in humans. Circulation. Vol. 89, pp. 511-521.] before the drug, and chang ed to Type I before atrial fibrillation termination. Thus, pilsicainid e was more effective to terminate vagally induced atrial fibrillation than was propafenone despite a greater effect of propafenone than of p ilsicainide on wavelength. In this canine atrial fibrillation model, t he suppression of conduction velocity may play an important role in ch anging the activation pattern of atrial fibrillation and thus, termina ting atrial fibrillation. (C) 1998 Elsevier Science B.V. All rights re served.