Differentiation of the electrophysiological effects on the atrial myocardium between the pure Na channel blocker, pilsicainide, and flecainide.
The purpose of this study was to identify the difference between the pure Na channel blocker, pilsicainide and Ic-antiarrhythmic drug, flecainide, on the atrial electrophysiological characteristics.


METHODS
The subjects consisted of 24 patients (48 +/- 12 years-old: P-group) in whom pilsicainide was administrated intravenously (1 mg/kg/10 min) and 31 patients (47 +/- 15 years-old: F-group) in whom flecainide was administrated intravenously (2 mg/kg/10 min). The atrial effective refractory period (ERP-A), intra-atrial conduction time (CT), max intra-atrial conduction delay (Max CD), repetitive atrial firing zone (RAFZ), fragmented atrial activity zone (FAZ) and intra-atrial conduction delay zone (CDZ) were measured before and after the drugs.


RESULTS
Pilsicainide and flecainide significantly prolonged the ERP-A (211 +/- 27 msec to 246 +/- 39 msec; p < 0.001, 217 +/- 25 msec to 244 +/- 33 msec; p < 0.001, respectively) and CT (121 +/- 33 msec to 149 +/- 43 msec; p < 0.001, 122 +/- 22 msec to 153 +/- 27 msec; p < 0.001, respectively) to the same degree. However, the Max CD was shortened by pilsicainide, but not by flecainide. The RAFZ, FAZ and CDZ decreased in the P-group (21 +/- 25 msec to 4 +/- 10 msec; p < 0.01, 24 +/- 24 msec to 14 +/- 18 msec; p < 0.05, 56 +/- 29 msec to 43 +/- 32 msec, p < 0.05, respectively), but not in the F-group.


CONCLUSIONS
The effects of atrial conduction delays may differ between pilsicainide and flecainide. Further examination will be needed to explain this mechanism.
Kanemoto
Masashi
M
Division of Cardiovascular Medicine, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Shimizu
Akihiko
A
Yamagata
Toshihiko
T
Esato
Masahiro
M
Ueyama
Takeshi
T
Yoshiga
Yasuhiro
Y
Kakugawa
Hiroyuki
H
Kametani
Ryousuke
R
Inoue
Noriko
N
Sawa
Akira
A
Matsuzaki
Masunori
M
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000097:blood / Q000627:therapeutic use*; D001282:Atrial Flutter / Q000188:drug therapy; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D005424:Flecainide / Q000097:blood / Q000627:therapeutic use*; D006325:Heart Atria / Q000187:drug effects* / Q000503:physiopathology; D006329:Heart Conduction System / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects; D006801:Humans; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009206:Myocardium; D011446:Prospective Studies; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D012107:Research Design; D026941:Sodium Channel Blockers / Q000097:blood / Q000627:therapeutic use*; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000188:drug therapy; D017180:Tachycardia, Ventricular / Q000188:drug therapy; D016896:Treatment Outcome; D014927:Wolff-Parkinson-White Syndrome / Q000188:drug therapy
D000889:Anti-Arrhythmia Agents; D026941:Sodium Channel Blockers; D008012:Lidocaine; C042288:pilsicainide; D005424:Flecainide