Atrial electrophysiologic abnormalities in patients with Wolff-Parkinson-White syndrome but without paroxysmal atrial fibrillation.
BACKGROUND
Paroxysmal atrial fibrillation (PAF) frequently occurs in patients with Wolff-Parkinson-White (WPW) syndrome.


OBJECTIVE
The purpose of this study was to analyze the atrial electrophysiologic abnormalities and vulnerability to develop atrial fibrillation (AF) in patients with WPW syndrome but with no previous history of PAF.


METHODS
We investigated atrial electrophysiologic abnormalities and vulnerability to AF in patients with WPW syndrome but without PAF. An electrophysiologic study was performed in 28 patients with WPW syndrome, 23 with atrioventricular nodal reentrant tachycardia (AVNRT) and 25 with other arrhythmias (control), all of whom had no history of PAF. The following atrial excitability parameters were assessed: effective refractory period (ERP), spontaneous or paced (A1) and extrastimulated (A2) atrial electrogram widths, percent maximum atrial fragmentation (%MAF; A2/A1 x 100), wavelength index (WLI; ERP/A2), and inducibility of AF.


RESULTS
The ERP tended to be shorter in patients with WPW syndrome and in those with AVNRT than in the control group. The %MAF increased (154 +/- 33 vs. 137 +/- 23%, p < 0.05) and WLI decreased (2.7 +/- 0.8 vs. 3.4 +/- 1.0, p < 0.05) significantly in patients with WPW syndrome compared with the control group; however, these parameters in patients with AVNRT showed intermediate values. Atrial fibrillation was more inducible in patients with WPW syndrome (4/28 [14.3%]) than in those with AVNRT (4.3% [1/23]) and the control group (0/25 [0%]). With respect to patients with WPW syndrome and with and without inducible AF, the %MAF increased (195 +/- 23 vs. 148 +/- 30%, p < 0.01) and the WLI decreased (2.2 +/- 0.3 vs. 2.9 +/- 0.9, p < 0.05) in subjects with inducible AF.


CONCLUSIONS
Atrial electrophysiologic abnormalities, especially atrial conduction delays, are more prominent in patients with WPW syndrome, even if they had no previous history of PAF. These abnormalities may play an important role in determining the vulnerability to AF.
Department of Cardiology and Clinical Research, National Zentsuji Hospital, Kagawa, Japan. ksakabe@jun.ncvc.go.jp
Koichi
K
Sakabe
Nobuo
N
Fukuda
Teru
T
Nada
Hisanori
H
Shinohara
Yoshiyuki
Y
Tamura
Tetsuzo
T
Wakatsuki
Akiyoshi
A
Nishikado
Takashi
T
Oki
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000503:physiopathology*; D016280:Atrial Function, Right / Q000502:physiology; D022062:Electrophysiologic Techniques, Cardiac; D004594:Electrophysiology; D005260:Female; D006325:Heart Atria / Q000002:abnormalities / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012032:Refractory Period, Electrophysiological / Q000502:physiology; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology; D014927:Wolff-Parkinson-White Syndrome / Q000503:physiopathology*