[Genesis of auricular fibrillation in the Wolff-Parkinson-White syndrome]

Atrial fibrillation seems to be more common in the absence of associated cardiac disease in the Wolff-Parkinson-White syndrome (WPW) than in subjects of the same age without this condition. The aim of this study was to analyse the electrophysiological mechanism of AF and to establish its relationship to the accessory pathway. The series comprises 14 out of 51 patients with WPW undergoing classical endocavitary investigation associating the recording of cardiac potentials from the His bundle, right atrium (RA), left atrium (LA) via the coronary sinus and atrial and ventricular stimulation techniques. Three mechanisms of inducing AF were analysed : - AF triggered by RA stimulation : either by a premature extra stimulus or overdrive atrial pacing. In all cases, the accessory pathway was right sides. - AF triggered by overdrive ventricular pacing : three cases were left sided accessory pathways in which atrial desynchronisation was localised in the LA. - Conversion of reciprocating tachycardia to AF (9 cases). In 2 cases, this was preceded by a progressive acceleration of the heart rate. Of 3 left sided accessory pathways, the atrial desynchronisation was located in the LA in 2 cases. The factors which facilitate AF in THE WPW syndrome are discussed : increased atrial vulnerability, the role of the rapid return of ventricular excitation to the atria through the accessory pathway. Our observations suggest that the accessory pathway plays a role in the genesis of AF in the WPW syndrome.