THE ROLE OF THE ACCESSORY PATHWAY IN THE ONSET OF ATRIAL-FIBRILLATIONIN WOLFF-PARKINSON-WHITE SYNDROME

To determine the role of the accessory pathway in the pathogenesis of atrial fibrillation, we compared electrophysiological findings in 17 p atients (44.7+/-10.2 years) with a history of atrial fibrillation befo re and after surgical ablation of the accessory pathway. The PA interv al was shortened, and the atrial refractory periods and the potential minimal wavelength of an atrial impulse (FRP(A)/PA) were significantly increased, after surgery. Fragmented atrial activity (an increase of 150% or more in the duration of the high right atrial electrogram) was observed in 80% of the patients before surgery and in 25% after surge ry. Its zone was significantly decreased after surgery. Repetitive atr ial firing was defined as the occurrence of 3 or more successive atria l electrograms induced by a premature stimulation. This was observed i n 60% of the patients before surgery, but in none after surgery. Atria l fibrillation was induced in 16 patients during the preoperative stud y, but in only 1 patient postoperatively. In conclusion, these results suggest that accessory pathways affect atrial vulnerability and play an important role in the onset of atrial fibrillation in WPW syndrome.