Initiation of atrial fibrillation in the Wolff-Parkinson-White syndrome: the importance of the accessory pathway.

Atrial fibrillation in the Wolff-Parkinson-White syndrome may be related to microreentry in the accessory pathway. If such is the case, catheter ablation of the accessory pathway should eliminate atrial fibrillation. Among 95 patients undergoing catheter ablation, 20 had atrial fibrillation during standard electrophysiologic study (atrial vulnerability) before ablation. There were 16 women and four men with a mean age of 32 years. Before ablation six patients required electrical cardioversion. Thirty minutes after ablation, 11 continued to have inducible atrial fibrillation. Atrial fibrillation terminated spontaneously in every patient after ablation. A control group of 20 patients with accessory pathway ablation had no inducible atrial fibrillation before or after ablation. Catheter ablation had no effect on atrial properties including functional refractory period (227 +/- 37 vs 215 +/- 29 msec before versus after ablation, mean +/- SD) or wavelength (7.4 +/- 3.2 vs 7.2 +/- 2.7 before versus after ablation). These data suggest that an intact accessory pathway is not necessary for initiation of atrial fibrillation in most patients with Wolff-Parkinson-White syndrome. A rapid ventricular response over the accessory pathway may facilitate the perpetuation of atrial fibrillation in persons prone to this arrhythmia.