Electrophysiological properties in paroxysmal atrial fibrillation complicated with the Wolff-Parkinson-White syndrome: comparison with paroxysmal atrial fibrillation alone.

Electrophysiological studies were performed in 26 patients with atrial fibrillation (AF). Thirteen patients had the Wolff-Parkinson-White (WPW) syndrome (group A), and another 13 patients did not have the WPW syndrome (group B). The right atrium effective refractory period was significantly shorter in group A than in group B. The wavelength index which was defined as the ratio of the refractory period to the conduction delay was significantly lower in group A than in group B. Accordingly, patients in group A had a greater tendency to produce atrial reentry than those in group B.