Electrophysiological features of orthodromic atrioventricular reentry tachycardia in patients with wolff-Parkinson-white syndrome and atrial fibrillation.

The aim of this study was to compare the electrophysiological features of tachycardia between WPW patients with and without AF. The study population consisted of 114 patients with WPW syndrome and reciprocating tachycardia during electrophysiological study. Two groups were selected: group I with AF during the procedure(n = 42)and the control group n = 72 without AF (group II). Cycle length (V-V interval), antero A-V, retrograde V-A conduction time during tachycardia and indexes V-A/V-V were analyzed. In addition, the relation between antero-, retrograde conduction time, and V-V was evaluated. Selection of the most predictive factor for AF presence was performed using regression analysis. Significant differences between the two groups were observed. These included a higher rate of tachycardia, shorter anterograde conduction time, A-V/V-V-indexes, longer retrograde conduction time, and V-A/V-V-indexes in group I compared with group II. Significant, positive correlations between anterograde conduction time and V-V were present in both groups, but retrograde conduction correlated significantly with the V-V-interval only in group II and group I (r = 0.37 vs r =-0.01, respectively). Significant, negative correlations between A-V and V-A conduction time in all analyzed points has been found to exist in group I (r =-0.45 for the point of maximal preexcitation [PMP]), whereas there were no significant correlations between these parameters in group II (r = 0.04). The most powerful AF predictor has been identified as the V-A/V-V index. The presence of AF in WPW syndrome may be associated with discrete patient characteristics. Ventricular activation occurs earlier, and atrial later, in the tachycardia cycle in AF than in patients free of AF. The different ability of the accessory pathway for adaptation to tachycardia rate changes in group I causes prolonged retrograde conduction over the pathway while the tachycardia rate increases.