Factors Associated with Recurrence of Accessory Pathway Conduction After Radiofrequency Catheter Ablation

Catheter ablation of 215 accessory pathways (APs) using radiofrequency current (RF) was attempted in 204 consecutive patients. Two hundred twelve of the 215 (99%) APs were successfully ablated. After a minimum follow‐up period of 1 month (mean 8.5 ± 5.4 months), AP conduction had returned in 17 patients (8%). Recurrence of AP conduction was manifest by atrioventricular (AV) reentrant tachycardia in six patients, palpitations suggestive of AV reentrant tachycardia in five patients, ventricular preexcitation on electrocardiogram in five patients, and inducible AV reentrant tachycardia during a follow‐up electrophysiological study in one asymptomatic patient. AP conduction returned as early as 12 hours and as late as 4.7 months, but was evident within 2 months of ablution in 15 of 17 (88%) patients. AP conduction recurred in 12%‐14% of anteroseptal, right free‐wall, and posteroseptal APs, but only 5% of left free‐wall APs (P < 0.01). Retrograde only conducting APs (concealed APs) had recurrence of AP conduction more frequently (16%) than APs that exhibited antegrade conduction (5.5%; P < 0.01). Failure to record AP potentials from the ablation electrode, reflecting poor AP localization, was a strong predictor for recurrence of AP conduction. AP conduction returned in 19% of 48 APs when AP potentials were not recorded, compared to 5% of 164 APs where AP potentials were recorded from the ablation electrode (P < 0.01). The time to block of AP conduction from the onset of RF current application was longer in APs with recurrence of conduction (4.9 ± 6.1 sec vs 2.9 ± 3.4 sec; P < 0.02). Recurrence of AP conduction was more frequent when the stability of the ablation electrode was poor (12% of 41 APs vs 7% of 171 APs with stable electrode placement], and when the AP had multiple components (11% of 36 APs ablated at multiple sites vs 7% of 176 APs where AP was ablated at a single site), but these were not statistically significant. All 17 patients with recurrence of AP conduction underwent a second successful ablation. In conclusion, the overall incidence of recurrence of AP conduction is low, but is higher for right free‐wall and septal APs, concealed APs, and probably relates to poor AP localization.