Catheter ablation of accessory pathways using radiofrequency(RF) energy was recently introduced to cure accessory pathway related tachyarrhythmias. The purpose of the present study was to evaluate the efficacy and safety of radiofrequency catheter ablation of accessory pathways and to determine factors influencing the outcome of catheter ablation.

Electrophysiology study was performed with standard technique and catheter ablation of accessory pathways using RF and conventional ablation technique. The outcome of RF catheter ablation were evaluated according to the location and the overtness of accessory pathways. Eighty patients(Mean ±SD age, 36±15 years ; 50 male, 30 female)comprising 49(61%) with Wolff-Parkinson-White(WPW) syndrome and 31(39%) with atrioventricular reentry tachycardia(AVRT) using concealed bypass tract underwent RF catheter ablation for total of 85 accessory pathways in the Chonnam University Hospital. Five(6.3%) patients had multiple accessory pathways.

Seventy-nine(92.9%) out of 85 pathways and all the pathways in 75(93.8%) out of 80 patients were ablated successfully. The success rate showed no significant difference between patients with overt accessory pathways and patients with concealed accessory pathways(92.0% vs. 93.9%). However, the success rate in right free wall location(72.7% of 11) was significantly lower than that in the other sites (95.9% of 74, p<0.05). More attempts were tried to ablate right-sided accessory pathway than left-sided pathways(6.4±24.1 vs. 3.8±6.8, p<0.05). Three(3.8%) pathways recurred within 30 minutes after the initial successful ablation. Four(5.1%) pathways recurred from 16 hours to 7 months after completion of the initial successful ablation session during the mean follow-up period of 43±24 weeks(range, 2-84 weeks). This late recurrence was more frequent, although statistically insignificant, in right-sided accessory pathways(11.1% vs. 3.3%, p=0.22). All 4 recurrent pathways(1 at the same session, 3 at the repeated sessions) reattempted for ablation were successfully ablated. As procedure-related complications, second degree AV block developed in a patients with mid septal and posteroseptal pahways and hemopericardium in a patients with a left anterolateral pathway.

RF catheter ablation of atrioventricular accessory pathways is very effective and safe, with a success rate of 93.8% and a complication rate of 2.5%. Right-sided accessory pathways are more difficult to ablate than left-sided accessory pathways, requiring the development of a better technique for right free wall pathways.