Radiofrequency (RF) catheter ablation of accessory pathways is generally accepted as the procedure of choice for symptomatic patients with tachycardia. The success rate of RF catheter ablation has been reported to be greater then 90%. Previous several studies have shown that the recurrence rate of accessory pathway function after initially successful ablation is about 10%. However, accessory pathway conduction may recur after apparently successful ablation, possibly due to transient modification of the pathway rather than permanent destruction of accessory pathway. During RF catheter ablation, prediction of permanent destruction of pathway , which means long-term success of catheter ablation, is very important.

All ablation procedures were performed using a 4 mm tipped deflectable catheter (Diag, Webster or EPT). RF energy was delivered using the RF generater (Radionics RFG-3C). After positioning the ablation catheter at the target site RF energy of 40-60V was applied for 30-60sec. After successful elimination of accessory pathway conduction, all patients underwent routine history taking, physical examination, and a 12 lead electrocardiogram recording at 1 week, 1, 2, 3, and 12 month after ablation. AV interval, AV ratio, presence of AP potential, and time from RF delivery to loss of delta were measured at the last local electrograms at the successful sites. Statistics: The continuous variables was evaluated by using an unpaired Student? T test and discrete variables, using chi-square test and fischer? exact test between groups with recurrence and without recurrence during follow-up.

RF catheter ablation was initially successful in 35 patients with Wolff-Parkinson-White syndrome. After initially successful RF ablation, follow-up examinations were done during 55 40 weeks. Time from RF delivery to loss of delta was shorter in the group without recurrence during follow-up. Times from RF energy to loss of delta less than 5 sec was for long- term success without recurrence.

Time required to eliminate an accessory pathway conduction is a predictor for long term success. However, local electrogram characteristics during successful RF catheter ablation may not be useful to predict long term success of RF catheter ablation in patients with manifest accessory atrioventricular connections.