Prediction of long-term success after initially successful radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome

Abstract

Background：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%. Several previous studies have demonstrated that the recurrence rate of accessory pathway function following initially successful ablation is about 10%. However, accessory pathway conduction may recur even after an apparently successful ablation, possibly due to transient modification of the pathway rather than permanent destruction of the accessory pathway. During RF catheter ablation, prediction of permanent destruction of pathway, ensuring long-term success of the catheter ablation, is very important. Methods：All ablation procedures were performed using a 4 mm tipped deflectable catheter (Diag, Webster or EPT. RF energy was delivered using an RF generater (Radionics RFG-3C. After positioning the ablation catheter at the target site, RF energy of 40-60 V was applied for 30-60 sec. After successful elimination of accessory pathway conduction, all patients underwent routine history taking, physical examination, and a 12 lead electrocardiogram recording at 1 week and 1, 2, 3, and 12 months after ablation. The AV interval, AV ratio, presence of AP potential, and time from RF delivery to loss of delta were measured at the time of the last local electrograms at the successful sites. Statistics：The continuous variables were evaluated using an unpaired Students T test and the discrete, variables using chi-square test and fischers exact test between the groups, with and without recurrence, during follow-up. Results：RF catheter ablation was initially successful in 35 patients with Wolff-Parkinson-White syndrome. Following initially successful RF ablation, follow-up examinations were done during 55±40 weeks. The 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 of less than 5 sec were indicative for long- term success without recurrence. Conclusion：The 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 for predicting the long term success of RF catheter ablation in patients with manifest accessory atrioventricular connections.(Korean Circulation J 2001;31(8 :794-800