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

Background：Radiofrequency (RF) catheter ablation of accessory pathways is generally accepted as the\nprocedure of choice for symptomatic patients with tachycardia. The success rate of RF catheter ablation has\nbeen reported to be greater then 90%. Several previous studies have demonstrated that the recurrence rate of\naccessory pathway function following initially successful ablation is about 10%. However, accessory pathway\nconduction may recur even after an apparently successful ablation, possibly due to transient modification of\nthe pathway rather than permanent destruction of the accessory pathway. During RF catheter ablation, prediction\nof permanent destruction of pathway, ensuring long-term success of the catheter ablation, is very important.\nMethods：All ablation procedures were performed using a 4 mm tipped deflectable catheter (Diag, Webster\nor EPT). RF energy was delivered using an RF generater (Radionics RFG-3C). After positioning the ablation\ncatheter at the target site, RF energy of 40-60 V was applied for 30-60 sec. After successful elimination of\naccessory pathway conduction, all patients underwent routine history taking, physical examination, and a 12\nlead electrocardiogram recording at 1 week and 1, 2, 3, and 12 months after ablation. The AV interval, AV\nratio, presence of AP potential, and time from RF delivery to loss of delta were measured at the time of the\nlast local electrograms at the successful sites. Statistics：The continuous variables were evaluated using an\nunpaired Students T test and the discrete, variables using chi-square test and fischers exact test between the\ngroups, with and without recurrence, during follow-up. Results：RF catheter ablation was initially successful\nin 35 patients with Wolff-Parkinson-White syndrome. Following initially successful RF ablation, follow-up\nexaminations were done during 55±40 weeks. The time from RF delivery to loss of delta was shorter in the\ngroup without recurrence during follow-up. Times from RF energy to loss of delta of less than 5 sec were indicative\nfor long- term success without recurrence. Conclusion：The time required to eliminate an accessory\npathway conduction is a predictor for long term success. However, local electrogram characteristics during\nsuccessful RF catheter ablation may not be useful for predicting the long term success of RF catheter ablation\nin patients with manifest accessory atrioventricular connections.(Korean Circulation J 2001;31(8):794-800)