Effects of slow pathway ablation on fast pathway function in patients with atrioventricular nodal reentrant tachycardia: Cryo- vs. radiofrequency ablation

Abstract

Background: In typical atrioventricular nodal reentrant tachycardia, radiofrequency (RF) ablation of the slow pathway (SP) is known to change the effective refractory period of the fast pathway (ERP FP) after successful RF ablation of the SP. The purpose of this study was to ascertain the mechanism of the ERP FP changes after SP ablation by comparing the results of both cryo- and RF ablation. Methods and Results: A total of 112 patients were enrolled prospectively and their electrophysiological properties analyzed before and after successful SP ablation. Patients were grouped into cryoablation (n=54) and RF ablation (n=58) groups and each group was subdivided into complete ablation (CG) and modification (MG) based on the presence of the SP after successful ablation. CG was performed in 64 patients: 30 by cryoablation and 34 by RF ablation. In patients who underwent complete SP ablation, the ERP FP was shortened significantly after cryoablation (375±74 vs. 281±39 ms, P<0.01), without significant change in the atrio-His (AH) or sinus cycle length (SCL) interval. Similarly, the ERPFP was shortened significantly (358±106 vs. 289±84 ms, P=0.01) also after RF ablation without change in AH or SCL interval. Conclusions: ERP FP shortening was observed after complete SP ablation with both cryo- and RF ablation without significant changes in indices of autonomic activity.