High-density electroanatomic mapping of atriofascicular pathways using multipolar mapping catheters can identify oblique pathways and avoid mechanical bump termination

Background: Atriofascicular fibers (AFFs) are rare accessory pathways that have higher rates of recurrence after ablation because of either failure to identify AFF (M) potentials or mechanical termination with contact. Objective: We aimed to evaluate whether electroanatomic mapping (EAM) using multielectrode, high-density nonlinear catheters can reliably localize AFF potentials and determine a site for ablation without causing mechanical termination. Methods: Seven patients underwent electrophysiology studies (EPS) and EAM using high-density, multielectrode catheters for antidromic tachycardia using AFFs. Results: Mean age at ablation was 15.5 ± 7.4 years, and 2 (29%) were female. Two had Ebstein's anomaly. Three of 7 (43%) had previous ablation attempts. Of the previous attempts, 3 (60%) were complicated by mechanical termination during mapping. None of the previous ablation attempts was performed using high-density mapping catheters. HD Grid with Ensite NavX (Abbott Cardiovascular, Abbott Park, IL) was used in 3; the remainder used the PentaRay (3) or Optrell (1) catheters with CARTO (Biosense Webster, Irvine, CA). The AFF course was mapped to the lateral tricuspid annulus in all. Four of 7 had oblique courses with atrial insertion superior to the ventricular insertion. Multielectrode mapping catheters did not result in mechanical termination in any of these cases, whereas mechanical termination with ablation catheters occurred in 4 (57%). Successful ablation was performed in all with no recurrence over a 15 ± 6-month follow-up. Conclusion: EAM using high-density multielectrode mapping catheters allow localization of atriofascicular pathways without causing mechanical termination and may improve long-term success of ablation. Majority of the pathways had oblique courses with atrial insertion superior to the ventricular insertion.