Electrogram Morphology Recurrence for Mapping Persistent Atrial Fibrillation: Initial vs Redo Catheter Ablation

Background: Electrogram (EGM) morphology recurrence (EMR) mapping of persistent atrial fibrillation (AF) quantifies consistency of activation and is expected to be high and rapid near AF drivers. Objectives: The purpose of this study was to compare EMR in left atria (LA) and right atria (RA) in patients undergoing first vs redo ablation for persistent AF. Methods: Multisite LA/RA mapping (LA: 281 ± 176 sites/patient; RA: 239 ± 166 sites/patient) before persistent AF ablation was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (Group 1, n = 32) or redo ablation (Group 2, n = 10). After cross-correlation of each automatically detected EGM with every other EGM per recording, the most recurrent electrogram morphology was identified and its frequency (Rec%) and recurrence cycle length (CL_R) were computed. Results: In Groups 1 and 2, minimum CL_R was 172.8 ± 26.0 milliseconds (LA: 178.2 ± 37.6 milliseconds, RA: 204.4 ± 34.0 milliseconds, P = 0.0005) and 186.5 ± 28.3 milliseconds (LA: 196.1 ± 38.1 milliseconds vs RA: 199.0 ± 30.2 milliseconds, P = 0.75), with Rec% 94.7% ± 10% and 93.8% ± 9.2%. Group 2 minimum CL_R was not different from Group 1 (P = 0.20). Shortest CL_R was in the LA in 84% of Group 1 and 50% of Group 2 patients (P = 0.04). Only 1 of 10 patients in Group 2 had the shortest CL_R in the pulmonary veins (PVs) compared with 19 of 32 in Group 1 (P = 0.01). Most sites (77.6%) had Rec% <50%. Conclusions: EMR identified the shortest CL_R sites in the PVs in 59% of patients undergoing initial persistent AF ablation, consistent with reported success rates of ∼50% for PV isolation. The majority of sites have low recurrence and may reflect bystander sites not critical for maintaining AF. EMR provides a robust new method for quantifying consistency and rapidity of activation direction at multiple atrial sites.