Abstract
Background: Electrogram (EGM) morphology recurrence (EMR) mapping of persistent atrial fibrillation (PeAF) quantifies consistency of activation at each site and is expected to be high and rapid near drivers of PeAF. Objective: To compare EMR in the left (LA) and right atrium (RA) in patients undergoing first- vs second-time PeAF catheter ablation (CA). Methods: Multisite bipolar EGM mapping of the LA (265±153 sites) and RA (224±148 sites) prior to CA for PeAF was performed in 40 patients (29 males, age 63±9 yrs, CHA2DS2-VASc 2.4±1.5, LVEF 48±12%) undergoing first (Group 1, n=31) or second-time (Group 2, n=9) CA. After cross-correlation of each automatically detected EGM with every other EGM in the recording, the most recurrent EGM morphology was identified and its frequency (Rec%) and cycle length of recurrence (CL R ) were computed (figure). The minimum CL R sites were identified. Results: In group 1, shortest CL R was in the LA in 26 patients (84%) and RA in 5 patients (16%). In the LA, there were 1 (n=23), 2 (n=2), or 3 (n=1) areas of shortest CL R , most commonly in the pulmonary veins (PV; n=19). In the RA, there was only 1 area of shortest CL R . Minimum CL R was 174.1±25.4 ms (LA-179.6±37.4 vs RA-207.9±34.5, p=0.0004), with Rec% 95±10%. In group 2, shortest CL R was in the LA in 5 patients and RA in 5 patients (56%)– one had both LA and RA. In the LA/RA, there were 1 (n=3/4) or 2 (n=2/1) areas of shortest CL R . The most common LA site was non-PV (6/7, 85.7%). The minimum CL R was 182.1±26.2ms (LA-190.8±36.2 vs RA-196.0±30.5, p=0.6), with Rec% 96±5%. Conclusion: In 61% of patients undergoing initial CA for PeAF, EMR identified LA drivers in the PVs which may explain why PV isolation has been reported to have 50-60% success rates in PeAF. In patients undergoing a 2 nd ablation for PeAF, EMR identified predominantly nonPV drivers with even distribution of shortest CL R between RA and LA and diminished CL R gradient between the LA and RA. EMR may be a useful mapping tool to characterize potential drivers of PeAF.