Electrogram morphology recurrence guided catheter ablation for repeat ablation of persistent atrial fibrillation

Abstract

Background: There are no standard mapping approaches for patients with persistent atrial fibrillation (PeAF), particularly after failed prior catheter ablation (CA). In this study, we assess the feasibility of using Electrogram Morphology Recurrence (EMR) to guide ablation.

Methods: Ten patients with recurrent PeAF after prior CA underwent detailed mapping of both atria during PeAF using the PentaRay (4 mm interelectrode spacing) and 3D mapping with CARTO. At each site, 15 s recordings were made. Custom software identified each electrogram and cross-correlation was used to identify the most recurrent electrogram morphology from which the % recurrence and cycle length of the most repeatable morphology (CL_R) was calculated. Sites of shortest CL_R and sites within 5 ms of shortest CL_R with recurrence ≥ 80% were used to inform CA strategy.

Results: A mean of 342.9 ± 131.9 LA and 328.6 ± 91.5 RA sites were recorded per patient. Nine had PV reconnection. Shortest CL_R sites guided ablation in 6/10 patients while 1 patient failed to fulfill shortest CL_R criteria, and another 3 did not undergo CA guided by shortest CL_R due to operator preference. On 12-month follow-up, all 4 patients without shortest CL_R guided CA had recurrent PeAF. Of the 6 patients with shortest CL_R guided CA, 5 patients did not have recurrent PeAF (p = 0.048), although 1 had paroxysmal AF and 2 had atypical atrial flutter.

Conclusion: EMR is a feasible, novel technique to guide CA in patients with PeAF. Further evaluation is needed to provide an electrogram-based method for mapping guided targeted ablation of key areas.

Keywords: Ablation; Electrograms; Mapping; Persistent atrial fibrillation.

Fig. 1

Illustration demonstrating two examples of different recurrence plots, the corresponding electrograms, color coded Rec% maps, and color coded CL_R maps. A The cross correlation plot of the bipolar electrogram (EGM) from the superior vena cava (SVC) demonstrates 100% recurrence of the most repeatable electrogram (Rec%). Therefore, the cycle length, 185 ms, matches the cycle length of the most recurrent morphology (CL_R), also 185 ms. B The 3D electroanatomic plot of the right atrium shows the color-coded Rec% map with high Rec% sites in red. In this plot the shortest CL_R site corresponds with high Rec% region is identified in the SVC. Electrical isolation of the SVC was performed. This patient also had pulmonary vein isolation (PVI) of a reconnected PV as well as ablation directed towards the septal left atrium, another site within 5 ms of the shortest CL_R. There was no recurrent atrial fibrillation or flutter in this patient although she insisted on staying on her sotalol therapy which had not prevented pre-ablation persistent atrial fibrillation (PeAF). C In another patient, the EGM shows rapid and fractionated signals with mean cycle length of 159 ms. However, Rec% was 71%. Therefore, the shortest CL_R was 226 ms. D This is the corresponding color-coded Rec% maps. It shows localized sites with high Rec% (> 80%) in the PVs but the calculated CL_R was 287–381 ms for all these sites which was longer than CL_R in the RA. Despite re-isolation of the pulmonary veins, and an empiric left atrial posterior wall ablation, AF recurred

Fig. 2

Distribution of sites of shortest cycle length of the most recurrent morphology (CL_R) in 10 patients undergoing repeat ablation for persistent atrial fibrillation

Fig. 3

Outcomes of EMR guided ablation in PeAF patients undergoing repeat Catheter ablation