Novel mapping tool to identify drivers in persistent atrial fibrillation: first clinical experience
Authors: Latcu D G , Milanese S , Kingston A , Canepa S , Lerebours C , Gutrod S , Enache B , Benhenda N , Saoudi N 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Developing ablation strategies beyond pulmonary vein isolation (PVI) in persistent atrial fibrillation (persAF) is still a challenge. To date, few diagnostic tools have allowed identification of potential drivers during AF, with questionable results. There is a need for a tool that allows to consistently display and detect EGMs and identify optimal ablations targets. A novel mapping tool can provide algorithmic detection of ablation targets based on EGM properties specific to relatively stable localized rotational activations.

Objective
Describing an initial series of patients (pts) where Ockham mapping was used during AF to identify ablation targets and treat PersAF.

Methods
PersAF pts presenting in AF for were mapped using an ultra-high density mapping system (RHYTHMIA). A novel PersAF mapping feature (Ockham) was used to detect ablation targets by calculating local cycle length (LCL) and local spread of activation time within that LCL (Duty Cycle) for consistent EGMs. A scatterplot tool (F1 A) was used to identify regions of consistent (relatively stable) local activation. Among these areas, those with fast CL and high DC (&gt;90%) were used to guide the optimal PVI line placement. Additionally, during remapping the same approach was used to target ablation beyond PVI.RF was delivered at 40-45 W via a StablePointTM IntallaNav OI catheter aiming at the maximum impedance drop (30 ohms).Durable PVI was verified by EGM visualization. In case of ongoing AF at the end of the procedure patients were monitored for 48 h before eventual cardioversion. Follow-up was by Holter every 3 months (more if symptoms). Data are median [IQR].

Results
The novel mapping tool was used on 31 PersAF pts (68±9.5 years, 71% male, 20 De Novo).A median of 41228 [32789-46512] EGMs was collected before PVI. After PVI, 3 de novo pts had AF terminate into AT. Additional targets were identified in the other ones from a second post-PVI map. 81% of the extra-venous potential drivers identified on the post-PVI maps were already present on the pre-PVI map, supporting the reproducibility of the tool. Pts had a median of 3 [1-4.25] extra-PV drivers targets. Across all pts, following PVI and targeted ablation, there was progressive AF organization demonstrated by global activation slowing (a rightward shift of CL; F1 B), which in approximately half of the patients formed bi-modal curves clustered around 2 discrete CL values. Acutely, 88% of patients had AF terminate to SR or AT. At 10 months [5.75-13] follow-up, 3 (15%) patients had recurrence of persAF, and 2 (10%) patients had AT recurrences. No complication occurred.

Discussion
This clinical experience demonstrates that this tool can identify limited, but highly selective, reproducible extra-PV AF drivers. Since PersAF pts have high variability in arrhythmogenic sites, this novel tool allows efficient identification of ablation targets based on EGM properties for an individualized approach to ablation beyond PVI.