Right atrial activation features characterized via a novel mapping tool in persistent atrial fibrillation patients undergoing ultra-high-density mapping

Abstract Introduction Atrial Fibrillation (AF)-induced electrical remodelling, and histological changes have been demonstrated to concomitantly extend to both atria. However, the right atrium (RA) has often been overlooked as a chamber contributing to AF vulnerability. Ockham is a novel ultrahigh density (UHD) mapping tool, which automatically provides algorithmic detection of AF regions of interest (ROIs) with consistent morphology and activations from intracardiac electrograms (EGMs). Purpose To describe procedural findings in a series of patients with persistent and long-standing persistent AF (PersAF and LSPAF) undergoing biatrial UHD mapping. Methods We included consecutive AF patients undergoing first-time catheter ablation via a 5-spline pulsed field ablation (PFA) catheter. UHD mapping of the RA and left atrium (LA) using a 64-pole catheter was performed before PFA. Ockham was used to detect ROIs by assessing local cycle length (CL) and local spread of activation time within that local CL [Duty Cycle (DC)] for consistent EGMs. A scatterplot tool (Figure 1A,B,C) of each atrium was generated (RA: orange; LA: white), which displayed points corresponding to EGMs with consistent local activation and indicating different CL (x-axis) and DC (y-axis) values. PFA was performed targeting the pulmonary veins (PV), posterior wall (PW) and adjacent Ockham-detected ROIs. Results Thirteen (69±7y, 38.5% males) patients were enrolled (AF duration: 14 months [IQR:7-19]; 53.8% LSPAF). RA and LA mapping duration was 26±11min (13587±4049 EGMs) and 31±11min (22243±7643 EGMs), respectively. RA mapping identified a median of 2 [2-3] AF sources/patient, mainly localized at the base of the right atrial appendage (76.9%), crista terminalis (38.5%), septum (30.7%), superior vena cava/RA junction (30.7%). LA mapping documented 3 [3-4] AF sources/patient, mainly localized at the PV antra (76.9%), PW (76.9%), or adjacent sites (69.2%). Peak CL values for the RA and LA were 173±22ms and 179±24ms (p=0.54), respectively. The scatter plot showed a peak of points with a 100%-DC value in 9 (69.2) LA and 6 (46.2%) RA maps (Figure1A,C). PFA of PVs, PW and adjacent ROI led to AF termination in 11 (84.6%) patients, which occurred concomitantly to ablation of a ROI in 76.9% of patients (Figure 1A). All 3 patients without AF termination (Figure 1B-C) had a peak CL slower in the LA compared to the RA (211ms vs. 186ms; 177ms vs 171ms; 151ms vs. 138ms). One of them showed a scatterplot of the LA characterized by 2 discrete CL peaks on the histogram (Figure 1C). Conclusions An individualized strategy for PV and PW isolation targeting adjacent ROIs detected by Ockham effectively terminated AF in 84.6% of patients. Maintenance of AF following PFA occurred in patients with a slower or double CL peak in the LA. Further data may help identify scatterplot patterns suggesting a role of the RA in AF initiation and maintenance, thereby justifying a biatrial ablation strategy.Scatter plots