Non-invasive assessment of substrate modification during atrial fibrillation ablation with pulse field ablation using imageless ECGI

Abstract Background Atrial fibrillation (AF) is sustained by fast driver regions with short atrial fibrillation cycle lengths (AFCL). Successful ablation strategies progressively increase atrial cycle lengths, leading to AF termination. Pulse Field Ablation (PFA) is a promising treatment that achieves targeted substrate modification by disrupting these drivers. Imageless Electrocardiographic Imaging (ECGI) provides a non-invasive, panoramic view of cardiac electrical activity, enabling a real-time assessment of AF substrate modification through AFCL mapping across the atria. Purpose This study aims to assess substrate modification in persistent AF patients using ECGI to monitor AFCL before and after the PFA procedure, evaluating its effectiveness in disrupting AF substrates. Methods Seventeen patients (65.4±8.5 years, 10 males) with persistent AF underwent a PFA procedure targeting pulmonary veins (PPV) and the posterior left atrial wall. Imageless ECGI was performed using a 128-electrode vest placed on each patient’s torso and a 3D body surface reconstruction. One-minute ECGI solution segments were selected pre- and post-ablation. In pre-ablation segments, AFCL distributions were tracked on each 4s segment to identify regions with high (dominant) and low (non-dominant) recurrence of short cycle length (Figure 1A), which were then re-evaluated post-ablation to assess substrate changes. Statistical analysis was used to determine the significance of AFCL changes within identified areas, providing insights into the effectiveness of PFA in disrupting AF substrates. Results ECGI mapping provided a detailed panoramic visualization of AFCL distributions. Isolation of the pulmonary veins and the posterior wall was associated with a general increment in AFCL across the atria. Non-dominant areas identified pre-ablation showed an AFCL increase of 25±14 ms, while dominant regions exhibited a more pronounced AFCL enlargement of 38±14 ms post-ablation. The percentage of increase in AFCL was more significant in dominant areas compared to non-dominant areas (24±9.2 % vs. 14.2±7.3 %, p=0.001), suggesting that PFA effectively alters AF-driving substrates. Conclusion Non-invasive ECGI mapping could be an effective tool for assessing substrate modification during AF treatment with PFA. By enabling detailed visualization and tracking of cycle length changes across atrial regions, ECGI identified a significant post-ablation increase in AFCL, particularly in recurrent dominant areas. These insights underscore the potential of ECGI to enhance patient-specific ablation strategies and improve treatment outcomes in persistent AF.