Atrial fibrillation source ablation guided by preferential conduction directions is superior to conventional ablation strategies in preventing re-initiation in a realistic 3D in-silico model

Abstract Background and Aims Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation, but recurrence rates remain high. Ablating AF sources beyond PVI may prevent re-initiations. This proof-of-principle in silico study compares a novel source ablation approach guided by preferential conduction directions against conventional strategies in preventing AF re-initiation. Methods We compared two conventional ablation strategies—PVI alone and PVI with posterior wall isolation (box ablation)—to our novel source-based approach (Abstract Figure 1). In this approach, after PVI, a virtual high-density mapping catheter (4x4 electrode grid, 3 mm spacing) was guided sequentially against the preferential conduction direction until a source was identified through local conduction analysis or by encircling the source region. This process was repeated starting from different positions to capture multiple regions harboring sources. The identified sources were then clustered and marked as ablation targets, which were subsequently ablated and connected to non-conducting boundaries. Ablation strategies were assessed by evaluating AF re-initiation rates on a realistic in-silico model of the atria. Incremental pacing (20 sites) was used to assess AF initiation rates, and the ablated and electrically isolated areas were quantified. We performed these analyses in anatomies without and with endomysial fibrosis to assess the approaches at different stages of AF progression. Results Compared to no ablation, PVI reduced initiation rates in non-fibrotic and fibrotic atria (30% vs. 15% [p=0.48] and 60% vs. 55% [p=0.66], respectively, Abstract Figure 2 [top]). Box ablation did not improve PVI re-initiation rates (15%) and isolated larger portions of the left atrium (total isolated area with PVI: 34%, box: 45%). In contrast, source ablation guided by preferential conduction direction completely prevented AF re-initiation, regardless of the degree of structural remodeling, while isolating smaller left atrial areas (without fibrosis: 38%; with fibrosis: 41%, Abstract Figure 2 [bottom]) and included right atrial lesions. Macro-reentrant tachycardias frequently occurred after source ablation but could all be terminated with minimal additional lesions. Conclusion Source ablation guided by preferential conduction directions prevented AF re-initiation in silico while isolating smaller left atrial areas as compared to PVI alone and combined with box ablation.Figure 1:Methods overview Figure 2:Results overview