Catheter configuration for mapping micro-anatomic reentries sustaining atrial fibrillation: A simulation study

Atrial fibrillation (AF) can be sustained by intramural reentrant circuits within three-dimensional arrhythmogenic hubs formed by fibrotically-insulated myobundles. However, the efficacy of different multi-electrode mapping (MEM) to identify the micro-reentrant pathways sustaining AF remains undefined. An anisotropic atrial tissue structure (30 × 30 × 4 mm), incorporating a sub-endocardial laterally-insulated myobundle (15 × 2.5 × 1.5 mm) was simulated reflecting persistent AF conditions. Simulations included endocardial unipolar, bipolar, and omnipolar electrograms, with local activation time maps calculated for reentry visualization. N = 656 MEM configurations were evaluated, varying inter-electrode distances (1, 3, 6 and 9 mm), orientations (parallel and perpendicular), contact distances to the wall (0.25 and 1.0 mm), and electrode positions (in 1-mm increments) relative to the reentrant circuit. Conduction along the reentrant pathway was identified by electrograms within <3 mm of the micro-reentrant circuit, and confirmed by their comparison to action potential traces. However, detection on electrogram (EGM) traces was highly dependent on catheter configuration and distance to the atrial wall. Dense unipolar MEM configurations (1-6 mm spacing) facilitated pathway identification, while bipolar MEM required electrode pairs to align with the myobundle for effective detection. Omnipolar configurations offered no significant advantages over unipolar for modest inter-electrode spacings (1-6 mm) but improved detection accuracy at larger spacings (9 mm). Mapping was affected by micro-reentrant track width, though reentrant mapping still detected tracks thinner than electrode spacing. Track thickness and conduction velocity did not impair detection and sometimes improved it. Unipolar MEM configurations (1-6 mm spacing) with optimal contact enabled the detection of sub-endocardial reentry pathways sustaining AF in 50-100% of simulated cases. Combining unipolar and omnipolar mapping approaches (3 mm spacing) may enhance the detection rates of AF micro-reentry. These findings provide critical insights into optimizing MEM techniques for human AF reentrant circuit detection and may improve the efficacy of AF ablation procedures.