Local conduction velocities influenced the complexity and stability of atrial fibrillation (AF) patterns. Findings were presented at the European Society of Cardiology (ESC) Congress 2025.

This prospective study included 52 consecutive patients presenting with AF who underwent either AF ablation or electrical cardioversion. Continuous periprocedural non-invasive ECG imaging (ECGi) assessed local conduction velocities and AF dynamics. Stable AF drivers were defined as sites with the shortest local cycle lengths persisting for more than half of the recording period. Driver-stability maps were created and compared to conduction velocities in sinus rhythm.

Each patient had a mean of 2.8 slow-conduction areas and 2.2 stable AF drivers. Stable drivers were predominantly located in slow-conduction regions (77%). Patients with more slow-conduction areas had more complex but less stable AF patterns. Both the number of slow-conduction areas (hazard ratio 5.2, p=0.033) and AF complexity (hazard ratio 4.3, p=0.0025) independently predicted arrhythmia recurrence. Patients with more than two drivers had higher recurrence (45% vs 24%, p=0.001).

ECGi mapping showed that slow-conduction areas determined stable AF driver locations and pattern complexity. Both factors predicted arrhythmia recurrence at 12 months.