Regional conduction velocities determined by non-invasive mapping are associated with arrhythmia-free survival after atrial fibrillation ablation

Background Atrial arrhythmogenic substrate is a key determinant of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI), and reduced conduction-velocities have been linked to adverse outcome. However, a non-invasive method to assess such electrophysiological substrate is not available to date. Objective This study aimed to non-invasively assess regional conduction-velocities and their association with arrhythmia-free survival following PVI. Methods 52 consecutive patients scheduled for AF ablation (PVI-only) and 19 healthy controls were prospectively included and received electrocardiographic imaging (ECGi) to non-invasively determine regional atrial conduction-velocities in sinus rhythm. A novel ECGi technology obviating the need of additional CT- or CMR-imaging was applied and validated using invasive mapping. Results Mean ECGi-determined atrial conduction-velocities were significantly lower in AF-patients than in healthy controls (1.45±0.15 versus 1.64±0.15m/s; p<0.0001). Differences were particularly pronounced in a regional analysis considering only the segment with the lowest average conduction-velocity in each patient (0.8±0.22 versus 1.08±0.26m/s; p<0.0001). This average conduction velocity of the „slowest“ segment was independently associated with arrhythmia recurrence and better discriminated between PVI-responders and non-responders than previously proposed predictors including left atrial size or late-gadolinium-enhancement (MRI). Patients without slow-conduction areas (mean conduction-velocity <0.78m/s) showed significantly higher 12-months arrhythmia-free survival than those with one or more slow-conduction areas (88.9% versus 48.0%, p=0.002). Conclusions This is the first study to investigate regional atrial conduction velocities non-invasively. The absence of ECGi-determined slow-conduction areas well discriminates PVI-responders from non-responders. Such non-invasive assessment of electrical arrhythmogenic substrate may guide treatment strategies and be a step towards personalised AF therapy.