Background: Atrial fibrillation (AF) is a complex arrhythmia and a leading cause of cardiovascular morbidity. Pulmonary vein isolation (PVI) is the mainstay therapy for paroxysmal atrial fibrillation (PAF). Although triggers from the pulmonary veins (PV) are encountered in up to 90% of patients undergoing PVI, the long-term outcome of a PVI-only strategy differs significantly between PAF and persistent atrial fibrillation (PeAF). Despite the lack of data from randomized trials comparing ablation strategies for PeAF, current guidelines suggest that adjuvant substrate modification should be considered in addition to PVI. However, recommendations as to suitable ablation approaches are vague. Two main non-PV mechanisms have been proposed as the drivers of PeAF: 1) Multi-wavelet drivers of rapid reentry (e.g. rotors) or 2) focal activation patterns whose wave-fronts break down resulting in fibrillatory conduction.
Objective: Morphology analysis and identification of the spatial distribution of non-PV AF drivers due were obtained using a new non-contact unipolar high-resolution system taking advantage of a basket catheter with 48 ultrasounds transducers for 3D anatomy reconstruction and 48 electrodes enabling continuous dipole density mapping.
Methods: Data were obtained from 10 patients with PeAF in a single center. Three different wave front patterns were analyzed in left atrium (LA):  1) focal activity (FA), 2) localized rotational activation (LRA) and 3) localized irregular activation (LIA). The spatial distribution of these triggers was analyzed and resulting AF wave-fronts were compared prior to PVI.
Results: For all 10 patients, 3D anatomy and activation mapping were acquired. A total of 46 patterns were identified prior to PVI (Fig.1), among them 22 FA, 13 LRA and 11 LIA. The anterior wall (n=13), posterior wall (n=10) and septum (n=8) were identified as predominant sites of patterns. Comparison of the predominant sites showed that FA were most frequent at the septum (n=05 vs n=04 (anterior wall) vs n=04 (posterior wall)), LRA were predominant at anterior wall (n= 05 vs n=04 (posterior wall) vs n=01 (septum)). LIA was more frequent at the anterior wall (n=04 vs. n=02 (septum) vs. n=02 (posterior wall)).
Conclusions: AF drivers in the LA were mostly encountered at anterior wall, posterior wall and septum. Analyzing such spatial distribution of AF drivers can help to understand AF mechanisms and subsequently guide extra-PVI adjuvant ablation strategies.