Role of high dominant frequency sites in nonparoxysmal atrial fibrillation patients: Insights from high-density frequency and fractionation mapping

Background: The adjunctive role of dominant frequency (DF) mapping during complex fractionated electrogram (CFE) ablation of atrial fibrillation (AF) has not been clarified. Objective: The purpose of this study was to investigate whether DF distribution or substrate properties are related to fibrillatory activity in the left atrium (LA) and to evaluate the effect of CFE ablation on the different patterns of DF distribution. Methods: The study enrolled 50 nonparoxysmal AF patients who underwent mapping, pulmonary vein isolation, and CFE ablation. High-density DF and CFE mapping were performed from the center of DF_max centrifugally to the rest of the LA. The LA substrate was classified into two types depending on the presence of intra-LA DF gradients as type 1 (>20% of the average DF) or type 2 (<20% of the average DF). Results: In type 1, maximal CFE and DF gradients were observed at the boundary (n = 14) or center (n = 16) of the DF_max region. In type 2 (n = 20), less intra-LA DF gradient was observed (4.27 ± 1.92 Hz vs 1.14 ± 0.52 Hz for types 1 and 2, P <.001) and a large proportion of continuous CFEs extended from the center of DF_max (19% ± 11% and 42% ± 15% of the LA for types 1 and type 2, P = .001). The procedure termination rate and long-term sinus rhythm maintenance rate were lower in patients with a smaller DF gradient (P <.05). Conclusion: The spatial distribution of fractionated activity was associated with particular DF patterns in nonparoxysmal AF patients. Patients with an evident intra-LA DF gradient responded better to pulmonary vein isolation and continuous CFE ablation.