Hierarchical Schema for Identifying Focal Electrical Sources During Human Atrial Fibrillation: Implications for Catheter-Based Atrial Substrate Ablation.

OBJECTIVES: The study sought to localize focal sources (FS) during atrial fibrillation (AF) using periodic component analysis (PiCA) and QS unipolar electrogram (EGM) morphology based on the assumption that periodic activation with centrifugal propagation is inherent to a FS. BACKGROUND: The localization of FS maintaining AF remains challenging, due to limitations in conventional time-frequency domain analysis. This is relevant to identifying targets for AF substrate ablation. METHODS: In 41 patients (age 56 ± 9 years, 76% persistent AF), bipolar EGMs were recorded in the left atrium (LA) during AF with a roving 20-pole catheter. Bipolar EGMs with periodicity were determined using PiCA. FS were defined as periodic sites with predominantly QS unipolar EGM morphology. RESULTS: For each patient, 456 ± 109 bipolar EGMs were recorded, of which 261 ± 15 (60%) demonstrated periodicity. FS were identified in 63% of patients (pulmonary vein [PV] 1.5 ± 1.5; extra-PV 2.6 ± 2.3). After PV antral ablation and follow-up of 14 ± 9 months, 37% of patients had symptomatic AF recurrence. Mean global LA periodicity cycle length was shorter in patients with AF recurrence compared to those without (143 ± 20 ms vs. 154 ± 9 ms; p = 0.02). Among 12 (29%) patients with FS exclusively in the PV, only 1 (8%) had AF recurrence. AF recurrence was significantly higher (50%; p = 0.01) in 14 (34%) patients with extra-PV FS. CONCLUSIONS: Our novel hierarchical analysis schema, incorporating PiCA and unipolar EGM morphology, detected a small number of FS in patients with predominantly persistent AF. FS in the PV was associated with successful PV antral ablation. Further prospective studies are required to determine whether these FS maintain AF and represent ablation targets.