High-Density Spectral Analysis for Bi-Atrial Arrhythmogenic Substrate During Non-Paroxysmal Atrial Fibrillation

Spectral analysis has been utilized to identify localized sites exhibiting high dominant frequency (DF) and high regularity-the critical arrhythmogenic substrate driving atrial fibrillation (AF). This study aimed to elucidate the spectral characteristics of focal activation (FoA) and rotational activation (RoA) sites during AF using a high-density mapping system.

CARTOFINDER mapping was prospectively performed in both atria of 47 consecutive non-paroxysmal AF patients using the Octaray catheter prior to ablation. Endocardial unipolar electrograms were exported offline for spectral analysis of DF and the regularity index (RI).

CARTOFINDER assessed a total of 48 153 mapping points. Given substantial inter-subject variability in mean DF, the difference between each point's DF and the subject-level mean DF was defined as the dominant frequency deviation (DFD). The left atrium (LA) demonstrated significantly higher DFD and RI than the right atrium (both p < 0.001), with the LA roof recording the highest values across all segments. Both FoA and RoA sites exhibited significantly higher DFD and RI compared with sites without FoA and RoA (both p < 0.001). DFD and RI increased progressively with increasing FoA repetitions (both p < 0.001). In contrast, high-repetition RoA sites (> 16 repetitions) showed a significantly higher RI (0.42 ± 0.13 vs. 0.36 ± 0.12, p < 0.001) but a paradoxically lower DFD (0.14 ± 0.64 Hz vs. 0.26 ± 0.74 Hz, p < 0.001) compared with low-repetition RoA sites.

The combination of CARTOFINDER mapping and spectral analysis may contribute to the mechanistic understanding of non-paroxysmal AF.