Parasympathetic Tone Selectively Modulates Electrogram Fragmentation and Spectral Properties in Right Atrial...

EGM fragmentation and spectral analysis have both been proposed to identify ganglionated plexi (GP) regions in the context of cardioneuroablation. However, their correlation has never been fully investigated, and it remains unclear whether these properties are related to structural or functional characteristics. The aim of this study is to evaluate how these features are related and modulated by parasympathetic tone.

The study population included 13 patients (mean age 34 ± 12 years, 69% male) undergoing an electrophysiological study. High-density right atrial mapping was performed using a multielectrode catheter during baseline conditions and after atropine administration. Spectral analysis of each point was obtained by fast Fourier transformation, deriving mean, median, and skewness.

Baseline maps showed fragmented EGM areas in the posterior-septal wall, corresponding to right atrial GP distribution. When compared to the remaining atrial myocardium, GP regions showed greater mean and median frequencies and lower skewness (p < 0.001). Following atropine, only GP regions showed a significant decrease in mean (112.6 ± 13.9 to 101 ± 8.1 Hz, p = 0.02) and median frequency (p = 0.02), as well as an increase in skewness (0.03 ± 0.43 to 0.30 ± 0.27, p = 0.015), indicating a shift toward the spectral profile of compact myocardium. In non-GP locations, no significant spectral alterations were found.

EGM fragmentation and spectral properties are strongly correlated. Parasympathetic tone modulates both features exclusively in GP areas. The distinct signal pattern of GP regions may be a result of both local cholinergic release and structural cellular discontinuity with potential implications for a more precise targeting in the context of CNA.