Impact of Pericardial Fat on Intracardiac Atrial Impedance and Generator Impedance

Generator impedance (GI) is a critical parameter that is measured during radiofrequency (RF) ablation. Factors influencing GI and its relationship with intracardiac atrial impedance (IAI) remain unclear; hence, this study aimed to investigate the determinants of IAI and assess their correlation with GI.

A total of 104 patients who underwent atrial arrythmia ablation were included in this single-center retrospective study. Pericardial fat (PF) volume was assessed using preoperative contrast-enhanced computed tomography, and IAI was measured intraoperatively using the BeeAT catheter. The GI was recorded during the first RF application in 48 patients with atrial fibrillation (AF). Multivariate regression analyses were performed to identify the factors influencing IAI and GI.

A positive correlation was observed between the IAI and GI (n = 48, r = 0.63, p < 0.001), and the IAI was an independent predictor of GI by multivariate regression analysis. PF volume (β = 0.45, p < 0.001), serum sodium levels (β = -0.26, p = 0.001), and hemoglobin concentrations (β = 0.23, p = 0.015) were significant determinants of IAI, but not body mass index (BMI). Although PF volume was positively correlated with BMI (r = 0.52, p < 0.001), the high PF/BMI ratio group had the highest IAI (68.3 ± 10.9 Ω), which significantly exceeded both the low PF/BMI group (53.3 ± 8.5 Ω, p < 0.001) and the average PF/BMI group (58.2 ± 8.9 Ω, p < 0.001).

IAI was significantly influenced by the PF volume and blood components, and served as a key determinant of GI during AF ablation. These findings suggest that the IAI may be a valuable real-time indicator for optimizing ablation strategies based on patient-specific characteristics.