Association of Epicardial Adipose Tissue Thickness With Heart Rate Variability and Electrocardiographic Markers of Electrical Heterogeneity in Obesity.

BACKGROUND: Obesity is associated with atrial and ventricular arrhythmias, but the links among excess adiposity, autonomic dysfunction, and electrical heterogeneity remain incompletely defined. We examined whether epicardial adipose tissue (EAT) thickness was associated with heart rate variability (HRV) indices and electrocardiographic markers of electrical heterogeneity in adults with obesity. METHODS: In this cross-sectional study conducted between January 2023 and June 2025, 129 adults with obesity (BMI ≥ 30 kg/m2) and 156 normal-weight controls (BMI < 25 kg/m2) with broadly similar group-level age and sex distributions were evaluated. EAT thickness was measured by transthoracic echocardiography. Autonomic modulation was assessed by 24-h HRV. Electrocardiograms were analyzed for P-wave dispersion (PWD), Tpeak-to-Tend (Tp-e) interval, Tp-e dispersion, and Tp-e/QT ratio. The prespecified primary endpoints were PWD and Tp-e interval. RESULTS: Compared with controls, individuals with obesity had greater EAT thickness (7.2 ± 1.1 vs. 4.2 ± 2.1 mm), higher PWD (30.9 ± 5.8 vs. 17.5 ± 2.4 ms), and longer Tp-e interval (96.2 ± 8.8 vs. 83.5 ± 7.4 ms; all p < 0.001). Between-group differences were 13.6 ms for PWD (95% CI 12.5-14.7) and 12.7 ms for Tp-e (95% CI 10.8-14.6). Obesity was also associated with lower SDNN and RMSSD, higher LF/HF ratio, and higher Tp-e dispersion, whereas Tp-e/QT showed only a nominal exploratory difference. In multivariable linear regression, EAT thickness remained independently associated with PWD (standardized β = 0.38, p < 0.001) and Tp-e interval (standardized β = 0.35, p < 0.001). CONCLUSION: Greater EAT thickness in obesity was associated with an unfavorable HRV profile and increased atrial and ventricular electrical heterogeneity. These findings are associative and should not be interpreted as clinical rhythm-risk stratification.