Epicardial Fat is Associated with Ventricular Dilation in Patients After the Fontan Operation

Epicardial and hepatic fat are suspected to play a role in cardiac remodeling. The primary objective of this study was to identify the cardiac MRI (CMR) parameters that are associated with indexed epicardial fat mass (EFM_i) and hepatic steatosis in patients after the Fontan operation. This was a single-center, retrospective analysis of Fontan patients. Epicardial and subcutaneous fat were analyzed with CMR post-processing software, cvi42 (Circle Cardiovascular Imaging, Calgary, Alberta, Canada). Hepatic steatosis was measured with controlled attenuation parameter (CAP) scores via vibration controlled transient elastography. The cohort included 82 patients (65% male, median age 16 years). On univariate analysis, EFM_i correlated with BMI (ρ = 0.52, p < 0.001), age (ρ = 0.48, p < 0.001), ESV_i (ρ = 0.44, p < 0.001), EDV_i (ρ = 0.42, p < 0.001), ventricular mass_i (ρ = 0.41, p < 0.01), subcutaneous fat thickness (ρ = 0.32, p < 0.01), ejection fraction (ρ=-0.37, p < 0.001), and inferior vena cava (IVC) flow_i (ρ=-0.26, p < 0.05). On multivariable regression analysis, BMI (β 2.21, p < 0.001) and EDV_i (β 0.33, p < 0.001) were independently associated with EFM_i (R² = 0.51). On univariate analysis, CAP scores correlated with BMI (ρ = 0.54, p < 0.001), subcutaneous fat thickness (ρ = 0.49, p < 0.001), subcutaneous fat mass_i (ρ = 0.44, p < 0.001), age (ρ = 0.36, p < 0.01), EFM_i (ρ = 0.36, p < 0.001), and ventricular mass_i (ρ = 0.24, p < 0.05). On linear regression analysis, BMI (β 6.6, p < 0.001) was independently associated with CAP scores (R² = 0.27). Neither EFM_i nor CAP was significantly associated with adverse clinical events. BMI is strongly associated with epicardial and hepatic fat distribution. Epicardial fat mass is also associated with ventricular dilation.