Increased epicardial adipose tissue area and radiodensity in sarcopenic obesity.

Abstract

Background: Sarcopenic obesity (SO) confers substantially greater cardiometabolic risk than either sarcopenia or obesity alone, but the tissue-level structural alterations underlying this risk remain unclear. Epicardial adipose tissue (EAT) characteristics, including both area and radiodensity, may provide clinically relevant insight into the cardiometabolic burden associated with this complex muscle-fat imbalance.

Methods: We conducted a cross-sectional study of 1678 adults undergoing health examinations. Participants were categorized into normal, sarcopenia, obesity, and SO phenotypes based on the European Society for Clinical Nutrition and Metabolism and the European Association for the Study of Obesity (ESPEN/EASO) conceptual framework. Body composition and grip strength were assessed according to the Asian Working Group for Sarcopenia (AWGS) 2025 criteria. EAT area (cm²) and radiodensity (attenuation, measured in Hounsfield units [HU]) were quantified via non-contrast chest computed tomography. Associations were assessed using multivariable linear regression, interaction analysis, and sex-stratified restricted cubic splines.

Results: The SO phenotype was identified in 45 individuals. Following multivariable adjustment, SO was independently associated with a larger EAT area (beta = 6.93 cm²; 95% CI, 5.84 to 8.03) and a higher (less negative) EAT radiodensity (beta = 9.23 HU; 95% CI, 8.03 to 10.43) compared with the normal phenotype. Effect estimates were larger for SO than for isolated obesity. An interaction between sarcopenia and obesity was observed for EAT area (interaction beta = 1.53 cm²; 95% CI, 0.05 to 3.01; P for interaction = 0.042), whereas no significant interaction was observed for EAT radiodensity. In sex-stratified analyses, grip strength showed a pronounced non-linear association with EAT radiodensity.

Conclusions: In this cross-sectional study, SO was associated with larger EAT area and higher EAT radiodensity. These findings support the presence of a distinct EAT phenotype in SO and suggest that CT-derived EAT measures may be useful imaging markers that warrant prospective validation.