Epicardial and pericardial adipose tissue and circulating biomarkers in patients with atrial fibrillation: insights from the RACE V study

Background Epicardial (EAT) and pericardial adipose tissue (PAT) are metabolically active depots surrounding the heart and may contribute to the inflammatory and metabolic alterations observed in atrial fibrillation. However, their systemic effects remain poorly understood. The aim of this study was to assess the association between EAT, PAT, and circulating biomarkers. Methods In RACE V, patients with paroxysmal atrial fibrillation were included. At baseline, CT imaging and circulating biomarker profiling were performed using the Olink Explore 384 Cardiometabolic panel (369 proteins). EAT and PAT were quantified on CT and expressed in millilitres, indexed for height. Linear regression analyses and protein enrichment analyses were used to explore associations between EAT/PAT and serum biomarkers. Results In total, 564 patients were included in the present analysis. Mean age was 64±10 years, 234 (41%) were female, 145 (26%) patients were obese, and 318 (56%) had increased waist circumference reflecting central obesity. Median EAT was 31 [23-42] ml/m2 and median PAT was 54 [39-74] ml/m2. After adjustment for age, sex and increased waist circumference, significant associations remained for 55 biomarkers with EAT and for 75 biomarkers with PAT (Figure 1). Of these, 51 biomarkers were shared between both depots (Figure 2). Enriched pathways were related to lipid metabolism and inflammatory activation. EAT showed predominant enrichment of immune-related pathways, whereas PAT demonstrated additional links to renal and vascular development. Conclusions Both EAT and PAT were associated with multiple circulating biomarkers in patients with AF, demonstrating both overlapping and depot-specific biomarker profiles. Shared pathways were related to lipid metabolism and inflammatory activation, with EAT showing predominantly immune-related enrichment and PAT reflecting broader metabolic regulation.