Association between epicardial adipose tissue compartments, pericoronary inflammation, and CAD-RADS classification in patients with atrial fibrillation

Abstract Background Atrial fibrillation (AF) is linked to increased epicardial adipose tissue (EAT) and inflammation, impacting atrial structure and function. Cardiac computed tomography (CCT) enables assessment of EAT volume and the fat attenuation index (FAI), a marker of coronary inflammation. Combined with the Coronary Artery Disease–Reporting and Data System (CAD-RADS) classification, these imaging markers may support risk stratification in AF. Purpose This study aimed to determine whether increased volumes of EAT compartments around the atria are associated with AF. A secondary objective was to explore the relationship between CAD-RADS classification and FAI scores, as assessed using the AI-driven CaRi-Heart® and syngo.via Frontier® platform. Methods This retrospective study included patients with and without AF, presenting with chest pain and a low-to-intermediate likelihood of CAD, all of whom underwent CCT. Volumes of EAT compartments—including total EAT, left atrial EAT (LA-EAT), and biatrial EAT (BA-EAT)—were measured, alongside CAD-RADS classification and FAI values for the three major epicardial coronary arteries. Results The study included 122 participants (mean age: 63.62 ± 7.75 years; 75 males), divided into AF and non-AF groups matched for age, sex, and risk factors. As expected, AF patients had significantly higher EAT volumes (total EAT: 231.8 ± 45.85 vs. 153.2 ± 54.14 mL, p < 0.0001; LA-EAT: 23.55 ± 6.44 vs. 15.54 ± 8.49 mL, p < 0.0001; BA-EAT: 50.24 ± 12.69 vs. 39.84 ± 15.70 mL, p = 0.0002). ROC analysis demonstrated strong diagnostic value for all EAT parameters in detecting AF: total EAT showed the highest performance (AUC = 0.869, 95% CI: 0.79–0.92), followed by LA-EAT (AUC = 0.776, 95% CI: 0.69–0.84) and BA-EAT (AUC = 0.703, 95% CI: 0.61–0.78), all statistically significant (p < 0.0001) with good sensitivity and specificity. AF patients had a higher, though not statistically significant, prevalence of advanced CAD-RADS categories (2–3: 40.5% vs. 31.3%, p = 0.323; 4–5: 33.3% vs. 21.3%, p = 0.189), while CAD-RADS 0–1 was significantly more common in non-AF individuals (47.8% vs. 26.2%, p = 0.032). The total FAI score was higher in the AF group (14.83 ± 10.16 vs. 12.37 ± 7.89, p = 0.0447), though per-vessel differences were not significant. FAI Score Centile analysis revealed a higher inflammatory burden in AF, with more very high percentiles (33.3% vs. 13.8%, p = 0.0172) and fewer minimal values (9.5% vs. 31.3%, p = 0.0073). Conclusions Our results confirm that higher EAT volumes and elevated FAI scores are associated with AF, reflecting increased pericoronary inflammation. Although advanced CAD-RADS categories were more frequent in AF patients, only the lowest category showed a significant difference. These findings highlight the potential of EAT, FAI, and CAD-RADS as non-invasive imaging markers for AF risk assessment.Graphical overview of the study workflow (A) FAI risk and (B) CAD-RADS categories