Coronary Artery Inflammation and Epicardial Adipose Tissue Volume in Relation with Atrial Fibrillation Development

Abstract

Background/Objectives: Atrial fibrillation (AF) is associated with increased epicardial adipose tissue (EAT), atrial dilation, and coronary inflammation, though causality remains unclear. Cardiac computed tomography (CCT) allows for precise quantification of EAT volume and the left atrial volume index (LAVI), along with the calculation of the fat attenuation index (FAI), indicating coronary inflammation. Combined with the Coronary Artery Disease-Reporting and Data System (CAD-RADS), these imaging markers may improve AF risk stratification. This study evaluates the association between peri-atrial EAT volumes, LAVI, CAD-RADS, and FAI scores in AF patients using advanced AI platforms. Methods: This retrospective study analyzed 122 patients presenting with angina-type pain and a low-to-intermediate likelihood of CAD, who underwent CCT. Patients were divided into two groups based on rhythm status: 42 with AF and 80 without AF. Total EAT, left atrial (LA-EAT), and bi-atrial EAT (BA-EAT) volumes were assessed, along with LAV, CAD-RADS classification, and FAI scores measured using CaRi-Heart^® and syngo.via Frontier^®. Results: AF patients exhibited 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) and elevated LAVI values (57.7 ± 11.44 vs. 45.9 ± 12.58 mL/m², p < 0.0001). ROC analyses confirmed strong diagnostic performance of total EAT (AUC = 0.869), LA-EAT (AUC = 0.776), BA-EAT (AUC = 0.703), and the LAVI (AUC = 0.756). Higher CAD-RADS categories (2-5) were more frequent in AF, although significant differences were observed only in the lowest category (0-1; 26.2% AF vs. 47.8% non-AF, p = 0.032). Total FAI scores were also higher in AF patients (14.83 ± 10.16 vs. 12.37 ± 7.89, p = 0.044). Conclusions: Increased EAT volumes, an elevated LAVI, and higher FAI scores are significantly associated with AF, suggesting a combined structural and inflammatory substrate. EAT, the LAVI, the FAI, and CAD-RADS collectively represent valuable non-invasive imaging biomarkers for early AF risk assessment.

Keywords: CAD-RADS classification; atrial fibrillation; coronary computed tomography; epicardial adipose tissue; fat attenuation index; left atrial volume index; pericoronary inflammation.

Figure 1

Flow diagram illustrating the study design and patient selection process. Abbreviations: LAV–left atrial volume; EAT–epicardial adipose tissue; CAD–coronary artery disease; CAD-RADS–Coronary Artery Disease-Reporting and Data System; PCAT–pericoronary adipose tissue; FAI–fat attenuation index.

Figure 2

Imaging of the heart with quantification of EAT, marked by a red contour. Two representative cases from the study are shown: (a) a patient without AF, displaying a relatively low volume of EAT; (b) a patient with AF, showing a noticeably larger amount of EAT.

Figure 3

ROC curve analysis evaluating the diagnostic performance of EAT parameters and left atrial structural markers for predicting AF using CCT. (a) LAVI–Left Atrial Volume Index (red line, light red background area); (b) Total EAT–Epicardial Adipose Tissue (dark blue line, light blue background area); (c) combined score of EAT and LAVI (orange line, yellow background area); (d) comparison of all ROC curves demonstrating the relative predictive accuracy of each parameter in identifying AF, with each curve represented by a different color: LAV volume (blue), LAVI (green dotted), EAT (blue dotted), EAT + LAVI (orange), EAT-LA (pink dotted), and EAT-BA (purple dotted). Dots on each ROC curve indicate the optimal cutoff points determined by the Youden index.

Figure 4

ROC analysis to evaluate the prognostic value of (a) CACs (black line, grey background area), (b) FAI score (red line, light red background area), and (c) CaRi-Heart^® Risk Score (olive green line, light yellow background area) in differentiating AF and non-AF patients. Dots on each ROC curve indicate the optimal cutoff points determined by the Youden index. Abbreviations: CACs–coronary artery calcium score; FAI–fat attenuation index; ROC–Receiver Operating Characteristic.

Figure 5

Regional analysis of (a) FAI score values and the (b) total FAI score, between the two study groups. Abbreviations: FAI–fat attenuation index.