Epicardial Fat Tissue Volume Within 1 mm of the Left Atrium Combined With Left Atrial Appendage Volume is Associated With Thrombus in Nonvalvular Atrial Fibrillation: A CCTA‐Based Risk Stratification Model

Background Accurate prediction of left atrial appendage thrombus (LAAT) is critical for stroke prevention in patients with nonvalvular atrial fibrillation (AF). We investigated the incremental value of epicardial fat tissue (EFT) metrics derived from cardiac computed tomography angiography (CCTA) beyond conventional risk factors. Methods In this retrospective study of 287 AF patients prior to ablation, CCTA was used to measure left atrial appendage volume (LAAV) and EFT volume within 1 mm of the left atrium (EFT1). Multivariate logistic regression analysis identified predictors of LAAT or prethrombotic state (thrombus/spontaneous echo contrast), which were incorporated into a nomogram. Model performance was evaluated using the area under the curve (AUC), calibration plots, and decision curve analysis. Results The thrombus group exhibited significantly larger LAAV (15.07 ± 2.7 mL vs. 11.94 ± 2.55 mL, p < 0.001) and EFT1 volume (6.39 ± 1.38 mL vs. 5.36 ± 1.47 mL, p < 0.001) compared to the normal/SEC group. Multivariate analysis identified EFT1 (odds ratio [OR] = 1.57 per mL), LAAV (OR = 1.56 per mL), and the CHA 2 DS 2 ‐VA score (OR = 1.34 per point) as independent predictors. The resulting nomogram demonstrated excellent discrimination for LAAT (AUC = 0.851) and for thrombus/SEC (AUC = 0.819), with good calibration and clinical utility. Conclusion EFT1, the EFT volume immediately adjacent to the left atrium, is strongly associated with LAAT. The novel nomogram integrating EFT1, LAAV, and the CHA 2 DS 2 ‐VA score provides enhanced risk stratification for thrombotic and prethrombotic states in patients with AF.