CFD-Based Prediction of the Risk of Thrombus Growth in left Atrial Appendage with Different Morphologies

The left atrial appendage (LAA) is the primary site of thrombosis in atrial fibrillation (AF) patients, with morphological complexity influencing hemodynamics and thrombotic risk. While the CHA2DS2-VASc score lacks anatomical specificity, current models also fail to predict dynamic thrombus growth. This study integrated computational fluid dynamics (CFD) and thrombus growth modelling with CTA data from 4 patients to construct 3D numerical models of chicken wing, windsock, cauliflower, and cactus LAA morphologies. Key hemo-dynamic parameters—time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and endothelial cell activation potential (ECAP)—were analyzed alongside a novel composite index (RISK) to quantify thrombogenic risk. Cauliflower and cactus morphologies exhibited multi-branched structures, geometric irregularity, and tortuous flow paths. These correlated with adverse hemodynamics: low TAWSS, elevated OSI/RRT/ECAP, and rapid thrombus progression (cauliflower cavity occlusion in 5 cycles; cactus 95% volume occupancy). In contrast, chicken wing and windsock morphologies with simpler branching and regular structures demonstrated stable hemodynamics and lower thrombotic risk (RISK ¿0.9 areas: 14.48%-15.37%). Findings highlight morpho-logical complexity as a core thrombotic determinant. Complex LAA types (e.g., cauliflower, cactus) promote thrombosis through prolonged stasis, endothelial activation, and abnormal shear. Clinically, early intervention—personalized anticoagulation or occlusion—may be warranted for high-risk morphologies, particularly cauliflower-type LAA, to mitigate stroke risk.