Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and is known as an independent risk factor for stroke. During an AF episode, the physiological flow pattern within the left atrium (LA) is altered. This disturbed atrial flow leads to an increased risk of thrombosis within the left atrial appendage (LAA). These thrombi formed in the LAA can travel to the brain and cause a stroke. Despite recent efforts, the mechanistic link between atrial flow patterns, atrial morphology, and stasis risk remains elusive [1]. The aim of this work is to develop a computational framework that allows one to identify representative atrial flow patterns and their specific features, and their incidence on LAA blood stasis. To this end, we combined the application of patient-specific numerical atrial simulations with three recently proposed techniques: a kinematic model to uniformize the influence of fibrosis on the atrial wall [2], a projection on a universal LAA coordinate system to facilitate data comparison between patients, and the calculation of stagnant volume [3]. To show proof of concept of this approach, we applied the above techniques to LA flow fields obtained by computational fluid dynamics simulations in patient-specific anatomies of patients with AF. The results show the existence of three distinct phenotypic flow patterns which strongly influence LAA blood stasis and thus thrombus formation. The analysis also gave us the opportunity to check how this atrial flow patterns are affected by variations in the flow-split ratio, atrial wall-motion, and other common modeling hypotheses. REFERENCES [1] M. García-Villalba et al., Demonstration of patient-specific simulations to asses left atrial appendage thrombogenesis risk, Frontiers in Physiology, 12:596596, 2021. [2] M. Corti et al., Impact of atrial fibrillation on left atrium haemodynamics: A computational fluid dynamics study, Computers in Biology and Medicine, 150:106143, 2022. [3] J. Dueñas-Pamplona et al., Morphing the left atrium geometry, A deeper insight into blood stasis within the left atrial appendage, Applied Mathematical Modelling, 107:27-45, 2022. Acknowledgements: “Programa de Excelencia para el Profesorado Universitario de la CAM”