Atrial fibrillation increases the risk of cerebrovascular events, being responsible of 15-18% of all strokes. The morphological and functional remodelling of the left atrium caused by atrial fibrillation favours blood stasis and, consequently, stroke risk. Several studies suggest that haemodynamic information on the left atrium and the left atrial appendage may help to better characterize stroke risk. The aim of this study was to develop a personalized computational fluid dynamics model of the left atrium which could clarify the haemodynamic implications of atrial fibrillation on a patient-specific basis. In this paper, we present the developed model and its application to two atrial fibrillation patients as a preliminary advancement towards an optimized stroke risk stratification pipeline.