Atrial cardiomyopathy has been defined as any electrical and/or mechanical dysfunction of the left atrium. This dysfunction can lead to Atrial Fibrillation (AF), which is responsible for a third of all ischemic strokes. However, atrial fibrillation is not the only left atrium-related cause of stroke. Indeed, changes in LA wall mechanics, caused by remodelling of the wall (fibrotic myocardium mostly), can result in thrombogenic blood flow patterns. Structural and electrical changes in the LA are interconnected and their effect on atrial flow patterns are not fully understood. This project aims to develop new clinical diagnosis tools to detect the biomechanical changes in the LA wall and the alterations of the intra-atrial flows to anticipate the risks of strokes. For this, this project with combine characterisation methods from both structural and fluid points of view. This multidisciplinary project will answer to the following four objectives: - To develop a metric to quantify locally the degree of left atrium wall fibrosis in terms of mechanics and to understand its effect on the wall mechanical behaviour, based on the mechanical and biological characterisation of surgical biopsies, - To develop a methodology to measure left atrium mechanical properties in vivo for patients, from CRM images - To create a mechanistic link between left atrium flow patterns and the risk of thrombus formation, based on the analysis of 4D MRI data, - To assess how much fibrosis impacts the risk of thrombus formation in the left atrium. This project could lead to the development of new tools for the diagnostic of atrial cardiomyopathies, which would help the development of new treatment strategies.