Modelling of thrombus formation, growth and embolisation in the left atrial appendage under atrial fibrillation

Left atrial appendage (LAA) thrombosis is a frequent and serious complication associated with atrial fibrillation (AF), which significantly increases the risk of ischemic events. The presence of a thrombus within the LAA can disrupt normal blood flow and eventually embolise, leading to impaired circulation and severe complications. An innovative fluid-structure interaction model, based on the smoothed particle hydrodynamics method, is used to simulate the formation and behaviour of thrombi in a patient-specific LAA morphology under AF condition. The clotting process is modelled by tracking the concentrations of key components involved in the coagulation cascade. The approach transforms fluid particles into a solid phase by applying internal spring forces when specific biochemical and haemodynamic conditions occur. The findings shed light on the haemodynamic and biochemical mechanisms driving thrombus formation and migration within the LAA, highlighting regions of clot growth and subsequent embolisation. Thrombus formation begins at the LAA tip, gradually expanding through lobes and trabeculae, and ultimately progressing internally to high-recirculation regions, increasing the risk of embolisation and of potential clinical complications. By accurately predicting thrombus formation, growth and fragmentation, this study offers valuable insight into the mechanisms associated with the thromboembolic risk in AF. These are crucial for developing targeted therapeutic strategies to minimise the risk of thromboembolic events in patient with AF.