Thrombosis and thromboembolism in atrial fibrillation: pathophysiological background

Abstract Atrial fibrillation presents a situation whereby all three elements of Virchow’s triad of thrombosis are met within the left atrium. Chronic endothelial injury and dysfunction results in fibrotic remodelling of the left atrium, and fibrillation impairs contractile function, resulting in blood stasis. Meanwhile, the coagulation system activates abnormally, and fibrinolysis is impaired. This creates a prothrombotic state for thrombus formation, particularly within the left atrial appendage, which may lead to systemic thromboembolism and stroke.