Libman–Sacks endocarditis is a form of non-bacterial endocarditis that is seen in association with systemic lupus erythematosus, antiphospholipid syndrome, and malignancies. It is one of the most common cardiac manifestations of lupus (the most common being pericarditis). Presentation Libman–Sacks endocarditis itself is typically asymptomatic. Affected persons most commonly present with embolisms secondary to dislodged vegetations. However, in some cases, severe valvular dysfunction may develop. People with systemic lupus erythematosus may present with other symptoms of the underlying diseases that give rise to Libman–Sacks endocarditis. Complications Libman–Sacks endocarditis may result in arterial emboli, valvular insufficiency, and heart failure. Infective endocarditis occurs more frequently with those with systemic lupus erythematosus. Emboli Vegetations occurring in the context of Libman–Sacks endocarditis may dislodge to form emboli and cause embolism (including cerebral embolism (presenting as stroke or transient ischaemic attack), mesenteric ischaemia (presenting with severe abdominal pain), or peripheral arterial embolism (presenting with limb coldness)). Causes Libman–Sacks endocarditis occurs in association with systemic lupus erythematosus, antiphospholipid syndrome, and malignancies. Systemic lupus erythematosus In systemic lupus erythematosus, Libman–Sacks endocarditis has been linked to pericarditis, presence of anticardiolipin antibodies, arterial and venous thromboses, and neuropsychiatric manifestations of systemic lupus erythematosus. Libman–Sacks endocarditis is associated with greater systemic lupus erythematosus duration and severity. In some cases, Libman–Sacks endocarditis may be the presenting pathology in systemic lupus erythematosus, especially in the presence of concurrent antiphospholipid syndrome. Pathophysiology The initial cause of Libman–Sacks endocarditis is poorly understood. It is thought to occur in the context of a hypercoagulable state which leads to endothelial injury and subsequent deposition of thrombi and inflammatory molecules in affected valves. The vegetations that are thus formed consist of immune complexes, platelet thrombi, fibrin, and mononuclear cells. The vegetations may dislodge and cause embolisms. Histopathology Libman–Sacks endocarditis involves formation of cardiac lesions that may take the form of vegetations or thickening of the valvular leaflets. The vegetations are small and formed from strands of fibrin, neutrophils, lymphocytes, and histiocytes. Vegetations are most often small-to-moderate in size (up to 10 mm), but may sometimes be large (larger than 10 mm). The mitral valve is typically affected, and the vegetations occur on the ventricular and atrial surface of the valve. Though the left-sided heart valves (mitral and aortic) are most commonly affected, any heart valve as well as adjoining structures may become involved. Libman–Sacks lesions rarely produce significant valve dysfunction and the lesions only rarely embolize. However, there