Libman-Sacks (verrucous)

Libman-Sacks endocarditis results from deposition of immune complexes and fibrin-platelet thrombi on heart valves in the setting of autoimmune disease, most commonly SLE (occurs in up to 50% of SLE patients on echocardiography, though often subclinical) and antiphospholipid syndrome. Unlike infective endocarditis, the vegetations are sterile and tend to form on both the atrial and ventricular surfaces of the mitral valve (and aortic valve), as well as the undersurface of the leaflets and chordae tendineae—reflecting a different mechanism of valve injury not solely dependent on blood flow turbulence. Histologically, the verrucae consist of fibrin, platelet thrombi, immune complexes, hematoxylin bodies, and mononuclear inflammatory cells, with fibrinoid necrosis of the valve tissue. Clinically, most cases are asymptomatic, but the vegetations can cause valve regurgitation (most commonly mitral regurgitation), rarely stenosis, and can serve as a nidus for secondary infective endocarditis or thromboembolism (stroke risk is increased, especially with concurrent antiphospholipid antibodies). Diagnosis is typically made via echocardiography (transesophageal echo is more sensitive) in a patient with known SLE or antiphospholipid syndrome. Management involves treating the underlying autoimmune condition and anticoagulation if there is thromboembolic risk or antiphospholipid syndrome; valve replacement may be required for severe regurgitation. On USMLE, Libman-Sacks is a classic association to test with SLE pathology and should be distinguished from infective endocarditis (vegetations on valve closure line, associated with fever and positive blood cultures) and rheumatic heart disease (post-streptococcal, affects valve commissures leading to fibrosis and stenosis).