Libman-Sacks (LS) endocarditis is a form of nonbacterial thrombotic endocarditis (NBTE). It is a term which is used for sterile vegetations on the cardiac valves. These sterile vegetations are often associated with malignancies, systemic lupus erythematosus (SLE), and antiphospholipid antibody syndrome (APS). Other terms used to describe these vegetations include marantic and verrucous endocarditis. The first time this form of endocarditis was described was in 1924 by Emanuel Libman and Benjamin Sacks. Libman-Sacks endocarditis most commonly affects the mitral and aortic valves, but other valves may also be involved. LS endocarditis can be complicated by embolic cerebrovascular disease, peripheral arterial embolism, and by superimposed infective endocarditis. It is also associated with increased mortality. Therefore, early recognition of LS endocarditis and appropriate treatment are of paramount importance in preventing complications.
Overall, the most common association of LS endocarditis is with malignancies, followed by SLE. The initial development of Libman-Sacks endocarditis is thought to be an endothelial injury in the setting of a hypercoagulable state. This causes deposition of platelet thrombi and inflammatory molecules in the cardiac valves. LS vegetations comprise immune complexes, mononuclear cells, fibrin, and platelet thrombi.
In patients with SLE, the reported prevalence of LS vegetations are 1 in 10 patients. LS endocarditis most commonly affects patients between 40 to 80 years of age. A significant correlation was found between LS endocarditis and SLE duration and activity.
In one study, the rate of LS endocarditis was higher in patients with underlying malignancy compared to the general population on autopsy (1.25% versus 0.2%). The highest incidence of LS endocarditis in this study was observed in patients with pancreatic adenocarcinoma.
The initial cause of LS endocarditis is not well understood. It is thought to be an endothelial injury in the setting of a hypercoagulable state, such us malignancy, SLE, and APS. Endothelial damage causes local deposition of platelets thrombi and inflammatory molecules in the affected valves. The vegetations comprise immune complexes, mononuclear cells, fibrin, and platelet thrombi. They can dislodge and cause devastating embolic infarctions. In a study of 76 patients with SLE, the presence of LS endocarditis was associated with a higher risk for embolic cerebral vascular disease.
In histopathology, LS endocarditis is associated with leaflet thickening. The vegetations can involve the entire surface of the leaflets, and appear in coalescent or clusters. They also have a granular or verrucous appearance.
Patients with Libman-Sacks endocarditis are usually asymptomatic.
The most common manifestations are secondary to embolism. A cerebrovascular embolism can present with signs and symptoms of a stroke or a transient ischemic attack. Systemic thromboembolism can manifest as peripheral arterial embolism presenting as cold limbs or mesenteric ischemia presenting as severe abdominal pain.
Patient with underlying SLE may show manifestations of the underlying disease such as malar rash, pleuritis, pericarditis, and nephrotic syndrome. Similarly, patients with APS might present with recurrent miscarriages and venous/arterial thrombosis.
There are no laboratory tests to confirm the diagnosis of LS endocarditis. In patients suspected of LS endocarditis, a full assessment should be done with complete blood count, complete metabolic panel, and blood cultures to differentiate from other etiologies such as infective endocarditis. A hypercoagulable workup should also be obtained in each case suspected of LS endocarditis including lupus anticoagulant and antiphospholipid antibodies. However, the primary evaluation for LSE is by echocardiography. Trans-esophageal echocardiography has greater sensitivity and specificity than trans-thoracic echocardiography. Irregular borders, heterogeneous echo density, and an absence of independent motion characterize the masses (i.e., verrucous vegetations) on the cardiac valves and endocardium. The masses are usually small and sessile, but they can be as large as 10 mm. The basal and mid portion of the mitral and aortic valves are involved most commonly. Diffuse or focal leaflet thickening of the mitral and aortic valves can be observed. The involved valves may exhibit regurgitation. Coexistent cardiac complications of systemic lupus erythematosus may include pericardial effusion or thickening.
The treatment for patients with LS endocarditis is not well established, partially due to the scarcity of information on the natural history of the disease in untreated patients. The underlying disease (SLE or APS) should be treated. Anticoagulation should be considered as secondary prevention for thromboembolic phenomena in patients who have had a thromboembolic event. In cases of significant valvular dysfunction, surgery should be performed according to established guidelines for valvular heart disease. Patients with LS should be closely followed up during treatment, as they can still develop thromboembolic phenomena while on anticoagulation. Scheduled echocardiography (every 3 to 6 months) should also be considered to follow the progression/resolution of the disease.
Differential diagnosis of LS endocarditis includes rheumatic valvular disease, atrial myxoma, degenerative valvular disease, infective endocarditis, vasculitis, cholesterol emboli syndrome, fibroelastoma, and Lambl’s excrescences. Lambl’s excrescences originate at valve closure sites (most commonly on the aortic valve). They are believed to be normal variants, but some reports propose embolic potential. Laboratory studies should include a complete blood count, complete metabolic panel, and blood cultures to exclude infective endocarditis. A workup for SLE and APS should be performed if that diagnosis is not already established.
The prognosis of LS endocarditis has not been fully studied and there continues to be a need for further studies to better define prognosis. From clinical observations, the prognosis of LS is considered poor. Patients may develop recurrent thromboembolic events, cognitive disability, and death.
Libman-Sacks endocarditis should be considered in patients with underlying malignancy, systemic lupus erythematosus, and antiphospholipid antibody syndrome, who present with a thromboembolic phenomenon. A full assessment with complete blood count, complete metabolic panel, and blood cultures should be done to rule out other etiologies such as infective endocarditis. The diagnosis of LS generally gets delayed as we look for other etiologies of patients presenting illness (thromboembolic event). Trans-esophageal echocardiography must be performed as it has greater sensitivity and specificity than trans-thoracic echocardiography to evaluate for LS endocarditis. Treatment of LS should be directed at the underlying disease (SLE or APS). Anticoagulation can be considered in patients with a thromboembolic event for secondary prevention. Prognosis is poor as patients usually have recurrent thromboembolic events, cognitive disability, and death. There continues to be a need for further studies in patients with LS endocarditis to define early detection, management strategies, and prognosis.