Libman-Sacks endocarditis is a lesion of the endocardium (the inner lining of the heart and valves) in systemic lupus erythematosus (SLE). In most cases, it proceeds asymptomatically or with an extremely erased clinical picture. Sometimes there may be palpitations, pain in the heart, subfebrile fever. The diagnosis is made on the basis of clinical and laboratory criteria of SLE, echocardiography. The principles of drug treatment are the same as for SLE – glucocorticoids, cytostatics, aminoquinoline agents. If the valves are seriously damaged, surgery may be required.
Libman-Sacks endocarditis (LSE, syn. ‒ non-bacterial thrombotic endocarditis, lupus thromboendocarditis) is not an independent disease, but a component of systemic lupus erythematosus. It was first described in 1924 by American doctors E. Libman and B. Sachs as warty endocarditis in patients with SLE, which differs from rheumatic and infectious endocarditis. According to various data, endocarditis develops in 11-72% of patients with active lupus. It is more often associated with secondary antiphospholipid syndrome (APS) on the background of lupus erythematosus. In LSE, other cardiac membranes – the myocardium and pericardium – are almost always involved. Mostly young women (25-40 years old) suffer.
To date, the exact cause of Libman-Sacks endocarditis, as well as SLE, remains unknown. The role of viruses (Epstein-Barr virus, cytomegalovirus, parvovirus B19) stimulating the formation of autoantibodies is assumed. The most serious provoking effect is provided by ultraviolet radiation.
Predisposing factors are some medications (hydralazine, novocainamide, oral contraceptives) and constant contact with heavy metals (mercury, cadmium, silicon). Hereditary predisposition is important, as evidenced by the high incidence of lupus erythematosus and thrombotic endocarditis among close relatives. During the studies, the association of LSE with tissue compatibility antigens HLA A1, A3, A10, B7, B8 was established.
Under the influence of ultraviolet radiation and other factors, a huge spectrum of autoantibodies to various components of cells (mainly to nuclei), including endocardial cells, is synthesized in lymphocytes. The cells of the immune system begin to attack the cells of the macroorganism, which leads to tissue damage. Circulating immune complexes of antibodies and autoantigens settle on the endothelium of small vessels, heart valves. An inflammatory process develops in the endocardium.
The parietal endocardium thickens. Fibrin and platelets settle on the valves, blood clots form. The intensity of thrombosis on the valves is enhanced by substances produced during secondary APS and causing hypercoagulation (beta-glycoprotein, antibodies to phospholipids, cardiolipin). Mitral and aortic valves are more often affected. Pathoanatomic changes include infiltration by lymphocytes and mononuclears, fibrinoid necrosis, vegetations and blood clots on the valves.
Endocarditis develops no earlier than 5 years after the onset of SLE disease. The clinical picture is extremely poor. In the vast majority of cases, there is a latent course of endocardial inflammation. Sometimes the patient experiences minor aching pains in the heart, palpitations, a feeling of interruptions. Body temperature is subfebrile or normal.
Very rarely, with a prolonged course of lupus endocarditis, signs of congestive heart failure appear – difficulty breathing (according to the type of mixed shortness of breath) during exercise, heaviness in the legs and their swelling, dull pain in the right hypochondrium due to liver enlargement. Symptoms of SLE always come to the fore – joint pain, skin rashes, ulcers on the mucous membrane of the oral cavity, etc.
Libman-Sacks endocarditis itself rarely causes complications. The predominant number of adverse effects is associated with the underlying disease. Antiphospholipid syndrome increases the risk of thromboembolism of the brain and visceral arteries (stroke, intestinal infarction, spleen). Also, valves with LSE are often infected with bacterial microflora, resulting in secondary infectious endocarditis. Vegetations on the valves can disrupt their function. This leads to the formation of a heart defect (more often insufficiency than stenosis) and a violation of the general circulation. Extremely rarely, complete destruction of the valves may occur, requiring emergency medical intervention.
Patients with lupus endocarditis are treated by rheumatologists. It is extremely difficult to suspect LSE in a person. During auscultation, you can listen to rough systolic noise at the apex of the heart, diastolic noise in the projection of the aortic valve, weakening of the I tone. To prove the presence of lupus endocarditis in a patient, it is necessary to confirm SLE. To do this, an additional examination is carried out, which includes:
- Laboratory tests. Markers of inflammation – leukocytes, ESR and C-reactive protein – were elevated in general and biochemical blood tests. Immunological examination of blood reveals high titers of antinuclear factor, antibodies (AT) to DNA and nucleoproteins. With APS, AT to cardiolipin, phospholipids, beta-glycoprotein are found in the blood. A large amount of protein is found in the urine.
- Instrumental research. Transesophageal echocardiography (EchoCG) is the most reliable method of diagnosing lupus endocarditis. Ultrasound of the heart shows thickening of the valve flaps, mobile vegetation up to 1 mm in size on the valves, their destruction. Sometimes regurgitation (reverse blood flow) and parietal thrombi, effusion in the pericardium (with pericarditis) are determined.
There are special clinical, laboratory and instrumental criteria for lupus erythematosus. At least 4 criteria are necessary for the diagnosis of SLE. If the patient has less than 3 criteria, this makes the presence of lupus endocarditis doubtful. It is very important to distinguish LSE from infectious endocarditis. To do this, a 3-fold bacterial blood culture is performed. LSE also needs to be differentiated with endocardial damage in rheumatic fever and other diseases (fibroelastosis, Leffler syndrome, eosinophilic vasculitis).
Patients with LSE are subject to mandatory hospitalization in the rheumatology department. In a serious condition of the patient, methods of extracorporeal blood purification – plasmapheresis, double filtration, cryofiltration – are used to remove autoantibodies and immune complexes from the blood that damage internal organs. In case of massive damage to the valve apparatus, surgical operation is required – valvuloplasty or prosthetics. Drug treatment is carried out according to the same principles as for lupus erythematosus and antiphospholipid syndrome:
- Anti-inflammatory therapy. The basis of therapy is drugs that suppress the inflammatory process. These include synthetic antimalarial aminoquinoline agents (chloroquine, hydroxychloroquine), glucocorticosteroids (prednisolone, methylprednisolone), immunosuppressants (cyclophosphamide, azathioprine). If they are ineffective, monoclonal antibodies are used.
- Anticoagulation therapy. Antiplatelet agents are prescribed to prevent thrombosis. If the patient had at least one episode of venous or arterial thrombosis, anticoagulants are added to the treatment – low molecular weight heparins, vitamin K antagonists, thrombin inhibitors. In case of resistance to standard therapy, human immunoglobulin is administered.
Prognosis and prevention
Libman-Sacks endocarditis is a relatively benign pathology. Adverse consequences in the form of death are caused by a high degree of SLE activity and thromboembolism in antiphospholipid syndrome. Since the cause of both lupus endocarditis and lupus erythematosus is unknown, no methods of primary prevention have been developed. Patients suffering from systemic lupus erythematosus should consult a doctor before immunization and starting taking oral contraceptives, since estrogens and some vaccines can provoke an exacerbation of lupus.