[Left atrial thrombosis in patients with antiphospholipid antibody syndrome and mesenchymal abnormal septum]

Antiphospholipid antibodies are a heterogeneous family of immunoglobulins that includes lupus anticoagulant and anticardiolipin antibodies. They are strongly associated with a clinical syndrome characterized by venous and arterial thrombosis and spontaneous fetal losses. This syndrome may be primary or else secondary to autoimmune or neoplastic diseases. The cardiovascular system is frequently involved with mitral or aortic insufficiency, juvenile myocardial infarction, and primitive pulmonary hypertension. However, the occurrence of intracardiac thrombi is rare. We describe a case of an intracardiac right atrial thrombus in a 19-year-old asymptomatic woman who was admitted in December 1998 to the Thrombosis Center owing to the finding, during routine work-up, of a prolonged activated partial thromboplastin time (71 s) and thrombocytopenia (71 x 1000/mm3), a positive antinuclear antibody test (1/320), positivity for lupus anticoagulant, and increased IgG (92 GPL-U/ml) and IgM (27 MPL-U/ml) anticardiolipin antibodies. Six months later, the patient presented with headache, edema and cyanosis of the face and jugular swelling. Transthoracic and transesophageal echocardiography revealed a right atrial mass which was clearly distinguishable from the tricuspid valve and extended to the superior vena cava. The patient was successfully submitted to surgical excision of the thrombus. Histology revealed that the mass was adherent to an abnormal septum consisting of mesenchymal tissue. Although the American Rheumatology Association criteria for the diagnosis of systemic lupus erythematosus were not fulfilled, the positivity of antinuclear antibody test is in favor of a lupus-like syndrome. The decision to opt for surgical excision of the thrombus was determined by the unclear nature of the atrial mass. It may be necessary that such patients be submitted to anticoagulant therapy for the rest of their lives or temporarily (6-12 months). This underscores the importance of the anatomical abnormality as a promoting factor. Transthoracic echocardiography (as well as transesophageal echocardiography in selected cases) must be considered as an essential component of the initial diagnostic work-up in patients presenting with antiphospholipid antibodies.