A huge left atrial thrombus in patient with severe mitral stenosis

Rheumatic heart disease is the major cause of mitral stenosis and remains still an important cause of morbidity and mortality especially in developing countries where up to 1% of schoolchildren show clinical signs of rheumatic fever. The mechanisms leading to rheumatic valve disease (with involvement of mitral valve >80%) is based on antigenic mimicity of the M protein antigen found in both heart structures and group A hemolytic Streptococcus and autoimmune reaction. Mitral stenosis progress in time from leaflet thickening and commissural fusion to severe calcification of the valve and subvalvular apparatus which excludes percutaneous balloon valvuloplasty. Beyond of valve calcification left atrium dilates and atrial fibrillation often occurs which may result in thrombi formation. Vast majority of left atrial thrombi is located in the left atrial appendage (LAA). These occupying left atrial cavity (LAC) are usually much larger, connected with mitral valve stenosis, and easily detectable on transthoracic echocardiography, but often resistant to anticoagulation. Left atrial thrombi may be present in >30% patients with severe mitral stenosis and atrial fibrillation. Our case shows an extremely large thrombus (the longest dimension 10 cm) filling the left atrial cavity in an elder female patient with severe mitral stenosis, combined aortic valve disease, impaired left ventricle systolic function and long-lasting atrial fibrillation. Beside the organized thrombus, the rest of the left atrium cavity was filled by dense spontaneous echocontrast reflecting very slowed blood flow. Despite severe symptoms and contraindications to balloon valvuloplasty the patient repeatedly refused surgery and remained on medical therapy. Due to good transthoracic window we did not perform transesophageal examination. The huge bulk of the thrombi, dense echocontrast, coexistence of pleural fluid and possibility of good quality imaging of the heart from posterior chest wall make the presented case unusual.