[Thrombus in the left atrium -- is it always treated properly?].

A case of a 61-year-old female with a history of stroke in a course of mitral stenosis with atrial fibrillation is reported. Mitral commissurotomy was conducted eight years after the diagnosis. The chest X-ray revealed large calcified mass in the left atrium. During surgical mitral valve replacement the mass has been removed and identified as calcified thrombus. Despite numerous risk factors, anticoagulation has not been introduced until a few months before the operation.