[Sudden death associated with myocardial damage caused by microthrombi in a patient with thrombotic thrombocytopenic purpura].

We describe a 35-year-old woman with Down's syndrome who was admitted to a clinic with anorexia and vomiting. Since laboratory findings showed anemia (Hb 7.4 g/dl) and thrombocytopenia (0.5 × 10⁴/μl), she was transferred to our hospital for treatment. Further laboratory examinations revealed schistocytes, LDH elevation, and a negative Coombs' test. Thrombotic thrombocytopenic purpura (TTP) was suspected. Plasma exchange (PEX) and prednisolone administration were thus immediately initiated. Prior to these treatments, ADAMTS13 activity was less than 5% and inhibitors were detected at a level of 0.8 Bethesda U/ml. Although her platelet count had risen to 13.0 × 10⁴/μl by day 6 (post 4 sessions of PEX), it had decreased to 1.8 × 10⁴/μl on day 7. Despite ongoing PEX, thrombocytopenia persisted. On day 21, she suddenly died. Autopsy findings revealed no evidence of myocardial necrosis or coronary artery thrombosis. Extensive microthrombi were, however, detected in precapillary arterioles, capillaries, and post-capillary venules of the heart. Therefore, this patient's sudden death was clinically suspected to have been caused by cardiomyopathy, which had produced cardiogenic shock.