Peripheral Thrombosis and Necrosis after Minimally Invasive Redo Mitral Valve Replacement due to Unknown Etiology: Difficult Diagnosis of Heparin Induced Thrombocytopenia

We report on a 75-year-old male with acute onset of peripheral thrombosis causing necrosis of the fingers, elbow, and toes associated with thrombocytopenia after minimally invasive redo mitral valve replacement. Both warfarin and dalteparin were commenced on postoperative day 1 and his INR reached 2.1 on postoperative day 4. On postoperative day 5, the patient developed peripheral thrombosis which progressed to necrosis on postoperative day 6. Platelet counts decreased significantly on the same day. His clinical features were compatible with heparin induced thrombocytopenia (HIT). However, serology testing was negative and the diagnosis was never confirmed. The patient was treated for HIT and platelet count improved eventually. Although no clear consensus exists, we believe this case illustrates why therapy for HIT should be initiated when clinical features strongly suggest HIT despite a negative serology test, unless an alternate diagnosis can be found.