Abstract 497: Clinical Significance of Heparin Induced Thrombocytopenic Thrombotic Syndrome with Initiation of Anti-heparin Antibodies Negative: A Case Report and Literature Review

Abstract

Introduction Heparin induced thrombocytopenia thrombosis Syndrome has a high mortality and morbidity in cardiac surgical patients in spite of early diagnosis and management. We present a case with multiple acute deep venous thrombosis (DVT) after using unfractionated heparin (UFH) during coronary artery bypass graft (CABG) with initiation of HIT antibodies negative. Case presentation A 70-year-old male complained of left leg pain 2 days after CABG for an acute ST-elevation myocardial infarction. Patient was treated with UFH intravenous during CABG. Platelet count was 78 x 109/L that was 130 x 109/L before the procedure. Anti-heparin antibodies IgM/IgG were negative. Venous Doppler ultrasound showed an acute deep venous thrombosis (DVT) in the left peroneal vein. However, after the patient was treated with Coumadin anticoagulation for 7 days with INR in therapeutic range (2-3), the patient presented for right low extremity pain. Platelet count was 40 x 109/L. Anti-heparin antibodies IgM and IgG were repeatedly positive. Venous Doppler ultrasound showed multiple bilateral lower extremities acute DVTs. Patient had thrombectomy and continued with coumadin anticoagulation at INR in therapeutic range for 3 months. Discussion HITTS is an immune-mediated drug reaction that occurs more frequently in patients undergoing cardiovascular surgery. Thrombosis caused by the HIT/T syndrome is most commonly venous thromboembolism. Thrombosis is arterial in about 20% of cases, including acute limb ischemia, myocardial infarction, or stroke. Previous clinical data has shown that about 40% of high titer-negative HIT antibodies were associated with a positive result in repeated testing several days later, which is the same as our presentation. The mortality and morbidity rates of HITTS are approximately 30% and 60%, respectively, and an additional ~10% of patients require amputations or suffer other major morbidity. However, with early recognition and intervention, mortality can be reduced from >30 to <10%. Obviously, repeated testing to identify patients who have HIT despite a negative initial HIT test in several days is greatly recommended. Diagnosis is essentially clinical and negative results from laboratory assays do not exclude the diagnosis.