AORTIC THROMBOSIS AFTER CARDIAC SURGERY FROM HEPARIN-INDUCED THROMBOCYTOPENIA

Abstract

SESSION TITLE: Fellows Critical Care Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Heparin-induced thrombocytopenia (HIT) is a complication caused by exposure to heparin. Although incidence after cardiac surgery is of 0.3%, there is a 50% increase in mortality when HIT occurs [1]. CASE PRESENTATION: A 65-year-old male with history of diabetes mellitus presented with chest pain. Two days prior to coronary artery bypass grafting (CABG), coronary angiography revealed triple vessel disease. He received 3000 units of heparin for the procedure. He underwent on-pump CABG, where 19,500 units of heparin were given. After surgery, platelet count decreased with nadir of 105×103 /μL (40% decrease) on postoperative day (POD) 4. He complained of abdominal and lower extremities’ pain on POD 5. Computed tomography (CT) showed a thrombosed infrarenal aorta (Fig 1). Vascular team performed axillary and femoral artery bypass surgery. He complained of abdominal pain and CT showed dilated loops of bowel with pneumatosis intestinalis on POD 7. Laparotomy was performed and necrosed small bowel was resected. HIT was suspected due to thromboembolic events (4Ts score was 6; high risk of HIT) [2]. Particle Immuno-Filtration Assay (PIFA®) and Serotonin Release Assay (SRA) were ordered and results came negative. Assays were done for second time on POD 10 and PIFA® resulted negative. Echocardiogram revealed small thrombus in left ventricle apex on POD 11. Although SRA result was pending, heparin was discontinued and argatroban was administered. SRA test came positive on POD 12. Platelet count began recovering and there was no more thromboembolic event. Platelet count returned to normal at 5-month follow-up (Fig 2). DISCUSSION: There are two requirements to determine presence of HIT: a) clinical diagnosis and b) detection of heparin antibodies activating platelet (through positive SRA). Clinical diagnosis can be completed by use of 4Ts score [2] (Fig 3). If 4Ts score is more than 4 (intermediate risk), the serological tests should be performed. There are two types of tests for HIT: one is the antigen assay PIFA® and the other is the functional assay SRA. Both have high sensitivity of 90%. PIFA® is used for screening, has a specificity ranging from 50% to 89% and its result can be available within 15 minutes. SRA has a higher specificity of more than 90%. To confirm the diagnosis, SRA result should be positive, although several days may take to obtain result. CONCLUSIONS: If the serological test shows negative and HIT is still suspected clinically, the test should be repeated. High clinical suspicion should lead to termination of heparin and initiation of argatroban. Reference #1: Seigerman M., Cavallaro P., Itagaki S., Chung I., Chikwe J. Incidence and outcomes of heparin-induced thrombocytopenia in patients undergoing cardiac surgery in North America: an analysis of the nationwide inpatient sample. J Cardiothorac Vasc Anesth. 2014;28:98-102. Reference #2: East M.J., Cserti-Gazdewich M.C., Granton T.J. Heparin-induced thrombocytopenia in the critically ill patient. Chest. 2018; 154:678-690. Reference #3: Ortel T.L. Heparin-induced thrombocytopenia: when a low platelet count is a mandate for anticoagulation. Hematology Am Soc Hematol Educ Program. 2009;225-232. Fig 1; Contrast computed tomography (CT) showed total occlusion of the infrarenal abdominal artery and bilateral iliac arteries. DISCLOSURES: No relevant relationships by Youdelman Benjamin, source=Admin input No relevant relationships by Shinichiro Ikeda, source=Web Response No relevant relationships by Ronald Kaleya, source=Web Response No relevant relationships by Robert Rhee, source=Web Response