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An event is serious (based on the ICH definition) when the patient outcome is:
* death
* life-threatening
* hospitalisation
* disability
* congenital anomaly
* other medically important event
A 56-year-old man developed heparin-induced thrombocytopenia (HIT) during prophylactic anticoagulation treatment with heparin [dosages not stated].
The man, who had hypertension, presented with shortness of breath from 6 days. He was afebrile, haemodynamically stable, and his oxygen saturation was 84% on room air. After investigation, he was diagnosed with COVID-19 pneumonia. He was admitted to the medical ICU and hydroxychloroquine and IV azithromycin were initiated as off-label treatments for the COVID-19 pneumonia. Additionally, he started receiving prophylactic anticoagulation treatment with SC heparin. On the same day he was intubated due to increased oxygen requirement. On day 18, he experienced an acute drop in the platelets count. A bedside ultrasound revealed acute deep vein thrombosis involving the left femoral and right internal jugular veins.
Heparin infusion was initiated for the man's thrombosis. Peripheral blood smear only revealed thrombocytopenia. Prothrombin time, partial thromboplastin time and international normalised ratio were all normal. However, fibrinogen and lactate dehydrogenase were found to be increased. Haptoglobin, reticulocytes index and total bilirubin values did not suggest any possibility of acute haemolysis. The 4T score was 5, which was consistent with an intermediate probability of HIT. Anamnesis revealed that he never had thrombocytopenia and had received prophylactic SC heparin during the previous admissions without any complications. Platelet factor 4 (PF4) antibodies were found to be positive with 1.6 optical density and 97% inhibition. Heparin was therefore discontinued immediately, and a continuous infusion of argatroban was initiated. Later, heparin-induced platelet activation assay results were also found to be positive, which confirmed the diagnosis of HIT. Following discontinuation of heparin, his platelet count continued to increase. His anticoagulation was eventually switched to oral warfarin and was discharged after 44 days of ICU admission. At the time of discharge, his platelet count was found to be above the baseline levels.