RESUMO
We present the case of a man in his 70s admitted to the intensive care unit (ICU) after mitral valve replacement and coronary artery bypass graft surgery requiring extracorporeal membrane oxygenation support due to haemodynamic instability. He received anticoagulation therapy with heparin sodium and, after 5 days, the patient presented with thrombocytopenia and deep venous thrombosis. Heparin-induced thrombocytopenia was suspected based on a positive 4T score and confirmed by antiplatelet factor 4/heparin antibodies, so argatroban was initiated as an alternative anticoagulation therapy. In the following days the patient developed severe neutropenia requiring discontinuation of argatroban and the administration of granulocyte colony-stimulating factor. According to the Naranjo Adverse Drug Reaction Probability Scale, this event would be classified as a 'probable' argatroban-related adverse event. Argatroban should be conisdered as a possible cause of neutropenia and appropriate interventions need to be implemented due to the gravity of this adverse event in the ICU.