The Question
A 68-year-old man is recovering on the surgical ward 7 days after undergoing coronary artery bypass grafting for three-vessel disease. His postoperative course has been unremarkable, and he has been receiving subcutaneous unfractionated heparin for venous thromboembolism prophylaxis. The nurse calls to report that the patient's platelet count has decreased significantly. His medical history is notable for hypertension and hyperlipidemia. On examination, his temperature is 37.1°C (98.8°F), blood pressure is 128/76 mm Hg, pulse is 88/min, and respirations are 14/min. He is well-appearing and in no distress. Cardiopulmonary examination is normal. His surgical incisions are clean and healing well. There are a few scattered petechiae on his lower legs bilaterally. There is no evidence of active bleeding. Laboratory studies show: Sodium: 138 mEq/L Potassium: 4.1 mEq/L Creatinine: 0.9 mg/dL Hemoglobin: 10.8 g/dL Platelet count: 65,000/mcL A review of his records shows a platelet count of 140,000/mcL yesterday and a pre-operative baseline of 280,000/mcL. Which of the following is the most appropriate next step in management?
See the answer and explanation below:
Post-Call Recovery Reads
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View on AmazonThe Correct Answer
A
Explanation
Clinical Pearl:
In suspected heparin-induced thrombocytopenia (HIT), the first step is to immediately stop all forms of heparin and start a non-heparin anticoagulant, even before confirmatory serologic testing is complete. Delaying treatment significantly increases the risk of catastrophic thrombosis.
Explanation:
This patient's presentation is classic for heparin-induced thrombocytopenia (HIT), a severe, prothrombotic, immune-mediated reaction to heparin. Key features include the timing of onset (5 to 10 days after heparin initiation) and the magnitude of platelet drop (greater than 50% from baseline). The most critical initial action is to discontinue all forms of heparin, including flushes and coated catheters, and to start a non-heparin anticoagulant such as argatroban or bivalirudin. This is necessary because HIT antibodies activate platelets, creating a high risk of arterial and venous thrombosis. Therefore, discontinuing heparin and starting a direct thrombin inhibitor is the correct answer. Administering platelets is contraindicated as it can paradoxically increase the thrombotic risk by providing more substrate for the pathogenic antibodies. While a hematology consultation is appropriate, waiting for their recommendations before acting is dangerous. Switching to low-molecular-weight heparin is incorrect because there is high cross-reactivity with HIT antibodies. IVIG and corticosteroids are treatments for immune thrombocytopenic purpura (ITP), which is less likely in this clinical context of recent heparin exposure.
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