The Question
A 68-year-old man is evaluated on postoperative day 7 after a coronary artery bypass grafting procedure. He reports the acute onset of swelling, pain, and redness in his right leg. His medical history is notable for hypertension and hyperlipidemia. Since surgery, he has been receiving prophylactic unfractionated heparin. His temperature is 37.6°C (99.7°F), blood pressure is 140/85 mm Hg, pulse is 92/min, and respirations are 16/min. Examination reveals a warm, erythematous, and swollen right lower extremity with calf tenderness. There are no skin lesions or signs of bleeding. His platelet count upon admission was 280,000/mcL; today, it is 115,000/mcL. A compression ultrasound confirms an extensive deep vein thrombosis in the right femoral and popliteal veins. 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
D
Explanation
Clinical Pearl:
In a patient with high clinical suspicion for heparin-induced thrombocytopenia (HIT), such as a platelet drop >50% plus a new thrombosis 5-10 days after heparin exposure, heparin must be stopped immediately and a non-heparin anticoagulant started without waiting for confirmatory tests.
Explanation:
This patient's presentation is classic for heparin-induced thrombocytopenia (HIT), a highly prothrombotic condition. Key features include the timing of platelet drop (5-14 days after heparin initiation), the magnitude of the drop (greater than 50% from baseline), and the presence of a new thrombosis. The most critical immediate action is to discontinue all heparin products and initiate an alternative, non-heparin anticoagulant. Argatroban, a direct thrombin inhibitor, is a standard choice. Waiting for confirmatory test results, such as the heparin-PF4 antibody ELISA or serotonin release assay, would dangerously delay treatment. Administering platelets is contraindicated as it can "add fuel to the fire" and worsen thrombosis. Initiating warfarin alone is also contraindicated in acute HIT, as the initial drop in protein C levels can lead to a paradoxical hypercoagulable state and venous limb gangrene. An IVC filter does not address the underlying pathophysiology and is reserved for situations where anticoagulation is impossible.
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