Be alert for HIT in presentation and patient history[30]

Clinical case history

HIT: Be Aware
A 60-year-old woman underwent repair of an aortic aneurysm with aortic valve replacement. Postoperatively the patient received LMWH followed by warfarin therapy.

HIT: Be Alert
She presented to the emergency department 33 days after initial heparin exposure with proximal-thigh deep vein thrombosis despite a prothrombin international normalized ratio (INR) of 4.2. Platelet count was 420,000/mcL.

HIT: Take Action
Immediately after receiving an intravenous heparin bolus, she developed dyspnea, tachycardia, and hypotension. Hours after bolus dose, platelet count dropped to 47,000/mcL. She needed therapy with a direct thrombin inhibitor immediately. The patient later tested positive on ELISA for heparin antibody.

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Questions to Ask

Has the patient been hospitalized recently? If so, was the patient likely to have received heparin?

Many patients seen in the ED have recently been hospitalized. Hospitalization generally includes exposure to heparin (e.g., catheter flushes, coated stents, infusions, LMWH. Patients may have antibodies from prior exposure.

Has the patient been using LMWH at home?

UFH carries the greatest risk of HIT but HIT also results from the use of LMWH.[33,34]

What is the platelet count?

Clinicians should suspect HIT any time the platelet count drops to less than 50% of baseline or is less than 150,000/mcL.[2]

Is there a new thrombosis present?

Formation of thrombi is a hallmark of HIT with or without thrombosis as HIT is a hypercoagable state.[30] The most common thromboembolic complications of HIT are DVT, PE, MI, and stroke. These manifestations may be clinically overt or may not be seen unless further diagnostic evaluation is performed.[9,18]

Indications
Argatroban is indicated as an anticoagulant for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia.

Argatroban is indicated as an anticoagulant in patients with or at risk for heparin-induced thrombocytopenia undergoing percutaneous coronary intervention (PCI).

Important Safety Information

As with all anticoagulants, bleeding is a serious concern. Argatroban is contraindicated in patients with overt major bleeding or those with hypersensitivity to the product or any of its components. Argatroban should be used with extreme caution in disease states or other circumstances in which there is an increased risk of hemorrhage. Overall major bleeding was reported in 5.3% of patients with HIT treated with Argatroban versus 6.7% of the historical controls. Overall major bleeding was reported in 1.8% of patients undergoing PCI treated with Argatroban versus 3.1% of the historical controls. Intracranial bleeding was not observed in the 568 patients treated with Argatroban for HIT (with or without thrombosis) or in the 91 patients who underwent PCI. The most common nonhemorrhagic side effects in HIT patients, regardless of the relationship to treatment, were dyspnea, hypotension, and fever. In patients undergoing PCI, the nonhemorrhagic side effects, regardless of the relationship to treatment, included chest pain, hypotension, and back pain. Please see full Prescribing Information for additional safety information on Argatroban.