A 62-year-old hospitalized man is evaluated for new-onset, right lower extremity pain. The patient underwent bypass surgery for 3-vessel coronary artery disease 2 months ago. He arrived at the emergency department 2 nights ago due to recurrent chest pains. At that time, ECG showed sinus rhythm with no ST-segment changes, but cardiac troponin I levels were elevated. The patient was initiated on unfractionated heparin, antiplatelet agents, a beta blocker, and a nitrate. A coronary angiogram was performed via the radial artery; it revealed graft insertion site stenosis and was treated with stenting. Postintervention echocardiography revealed left ventricular ejection fraction of 50% with no regional wall motion abnormalities. This morning, the patient had new, sudden-onset, right lower extremity pain. He has never had pain in that extremity before. The patient has a history of hypertension, hyperlipidemia, and type 2 diabetes mellitus. Current medications include aspirin, clopidogrel, rosuvastatin, metoprolol, losartan, isosorbide mononitrate, basal-bolus insulins, and subcutaneous heparin at a prophylactic dose. The patient is a former smoker with a 30-pack-year history. Temperature is 37.6 C (99.7 F), blood pressure is 138/84 mm Hg, pulse is 96/min, and respirations are 18/min. Physical examination reveals normal jugular venous pressure, clear lungs, no heart murmurs, and a soft, nontender abdomen. The right leg is tender and cool to the touch when compared to the left leg. Right lower extremity distal pulses are diminished, but capillary refill is intact. Left leg examination is normal with the exception of healed scars from previous saphenous vein harvesting. Neurological examination is normal. Laboratory results are as follows:
Analgesics and other supportive measures are provided, and vascular surgery is consulted. Diagnostic studies are performed, but the results are pending. Which of the following is the most appropriate next step in management of this patient?

Question

A 62-year-old hospitalized man is evaluated for new-onset, right lower extremity pain.  The patient underwent bypass surgery for 3-vessel coronary artery disease 2 months ago.  He arrived at the emergency department 2 nights ago due to recurrent chest pains.  At that time, ECG showed sinus rhythm with no ST-segment changes, but cardiac troponin I levels were elevated.  The patient was initiated on unfractionated heparin, antiplatelet agents, a beta blocker, and a nitrate.  A coronary angiogram was performed via the radial artery; it revealed graft insertion site stenosis and was treated with stenting.  Postintervention echocardiography revealed left ventricular ejection fraction of 50% with no regional wall motion abnormalities.  This morning, the patient had new, sudden-onset, right lower extremity pain.  He has never had pain in that extremity before.  The patient has a history of hypertension, hyperlipidemia, and type 2 diabetes mellitus.  Current medications include aspirin, clopidogrel, rosuvastatin, metoprolol, losartan, isosorbide mononitrate, basal-bolus insulins, and subcutaneous heparin at a prophylactic dose.  The patient is a former smoker with a 30-pack-year history.  Temperature is 37.6 C (99.7 F), blood pressure is 138/84 mm Hg, pulse is 96/min, and respirations are 18/min.  Physical examination reveals normal jugular venous pressure, clear lungs, no heart murmurs, and a soft, nontender abdomen.  The right leg is tender and cool to the touch when compared to the left leg.  Right lower extremity distal pulses are diminished, but capillary refill is intact.  Left leg examination is normal with the exception of healed scars from previous saphenous vein harvesting.  Neurological examination is normal.  Laboratory results are as follows:
 Analgesics and other supportive measures are provided, and vascular surgery is consulted.  Diagnostic studies are performed, but the results are pending.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

Explanation: Patients with suspected type 2 heparin-induced thrombocytopenia (HIT) require the cessation of all heparin-containing products and the initiation of an alternate non-heparin anticoagulant; first-line alternate anticoagulants include direct thrombin inhibitors (eg, argatroban, bivalirudin) and fondaparinux. The diagnosis of type 2 HIT is confirmed by HIT antibody testing, but results may take several days to return. As type 2 HIT is life-threatening, empiric treatment should be initiated when clinical suspicion is high and/or the 4 Ts score is intermediate or high probability (Choice A). (Choice B) The initiation of warfarin therapy transiently causes a hypercoagulable state due to rapid declines in protein C levels. As such, warfarin should not be used initially in patients with type 2 HIT. However, patients can transition to warfarin after an alternate anticoagulant is initiated and platelet counts have increased to >150,000/mm³. (Choice D) Patients with type 2 HIT remain at elevated risk of antibody-mediated platelet activation for several days after heparin cessation. As such, heparin cessation alone is insufficient for treatment; an alternate, non-heparin anticoagulant is also required. (Choice E) All forms of heparin, including low-molecular-weight heparin, must be stopped to prevent the formation of heparin-platelet factor 4 complexes and the stimulation of additional HIT antibodies. Educational objective: Patients with suspected type 2 heparin-induced thrombocytopenia require HIT antibody testing, the cessation of all heparin-containing products, and the initiation of an alternate non-heparin anticoagulant (eg, a direct thrombin inhibitor). Treatment should not be delayed for pending HIT antibody test results due to the life-threatening nature of the condition. References: Treatment and prevention of heparin-induced thrombocytopenia: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/22315270)

A 62-Year-Old Hospitalized Man Is Evaluated for New-Onset, Right Lower