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:
Immunoassay for heparin-induced thrombocytopenia antibody returns positive. His condition improves with treatment. Which of the following is the most accurate statement regarding heparin use and risk of recurrence of this patient's current condition?

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:
 Immunoassay for heparin-induced thrombocytopenia antibody returns positive.  His condition improves with treatment.  Which of the following is the most accurate statement regarding heparin use and risk of recurrence of this patient's current condition?

Quizplus · Accepted Answer

Explanation: Heparin-induced thrombocytopenia (HIT) antibodies are generally short-lived (2-3 months) and usually do not demonstrate an anamnestic response during heparin rechallenge. However, due to the life-threatening nature of the condition, patients who develop type 2 HIT are advised to avoid all forms of heparin for life to limit the risk of new antibody formation (and recurrence). Unfractionated heparin, low-molecular-weight heparin, heparin flushes for arterial lines, and heparin-coated catheters all require avoidance, and a "heparin allergy" should be listed in the medical record (Choice E). (Choice A) Although corticosteroids have a profound effect on leukocyte function, B cells are minimally affected so antibody production is largely preserved. Therefore, corticosteroids are not typically used for type 2 HIT. (Choice B) Patients with type 2 HIT are considered at risk for recurrence regardless of the presence or absence of venous or arterial thrombus; avoidance of all heparin-containing products for life is recommended. (Choice C) Although some studies suggest that heparin rechallenge may not cause recurrence if HIT antibodies are cleared, current guidelines recommend that patients who develop type 2 HIT avoid heparin-containing products for life due to the high-risk nature of the condition and an incomplete understanding of the risk of heparin rechallenge. Educational objective: Patients diagnosed with heparin-induced thrombocytopenia are advised to avoid all forms of heparin (including low-molecular-weight heparin) for life to limit the risk of recurrence. References: Heparin-induced thrombocytopenia. Page(s): PMC4153428 (http://www.ncbi.nlm.nih.gov/pubmed/4153428)

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