A 50-year-old African American man comes to the emergency department because his left leg has been bothering him. He describes vague, diffuse left leg pain that is present both at rest and with activity. He denies any chest pain, shortness of breath, palpitations, syncope, or hemoptysis. He was discharged from the hospital one month ago after being diagnosed with and treated for a left popliteal vein thrombosis. Since his discharge from the hospital, he has been taking a stable dose of warfarin every evening, without medical followup. His blood pressure is 143/82 mmHg and his heart rate is 72/min. His oxygen saturation is 98% on room air. His BMI is 37 kg/m². There is marked swelling of the left leg. His INR (International Normalized Ratio) in the emergency room is 1.4. An ultrasound examination reveals venous thrombosis involving the common femoral vein. Which of the following is the best next step in managing this patient?

Question

Quizplus · Accepted Answer

Explanation: The extent of this patient's lower extremity deep venous thrombosis (DVT) has increased since it was first diagnosed one month ago - the thrombus was previously at the level of the popliteal vein and now has spread proximally to involve the common femoral vein as well. The increased DVT size is almost certainly the cause of his left lower extremity symptoms, and the proximal propagation of the thrombosis may place him at increased risk of developing a pulmonary embolism. Inadequate anticoagulation is the likely cause of this problem, since the goal INR level for this type of patient is between 2.0 and 3.0. The reason for this patient's under-anticoagulation is unclear. While the patient does describe taking the same dose of warfarin every day, he had no followup. It may be that, for his size (BMI is 37 kg/m²), the prescribed warfarin dose was too low. Outpatient follow-up of his INR would have revealed this problem. This should not be considered a failure of anticoagulation, as the patient was never adequately anticoagulated in the first place. The patient should be admitted to begin intravenous heparin therapy and will need an increase in his warfarin dose to reach an appropriate INR level. (Choice A) While this patient is at risk of developing a pulmonary embolism, he has no symptoms to suggest this at the current time and as such there is no indication for CT angiography of the chest. (Choice B) Placement of an IVC filter should be considered if appropriate anticoagulation fails, but the propagation of this patient's DVT is secondary to under-anticoagulation. (Choice D) Checking a D-dimer level is unnecessary since the test will surely be elevated given that the patient has a known thrombosis. The patient's dose of warfarin will need to be increased, but he must be started on heparin until his INR is at a therapeutic level. (Choice E) The patient should be admitted for heparin therapy until the INR reaches a therapeutic level. Educational objective: Under-anticoagulation can lead to worsening of thrombotic disease, and such patients should be started on intravenous heparin (or subcutaneous low molecular weight heparin) until a therapeutic INR is achieved with warfarin. Such cases should not be considered anticoagulation failures that warrant placement of an IVC filter.

A 50-Year-Old African American Man Comes to the Emergency Department