A 32-year-old man comes to the emergency department due to a day of worsening pain and swelling in his right leg. He has no fever, chest pain, or shortness of breath. The patient was hospitalized 2 weeks ago for right lower extremity deep vein thrombosis after a minor sports injury; he was discharged on warfarin. When he left the hospital, his INR was 2.2 (goal: 2-3). The patient has been taking warfarin daily; however, due to a busy work schedule, his dietary intake has been variable and last week he missed his clinic appointment for anticoagulation monitoring. He has no other medical problems. Blood pressure is 120/70 mm Hg, pulse is 70/min, and respirations are 14/min. Examination shows moderate pretibial edema in the right leg. Today, his INR is 1.3. Platelet count, creatinine, and liver function tests are within normal limits. Venous Doppler ultrasound shows a right popliteal vein thrombus that extends into the femoral vein and is worse than on previous ultrasound. What is the best next step in management of this patient?
Treatment of acute deep vein thrombosis/pulmonary embolism | ||
Oral factor Xa inhibitors | Warfarin | |
Mechanism | Direct factor Xa inhibition | Vitamin K antagonism |
Therapeutic onset | 2-4 hr | 5-7 days |
Overlap needed? | No | Yes, overlap with UFH |
Laboratory monitoring | No | PT/INR |
LMWH = low molecular weight heparin; UFH = unfractionated heparin. | ||
This patient was recently diagnosed with deep vein thrombosis (DVT). He has been compliant with taking his warfarin, but his schedule has prevented proper anticoagulation monitoring; his DVT has now progressed in the setting of a subtherapeutic INR. The risk of pulmonary embolism (PE) is higher with proximal (eg, femoral vein, iliac vein) than distal (eg, below the knee) DVT; therefore, he needs immediate anticoagulation.
Oral direct factor Xa inhibitors (eg, rivaroxaban, apixaban) are as effective as warfarin in the treatment of acute DVT or PE and do not increase the risk of bleeding complications. These drugs have the advantage of rapid onset of action, no requirement for laboratory (eg, INR) monitoring, and no requirement for overlap therapy with heparin. Therefore, these agents are becoming preferred for the treatment of acute DVT and PE. These drugs are an especially good option in patients who have difficulty with the dietary restrictions or frequent INR monitoring required with warfarin.
(Choice A) In this patient with a worsening DVT and an INR of <2.0, it is not appropriate to increase the warfarin dose without overlapping with heparin anticoagulation. In addition, if this patient remains on warfarin, it is likely that his diet and schedule will continue to cause issues with maintaining a therapeutic INR.
(Choice B) Thrombolytic therapy is typically reserved for hemodynamically unstable patients with PE. Less commonly, it is used for massive proximal DVT associated with significant symptomatic swelling and/or limb ischemia. It is not indicated in this patient with moderate pretibial edema and absence of hypotension and tachycardia.
(Choice C) Anticoagulation failure (eg, recurrent or extending thromboembolism while fully anticoagulated) or anticoagulation contraindication (eg, active bleeding) are indications for inferior vena cava filter placement. This patient is not considered to have anticoagulation failure as his INR is grossly subtherapeutic (he is not fully anticoagulated).
(Choice E) Aspirin is inadequate for the treatment of acute DVT.
Educational objective:
Oral direct factor Xa inhibitors (eg, rivaroxaban, apixaban) have similar efficacy to warfarin in the treatment of acute venous thromboembolism and do not increase the risk of bleeding complications. These drugs do not require laboratory monitoring or overlap therapy with heparin and are becoming preferred agents for the treatment of acute venous thromboembolism.