Review Question - QID 104679

This patient presents with signs and symptoms of a deep vein thrombosis (DVT). DVTs should be treated acutely with anticoagulation. For this patient with CKD and a glomerular filtration rate less than 30 ml/min, unfractionated heparin is the best initial agent.

The acute treatment of DVT is anticoagulation. A variety of options exist including factor Xa inhibitors, direct thrombin inhibitors, unfractionated and low molecular weight heparins (LMWH). Heparin is easily monitored using the activated partial thromboplastin time (aPTT), with a goal therapeutic aPTT of 1.5 times normal reference in patients with a first DVT event. In patients with CKD, unfractionated heparin is preferred and LMWH is contraindicated due to abnormal metabolism and excretion of the drug. Once anticoagulation with heparin is established, bridging to warfarin allows for outpatient anticoagulation with an oral regimen.

Wigle et al. discuss long term anticoagulation for patients with DVTs. They stress the importance of bridging to coumadin using other anticoagulants for a minimum of five days. For most patients, warfarin can be initiated at the time of initiation of heparin or lovenox (as bridging therapies), to decrease the time for achieving a therapeutic International Normalized Ratio (INR). A therapeutic INR should be demonstrated for two consecutive days before discontinuing bridging therapy. The American College of Physicians recommends anticoagulation for 3-6 months for venous thromboemboli (VTE) due to transient risk factors, and 12 months for recurrent VTEs.

Pruthi reviews the American College of Chest Physicians 2012 Guidelines for Anticoagulation Therapy and Prevention of Thrombosis. The authors address many of the recent advances in therapeutic options for DVTs, including LMWHs, dabigatran, and argatroban, which provide the convenience of daily dosing without the need for anticoagulation monitoring. Furthermore, for first time DVT episodes, anticoagulation for a period of at least 3 months is recommended.

Figure A shows an edematous and mildly erythematous right lower extremity. Figure B shows a lower extremity ultrasound with clot in the left common femoral vein. Figure C shows lab values with a normal complete blood count and an abnormally elevated BUN and creatinine consistent with the patient's history of CKD.

Incorrect Answers:
Answer 2: Warfarin is a VKA. It is not appropriate to begin warfarin alone,without bridging therapy, because of the risk of warfarin-induced skin necrosis.
Answer 3: Aspirin and clopidogrel are antiplatelet agents, which are not first line agents for DVTs.
Answer 4: LMWH is an appropriate first line agent for DVTs, however it is relatively contraindicated in patients with renal failure due to abnormal renal metabolism of the drug.
Answer 5: This patient does not have any contraindication to anticoagulation, and thus should be started on anticoagulation before placement of an inferior vena cava filter.