The following are key points to remember from this review on the diagnosis and treatment of lower extremity venous thromboembolism (VTE):

1. Lower extremity VTE is common, with incidence estimates between 88-112 per 100,000 person-years. Recurrence is also common, estimated at 20-36% over 10 years after an initial event.
2. Risk factors for VTE include older age, male sex, inherited thrombophilia, sickle cell disease, non-O blood type, smoking, malignancy, infection, inflammatory disorders, atherosclerotic cardiovascular disease, major surgery, chronic kidney disease, diabetes, heart failure, chronic pulmonary disease, pregnancy, hormonal therapy, and immobilization.
3. Diagnosis of VTE includes assessment of pretest probability. Most commonly, this is done with the Wells deep vein thrombosis (DVT) score in the outpatient setting. Results of this score guide the need for imaging. The Wells criteria do not perform well for hospitalized patients and, therefore, imaging should be performed when VTE is suspected.
4. If a DVT is felt to be unlikely based on Wells assessment, then an age-adjusted D-dimer test should be performed to determine if imaging is needed. The threshold is calculated as 10 x age (years) with a lower threshold of 500 ng/ml.
5. May-Thurner syndrome occurs when the right iliac artery compresses the left iliac vein and leads to thrombus formation or venous congestion. This accounts for 2-5% of all DVT and usually requires cross-sectional or invasive imaging for diagnosis.
6. For patients with proximal DVT or high-risk distal DVT, patients should receive anticoagulation for ≥3 months. For patients with low-risk distal DVT, a short duration of anticoagulants (4-6 weeks) or serial compression ultrasound to screen for progression can be considered.
7. Patients with isolated calf vein DVT should receive anticoagulation if they have severe symptoms or risk factors for extension/pulmonary embolism (e.g., hospitalization, prior VTE, cancer).
8. International guidelines recommend the use of a direct oral anticoagulant (DOAC) over a vitamin K antagonist (VKA) for eligible patients with acute DVT. VKA is often preferable for patients with advanced chronic kidney disease or in breastfeeding women. Low molecular weight heparin (LMWH) is preferred in patients with pregnancy.
9. Patients with newly diagnosed lower extremity DVT, adequate home support, and manageable symptoms who can afford the cost of a DOAC may be treated as an outpatient without hospital admission.
10. Patients with cancer-associated VTE are eligible for either LMWH or DOAC therapy. Patients with gastrointestinal malignancies and VTE may be better candidates for LMWH rather than DOAC (especially edoxaban).
11. Lower extremity superficial vein thrombophlebitis can be treated with a prophylactic dose of anticoagulation for 45 days. Randomized trial data support the use of fondaparinux 2.5 mg daily or rivaroxaban 10 mg daily.
12. Post-thrombotic syndrome is a clinical diagnosis made when lower extremity signs and symptoms persist 3-6 months after an acute DVT. These include chronic leg discomfort, edema, venous stasis skin changes, and venous ulceration (in advance stages).
13. In general, the role of catheter-directed thrombolysis for patients with lower extremity DVT is limited. This therapy should be reserved for highly select patients with severe symptoms or limb-threatening disease and a low risk of bleeding.
14. After the acute treatment period (3-6 months), the goal of extended therapy is to prevent VTE recurrence. For patients with an estimated annual recurrence risk of <3%, a short duration of anticoagulation is recommended. In practice, this means that most patients are candidates for extended duration treatment.
15. Use of DOAC therapy for extended duration secondary VTE prevention is more effective than aspirin therapy. Apixaban and rivaroxaban can be prescribed at “half-dose” strength (apixaban 2.5 mg twice daily, rivaroxaban 10 mg daily) in this extended secondary prevention phase.

Clinical Topics: Anticoagulation Management, Cardiac Surgery, Cardio-Oncology, Geriatric Cardiology, Noninvasive Imaging, Prevention, Pulmonary Hypertension and Venous Thromboembolism, Vascular Medicine, Anticoagulation Management and Venothromboembolism, Cardiac Surgery and Arrhythmias

Keywords: Anticoagulants, Cardiotoxicity, Diagnostic Imaging, Geriatrics, Heparin, Low-Molecular-Weight, Hyperemia, Kidney Diseases, May-Thurner Syndrome, Mechanical Thrombolysis, Pregnancy, Pulmonary Embolism, Risk Factors, Secondary Prevention, Thrombophilia, Thrombophlebitis, Vascular Diseases, Venous Thromboembolism, Venous Thrombosis, Vitamin K

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