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Anticoagulants Used for SVT Ward Off Thrombi, VTE

Key findings

  • 20% of patients with SVT, when it involves the great saphenous vein and a thrombus at least 5 cm. in length at the above-knee position, can also have concurrent VTE
  • Treatment with prophylactic dosing of fondaparinux for 45 days in SVT patients may also reduce the risk of SVT propagation and recurrence, but most importantly, the risk of future venous thromboembolism.

Superficial vein thrombosis (SVT) of the axial veins is a widespread clinical condition that carries a significant risk of propagation of thrombus, recurrence and subsequent venous thromboembolism (VTE). While anticoagulation has become the preferred treatment over conservative therapy, the dose and duration vary widely. Surgeon Sherry Scovell, MD, and colleagues at Massachusetts General Hospital assessed the standard of care for acute SVT, wanting to better understand the impact of dose and duration of anticoagulant on outcome measures. They examined study methods and the results for subsequent VTE and recurrence or extension of SVT.

The team reviewed six prospective, randomized controlled trials that studied acute superficial thrombophlebitis of the great saphenous vein, not involving the deep venous system as confirmed by duplex ultrasound imaging and treated with anticoagulants or NSAIDs. Due to a lack of parity between doses, durations and outcome measures, a full meta-analysis could not be done.

Included studies had sample sizes ranging from 60 to 3,002 patients and treatment durations of six to 12 weeks. Four studies used low-molecular-weight heparin (LMWH), while the other two used unfractionated heparin and the factor Xa inhibitor fondaparinux.

Relative to other options, treatment with an intermediate dose of LMWH (between prophylactic and therapeutic doses) for 30 days had a lower rate of thrombus extension and subsequent recurrence. The study that used prophylactic dosing of fondaparinux found that it decreased the rate of thrombus extension and recurrence, and subsequent VTE during and after anticoagulant treatment.

This study validated the standard of care of anticoagulation use for SVT. However, the research team stresses more inquiry should be given to better define optimal dose and duration of anticoagulants, the rate of subsequent VTE after anticoagulant use over the long-term, and even the relative benefit of other therapies to improve risk rates and outcomes.

Learn more about Mass General's Division of Vascular and Endovascular Surgery

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