Two Weeks of Low Molecular Weight Heparin for Isolated Symptomatic Distal Vein Thrombosis (TWISTER study)

Eileen Merriman, Sanjeev Chunilal, Tim Brighton, Vivien Chen, Simon McRae, Paul Ockelford, Jennifer Curnow, Huy Tran, Beng Chong, Mark Smith, Gordon Royle, Helen Crowther, Alison Slocombe, Huyen Tran

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3 Citations (Scopus)


Background: Treatment of low-risk patients with isolated symptomatic distal deep vein thrombi (IDDVT) is uncertain. Objective: assess whether two weeks of therapeutic anticoagulation is efficacious/safe for IDDVT. Primary outcome: symptomatic three-month venous thromboembolism (VTE) incidence in the two-week anticoagulation group. Secondary outcomes included post-thrombotic syndrome (PTS) and bleeding. Methods: Prospective multicentre cohort study. Consecutive low-risk IDDVT patients enrolled within 72 h of diagnosis and treated with therapeutic dose enoxaparin or rivaroxaban. At two weeks, patients had repeat complete whole leg compression ultrasound (CUS)/clinical review. If resolution of leg symptoms AND no radiological evidence of thrombus extension, anticoagulation was stopped. If ongoing symptoms and/or radiographic extension within distal veins, anticoagulation was continued for four more weeks. Patients with extension into the popliteal vein on two-week ultrasound were treated off-study. Patients were reviewed at three and six months. Findings/interpretation: 241 eligible patients received ≥2 weeks anticoagulation. 167/241 (69%) were assigned to the 2-week anticoagulation group; 71/241 (30%) to the six-week anticoagulation group; 3/241 patients (1%) had extension into the popliteal vein on two-week CUS. Two patients in the two-week anticoagulation group had symptomatic IDDVT recurrence in ≤3 months; VTE recurrence 2/156; 1.3%(95% CI 0.05–4.85%). 69% of patients had complete resolution of symptoms within two weeks. Six-month PTS rates were 8/184, 4.4%(95% CI 2.1–8.5%). No major bleeding was reported. Our findings suggest it's safe/efficacious to stop therapeutic anticoagulation at two weeks in low-risk IDDVT patients with resolution of symptoms/no extension on ultrasound. This could replace 6–12 weeks of anticoagulation for ambulatory, low-risk IDDVT patients. Trial registration: NCT01252420

Original languageEnglish
Pages (from-to)33-39
Number of pages7
JournalThrombosis Research
Publication statusPublished - Nov 2021


  • Anticoagulants
  • Calf vein thrombosis
  • Distal deep vein thrombosis
  • Pulmonary embolism
  • Venous thromboembolism

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