initial anticoagulation

Last edited 04/2020 and last reviewed 01/2021

initial and long term anticoagulation (first 3-6 months)

Initial phase of treatment, which include intensified anticoagulants is followed by long term anticoagulants for 3-6 months in majority of patients (1)

  • the goal is to rapidly extinguish thrombin and fibrin clot generation
  • multiple therapeutic options are available
    • conventional treatment involves parenteral heparin bridging to vitamin K antagonists (VKAs)
      • LMWH is usually preferred due to disadvantages of intravenous unfractionated heparin
        • inter-individual dose requirements that make close laboratory therapeutic monitoring a necessity
        • 8-10-fold higher risk for heparin-induced thrombocytopenia (HIT) than LMWH

      • UFH may be preferable in
        • patients with high bleeding risk
        • special patient populations e.g.
          • morbidly obese (BMI >= 40 kg/M2) and underweight patients (weight < 50 kg)
          • patients with severe renal impairment or unstable renal function (creatinine clearance <30 mL/min)

      • fondaparinux can also be employed as a parenteral agent for hospitalized patients in whom transition to a vitamin K antagonist (VKA) is anticipated

      • vitamin K antagonist (VKA) therapy can begin as soon as therapeutic levels of UFH/LMWH are achieved
        • parenteral therapy with UFH or LMWH should continue for at least 5 days of overlap and until an INR of 2 or more is achieved for 24 h

    • direct oral anticoagulants (DOACs)/ novel non-anti-vitamin K antagonist anticoagulants (NOACs)
      • have recently emerged as a treatment option for DVT
        • dabigatran and edoxaban therapy must include initial 7- 9 days treatment with a parenteral agent prior to beginning these agents.
        • apixaban and rivaroxaban can be used as a 'single drug approach' (without initial parenteral therapy)
      • is the preferred first-line anticoagulant therapy in non-cancer patients with proximal DVT
      • disadvantages include
        • longer elimination half-lives (7- 15 h) than UFH or LMWH
        • could accumulate in patients with suboptimal renal (estimated creatinine clearance <30 mL/min) or hepatic function

  • thrombolytic therapy
    • can be used in patients with acute extensive proximal lower extremity DVT or patients with proximal DVT that fails to respond to initial anticoagulation

  • vena cava filter
    • used when anticoagulation is absolutely contraindicated in patients with newly diagnosed proximal DVT
      • retrievable filter should be removed rapidly as soon as contraindications are resolved and anticoagulation can be started (2,3)

NICE suggest (4):

  • measure baseline full blood count, renal and hepatic function, PT and APTT but start anticoagulation before results available. Review and if necessary act on results within 24 hours
  • offer anticoagulation for at least 3 months. Take into account contraindications, comorbidities and the person’s preferences
  • after 3 months (3 to 6 months for active cancer) assess and discuss the benefits and risks of continuing, stopping or changing the anticoagulant with the person. See long-term anticoagulation for secondary prevention(linked item)

Anticagulatant considerations considered in terms of:

  • No renal impairment, active cancer, antiphospholipid syndrome or haemodynamic instability
    • offer apixaban or rivaroxaban
    • if neither suitable, offer one of:
      • LMWH for at least 5 days followed by dabigatran or edoxaban
      • LMWH and a VKA for at least 5 days, or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

  • Renal impairment (CrCl estimated using the Cockcroft and Gault formula; see the BNF)
    • CrCl 15 to 50 ml/min, offer one of:
      • apixaban
      • rivaroxaban
      • LMWH for at least 5 days then
        • edoxaban or
        • dabigatran if CrCl >= 30 ml/min
      • LMWH or UFH and a VKA for at least 5 days, or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

    • CrCl < 15 ml/min, offer one of:
        • LMWH
        • UFH
        • LMWH or UFH and a VKA for at least 5 days, or until INR at least 2.0 on 2 consecutive readings, then a VKA alone
    • Note cautions and requirements for dose adjustments and monitoring in SPCs. Follow local protocols, or specialist or MDT advice

  • Active cancer (receiving antimitotic treatment, diagnosed in past 6 months, recurrent, metastatic or inoperable
    • Consider a DOAC
    • if a DOAC is not suitable, consider one of:
      • LMWH
      • LMWH and a VKA for at least 5 days or until INR at least 2.0 on 2 consecutive readings, then a VKA alone
    • Offer anticoagulation for 3 to 6 months. Take into account tumour site, drug interactions including cancer drugs, and bleeding risk

  • Antiphospholipid syndrome (triple positive, established diagnosis)
    • Offer LMWH and a VKA for at least 5 days or until INR at least 2.0 on 2 consecutive readings, then a VKA alone

Reference: