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Time for a change? Switching anticoagulants in patients with AF or VTE

Patient case: Adapting treatment to changing needs

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Consider the following clinical situation:

  • Thomas is 75 years old and has been living with non-valvular atrial fibrillation (NVAF) for 6 years
  • Last year, Thomas’s wife died and so he moved in with his daughter and her two children
  • Since being diagnosed with AF, he has been treated with warfarin. Thomas likes a routine and had no problems keeping his international normalized ratio (INR) under control
  • He was previously able to walk to his warfarin-monitoring appointments and he enjoyed the time outdoors. But his new home is too far from the clinic and he cannot travel there easily
  • Thomas wants to know if there is a way of reducing the frequency of his medical appointments


When should anticoagulation be switched?

Every patient is different. But patients also change.


For patients who need anticoagulation, the choice of anticoagulant regimen should only be taken once the entire clinical situation has been considered.


One aspect of the treatment decision will be related to a patient’s clinical characteristics. For example, co-morbidities such as renal impairment may affect dosing of non-vitamin K antagonist oral anticoagulants (NOACs) for both patients with NVAF and patients with venous thromboembolism (VTE).1-4


Other factors include patient preference, and some patients may, for example, prefer a particular dosing frequency or wish to avoid injections.5-7 Similarly, just as Thomas has difficulty attending monitoring appointments for stroke prevention in NVAF, practical lifestyle factors may make certain treatments less appropriate.5

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Factors affecting anticoagulant choice in NVAF and VTE may change over time

Importantly, none of the factors mentioned above are fixed. Patients can develop additional comorbidities, renal function can decline and personal circumstances can change.


It may take a single major change or several small ones but, over time, a treatment regimen that was once appropriate may become unsuitable and will need to be reassessed.


How should switching be managed?

When a change in anticoagulant is required, specific guidance is provided by the European summaries of medical product characteristics (SmPCs) for different anticoagulants.1-4,8 This guidance is summarized in the table below.


Switching between a parenteral anticoagulant such as enoxaparin and a NOAC simply involves stopping one treatment and beginning the other after a short period of time, typically when the next dose would be due.1-4 Where guidance is provided, switching between NOACs is conducted in the same way.4


Similarly, switching from a VKA to a NOAC or enoxaparin requires the VKA to be stopped and the new anticoagulant to be started once the patient’s INR has dropped below a certain threshold.1-4,8


The most complicated switching process is when a patient changes to a VKA from another anticoagulant. In this case, specific instructions vary between anticoagulants, although they all require co-administration of the original anticoagulant and VKA for at least 2 days. Co-administration then continues until INR testing shows that it is appropriate to continue with only VKA.1-4,8


Importantly, switching should only take place following careful consideration of the specific dosing guideline and contraindications of the anticoagulant in question.

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Switching anticoagulants may be necessary for several reasons but the European SmPCs provide ample guidance for maintaining protection from thrombotic events.


Thomas’s change in circumstances means that his warfarin treatment is no longer as suitable as it once was. However, by switching to a NOAC, his need to attend a clinic for INR monitoring can be removed and his mind can be put at rest.


By considering patients as individuals, it is possible to make sure that they continue to receive the right dose of the right drug, for the right reason at the right time.


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