2.8.2.1 Atrial fibrillation

Prophylaxis of Stroke and Systemic Embolism in Non-valvular* Atrial Fibrilliation (AF)

ChoiceDrugDosage
1st choicesWarfarin tablets 1mg, 3mgDose:
As per international normalised ratio (INR)
Or
Non-vitamin K Antagonist Oral Anticoagulant (NOAC):
Apixaban▼See table below
Or
DabigatranSee table below
Or
Edoxaban▼See table below
Or
Rivaroxaban▼See table below
* Patients with mechanical valves or significant mitral valve stenosis are excluded from this treatment protocol

Doses of NOACs in renal impairment
(reduce dose in renal impairment based on Cockcroft Gault calculation of CrCl. Do not use estimated GFR)
DrugCreatinine Clearance
≥ 50 ml/min30-49 ml/min15-29 ml/min<15ml/min
Apixaban5 mg twice daily
Reduce to 2.5 mg twice daily in patients with two or more of the following characteristics:
-  Age ≥80 years
- Body weight ≤60kg
- Serum creatinine ≥1.5mg/dL (133 micromoles/L)
Reduce dose to 2.5mg twice dailyDo not use
DabigatranUsual dose is 150mg twice daily
Consider reducing to 110mg twice daily in patients aged 75-80years, or with moderate renal impairment, gastritis/ GORD or at increased risk of bleeding
Always reduce to 110mg twice daily in patients >80 years or if taking verapamil
Do not useDo not use
Edoxaban60mg once daily
Reduce to 30mg edoxaban once daily in patients with one or more of the following clinical factors:
-    Low body weight <60kg
-    Concomitant use of ciclosporin, dronedarone, erythromycin or ketoconazole
30mg once dailyDo not use
Rivaroxaban20 mg once daily with foodReduce dose to 15mg daily with foodDo not use

http://www.swmit.nhs.uk

Prescribing Notes

  • Refer to NICE CG 180 on the management of AF and NICE TA355 Edoxaban for preventing stroke and systemic embolism in people with non-valvular AF.
  • NICE have developed a patient decision aid that can be used in consultations to help patients make informed decisions regarding which anticoagulant option to take.  Warfarin is mandatory for patients with mechanical prosthetic valves or significant mitral stenosis.
  • Warfarin should remain first line in the following circumstances:
    • patients with severe renal dysfunction (eGFR<30mL/min/1.73m2)
    • patients requiring combination treatment with antiplatelet agents (specialist indication – see prescribing note).
    • patients for whom the ability to reverse the effects or to monitor the extent of anticoagulation is paramount (e.g. for adherence or safety reasons).
  • People in whom adherence to medicines is known to be an issue may not be suitable for NOACs. The anticoagulant effect of NOACs fades rapidly 12-24 hours after the last intake. Therefore strict compliance by the patient is crucial for adequate protection. In contrast, the anticoagulant effect of warfarin persists for several days after the last warfarin dose.
  • Sub-optimal compliance with warfarin alone is not an indication for changing therapy to a NOAC as many of the causes of non-compliance with warfarin may also result in non-compliance with the newer agents (e.g. alcoholism, chaotic lifestyle, wilful non-compliance).
  • Vitamin K (phytomenadione) can be given to reverse the effects of warfarin but takes 6-12 hours to become effective. If rapid reversal of warfarin is required specialist haematological advice on the agreed regional policy should be sought. Refer to the BNF.
  • Strategies for the reversal of the anticoagulant effects are limited and specialist haematological advice should be sought. An antidote for dabigatran is now available and antidotes for factor Xa inhibitors are in development. For information on the management of bleeding complications see ‘EHRA Practical Guide on the use of new oral anticoagulants in patients with non-valvular AF’.
  • Renal function should be monitored at least annually for patients taking NOACs. Ensure any necessary dose reductions are made.
  • Anticoagulation should not be withheld solely because the person is at risk of having a fall.
  • Only warfarin 1mg and 3mg tablets should be prescribed.
  • Indication and duration of treatment should be clearly recorded at initiation of treatment, the patient-held anticoagulant treatment booklet should be used. See BNF for details.
  • Clinical Knowledge Summaries provide a comprehensive overview in relation to oral anticoagulation and includes information that patients should be given prior to treatment and monitoring that should be carried out.
  •  See HSCB Guidance on the Safer Use of Oral Anticoagulant Therapy in Primary Care.
  • Patients should be warned of the hazards of treatment with anticoagulants. In particular, they should be aware of the need to report symptoms such as bruising. Anticoagulant treatment cards must be carried by patients and can be ordered by e-mailing the HSC Business Services Organisation at pharmacystationeryorders@hscni.net.
  • Dabigatran capsules cannot be crushed or opened and cannot be used in standard compliance aids due to the instability of the drug.
  • The MHRA have received a small number of reports suggesting lack of efficacy (thromboembolic events) in patients taking 15mg or 20mg rivaroxaban on an empty stomach. Remind patients to take rivaroxaban 15mg or 20mg tablets with food.
  • Guidance on the management of dental patients taking anticoagulants or antiplatelet drugs by the Scottish Dental Clinical Effectiveness Programme (SDECP) has been adopted for use in Northern Ireland and is available at http://www.sdcep.org.uk.

Cautions

  • A lower initial loading dose of warfarin is recommended in patients aged over 70 years.
  • There are many clinically important interactions with warfarin, clinicians are strongly advised to consult BNF before prescribing.
  • The MHRA Drug Safety Update December 2014 detailed the risk of serious haemorrhage with dabigatran, rivaroxaban and apixaban, clarified contraindications and reminded healthcare professionals of the need to monitor renal function.
  • The MHRA Drug Safety Update March 2013 detailed that dabigatran is contraindicated in patients with prosthetic heart valve(s) requiring anticoagulant treatment regardless of the length of time that has elapsed since valve replacement took place, because of the risk of thrombosis and haemorrhage.
  • Rivaroxaban and apixaban are also not recommended for use in patients with prosthetic heart valves.
  • Refer to BNF for full details of cautions, contraindications and interactions with NOACs.