antithrombotic treatment in chronic atrial fibrillation

Last edited 05/2021 and last reviewed 09/2022

Assessment of stroke and bleeding risks

Stroke risk

• use the CHA2DS2-VASc stroke risk score to assess stroke risk in people with any of the following:
  • symptomatic or asymptomatic paroxysmal, persistent or permanent atrial fibrillation
  • atrial flutter
  • a continuing risk of arrhythmia recurrence after cardioversion back to sinus rhythm

Interventions to prevent stroke

• Do not offer stroke prevention therapy to people aged under 65 years with atrial fibrillation and no risk factors other than their sex (that is, very low risk of stroke equating to a CHA2DS2-VASc score of 0 for men or 1 for women)

Bleeding risk

• assess the risk of bleeding when:
  • considering starting anticoagulation in people with atrial fibrillation and
  • reviewing people already taking anticoagulation
• use the ORBIT bleeding risk score to assess bleeding risk

• offer monitoring and support to modify risk factors for bleeding, including:
  • uncontrolled hypertension
  • poor control of international normalised ratio (INR) in patients on vitamin K antagonists
  • Concurrent medication, including antiplatelets, selective serotonin reuptake inhibitors (SSRIs) and non-steroidal anti-inflammatory drugs (NSAIDs)
  • harmful alcohol consumption
  • reversible causes of anaemia

Anticoagulation in chronic atrial fibrillation

• anticoagulation may be with apixaban, dabigatran etexilate, rivaroxaban or a vitamin K antagonist
  
  
  • consider anticoagulation for men a CHA2DS2-VASc score of 1. Take the bleeding risk into account
    • apixaban, dabigatran, edoxaban and rivaroxaban are all recommended as options
      
      
  • offer anticoagulation to people with a CHA2DS2-VASc score of 2 or above, taking bleeding risk into account
    • apixaban, dabigatran, edoxaban and rivaroxaban are all recommended as options
      
      
  • if direct-acting oral anticoagulants are contraindicated, not tolerated or not suitable in people with atrial fibrillation, offer a vitamin K antagonist
    
    
  • do not offer stroke prevention therapy to people aged under 65 years with atrial fibrillation and no risk factors other than their sex (that is, very low risk of stroke equating to a CHA2DS2-VASc score of 0 for men or 1 for women)
    
    
  • do not withhold anticoagulation solely because of a person's age or their risk of falls

Assessing anticoagulation control with vitamin K antagonists

• calculate the person's time in therapeutic range (TTR) at each visit. When calculating TTR:
  • use a validated method of measurement such as the Rosendaal method for computer-assisted dosing or proportion of tests in range for manual dosing
  • exclude measurements taken during the first 6 weeks of treatment
  • calculate TTR over a maintenance period of at least 6 months

Reassess anticoagulation for a person with poor anticoagulation control shown by any of the following:

• 2 INR values higher than 5 or 1 INR value higher than 8 within the past 6 months
  
  
• 2 INR values less than 1.5 within the past 6 months
  
  
• TTR less than 65%

Antiplatelets

• do not offer aspirin monotherapy solely for stroke prevention to people with atrial fibrillation

Reference:

• (1) NICE (April 2021). Atrial Fibrillation