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2625 pages added, reviewed or updated during the last month (last updated: 15/4/2021)

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prevention of thromboembolism in atrial fibrillation

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Atrial fibrillation is associated with an increased risk of peripheral thromboembolism (1).

  • the main risk factors for thromboembolic episodes are:
    • age
      • prevalence of AF also increases with age, from <0.5% in 40-50 years to 5% in those >65 years and 10% in those >75 (2)
    • hypertension
    • diabetes
    • previous history of thromboembolism
  • three quarters of strokes in patients with atrial fibrillation are thought to be caused by embolism from left atrial thrombus.
    • thrombus is found predominantly in the left atrial appendage.
    • transoesophageal echocardiography can detect left atrial thrombus in 15-30% of patients with chronic atrial fibrillation.

Antithrombotic therapy to prevent thrombo-embolism is recommended for all patients with AF, except in those at low risk (lone AF, aged <65 years, or with contraindications) (1).

The selection of antithrombotic therapy should be considered using the same criteria irrespective of the pattern of AF (i.e. paroxysmal, persistent, or permanent) (2).

The overall risk of stroke in non-rheumatic atrial fibrillation is 4.5% per year. The risk is higher in atrial fibrillation caused by rheumatic fever.

Assessment of the risk of bleeding should be considered when prescribing antithrombotic therapy (whether with vitamin K antagonist or aspirin)

  • the bleeding risk with aspirin should be considered as being similar to vitamin K antagonist, especially in the elderly
  • the HAS-BLED score should be considered as a calculation to assess bleeding risk, (2).


Last reviewed 01/2018