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Antithrombotic treatment in atrial fibrillation
  1. L Kalra1,
  2. G Y H Lip2,
  3. on behalf of the Guideline Development Group for the NICE clinical guideline for the management of atrial fibrillation
  1. 1Cardiovascular Division, King’s College London School of Medicine, London, UK
  2. 2University Department of Medicine, City Hospital, Birmingham, UK
  1. Correspondence to:
    L Kalra
    Department of Medicine, King’s College London School of Medicine, Denmark Hill Campus, Bessemer Road, London SE5 9PJ, UK; lalit.kalra{at}

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In this article we discuss thromboprophylaxis for patients with atrial fibrillation.


Patients with atrial fibrillation and valvular heart disease (valvular atrial fibrillation) have a substantially greater risk of stroke and other thromboembolic events. Specifically, the presence of mitral valve stenosis has been shown to be a substantial risk for stroke and thromboembolism, with these events occurring in 9–20% of patients, up to 75% of whom have cerebral emboli.1,2 Indeed, patients with mitral stenosis in sinus rhythm who develop atrial fibrillation have a 3–7 times increased risk of thromboembolism.2,3 Owing to the risk of stroke and thromboembolism, it has been considered unethical to conduct placebo-controlled trials of antithrombotic treatment in patients with mitral valve disease.


The presence of atrial fibrillation without any valve disease (non-valvular atrial fibrillation) increases the risk of stroke and thromboembolism fivefold.4 Silent cerebral infarction is also common,5 and there is also a clustering of stroke events at the time of onset of the atrial fibrillation.6 In contrast with valvular atrial fibrillation, however, many large randomised trials in the past two decades have examined the value of antithrombotic treatment in non-valvular atrial fibrillation.7

Nonetheless, anticoagulation remains generally underused in clinical practice.8,9,10,11,12 Despite the higher risk associated with stroke in elderly people, as well as the greatest benefit of anticoagulation, elderly people (>75 years) are a group of patients in whom there is suboptimal use of thromboprophylaxis for atrial fibrillation. The many reasons for poor uptake of anticoagulants include the view that major randomised trials were not representative of clinical practice because of tight inclusion criteria and bias towards younger patients,8 as well as fears that the level of anticoagulation control, therapeutic efficacy and low complication rates seen in randomised trials may not be matched …

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  • Published Online First 4 September 2006

  • Competing interests: None.