Preventing Stroke in Atrial Fibrillation: How to assess patient risk and how to treat?
‘Atrial fibrillation (AF) is a perverse consequence of success’ said Professor Richard Hobbs (Birmingham, UK) in describing how an ageing population and improved survival from coronary heart disease is resulting in an increasingly large cohort of patients with AF. There is a five fold increased risk of stroke for patients with AF and they are also at risk of multiple strokes and more severe strokes. This has major implications for patients, their families and healthcare systems.
There is a large body of evidence to support the use of antithrombotic agents in patients with AF to reduce stroke risk. ‘Warfarin is one of the most effective treatments we have in medicine’, said Professor Hobbs. The large treatment effect of warfarin in terms of reducing stroke risk must however be balanced against the risk of major bleeding. Risk stratification scores such as CHADS2 can be used to determine which patients should be offered warfarin rather than aspirin however many fall into the intermediate category. CHADS2 VASC is a more accurate tool which incorporates advanced age, sex and history of coronary artery disease in addition to the original score components.
The importance of considering treatment in the elderly was also discussed. ‘The average life expectancy age 65 is over 20 years….which means there is plenty of time for preventative strategies to be beneficial’ The results of the BAFTA study showed patients with AF over 75 years of age treated with warfarin had a significantly reduced risk of stroke compared to those treated with aspirin without an increased risk of major haemorrhage. However, warfarin does have a narrow therapeutic window and requires frequent dose adjustments so the recent evidence from the RE-LY study in favour of the direct thrombin inhibitor Dabigatran is encouraging. Unlike warfarin, direct thrombin inhibitors act at a single point on the coagulation cascade and do not require regular monitoring.
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