Anticoagulacion En Fibrilacion

REVIEW

Anticoagulation in atrial fibrillation: the present and the future

Marc R Dweck

• Anoop S V Shah • Keith A A Fox

Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK Correspondence to: Marc R Dweck. Email: mdweck@staffmail.ed.ac.uk

DECLARATIONS Competing interests None Funding MRD and KAAF are supported by the British Heart Foundation Ethical approvalNot applicable Guarantor KAAF Contributorship All authors contributed to the background reading and authorship of this manuscript Acknowledgements None

Summary Atrial fibrillation (AF) is the most common form of cardiac arrhythmia and associated with significant mortality and morbidity. It is a powerful predictor of future embolic stroke, such that anticoagulation is recommended in the majority ofpatients. For many years this has predominantly been in the form of vitamin K antagonists. However, there are well-documented difficulties with their administration that result in poor compliance and high discontinuation rates. Over recent years several oral alternative anticoagulant agents have become available with the potential to overcome many of these pitfalls. In this review, we discusscurrent recommendations for anticoagulant therapy in AF and how these may change in the future with the introduction of novel therapeutic options.

Introduction
Atrial fibrillation (AF) is the most common cardiac dysrhythmia, affecting over six million people in the European Union.1 Its prevalence increases with age, affecting 0.2% of the population aged 20 –55, but 9% of patients over the age of80.2 AF is associated with significant morbidity and mortality3 and is a strong independent risk predictor for embolic stroke. As a consequence, the default antithrombotic treatment for patients with AF is with vitamin K antagonists (mainly warfarin). Nevertheless, a substantial proportion of patients remain untreated with warfarin or discontinue warfarin anticoagulation. Several alternative oralanticoagulants have recently become available with the potential for improved compliance and reduced bleeding and stroke complications. The aim of this review is to discuss the current status of anticoagulation in AF and to examine the novel agents with the potential to change practice.

Stroke risk in AF
The most common thromboembolic complication observed in AF patients is ischaemic stroke.Patients with AF experience up to a five-fold increase in the risk of stroke with an annual incidence of 4.5% in patients left untreated.4 Furthermore, strokes in the context of AF are more likely to be severe and are often fatal. The risk of thromboembolic complications in non-valvular AF can be predicted using the CHADS2 scoring system, which is based upon the presence of heart failure, hypertension,age ≥75 years, diabetes mellitus and prior stroke or transient ischaemic attack. Those with a CHADS2 score of 0 have an annual risk of 2%, which rises to 18% in those with a score of 6.5 Recently, the CHA2DS2-V ASc scoring system has been introduced which also incorporates gender and peripheral vascular disease.6 The CHA2DS2-V ASc score has been shown to refine the risk prediction offered by CHADS2scoring and to improve the identification

J R Soc Med Cardiovasc Dis 2012;1:13. DOI 10.1258/cvd.2012.012018

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Journal of the Royal Society of Medicine Cardiovascular Disease

of those at very low risk for stroke (who do not need anticoagulation). It has been incorporated in the most recent European Society of Cardiology (ESC) guidelines.1 These guidelines suggest using oralanticoagulation in AF if the CHADS2 score is ≥2 or in those with a CHA2DS2-V ASc score of ≥1.

Warfarin therapy
Warfarin is an oral vitamin K antagonist. It exerts its anticoagulant effect by inhibiting the production of several different coagulation factors and has served as the mainstay for thromboembolic prophylaxis in AF. In patients with non-valvular AF and no history of stroke or transient...