Atrial fibrillation (AF) is the most common cardiac arrhythmia, and is associated with increased morbidity, mortality, and healthcare costs.1–3 The prevalence and incidence of AF are increasing; as many as 14 million people in Europe will have AF by 2060.4 The most devastating complication is ischaemic stroke. In at-risk individuals, oral anticoagulation (OAC) with a vitamin K antagonist (VKA) or non-VKA OAC (NOAC) can reduce the relative risk of ischaemic stroke by 64%.5 The trade-off with OAC is an increase in the risk of bleeding.
When presented with a patient with AF, clinicians must assess whether they expect the patient to derive net benefit from OAC. Currently, the European Society of Cardiology (ESC) Guidelines for the Diagnosis and Management of AF recommend using the CHA2DS2-VASc score to risk-stratify patients for stroke prevention.6 The guidelines recommend (Class I, Level of Evidence A) that OAC be prescribed to men with a CHA2DS2-VASc score ≥2 and to women with a CHA2DS2-VASc score ≥3. This group represents patients widely accepted as having a high risk of stroke and resultant large net clinical benefit from OAC. Accordingly, this group made up the majority of AF patients enrolled in both the early VKA trials and the contemporary NOAC trials.5,7 This is a strong recommendation that is built upon the highest quality of evidence.