Should patients on vitamin K antagonists be treated differently?

Abstract

This editorial refers to ‘Edoxaban versus warfarin in vitamin K antagonist-experienced and naive patients with atrial fibrillation’, by M.L. O'Donoghue et al. , on page doi: 10.1093/eurheartj/ehv014. Relative to warfarin, non-vitamin K oral anticoagulants (NOACs) are at least as good at preventing stroke or systemic embolism, cause less haemorrhagic stroke, and result in modestly lower mortality.1 Thus, the European Society of Cardiology has recommended NOACs in place of vitamin K antagonists (VKAs) in most patients with atrial fibrillation (class IIa, level of evidence A).2 According to one report, the use of NOACs in the USA has increased to > 60% of prescriptions for patients being initiated on oral anticoagulation.3 However, patients already treated with VKAs are usually not switched to NOACs.4 The low rates of switching from VKAs to NOACs relate to multiple factors including patient preference, medication cost, and clinical factors such as severe renal impairment. There is a common perception that a patient who is stable on a VKA will derive less benefit from a NOAC than a “VKA-naive”, patient who has not been previously treated with a VKA. The question remains whether or not this perception is supported by evidence. Not only does prior use of a VKA influence decisions to use a NOAC, but so does the degree of International Normalized Ratio (INR) control on a VKA, as measured by the time in therapeutic range (TTR). The prevailing opinion is that switching to a NOAC is less beneficial for patients on a VKA with a high TTR. In the Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE W) trial, patients who were at centres …