New Oral Anticoagulants for Stroke Prevention in Atrial Fibrillation: More Choices Bring More Challenges

摘要

Atrial fibrillation (AF) increases the risk of ischemic stroke approximately 5-fold.1 Whereas the average annual risk of stroke for AF patients averages 5%, the presence of additional risk factors such as heart failure, hypertension, diabetes, prior stroke, or age over 75 years increases this risk.2 To reduce this risk, guidelines from the American College of Chest Physicians for stroke prevention in AF strongly recommend an oral anticoagulant for patients at moderate to high risk for stroke .For decades warfarin has been the only available oral anticoagulant. An impressive body of clinical trial evidence has definitively shown that warfarin reduces the risk of ischemic stroke in AF patients by approximately two-thirds.2 However, long-term warfarin therapy also carries a substantial burden for the patient including a narrow therapeutic window, need for routine laboratory monitoring, and significant potential for drug and food interactions. These limitations likely account for the suboptimal utilization of warfarin in eligible patients with AF. For example, a recent population-based retrospective cohort study of 41,447 Medicare beneficiaries aged 66 years and older reported an overall warfarin use rate of 66.8%, a finding consistent with that of prior studies.Three novel oral anticoagulant drugs have been approved for stroke prevention in AF. Dabigatran,a direct thrombin inhibitor, and rivaroxaban, a factor Xa inhibitor, were approved in 2010 and 2011, respectively. In 2012, another factor Xa inhibitor, apixaban, received US Food and Drug Administration (FDA) approval. Although the availability of these newer oral anticoagulant drugs increases the therapeutic options for patients, it also presents challenges for clinicians who must now choose among the 4 agents. This article will discuss the advantages and disadvantages of these newer agents and their possible role in therapy.