New anticoagulants for stroke prophylaxis in atrial fibrillation: assessing the impact on medication adherence.

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, is a potent risk factor for stroke and transient ischemic attack. Most patients with AF receive antithrombotic stroke prophylaxis, often in the form of a vitamin K antagonist, typically warfarin. Drug treatment with warfarin is associated with significant management issues, such as an unpredictable dose response necessitating dose adjustments, frequent laboratory monitoring, and multiple interactions with other medications, as well as foods. A new generation of novel anticoagulants has emerged that includes dabigatran etexilate, a direct thrombin inhibitor, and rivaroxaban and apixaban, both highly selective factor Xa inhibitors. These newer agents possess a highly predictable pharmacokinetic-pharmacodynamic relationship, allowing for fixed dosing and no necessity for routine laboratory monitoring; additionally these agents have minimal drug interactions. Dabigatran etexilate and apixaban are both twice-daily medications, whereas rivaroxaban is administered once daily for stroke prophylaxis. The impact of dosing frequency on medication adherence with these agents has not been prospectively evaluated; however, the frequency of dosing intervals has been shown to affect medication adherence, which in turn may influence patient outcomes.