New antithrombotics for atrial fibrillation.

Atrial fibrillation (AF) is the most commonly occurring arrhythmia, and is a condition of both significant clinical and economic importance. An antithrombotic agent is considered mandatory as part of the management in most patients with AF. It has been conclusively demonstrated that long-term anticoagulation therapy can significantly reduce the risk of stroke in patients with nonvalvular AF. While vitamin K antagonists (VKAs) such as warfarin are highly effective, they possess numerous limitations that curtail their use, or make their use challenging for clinicians and patients. A new generation of anticoagulants are being investigated in phase III clinical trials in patients with AF. One or more of these agents have the potential to either replace or act as alternatives to VKA therapy in AF. This group includes the direct thrombin inhibitor, dabigatran, the direct factor Xa inhibitors rivaroxaban, apixaban, and edoxaban, and finally, the vitamin K analogue, tecarfarin. Additional agents are being developed in phase I or II clinical trials. The direct thrombin and factor Xa inhibitors are generally small, synthetic molecules with predictable pharmacokinetics, a predictable pharmacodynamic effect, few drug interactions and do not require routine therapeutic drug monitoring. These new anticoagulants may well represent a new era in anticoagulation. However, they do possess their own limitations and will present new challenges for clinicians.