Vitamin K antagonists are the only oral anticoagulants available and are considered as well-established treatment to prevent a first stroke or a recurrent stroke in patients with atrial fibrillation. The difficulties in the routine management of these patients cause an underuse of vitamin K antagonists. For long-term use, there is a need for safer and more effective oral anticoagulants that do not require routine monitoring of coagulation. Recently, new drugs have been developed and there are a number of clinical trials for the primary and secondary prevention of stroke in atrial fibrillation. The new anticoagulants that are being investigated target factor Xa or thrombin. The factor Xa inhibitors include indirect inhibitors such as idraparinux and biotinylated idraparinux that inhibit factor Xa by potentiating antithrombin. Also being investigated are apixaban and rivaroxaban, orally active agents that inhibit factor Xa directly. Direct thrombin inhibitors include ximelagatran and dabigatran etexilate. Although ximelagatran was withdrawn early because of liver toxicity, it provided convincing evidence that new oral anticoagulants have the potential to replace warfarin. However, even if these new drugs prove superior to dose-adjusted warfarin, their benefits must be substantial (retaining high efficacy with added safety and convenience) to offset their increased cost.

Keywords:
Vitamin K antagonists, Atrial fibrillation, Ximelagatran, Warfarin, Heparin, Anticoagulants, Ischemic stroke
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