New oral anticoagulants for stroke prevention in atrial fibrillation

摘要

We are at the dawn of a new era in oral anticoagulant therapy. For the past 65 years, the only available oral anticoagulants were the vitamin K antagonists, such as warfarin [1]. Although effective, these agents are difficult to administer because the dose varies from patient to patient reflecting, at least in part, common genetic polymorphisms that influence warfarin metabolism, differences in the dietary intake of vitamin K and multiple drug interactions [2]. Consequently, the anticoagulant response to warfarin is so variable that frequent monitoring is necessary to ensure that the level of anticoagulation is therapeutic. Such monitoring is burdensome for patients and physicians and costly for the healthcare system. In addition, even when monitoring is performed, the level of anticoagulation is above or below the therapeutic range in at least half the patients, which places them at risk of bleeding or thrombosis, respectively. Because of these limitations, warfarin is underused, particularly for stroke prevention in patients with atrial fibrillation [3-7]. Therefore, there is an urgent need for new oral anticoagulants that can be given in fixed doses and produce such a predictable level of anticoagulation that monitoring is unnecessary. Finally, this need has been fulfilled.