Oral anticoagulants for stroke prevention in atrial fibrillation: current status, special situations, and unmet needs.

In patients with non-valvular atrial fibrillation, oral anticoagulation with vitamin K antagonists reduces the risk of stroke by more than 60%. But vitamin K antagonists have limitations, including causing serious bleeding such as intracranial haemorrhage and the need for anticoagulation monitoring. In part related to these limitations, they are used in only about half of patients who should be treated according to guideline recommendations. In the past decade, oral agents have been developed that directly block the activity of thrombin (factor IIa), as well as drugs that directly inhibit activated factor X (Xa), which is the first protein in the final common pathway to the activation of thrombin. These novel non-vitamin K antagonist oral anticoagulants (NOACs) have been shown to be at least as good as warfarin for stroke prevention in atrial fibrillation and they have proved to have better safety profiles. Their net advantage is underscored by significantly lower all-cause mortality compared with warfarin in large clinical trials. Because of these features and their ease of use, they are recommended for stroke prevention in atrial fibrillation. They have also a fast onset and offset of action, but they currently lack specific antidotes. This paper addresses the role of anticoagulation for stroke prevention in atrial fibrillation in the era of NOACs, with a focus on special situations including management in the event of bleeding and around the time of procedures including cardioversion, catheter ablation, and device implantation. Also their use in patients with concomitant coronary artery disease, with advanced age, with chronic kidney disease, or with valvular heart disease will be discussed as well as the interaction of NOACs with other cardiac medication, and switching between anticoagulants.