A Review of Oral Anticoagulants in Patients with Atrial Fibrillation

There is a high prevalence of atrial fibrillation in the United States, particularly in the elderly population. Patients with atrial fibrillation are at an increased risk of stroke and anticoagulant therapy is recommended. However, many eligible patients are not receiving therapy due to limitations and concerns related to the use of the vitamin K antagonist warfarin, such as slow onset of action, variable drug metabolism, risk of bleeding, and requirement for monitoring. Novel oral anticoagulants (NOACs) have been developed and may be used as an alternative to warfarin. This review article summarizes the current clinical trial data for warfarin compared with the NOACs dabigatran (direct thrombin inhibitor), and rivaroxaban and apixaban (factor Xa inhibitors). Dabigatran (150 mg twice daily) demonstrated superiority in reducing the stroke or systemic embolism rate compared with warfarin (1.53% vs 1.69%; P < 0.001). The risk of major bleeding was similar for dabigatran and warfarin (3.32% per year vs 3.57% per year; P = 0.32). Rivaroxaban (20 mg once daily) demonstrated noninferiority in reducing the stroke or systemic embolism rate compared with warfarin (2.1% vs 2.4%; P < 0.001). There was no significant difference between rivaroxaban and warfarin for the risk of major bleeding and clinically relevant nonmajor bleeding (14.9% per year vs 14.5% per year; P = 0.44). Apixaban (5 mg twice daily) demonstrated superiority compared with warfarin in preventing stroke or systemic embolism (1.27% vs 1.60%; P = 0.01). Apixaban significantly reduced major bleeding compared with warfarin (2.13% per year vs 3.09% per year; P < 0.001). Compared with warfarin, all-cause mortality was numerically lower for dabigatran (P = 0.051) and similar for rivaroxaban (P = 0.15). Apixaban demonstrated significantly lower mortality rates compared with warfarin (3.52% vs 3.94%; P = 0.047). All 3 NOACS--dabigatran, rivaroxaban, and apixaban--significantly reduced intracranial hemorrhage compared with warfarin. Novel oral anticoagulants may be a suitable alternative to warfarin for different patient populations due to minimal drug interactions, lower bleeding risk, and no monitoring requirement.