Until recently, vitamin K antagonists, warfarin being the most commonly used agent in the United States, have been the only oral anticoagulant therapies available to prevent stroke in patients with atrial fibrillation (AF). In the last 5 years four new, non-vitamin K oral anticoagulants, the so-called NOACs or novel oral anticoagulants, have come to market and been approved by the Federal Drug Administration. Despite comparable if not superior efficacy in preventing AF-related stroke, and generally lower risks of major hemorrhage, particularly intracranial bleeding, the uptake of these agents has been slow. A number of barriers stand in the way of the more widespread use of these novel agents. Chief among them is concern about the lack of antidotes or reversal agents. Other concerns include the need for strict medication adherence, since missing even a single dose can lead to a non-anticoagulated state; out-of-pocket costs for patients; the lack of easily available laboratory tests to quantitatively assess the level of anticoagulant activity when these agents are being used; contraindications to use in patients with severe chronic kidney disease; and black-box warnings about the increased risk of thromboembolic events if these agents are discontinued prematurely. Fortunately, a number of reversal agents are in the pipeline. Three reversal agents, idarucizumab, andexanet alfa, and aripazine, have already progressed to human studies and show great promise as either antidotes for specific drugs or as universal reversal agents. The availability of these reversal agents will likely increase the clinical use of the non-vitamin K oral anticoagulants. In light of the many complex and nuanced issues surrounding the choice of an optimal anticoagulant for any AF patient, a patient-centered/shared decision-making approach will be useful.
Keywords: Anticoagulation; Atrial fibrillation; Non-vitamin K oral anticoagulants; Quality improvement; Warfarin.