Oral Anticoagulants to Reduce the Risk of Stroke in Atrial Fibrillation: How Should a Clinician Choose?

Abstract

Atrial fibrillation (AF), a common arrhythmia that occurs with increasing frequency in the aging population, is associated with increased mortality and morbidity. To ensure that patients receive adequate anticoagulant prophylaxis, clinical guidelines for anticoagulation advocate use of validated scoring systems to stratify patients by cardiovascular risk and predict the individual patient's risk of adverse effects of therapy. Recently approved oral anticoagulants-a direct thrombin inhibitor and the factor Xa inhibitors-may offer advantages over the 50-year standard, warfarin, for efficacy, safety, and ease of administration. Clinical trial experience with the newly approved agents and others, yet to be approved, will define their relative value in reducing the risk of thromboembolism associated with AF. This article discusses issues that may help clinicians choose among these newer agents and individualize treatment appropriately. Clinical VignetteA 52-year-old woman with a history of hypertension, diabetes mellitus, advanced emphysema, on long-term oxygen therapy with normal renal and left ventricular function, and diagnosed with atrial fibrillation of more than 2 days duration has decided to pursue a rate control strategy after discussions with her physician. She is reluctant to use warfarin because of the need for frequent monitoring, and is keen to know about the newer oral anticoagulants for atrial fibrillation. Which anticoagulant would be ideal for this patient?

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“…Rivaroxaban (Xarelto®) and apixaban (Elequis®) reach peak plasma concentration at around 3 hours and are well tolerated, exhibiting fewer side-effects than dabigatran. 42,43 Owing to the mechanisms of elimination, both drugs should be avoided in hepatic failure but can be used in mild to moderate renal failure. 44,45 Apixaban can be used safely at a reduced dose in severe renal failure.…”

“…48,49 Early trials demonstrated that rivaroxaban and apixaban were as effective as warfarin in the management of non-valvular AF with fewer bleeding complications. 43,50 Both drugs have also been shown to be as effective as LMWH in the prophylaxis of venous thromboembolism (VTE) in orthopaedic surgery patients and, again, fewer bleeding issues were observed. 42, 51,52 Enoxaban is another direct Xa inhibitor which may show promise in the future but has not yet been fully researched or approved for use.…”

“…42, 51,52 Enoxaban is another direct Xa inhibitor which may show promise in the future but has not yet been fully researched or approved for use. 43,53…”

“…47 It is worth noting that the half-life of rivaroxaban is 5−9 hours, whereas apixaban has a half-life of 9−14 hours, which will have implications for management of haemorrhage. 43…”