Editor–We read with great interest the article by Breen and Hunt which presented an overview of the new oral anticoagulants (Clin Med October 2011 pp 497–9). We wish to highlight three new studies published since their review was prepared, with important relevance to the topic of stroke prevention in atrial fibrillation (AF).
AVERROES was a double-blinded study comparing the use of the novel factor Xa inhibitor apixaban (5 mg twice daily) versus aspirin, in nearly 6,000 patients with AF, who were, either intolerant or unwilling to take oral vitamin K antagonist therapy.1 There was a considerable reduction in the rate of the primary endpoint of stroke and systemic embolus (SSE) in the apixaban group (1.6% per annum n 3.7% per annum; p<0.001), despite similar rates of intracranial haemorrhage, major bleeding and death.2
The double-blinded ROCKET AF study compared once daily (20 mg) oral Xa inhibitor rivaroxaban with dose-adjusted warfarin among 14,264 AF patients at higher risk for stroke. The rate of the primary endpoint of SSE was similar between rivaroxaban (1.7% per annum) and warfarin (2.2% per annum). While there were similar rates of major and non-major bleeding, rivaroxaban did lead to significantly fewer reports of intracranial and fatal bleeding. Finally, in the largest ever randomised stroke prevention in AF study, the double-blinded ARISTOTLE study randomised 18,201 patients to either oral apixaban (again 5 mg twice daily) or dose-adjusted warfarin.3 Not only was apixaban non-inferior but actually superior to warfarin for the SSE primary endpoint (1.27% n 1.60% respectively). Furthermore, the rates of major bleeding (2.13% n 3.09%), all cause mortality (3.52 n 3.94%) and haemorrhagic stroke (0.24% n 0.45%) were all significantly reduced with apixaban.
These data, along with previously published data from the single-blinded RELY study using the oral direct thrombin inhibitor dabigatran, provide consistent evidence to suggest that AF anticoagulation practice is set to dramatically change in the very near future.
References
- 1.Connolly SJ, Eikelboom J, Joyner C, et al. AVERROES Steering Committee and Investigators. Apixaban in patients with atrial fibrillation N Engl J Med 2011. 364 806–17 [DOI] [PubMed] [Google Scholar]
- 2.Patel MR, Mahaffey KW, Garg J, et al. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. ROCKET AF Investigators N Engl J Med 2011. 365 883–91 [DOI] [PubMed] [Google Scholar]
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