Is Warfarin Use in Patients With Valvular Atrial Fibrillation Becoming Extinct?

Atrial fibrillation (AF) is a significant health care problem affecting 5.2 million Americans with substantial morbidity and mortality.^1-2  Direct oral anticoagulants (DOACs) are firmly established as prevention for strokes in nonvalvular AF.^3-4 However, in valvular heart disease—which commonly coexists with AF—the effectiveness and safety of DOACs is not as well established.   

A recent study in the Annals of Internal Medicine examined the effectiveness and safety of DOACs compared to warfarin in patients with valvular AF.⁵ In 56,336 patients from a US based commercial health care database who had a least one dispensed prescription for either a DOAC or warfarin (1:1 match) over an approximately 9.5 year follow-up period, DOACs showed a lower risk for ischemic stroke or systemic embolism (hazard ratio [HR]. 0.64 [95% CI: 0.59-0.70]) with a lower risk for major bleeding (HR, 0.67 [95% CI: 0.63-0.72]) versus warfarin.  The effectiveness results were consistent for apixaban and rivaroxaban. The safety results were consistent for dabigatran, but not for effectiveness. 

These real-world data support the use of DOACs over warfarin in valvular AF.  The advantages of DOACs, including convenient dosing without routine laboratory monitoring, support these findings. DOACs, however, do require adequate renal and liver function with a history of good medication adherence. But should warfarin be abandoned in this setting? The answer is no. In patients with a stable pattern of international normalized ratios, where cost of a DOAC prescription is of major concern and where renal and liver function are worsening, warfarin remains a viable choice. 

Mark A. Munger, PharmD, FCCP, FACC, is a professor of pharmacotherapy and adjunct professor of internal medicine, at the University of Utah, where he also serves as the associate dean of Academic Affairs for the College of Pharmacy.

Disclaimer: The views and opinions expressed are those of the author(s) and do not necessarily reflect the official policy or position of the Population Health Learning Network or HMP Global, their employees, and affiliates. Any content provided by our bloggers or authors are of their opinion and are not intended to malign any religion, ethnic group, club, association, organization, company, individual, or anyone or anything.  

References: 

1. Colilla S, Crow A, Petkun W, Singer DE, Simon T, Liu X. Estimates of current and future incidence and prevalence of atrial fibrillation in the U.S. adult population. Am J Cardiol. 2013;112(8):1142-1147. doi:10.1016/j.amjcard.2013.05.063
2. Centers for Disease Control and Prevention.  Atrial fibrillation 2020. www.cdc.gov/heartdisease/atrial_fibrillation.htm.  Published on September 98, 2020. Accessed on April 22, 2021.
3. Granger CB, Alexander JH, McMurray JJ, et al. ARISTOTLE Committees and Invesigators. Apixaban versus warfarin in patients with atrial fibrillation. N Engl J Med 2011;365:981-92. doi: 10.1056/NEJMoa1107039
4. Patel MR, Mahaffey KW, Garg J, et al.  ROCKET AF Investigators. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. N Engl J Med 2011;365:883-91. doi: 10.1056/NEJMoa1009638
5. Dawwas GK, Dietrich E, Cuker A, Barnes GD, Leonard CE, Lewis JD. Effectiveness and Safety of Direct Oral Anticoagulants Versus Warfarin in Patients With Valvular Atrial Fibrillation : A Population-Based Cohort Study [published online ahead of print, 2021 Mar 30]. Ann Intern Med. 2021;10.7326/M20-6194. doi:10.7326/M20-6194