Author Affiliations: Department of Medicine, McMaster University, and Hamilton Health Sciences, Hamilton, Ontario, Canada.
In North America, approximately 170 000 patients undergo aortic valve replacement annually, and the majority of these patients receive a bioprosthetic, rather than a mechanical, prosthesis.1 Bioprosthetic valves are more commonly used because many of these patients are elderly and frail and have comorbid conditions that render them at increased risk of bleeding with the prolonged anticoagulation therapy that would be required with implantation of a mechanical valve. A 3-month course of warfarin with or without concomitant aspirin is frequently administered after implantation of a bioprosthetic valve, because observational studies suggest that there is a risk of thromboembolism until the valve support structures are endothelialized.2,3 Although the rates of thromboembolic events among patients given warfarin or the combination of warfarin plus aspirin after bioprosthetic aortic valve implantation appear to be lower than the event rates among patients given aspirin alone, warfarin treatment is associated with more bleeding.4 With the limited evidence to date based primarily on observational studies, the trade-off between reduced thromboembolic events with warfarin and increased bleeding remains uncertain.
Mehta SR, Weitz JI. Warfarin After Bioprosthetic Aortic Valve Implantation. JAMA. 2012;308(20):2147-2148. doi:10.1001/jama.2012.91476