In two articles reporting the results of GALILEO (Jan. 9 issue), Dangas et al.1 and De Backer et al.2 provide conflicting results on the benefit of rivaroxaban in transcatheter aortic-valve replacement (TAVR). TAVR valves are made of bioprosthetic leaflets mounted on a stent, and targeting both components of the valve is needed to avoid thrombosis. Artificial surfaces trigger thrombosis mainly through contact system activation, leading to a local burst of thrombin generation. Antiplatelet drugs may play a role in down-regulating local coagulation activation, since thrombin generation occurs on activated platelet membranes, but anticoagulant drugs are known to perform better in this situation.2 However, target-specific anticoagulant drugs are unlikely to overcome the burst of thrombin generated by contact with surfaces. This hypothesis is supported by the higher risk of thrombosis observed with catheters, bioprosthetic artificial hearts, and mechanical prostheses during anticoagulation with fondaparinux, rivaroxaban, and dabigatran, respectively, than with heparins and vitamin K antagonists, which target several upstream coagulation factors.3-5 The key to preventing clinical valve thrombosis in TAVR may lie in short-term and specific contact-phase inhibition on top of long-term single antiplatelet therapy.
Anne‑Céline Martin, M.D., Ph.D. European Hospital Georges Pompidou Paris, France email@example.com
David M. Smadja, Pharm.D., Ph.D. INSERM UMR-S 1140 Paris, France
Nicole Karam, M.D., Ph.D. University of Paris Paris, France
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A Controlled Trial of Rivaroxaban after Transcatheter Aortic-Valve Replacement.