Rivaroxaban in Patients with Atrial Fibrillation and a Bioprosthetic Mitral Valve

In the RIVER trial, published in the New England Journal of Medicine on November 26, 2020, investigators sought to determine the efficacy of rivaroxaban in patients with atrial fibrillation and a bioprosthetic mitral valve.  This was a randomized clinical trial, or rivaroxaban 20 mg once daily was compared with dose adjusted warfarin, with a target international eyes normalized ratio of 2.0–3.0 in patients with atrial fibrillation and a bioprosthetic mitral valve.  The primary outcome was a composite of death, major cardiovascular event including (valve thrombosis, CVA, TIA, embolism, or heart failure exacerbation requiring hospitalization) or major bleeding at 1 year.  A total of 1005 patients were enrolled at 49 sites in Brazil.  A primary outcome event occurred at a mean of 347.5 days in the rivaroxaban and 340.1 days in the warfarin arm.  Death from cardiovascular causes or thromboembolic events were seen in 17 patients in the rivaroxaban group and 26 patients in the warfarin clinic, HR 0.65 95% confidence interval, 0.35–1.20.  The incidence of stroke was 0.6% in the rivaroxaban group versus 2.4% in the warfarin clinic, hazard ratio of 0.25, 95% confidence interval 0.07–0.88.  Major bleeding occurred in 1.4% of patients in the rivaroxaban group versus 2.6% of the warfarin group, hazard ratio 0.54, 95% confidence interval 0.21–1.35.  The authors concluded “In patients with atrial fibrillation and a bioprosthetic mitral valve, rivaroxaban was noninferior to warfarin with respect to the mean time until the primary outcome of death, major cardiovascular events, or major bleeding at 12 months.”

Reference:

https://www.nejm.org/doi/full/10.1056/NEJMoa2029603

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