The study, which is the only randomized trial testing rixaroxaban in this patient population, builds on previous evidence established by the DCRI-led ROCKET-AF and ARISTOTLE studies.
Results from the RIVER trial reveal important new information for the treatment of atrial fibrillation in patients with bioprosthetic mitral valves.
The late-breaking science, presented Saturday at the virtual American Heart Association Scientific Sessions 2020 and published simultaneously in the New England Journal of Medicine, show that a direct oral anticoagulant called rivaroxaban is non-inferior to warfarin in this patient population.
The findings were presented by Otavio Berwanger, MD, PhD, of the HCor Research Institute in Brazil. DCRI’s Renato Lopes, MD, PhD (top), and John Alexander, MD, MHS (bottom), were part of the trial leadership, with Lopes also serving as the clinical events classification committee chair.
The RIVER trial randomized over 1,000 patients from 49 sites and followed them for 12 months. The primary endpoint was a composite of death, major adverse cardiovascular events, or major bleeding. Results were as follows:
- The group that received rivaroxaban experienced an average of 347.5 days free from the primary endpoint, while the group that received warfarin had an average of 340.1 days.
- In the rivaroxaban group, 3.4 percent of patients died due to cardiovascular causes or thromboembolic events; in the warfarin group, 5.15 percent of patients died.
- Incidence of stroke and major bleeding were also lower in the rivaroxaban group, while other serious adverse events were similar between groups.
“We have shown that rivaroxaban is not inferior to warfarin for patients with atrial fibrillation and bioprosthetic mitral valves in respect to efficacy and safety outcomes,” Berwanger said. “Interestingly, rivaroxaban seems to have a greater treatment effect when compared with warfarin in the subgroups of patients who underwent valve surgery within three months of randomization and who were taking antiplatelet therapy.”
Although rivaroxaban and another direct oral anticoagulant called apixaban had been proven to be non-inferior and superior to warfarin in previous DCRI-led studies—ROCKET-AF and ARISTOTLE, respectively—both of the prior studies included no or few patients with bioprosthetic valves. The goal of the RIVER trial was to obtain clearer evidence on the best treatment strategy for atrial fibrillation in these patients.
“To the best of our knowledge, RIVER is the largest randomized trial specifically designed to assess the effects of a direct oral anticoagulant when treating patients with atrial fibrillation and a bioprosthetic mitral valve,” Lopes said. “The study is also the only randomized trial testing rivaroxaban in this patient population. We now have solid evidence that can guide treatment decisions when we care for these patients in clinical practice.”