In patients with atrial fibrillation (AFib) and a bioprosthetic mitral valve, results from the RIVER trial show rivaroxaban was noninferior to warfarin in terms of death, major cardiovascular events or major bleeding at one year.

The trial, which was presented Nov. 14 during AHA 2020 and simultaneously published in the New England Journal of Medicine, enrolled 1,005 patients with AFib and a bioprosthetic mitral valve at 49 sites in Brazil. Patients were randomized to rivaroxaban (20 mg once daily) or dose-adjusted warfarin. The primary outcome was a composite of death, major adverse cardiovascular events or major bleeding at 12 months.

According to Otavio Berwanger, MD, PhD, et al., a primary outcome event occurred at a mean of 347.5 days in the rivaroxaban group compared with 340.1 days in the warfarin group (P<0.001 for noninferiority). "Those who received rivaroxaban for one year were free of a composite primary outcome of death, major cardiovascular events, or major bleeding for a mean of 7.4 days longer than their counterparts who received warfarin," they noted.

Broken down by event, death from cardiovascular causes or thromboembolic events occurred in 17 patients (3.4%) in the rivaroxaban group compared with 26 patients (5.1%) in the warfarin group. The incidence of stroke was 0.6% in the rivaroxaban group and 2.4% in the warfarin group, while major bleeding occurred in 7 patients (1.4%) in the rivaroxaban group and in 13 patients (2.6%) in the warfarin group. The frequency of other serious adverse events was similar across both groups, researchers said.

Berwanger and colleagues note that the RIVER trial provides "important insights about the management of oral anticoagulation after mitral-valve surgery" in AFib patients. "Since rivaroxaban does not require monitoring of the [international normalized ratio] and has an anticoagulant effect that is more consistent and less influenced by food or concomitant medications than warfarin, it represents an attractive alternative for this patient population," they said. However, they also urge that their findings "be interpreted with caution" and recommend additional studies before making changes to clinical practice.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Interventions and Structural Heart Disease

Keywords: AHA Annual Scientific Sessions, AHA20, Atrial Fibrillation, Mitral Valve, Anticoagulants, Heart Valve Diseases, Percutaneous Coronary Intervention, Arrhythmias, Cardiac

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