XANTUS: rationale and design of a noninterventional study of rivaroxaban for the prevention of stroke in patients with atrial fibrillation

Atrial fibrillation (AF) is associated with a fivefold increase in the risk of stroke. The Phase III ROCKET AF (Rivaroxaban Once-Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation) trial showed that rivaroxaban, an oral, direct Factor Xa inhibitor, was noninferior to warfarin for the reduction of stroke or systemic embolism in patients with AF. Compared with warfarin, rivaroxaban significantly reduced rates of intracranial and fatal hemorrhages, although not rates of bleeding overall. XANTUS (Xarelto (R) for Prevention of Stroke in Patients with Atrial Fibrillation) is a prospective, international, observational, postauthorization, noninterventional study designed to collect safety and efficacy data on the use of rivaroxaban for stroke prevention in AF in routine clinical practice. The key goal is to determine whether the safety profile of rivaroxaban established in ROCKET AF is also observed in routine clinical practice. XANTUS is designed as a single-arm cohort study to minimize selection bias, and will enroll approximately 6,000 patients (mostly from Europe) with nonvalvular AF prescribed rivaroxaban, irrespective of their level of stroke risk. Overall duration of follow-up will be 1 year; the first patient was enrolled in June 2012. Similar studies (XANTUS-EL [Xarelto (R) for Prevention of Stroke in Patients with Nonvalvular Atrial Fibrillation, Eastern Europe, Middle East, Africa and Latin America] and XANAP [Xarelto (R) for Prevention of Stroke in Patients with Atrial Fibrillation in Asia-Pacific]) are ongoing in Latin America and Asia-Pacific. Data from these studies will supplement those from ROCKET AF and provide practical information concerning the use of rivaroxaban for stroke prevention in AF.