Background: This is a randomized, active comparator-controlled, double-blind, double-dummy, parallel group, dose-finding Phase 2 study to compare the safety of the oral FXIa inhibitor BAY 2433334 to a NOAC (apixaban) in patients with atrial fibrillation. Trial Registration No: EudraCT: 2019-002365-35 Sponsor: Bayer Trial Status: recruiting Enrolling Centers: Worldwide: 115 Number of patients needed: 800 Core Study Team Basel: