The extent to which differences in results from Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) and Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial (ROCKET) atrial fibrillation (AF)—the landmark trials for the approval of apixaban and rivaroxaban, respectively, for non-valvular AF—were influenced by differences in their protocols is debated. Here, F10 is linked to atrial fibrillation.