In these patients with AF, a low -VASc score was associated with low thromboembolic risk regardless of whether the patients had bioprosthetic valves.S4.1.1-43 In addi- tion, in the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation; apixaban) and ENGAGE AF- TIMI 48 (edoxaban) AF trials, small numbers of these patients (with mitral or aortic bioprosthet- ic valve implants) were included. In these small subgroups, the findings suggested that apixaban (41 patients) and edoxaban (191 patients) ap- peared to be equitable alternatives to warfarin in patients with AF and remote bioprosthetic Although short- term anticoagulation of bioprosthetic valves after implantation is standard practice, further study is needed before the routine long-term use of the CHA2 -VASc score can be recom- mended in AF patients with bioprosthetic heart 5. One mechanical aortic valve replacement has FDA- approved recommendations of an INR of 1.5 to 2.0 (3 months after implantation) along with low- dose aspirin, based on a limited clinical trial.S4.1.1-46 This trial was designed to test whether it is safe and effective to treat patients with less aggres- sive anticoagulant therapy after implantation of an approved mechanical valve prosthesis (On-X). Although patients with AF were not excluded, very few were enrolled (see also the AHA/ACC valvular heart disease guidelinesS4.1.1-18 S4.1.1-19 ). 7. All 4 NOACs with FDA approval for use in patients with AF have dosing defined by renal function (creatinine or CrCl using the Cockcroft-Gault equation). 