Apixaban VS Warfarin in AF Pts First Three Months After Repair or BIO AVR MVR

Inclusion Criteria: * Age ≥18 years at the time of enrolment * Open heart aortic or mitral valve repair or biological valve replacement in the last 10 days * Atrial fibrillation requiring anticoagulation (including pre-existing or post-operative atrial fibrillation), * Informed consent from either the patient or a substitute decision-maker. Exclusion Criteria: * Mechanical valve replacement * Antiphospholipid syndrome (triple positive) * Severe renal failure (Cockcroft-Gault equation; creatinine clearance \<15 ml/min) * Known significant liver disease (Child-Pugh classification B and C) * Left ventricular thrombus * Ongoing bleeding, hemorrhagic disorders, or bleeding diathesis * Known contraindication for any DOAC or VKA * Women who are pregnant, breastfeeding, or of childbearing potential * Follow-up not possible