Inclusion Criteria:  Adults ≥18 years  Cardiac surgical procedures  Coronary artery bypass grafting (on or off pump) Bioprosthetic aortic valve replacement Mitral valve repair Ascending aorta procedures Tricuspid valve repair Pulmonic valve procedures.  An indication for oral anticoagulation  Pre-existing AF New post-operative atrial fibrillation Arterial embolism Venous thromboembolism.  Exclusion Criteria:  Cardiac surgical procedure  Redo-sternotomy Bioprosthetic mitral valve replacement Mechanical valve replacement Transcatheter valve procedure Aortic arch procedures Pericardectomy Post-operative extracorporeal membrane oxygenation Heart transplant Ventricular assist devices Congenital heart procedures Stroke within 4 weeks prior to surgery or postoperatively prior to initiation of study drug Recent history of heparin-induced thrombocytopenia (less than 3 months) High risk for bleeding (e.g. major bleed [intracranial hemorrhage, gastrointestinal bleed] within past 3 months, unexplained drop in hemoglobin pre-operatively) Postoperative bleeding requiring return to operating room for exploration prior to randomization Perioperative severe renal failure, defined as any eGFR <30 mL/min/1.73m2 or requirement of dialysis Perioperative liver failure with alanine aminotransferase > 3x upper limit of normal Pregnant or lactating women Patient unable to consent Contraindication to any study drug (including use of concomitant strong P-glycoprotein or cytochrome P450 enzyme inducers/inhibitors).