The Direct Oral Anticoagulation Versus Vitamin K Antagonist After Cardiac Surgery Trial

This study, called the Direct Oral Anticoagulation Versus Vitamin K Antagonist After Cardiac Surgery Trial (DOAC-CS), is comparing two types of blood thinners — direct oral anticoagulants (DOACs, such as rivaroxaban or apixaban) versus traditional vitamin K antagonists (like warfarin) — in patients who develop atrial fibrillation (an irregular heartbeat) around the time of open heart surgery. Both types of drugs prevent dangerous blood clots, but DOACs may be easier to manage and have fewer complications. You may be eligible if: - You are at least 18 years old - You had open heart surgery within the last 10 days - You have atrial fibrillation (either pre-existing or new after surgery) that requires blood thinning medication - You or your substitute decision-maker has given informed consent You may NOT be eligible if: - You received a mechanical valve replacement - You have antiphospholipid syndrome (triple positive) - You have severe kidney failure (creatinine clearance below 15 ml/min) - You have significant liver disease (Child-Pugh B or C) - You have a blood clot in your left heart ventricle - You have active bleeding or a bleeding disorder - You have a known contraindication to any DOAC or vitamin K antagonist - You are a woman who is pregnant, breastfeeding, or of childbearing potential - You had a left ventricular assist device or heart transplant - You have moderate to severe mitral valve disease that was not corrected during your surgery Talk to your cardiac surgeon or cardiologist if you are recovering from heart surgery and have atrial fibrillation.