This study looks at the best way to prevent blood clots in patients who get a heart rhythm problem called *atrial fibrillation (AF)* after heart surgery called *coronary artery bypass graft (CABG)*. AF is when the heart beats irregularly. Blood clots can cause strokes or heart attacks. The study compares two treatments: one uses *oral anticoagulation (OAC)*, which are medicines like *warfarin* or *apixaban* that help prevent clots, and the other uses only *antiplatelet* medicines, like *aspirin*. The study will check how well these treatments work over 90 days and if they cause bleeding.

• The study lasts for 90 days with follow-ups at 30, 60, and 180 days.
• Participants will be randomly assigned to either OAC with antiplatelet or antiplatelet-only therapy.
• For those not in the main study, there is an option to join a registry study with a brief survey.

Patients over 18 who had CABG surgery and developed new AF may join the study, unless they have certain health issues like other heart surgeries or serious liver disease. Up to 500 patients can also join a digital health study using a heart monitor.