This study is for adults with a heart condition called atrial fibrillation, where the heart beats too fast and unevenly. The research is testing two new drugs, REGN7508 and REGN9933, to see if they can help prevent blood clots better than a common medicine called apixaban. Blood clots can cause strokes, so it's important to find effective treatments.

During the study, doctors will check how much of the drugs are in the blood, if they cause side effects, and if the body reacts by making antibodies that could make the drugs less effective.

• The study involves regular check-ups to monitor health and drug effects.
• Participants should be ready for blood tests to check drug levels and effects.
• Some people may not qualify, like those with certain heart or kidney conditions.

If you're interested, you'll need to have a specific heart score (CHA2DS2-VA) and not have certain conditions like a recent stroke or severe kidney issues. This study helps understand if these new drugs are safe and effective for patients with atrial fibrillation.