The conditions and the treatment
Atrial fibrillation is a condition that affects the heart, making it beat irregularly and too fast. When this happens, the heart cannot efficiently pump blood around the body. Blood can also collect in one of the heart's chambers and clot. If this happens, the clot can move and block a blood vessel somewhere else in the body (called a systemic embolism). If this cuts off the blood supply to the brain it can cause a stroke or transient ischaemic attack (a mini stroke).
Edoxaban (Lixiana) is an anticoagulant medicine that helps to prevent blood from clotting. It does this by interfering with a substance in the body called thrombin, which is involved in the development of blood clots.
NHS Choices (www.nhs.uk) may be a good place to find out more.