Patients with Atrial Fibrillation have an increased risk of stroke; The Watchman Device can help to prevent this.
The CHADS-VASc score is used to quantify this risk (please see the section on atrial fibrillation for the details of the CHADS-VASc score). People who have a CHADS-VASc score of 1 or more are recommended to take Warfarin, or one of the novel anticoagulant drug, to reduce this risk. Unfortunately, there is also a risk of bleeding while taking one of these drugs. This risk is about 1 per 100 patients, each year.
If you are unlucky and develop a brain haemorrhage, bleeding from the bowel or another large area of bleeding after starting an anticoagulant, you would normally be told to stop this drug and not have it, or anything like it, again. Although this is good from a bleeding perspective, it means you will not be protected from developing a stroke. This was why the Watchman device was developed.