It is well established that people with Atrial Fibrillation (AF) are at increased risk of stroke; Anticoagulation can indefinitely mitigate that risk.
Stasis of blood in the atria (the upper chambers), which occurs when the atria fibrillate, is thought to increase the risk of clot formation, particularly within a structure called the left atrial appendage. If this clot breaks off, it can travel through the circulation to the brain, causing brain damage, ‘aka’ a stroke. Overall, this risk is 5-fold higher compared to people without AF. Although this association is extremely well documented, the exact role of AF in causing stroke is much less clear and there is increasing evidence that AF may perhaps be a marker of stroke risk rather than actually causing strokes. Nevertheless, there is compelling evidence that patients with AF who also have risk factors for stroke, benefit from taking anticoagulants indefinitely to mitigate that risk, which far outweighs the risk of bleeding in the vast majority of patients.