In addition, it is well known that AF significantly increases the risk of stroke. The majority of strokes occur due to blood clots forming in the LAA. Traditionally, the most effective treatment to minimise the risk of stroke has been to thin the blood with agents such as warfarin. This therapy requires regular blood tests at much inconvenience to patients and increases the risk of bleeding complications. Recently, a large study demonstrated that use of an implanted device (Watchman®) to occlude the LAA is as effective as warfarin in preventing stroke and confers a lower mortality rate.