Most of the patients with atrial fibrillation are known to have a risk of an embolic stroke( around a 5%) without anticoagulation. There are a minority of patient (elderly people, patients with a hemorrhagic risk, patients with renal insufficiency) in which anticoagulation is not feasible or imply a high haemorrhagic risk In such patients we have now a new method to prevent ischemic stroke. It is know that 90% of the thrombi are originated from left atrial appendage. The closure of appendage is done by transfemoral vein with a device like a cork Watchman or Amplatzer which close this little recess.