Transesophageal echocardiography plays a key role in the selection of suitable patients for cardioversion. If a transesophageal echocardiography is conducted prior to cardioversion of a patient with a persistent non-valvular atrial fibrillation, we expect in 12 % of the patients a thrombus in the left atrial appendage (Antithrombotic therapy in atrial fibrillation, American College of…