Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with approximately one million affected patients in Germany. Current estimates suggest that the life-time risk for AF is 30% for men and slightly less for women at the age of 40 years. Due to demographic changes in the German population, the incidence and prevalence of AF is expected to double within the next 30 years. AF almost doubles mortality and causes important morbidity, mainly due to thrombo-embolic complications and stroke. In addition, the arrhythmia in itself reduces the chronotropic adaptation of the heart to increased work load and reduces cardiac output, especially in patients with heart failure or other cardiac disease. Restoration of sinus rhythm would reduce this burden of disease.