Atrial fibrillation (AF) is the most studied cardiac arrhythmia in adults and leads to substantial morbidity and mortality. Best described etiological factors for AF are those secondary to cardiovascular disease explaining the marked increase in AF incidence with older age. In young and middle aged individuals however, particularly persistent AF and scar-related atrial arrhythmias may be due to atrial cardiomyopathy. A dedicated group of WECAM researchers studies the etiology, long-term prognosis and the optimal management of patients with atrial cardiomyopathy.