1. Cardiology Outpatient Clinic, The John Paul II Hospital, 31-202 Kraków, Poland
2. Department of Invasive Electrophysiology and Cardiac Pacing, Acibadem City Clinic Tokuda Hospital, 1407 Sofia, Bulgaria
3. The Davidai Center for Rhythm Disturbances and Pacing, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel
4. Department of Cardiology, Electrophysiology Department, ARNAS Ospedali Civico Di Cristina Benfratelli, 90127 Palermo, Italy
5. Clinic for Electrophysiology, Herz- und Diabeteszentrum NRW, Georgstr. 11, 32545 Bad Oeynhausen, Germany
6. Department of Electrocardiology, Institute of Cardiology, Faculty of Medicine, Jagiellonian University Medical College, 31-202 Kraków, Poland
7. Department of Electrocardiology, The John Paul II Hospital, 31-202 Kraków, Poland