1. First Department of Cardiology, Interventional Electrocardiology and Hypertension, Jagiellonian University, Medical College , Jakubowskiego 2, 30-688 Krakow , Poland
2. Center for Cardiovascular Health, Virginia Mason Franciscan Heath , Seattle, WA, USA
3. Cardiac Pacing Unit, University Hospital of Geneva , Geneva , Switzerland
4. Virginia Commonwealth University Medical Center , Richmond, VA, USA