1. Athens Heart Centre Athens Medical Centre, 11526 Athens, Greece
2. First Department of Cardiology, National and Kapodistrian University, Hippokration Hospital, 11527 Athens, Greece
3. Heart Rhythm Management Centre, Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, 1090 Brussels, Belgium
4. Section of Cardiovascular Medicine, Yale University School of Medicine, New Haven, CT 06510, USA