1. Heart Research Institute, Cardiovascular-Arrhythmia Center, College of Medicine, Chung-Ang University Hospital, Seoul, Korea.
2. Cardiovascular Research Foundation, New York, USA.
3. Chonnam National University Hospital, Gwangju, Korea.
4. Inje University Ilsan Paik Hospital, Koyang, Korea.
5. Jeju National University Hospital, Jeju, Korea.
6. Samsung Medical Center, Seoul, Korea.