1. Cardiovascular Center, Korea University Guro Hospital, Seoul, Korea.
2. Department of Cardiology, Eulji General Hospital, Eulji University, Seoul, Korea.
3. Department of Cardiology, Nankai Hospital, Tianjin Medical University, Tianjin, China.
4. Department of Cardiology, the Second Hospital of Tianjin Medical University, Tianjin, China.
5. Department of Thoracic and Cardiovascular Surgery, Eulji General Hospital, Eulji University, Seoul, Korea.