1. Department of Cardiology, Korea University Anam Hospital, Korea University Cardiovascular Center, Seoul, Korea.
2. Department of Cardiology, Seoul National University Boramae Hospital, Seoul, Korea.
3. Department of Cardiology, Department of Biostatistics, College of Medicine, Korea University, Seoul, Korea.
4. Department of Cardiology, Chonnam National University Hospital, Gwangju, Korea.
5. Department of Cardiology, Gachon Medical School Gil Medical Center, Incheon, Korea.
6. Department of Cardiology, Hallym University Chuncheon Sacred Heart Hospital, Chuncheon, Korea.