1. Division of Cardiology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Boramae Medical Center, Seoul, Korea.
2. Department of Biostatistics, Seoul National University Boramae Medical Center, Seoul, Korea.
3. Division of Cardiology, Korea University Anam Hospital, Seoul, Korea.
4. Division of Cardiology, Hallym University Medical Center, Chuncheon, Korea.
5. Division of Cardiology, Chonnam National University Hospital, Gwangju, Korea.
6. Division of Cardiology, Inje University Sanggye Paik Hospital, Seoul, Korea.
7. Gachon Medical School Gil Medical Center, Incheon, Korea.