1. Division of Cardiology, Severance Cardiovascular Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Division of Cardiology, Cardiovascular Center, Korea University Guro Hospital, Seoul, Korea.
3. Division of Cardiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
4. Division of Cardiology, National Health Insurance Service Ilsan Hospital, Goyang, Korea.
5. Division of Cardiology, Wonju Severance Hospital, Yonsei University Wonju College of Medicine, Wonju, Korea.
6. Division of Cardiology, Department of Internal Medicine, Dankook University College of Medicine, Cheonan, Korea.
7. Division of Cardiology, Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.