1. Division of Cardiology, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
2. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
3. Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
4. Division of Cardiology, Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.