1. Division of Cardiology, Cardiovascular Center, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
2. Division of Cardiology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Sungkyunkwan University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
5. Division of Cardiology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.