1. Division of Cardiology, Department of Internal Medicine, Korea University College of Medicine and Korea University Medical Center, Seoul 02841, Republic of Korea
2. Division of Cardiology, Department of Internal Medicine, Chungbuk National University Hospital, Chungju-si 28644, Republic of Korea
3. Department of Cardiology, Ajou University School of Medicine, Suwon 16499, Republic of Korea
4. Division of Cardiology, Department of Internal Medicine, Pusan National University Hsopital, Busan 49241, Republic of Korea
5. Division of Cardiology, Department of Internal Medicine, Inha University Hospital, Incheon 22332, Republic of Korea
6. Division of Cardiology, Department of Internal Medicine, Ewha University Hospital, Seoul 07804, Republic of Korea