1. Division of Cardiology, Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.
2. Division of Cardiology, Department of Internal Medicine, Kosin University Gospel Hospital, Busan, Korea.
3. Department of Cardiology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
4. East Lancashire Hospitals NHS Trust, Blackburn, Lancashire, UK.
5. Department of Internal Medicine and Cardiovascular Center, Seoul National University Hospital, Seoul, Korea.