1. Division of Cardiology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
2. Division of Cardiology, Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea.
3. Division of Cardiology, Severance Cardiovascular Hospital, Yonsei University College of Medicine, Seoul, Korea.
4. Division of Cardiology, Wonju Christian Hospital, Wonju, Korea.
5. Division of Cardiology, Ajou Univeristy Hospital, Suwon, Korea.
6. Department of Cardiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.