1. Division of Cardiology, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
2. Division of Cardiology, Chungnam National University Sejong Hospital, Sejong, Korea.
3. Division of Cardiology, Severance Cardiovascular Hospital, Yonsei University College of Medicine, Seoul, Korea.
4. Division of Cardiology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Korea.