1. Cardiology Division, Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Cardiology Division, Department of Internal Medicine, Chungju Medical Center, Chungju, Korea.
3. Cardiology Division, Department of Internal Medicine, NHIC Ilsan Hospital, Goyang, Korea.
4. Cardiology Division, Department of Internal Medicine, Gachon University, Incheon, Korea.
5. Cardiology Division, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.