1. Department of Cardiology, Inha University Hospital, Incheon, Korea.
2. Department of Cardiology, Sejong General Hospital, Bucheon, Korea.
3. Department of Biomedical Sciences, College of Medicine, Inha University, Incheon, Korea.
4. Department of Cardiology, Gil Medical Center, Gachon University, Incheon, Korea.
5. Department of Cardiology, Soon Chun Hyang University Bucheon Hospital, Bucheon, Korea.
6. Division of Cardiology, CHA Medical Center, Ilsan Hospital, Goyang, Korea.