1. Division of Cardiology, Department of Internal Medicine, Sejong General Hospital, Bucheon-si, Republic of Korea
2. Division of Cardiology, Soon Chun Hyang University Bucheon Hospital, Bucheon-si, Republic of Korea
3. Division of Cardiology, Inha University Hospital, Incheon, Republic of Korea
4. Division of Cardiology, Gachon University Gil Medical Center, Incheon, Republic of Korea
5. Division of Cardiology, Inje University Sanggye Paik Hospital, Seoul, Republic of Korea
6. Department of Biostatistics, Korea University College of Medicine, Seoul, Republic of Korea