1. Gachon Cardiovascular Research Institute, Gachon University, Incheon, Korea.
2. Division of Cardiovascular Disease, Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Korea.
3. Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.