1. Division of Cardiology, Department of Internal Medicine, Myongji Hospital, Hanyang University College of Medicine, Goyang, Korea.
2. Division of Cardiology, Department of Internal Medicine, Severance Cardiovascular Hospital, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
4. Division of Cardiology, Department of Internal Medicine, Sejong General Hospital, Bucheon, Korea.