1. Department of Cardiology in Internal Medicine, School of Medicine, Chungnam National University, Chungnam National University Hospital, Daejeon, Korea.
2. Department of Cardiology, Daegu Fatima Hospital, Daegu, Korea.
3. Department of Statistics, Kyungpook National University, Daegu, Korea.
4. Division of Cardiology, Department of Internal Medicine, Korea University Medical Center Anam Hospital, Seoul, Korea.