1. Division of Cardiology, Department of Internal Medicine, Chonnam National University Hospital, Gwangju, Korea.
2. Division of Cardiology, Department of Internal Medicine, Yeungnam University Hospital, Daegu, Korea.
3. Division of Cardiology, Department of Internal Medicine, Chungbuk National University Hospital, Cheongju, Korea.
4. Division of Cardiology, Department of Internal Medicine Gwangju Veterans Hospital, Gwangju, Korea.