1 Division of Cardiology, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2 Division of Cardiology, Department of Internal Medicine, Dongguk University Ilsan Hospital, Goyang, Korea.
3 Division of Cardiology, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea. oys@catholic.ac.kr.