1 Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chungnam National University Hospital, Chungnam National University School of Medicine, Daejeon, Republic of Korea.
2 Department of Emergency Medicine, College of Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea.
3 Division of Cardiology, Department of Internal Medicine, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Republic of Korea.
4 Department of Cardiovascular Surgery, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Republic of Korea.