1. Department of Thoracic and Cardiovascular Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, South Korea
2. Department of Thoracic and Cardiovascular Surgery, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, South Korea
3. Department of Thoracic and Cardiovascular Surgery, Pusan National University Yangsan Hospital, Medical Research Institute of Pusan National University, Busan, South Korea
4. Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea