Toru Inami1, Yoshihiko Seino2, Kyoichi Mizuno3. 1. Department of Cardiology, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan. Electronic address: t-inami@nms.ac.jp. 2. Department of Cardiology, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan. 3. Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan.