2 Department of Medical Science, University of Tokyo, Tokyo, Japan.
3 Department of Cardiovascular Surgery, The University of Tsukuba Hospital, Ibaraki, Japan.
4 Division of General Internal Medicine, Department of Internal Medicine, Tokyo Medical University Ibaraki Medical Center.
5 Department of Cardiovascular Surgery, The University of Tsukuba Hospital, Ibaraki, Japan. Electronic address: shimoda.tomonari.em@ms.hosp.tsukuba.ac.jp.