1 Keio University School of Medicine, Tokyo, Japan; Yokosuka Kyosai Hospital, Yokosuka, Japan.
2 Keio University School of Medicine, Tokyo, Japan; University of Missouri-Kansas City's Healthcare Institute for Innovations in Quality and Saint Luke's Mid America Heart Institute, Kansas City, Missouri, USA.
3 University of Missouri-Kansas City's Healthcare Institute for Innovations in Quality and Saint Luke's Mid America Heart Institute, Kansas City, Missouri, USA.
4 Keio University School of Medicine, Tokyo, Japan.
5 Keio University School of Medicine, Tokyo, Japan. Electronic address: sk@keio.jp.