[1] Chiba Univ, Grad Sch Med, Dept Cardiovasc Surg, Chiba, Japan
[2] Osaka Univ, Grad Sch Med, Dept Cardiovasc Surg, Osaka, Japan
[3] Univ Tokyo, Dept Cardiac Surg, Tokyo, Japan
[4] Tohoku Univ, Grad Sch Med, Dept Cardiovasc Surg, Sendai, Miyagi, Japan
[5] Kyushu Univ, Fac Med Sci, Dept Cardiovasc Surg, Fukuoka, Japan
[6] Tokyo Womens Med Univ Hosp, Dept Cardiovasc Surg, Tokyo, Japan
[7] Hokkaido Univ, Grad Sch Med, Dept Cardiovasc & Thorac Surg, Sapporo, Hokkaido, Japan
[8] Saitama Med Univ, Int Med Ctr, Dept Cardiovasc Surg, Hidaka, Japan
[9] Higashi Takarazuka Satoh Hosp, Dept Cardiovasc Surg, Takarazuka, Hyogo, Japan
[10] Natl Cerebral & Cardiovac Ctr, Osaka, Japan
[11] Maki Hosp, Maki Hlth Care Grp, Osaka, Japan
[12] Tokyo Metropolitan Geriatr Hosp & Inst Gerontol, Tokyo, Japan