[1] Yokohama City Univ, Med Cntr, Div Cardiol, Yokohama, Kanagawa 232, Japan
[2] Kumamoto Univ, Fac Life Sci, Dept Cardiovasc Med, Kumamoto, Japan
[3] Kumamoto Univ Hosp, Kumamoto, Japan
[4] Yokohama City Univ, Grad Sch Med, Dept Med Sci & Cardiorenal Med, Yokohama, Kanagawa 232, Japan