[1] Harvard Med Sch, Massachusetts Gen Hosp, Cardiol Div, 55 Fruit St,GRB 800, Boston, MA 02114 USA
[2] Harvard Med Sch, Biostat Ctr, Massachusetts Gen Hosp, Boston, MA 02114 USA
[3] Nippon Med Sch, Cardiovasc Ctr, Chiba Hokusoh Hosp, 1715 Kamakari, Inzai, Chiba 2701694, Japan
[4] Mitsukoshi Hlth & Welf Fdn, Tokyo, Japan
[5] Univ Tokyo, Grad Sch Med, Dept Cardiovasc Med, Tokyo, Japan
[6] Kyung Hee Univ Hosp, Div Cardiol, Seoul, South Korea