1. Department of Cardiology, Cardiovascular Center, Osaka Red Cross Hospital , 5-30 Fudegasaki, Tennouji-ku, 543-8555 Osaka , Japan
2. Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine , 54 Shogoin Kawahara-cho, Sakyo-ku, 606-8507 Kyoto , Japan
3. Department of Cardiovascular Surgery, Cardiovascular Center, Osaka Red Cross Hospital , Osaka , Japan
4. Department of Clinical Epidemiology, Hyogo College of Medicine , Hyogo , Japan