1. Division of Cardiology, Saiseikai Kumamoto Hospital , 5-3-1 Chikami, Minami-ku, Kumamoto 861-4193 , Japan
2. Division of Cardiology, National Hospital Organization Osaka National Hospital , 2-1-14 Houenzaka, Chuo-ku, Osaka 540-0006 , Japan
3. Cardiovascular Center, Sakurabashi Watanabe Hospital , 2-4-32 Umeda, Kita-ku, Osaka 530-0001 , Japan
4. Department of Cardiovascular Medicine, Tokyo Medical and Dental University , 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510 , Japan
5. The Institute of Statistical Mathematics , 10-3 Midori-cho, Tachikawa, Tokyo 190-8562 , Japan
6. Department of Clinical Research, Johnson & Johnson K.K. Medical Company, Chiyoda First Building West Tower, 3-5-2 Nishi-Kanda, Chiyoda-ku, Tokyo 101-0065 , Japan
7. Department of Cardiology, Institute of Medicine, University of Tsukuba , 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 , Japan