1. Division of cardiology, Kumamoto Rosai Hospital , 1670 Takehara, Yatsushiro city, Kumamoto 866-8533 , Japan
2. The Second Department of Internal Medicine, University of Occupational and Environmental Health , 1-1 Iseigaoka, Yahata-nishi, Kitakyusyu city, Fukuoka 807-8555 , Japan