1. Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku , Tokyo 113-8655, Japan
2. Department of Cardiology, Showa General Hospital , 8-1-1 Hanakoganei, Kodaira-shi, Tokyo 187-8510 , Japan
3. Division for Health Service Promotion, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku , Tokyo 113-0033, Japan