1. Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine Hokkaido University Sapporo Japan
2. Department of Clinical Research National Hospital Organization Hakodate National Hospital Hakodate Japan
3. Division of Cardiology Hakodate Municipal Hospital Hakodate Japan
4. Department of Cardiology Japan Community Health Care Organization Hokkaido Hospital Sapporo Japan
5. Department of Cardiology Kushiro City General Hospital Kushiro Japan
6. Department of Cardiology Tomakomai City Hospital Tomakomai Japan
7. Department of Cardiology Sunagawa City Medical Center Sunagawa Japan
8. Department of Cardiology Japan Red Cross Kitami Hospital Kitami Japan