1. Department of Cardiovascular, Renal and Metabolic MedicineSapporo Medical University School of Medicine South‐1, West‐16, Chuo‐ku Sapporo 060‐8543 Japan
2. Division of RehabilitationSapporo Medical University Hospital Sapporo Japan
3. Department of Public HealthSapporo Medical University School of Medicine Sapporo Japan
4. Department of Cardiovascular SurgerySapporo Medical University School of Medicine Sapporo Japan
5. Department of Cardiovascular SurgerySapporo Cardio Vascular Clinic, Sapporo Heart Center Sapporo Japan