1. Second Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan
2. Department of Rehabilitation Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan
3. Department of Cardiology, Kokura Memorial Hospital, Kitakyushu, Japan
4. Department of Echocardiography, Kokura Memorial Hospital, Kitakyushu, Japan
5. Department of Environmental Epidemiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan
6. Department of Cardiovascular Surgery, Kokura Memorial Hospital, Kitakyushu, Japan
7. Department of Laboratory and Transfusion Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan
8. Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Boston