1. Department of Cardiology Keio University School of Medicine 35 Shinanomachi, Shinjuku‐ku Tokyo 160‐8582 Japan
2. Department of Neurology, Graduate School of Medical Sciences Kumamoto University Kumamoto Japan
3. Department of Morphological and Physiological Sciences, Graduate School of Health Sciences Kumamoto University Kumamoto Japan
4. Department of Cardiology Showa General Hospital Tokyo Japan