1. Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center , 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565 , Japan
2. Department of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University School of Medicine , S1W17 Chuoh-ku, Sapporo, Hokkaido 060-8556 , Japan
3. Department of Advanced Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University , 1 Chome-1-1 Honjo, Chuo Ward, Kumamoto 860-8556, Japan