1. Department of Cardiovascular Medicine , Kagawa Prefectural Central Hospital, 1-2-1 Asahi-machi, Takamatsu, Kagawa 760-8557 , Japan
2. Department of Clinical Epidemiology , Hyogo College of Medicine, 1-1 Mukogawa, Nishinomiya, Hyogo 663-8501 , Japan
3. Department of Cardiovascular Therapeutics , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, Okayama 700-8558 , Japan
4. Division of Cardiology , Saiseikai Kumamoto Hospital, 5-3-1 Chikami, Minami-ku, Kumamoto 861-4193 , Japan
5. Department of Cardiovascular Medicine , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, Okayama 700-8558 , Japan