1. Division of Cardiology, Department of Internal Medicine, The Jikei University Katsushika Medical Center , 6-41-2 Aoto, Katsushika-ku, Tokyo 125-8506 , Japan
2. Division of Cardiology, Saitama Cardiovascular Respiratory Center, Kumagaya , Saitama , Japan
3. Division of Cardiology, Department of Internal Medicine, The Jikei University School of Medicine , Tokyo , Japan