1. Department of Cardiology, Japanese Red Cross Ishinomaki Hospital , 71 Nishimichishita, Hebita, Ishinomaki, Miyagi 996-8522 , Japan
2. Department of Cardiology, Hosogi Hospital , 37 Daizen-cho, Kochi 780-0926 , Japan
3. Department of Cardiology, Toyohashi Heart Center , 21-1 Gobudori, Oyama-cho, Toyohashi, Aichi 441-8071 , Japan