1. Department of Cardiovascular Medicine, Dokkyo Medical University, Mibu 321-0293, Tochigi, Japan
2. Gunma Prefectural Cardiovascular Center, Maebashi 371-0004, Gunma, Japan
3. Department of Cardiology, Na Homolce Hospital, 15030 Prague, Czech Republic
4. Department of Cardiovascular Medicine, Tohoku Medical and Pharmaceutical University, Sendai 983-8536, Miyagi, Japan