[1] Univ Tsukuba, Dept Cardiol, Fac Med, 1-1-1 Tennodai, Tsukuba, Ibaraki 3058575, Japan
[2] Ibaraki Cent Hosp, Dept Cardiol, 6528 Koibuchi, Kasama, Ibaraki 3091793, Japan
[3] Univ Tsukuba, Fac Med, Dept Anesthesiol, 1-1-1 Tennodai, Tsukuba, Ibaraki 3058575, Japan
[4] Moriya Daiichi Gen Hosp, Dept Cardiol, 1-17 Matsumaedai, Moriya 3020102, Japan
[5] Univ Tsukuba, Dept Internal Med Endocrinol & Metab, Fac Med, 1-1-1 Tennodai, Tsukuba, Ibaraki 3058575, Japan
[6] Hiramine Clin, 3-24-7 Shimorenjaku, Mitaka, Tokyo 1810013, Japan