Sou Hattori1, Eiji Ojima2, Hiroaki Satoh3. 1. Division of General Medicine, Mito Medical Center, University of Tsukuba, Ibaraki, Japan. 2. Division of Cardiology, Mito Medical Center, University of Tsukuba, Ibaraki, Japan. 3. Division of Respiratory Medicine, Mito Medical Center, University of Tsukuba, Ibaraki, Japan.