1 Department of Cardiology, Institute of Medicine, University of Tsukuba, Tsukuba, Japan; Institute of Arrhythmia, Tokyo Heart Rhythm Hospital, Tokyo, Japan. Electronic address: akihiko-ind@umin.ac.jp.
2 Department of Cardiology, Institute of Medicine, University of Tsukuba, Tsukuba, Japan.
3 Department of Cardiology, Institute of Medicine, University of Tsukuba, Tsukuba, Japan; Institute of Arrhythmia, Tokyo Heart Rhythm Hospital, Tokyo, Japan.
4 Institute of Arrhythmia, Tokyo Heart Rhythm Hospital, Tokyo, Japan.