1. The First Ward, Department of Cardiology, Rizhao People's Hospital, Rizhao, Shandong 276800, P.R. China
2. The Third Ward, Department of Cardiology, Rizhao People's Hospital, Rizhao, Shandong 276800, P.R. China
3. Department of Cardiology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong 260141, P.R. China