1. Department of Cardiology, Anqiu People’s Hospital, Weifang, Shandong 262100, PR China
2. Department of Cardiology, People’s Hospital of Rizhao, Rizhao, Shandong 276800, PR China
3. Departmentof Cardiology, Shanxian Haijiya Hospital, Heze, Shandong 274300, PR China