1. School of Medicine, Guizhou University, Guiyang, Guizhou 550025, P.R. China
2. Department of Emergency Medicine, Qingdao Municipal Hospital (Group), Qingdao, Shandong 266011, P.R. China
3. Department of Cardiology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
4. Department of Cardiology, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou 550004, P.R. China