1. Department of Cardiology, Yan'an Hospital of Kunming City, Kunming, Yunnan 650051, P.R. China
2. Department of Emergency Medicine, Yan'an Hospital of Kunming City, Kunming, Yunnan 650051, P.R. China
3. Department of Emergency Medicine, the First Hospital Affiliated to Kunming Medical University, Kunming, Yunnan 650032, P.R. China