Xile Bi1, Hongmei Yang1, Li Liu1, Qingsheng Wang2. 1. Department of Cardiology, The First Hospital of Qinhuangdao, Qinhuangdao, 066000, Hebei, China. 2. Department of Cardiology, The First Hospital of Qinhuangdao, Qinhuangdao, 066000, Hebei, China. qswang335@163.com.