Shi Tai1, Xinqun Hu1, Shenghua Zhou2. 1. Department of Cardiology, the Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China. 2. Department of Cardiology, the Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China. Email: zhougqin@21cn.com.