Department of Cardiology, Department of Library and Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, Shenyang, 110004, People's Republic of China. liqiangzheng@126.com. Department of Cardiology, Department of Library and Department of Clinical Epidemiology, Shengjing Hospital of China Medical University, Shenyang, 110004, People's Republic of China. Department of Respiratory, Shengjing Hospital of China Medical University, Shenyang, 110004, People's Republic of China. Department of General Medicine, Shengjing Hospital of China Medical University, Shenyang, 110004, People's Republic of China. Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang, 110004, People's Republic of China. Department of Cardiology, Shengjing Hospital of China Medical University, Shenyang, 110004, People's Republic of China. sunzhaoqing@vip.163.com.