1. Department of Cardiology, Heji Hospital Affiliated to Changzhi Medical College, Changzhi, 046011 Shanxi, China
2. Guizhou Medical University, Guiyang, 550025 Guizhou, China
3. Department of ECG Diagnosis, Second Hospital of Shanxi Medical University, Taiyuan, 030001 Shanxi, China
4. Department of Cardiology, Binhai Hospital of Peking University (Tianjin Fifth Central Hospital), Tianjin 300450, China