According to the Quality Control Standard of Electrocardiogram Examination in Medical Institutions, ECG examination is an important clinical auxiliary diagnostic means, which is of great significance to patients' health assessment and disease diagnosis. If the ECG test results are unqualified, medical institutions will re-examine them on the spot to ensure the accuracy and reliability of the results. The purpose of re-examination is to eliminate possible technical problems or operational errors and conduct ECG examination again to obtain accurate results. Therefore, the unqualified ECG will be re-examined on the spot.