There is no effect of an ECG on an empty stomach or an ECG after a meal. An ECG on an empty stomach does not have any effect. An ECG is actually an indication of the electrical activity of the heart. If fasting has an effect on ECG, it may only be seen in diabetic patients, who have hypoglycemia during fasting, and may have a corresponding lack of blood supply during ECG. But it does not show the effect of fasting on ECG, in fact, it is the effect of blood sugar on ECG. In terms of ECG examination, whether it is a physical examination or an outpatient cardiology examination including emergency examination, ECG is a routine examination and is as important as blood, urine and stool examination. This is because ECG can detect many problems, such as various arrhythmias, poor blood supply to the heart, too fast or too slow heart rate, and conduction block. Because most of the problems detected by ECG are benign lesions, clinical physical examination and observation are sufficient. If the subject’s ECG shows bradycardia with atrioventricular block, there may be a clear correlation with dizziness, weakness, and syncope, and these patients should be given pacemaker intervention clinically. In patients with a rapid heart rate such as atrial fibrillation, ventricular tachycardia, ventricular fibrillation or even episodes of supraventricular tachycardia, medication can be administered clinically or the cause can be sought.