The normal fastest heart rate on a 24-hour ECG is less than 100 beats/min at rest and greater than 100 beats/min in the active state. The normal heart rate on a 24-hour ambulatory electrocardiogram is 60 to 100 beats/min, and if the mainstream heart rate is more than 100 beats/min at rest, it is considered electrocardiographic abnormality and is classified as tachycardia. Occasionally and without symptoms is considered normal. If the fastest heart rate of 24-hour ECG exceeds the highest value, it is usually related to arrhythmia, commonly paroxysmal supraventricular tachycardia, paroxysmal ventricular tachycardia, tachycardia, rapid atrial fibrillation, etc. Sometimes, it is felt as panic attack, rapid heartbeat, dizziness, etc., and sometimes there is no obvious discomfort. Persistent increase in heart rate may also be associated with other diseases such as hyperthyroidism and anemia. If the 24-hour ambulatory electrocardiogram is high, you should consult a doctor as soon as possible and have an electrocardiogram, cardiac ultrasound, blood tests and thyroid function tests performed under the guidance of a medical professional to analyze the cause and then target the treatment.