Patients with hyperthyroidism do tend to have a fast heart rate when their condition is not well controlled. Hyperthyroidism can occur when the patient is at rest, for example, when the patient is resting or sleeping, the heart rate will be fast, while the heart rate of normal people will gradually slow down when they are resting or sleeping. The increased synthesis of thyroid hormones T3 and T4 in the body of hyperthyroidism patients leads to excitation of the sympathetic nervous system and increases the heart rate in a hypermetabolic state, so hyperthyroidism patients usually feel palpitations. If the condition is controlled, T3 and T4 levels will gradually return to normal and the phenomenon of rapid heartbeat will be improved. If the condition is not actively controlled and the heart rate is fast for a long time, it will easily lead to heart damage. Some patients are prone to arrhythmia, such as atrial fibrillation, arrhythmia and premature atrial beats, and others are prone to cardiac insufficiency. In addition, the rapid beating of the heart of hyperthyroidism patients for a long time may also affect the morphology of the heart, and patients may experience an increase in heart size, so some hyperthyroid patients may die suddenly due to cardiac reasons. The first thing hyperthyroidism patients are advised to do is to avoid iodine diet and reduce the intake of iodine-rich foods, such as seaweed and nori. Treatment for hyperthyroidism includes oral antithyroid medication, radioactive iodine-131 therapy, and surgery, and it is important to choose the appropriate treatment according to your condition under the guidance of your doctor. Regular monitoring of thyroid function, timely adjustment of treatment plan according to thyroid function, long-term control of T3 and T4 in the normal range, the heart rate will gradually return to normal.