If hyperthyroidism is left untreated for a long time, or if the treatment is ineffective or recurs repeatedly, it will eventually lead to serious damage to multiple systems throughout the body. The specific manifestations of hyperthyroidism are as follows: damage of hyperthyroidism to cardiovascular system: hyperthyroidism can lead to tachycardia, arrhythmia (such as premature beats, atrial fibrillation, etc.), elevated blood pressure, heart enlargement, heart failure, angina pectoris, myocardial infarction and other hyperthyroid heart diseases. The longer the duration of hyperthyroidism, the higher the possibility of hyperthyroid heart disease, and it takes longer for hyperthyroid heart disease to recover after hyperthyroidism is cured, and individual patients cannot even return to normal. Atrial fibrillation can also produce blood clots, which, when dislodged, can lead to cerebral embolism and cause paralysis.