Having atrial fibrillation but the heart ultrasound is fine means that there is no change in the structure of the heart, and the atrial fibrillation may be caused by reasons other than the structure of the heart. Atrial fibrillation can occur for a variety of reasons, some patients can be seen in heart valve disease, high blood pressure, etc., in the role of external factors, there is an increase in the heart is prone to atrial fibrillation. The heart ultrasound is not problematic, indicating that the occurrence of atrial fibrillation and structural changes in the heart have no obvious relationship. Some patients with atrial fibrillation may have atrial fibrillation as the main manifestation without any reason, which is clinically called idiopathic atrial fibrillation. Hyperthyroidism can also lead to atrial fibrillation, and the cause is related to elevated levels of thyroid hormones. Patients with coronary artery disease are also prone to atrial fibrillation, which may be related to myocardial ischemia, but these patients do not necessarily have structural changes in the heart. Patients with atrial fibrillation should routinely undergo cardiac ultrasound to assess the function of the heart. Patients without structural changes in the heart should find the cause of the disease under the guidance of a doctor and treat the primary disease while controlling atrial fibrillation.