Patients with atrial fibrillation are characterized by absolute arrhythmia, a weak first heart sound, and a pulse that is smaller than the heart rate. 1. Absolute arrhythmia: The electrocardiogram (ECG) of a patient with atrial fibrillation shows that the patient’s heartbeat is out of rhythm, which is characterized by absolute arrhythmia. 2. Unequal strength of the first heart sound: the first heart sound is strong and weak, without regularity. 3. Pulse rate less than heart rate: the patient’s pulse rate is less than the number of heartbeats per minute. When atrial fibrillation occurs, you should consult a doctor in time, and the specific treatment should follow the doctor’s instructions.