Common causes of atrial fibrillation include hypertension, valvular heart disease, heart failure, hyperthyroidism, post-operative cardiac surgery, cardiomyopathy, coronary artery disease, pericarditis, congenital heart disease, and pulmonary embolism. Heavy alcohol consumption and smoking increase the risk of developing atrial fibrillation. Other contributing factors include: exertion, emotional stress, mental stress, caffeine intake, hypoxia, electrolyte disturbances, severe infections and the effects of certain medications. Sometimes, atrial fibrillation can also occur in individuals under 65 years of age without any underlying cardiac disease nor other common triggers of atrial fibrillation, called isolated or idiopathic atrial fibrillation, which is not uncommon in clinical practice. Previously, the most common cause of atrial fibrillation in China was rheumatic valvular heart disease (referred to as rheumatic heart disease), especially rheumatic mitral stenosis. In recent decades, with the improvement of health conditions, the incidence of rheumatic heart disease has decreased significantly, and the atrial fibrillation caused by it has also decreased greatly, and hypertensive heart disease has become the most common cause of atrial fibrillation nowadays. Some of the elderly patients with atrial fibrillation are manifesting the tachycardia phase of bradycardia-tachycardia syndrome. The symptoms of atrial fibrillation are varied and depend on the presence or absence of organic heart disease, the basis of cardiac function, the fast or slow ventricular rate, and the form of the attack. Idiopathic atrial fibrillation and ventricular rate may be asymptomatic, but on the contrary, there may be symptoms such as panic, chest tightness, shortness of breath, dizziness and fatigue, and some patients also have a combination of sweating, increased urination and other manifestations of vegetative nerve dysfunction. Patients with particularly rapid heartbeat may experience a drop in blood pressure and cardiac insufficiency, which may lead to acute pulmonary edema, angina pectoris or cardiogenic shock in severe cases. In some patients with paroxysmal atrial fibrillation, when the heartbeat automatically returns to sinus rhythm from atrial fibrillation, a slowing of the heartbeat or even temporary cardiac arrest may occur. If no heartbeat appears for 2-3 seconds, the patient may experience blackness before the eyes or even a brief loss of consciousness so that he or she faints to the ground. There is also a significant proportion of patients who can have no obvious conscious symptoms, yet the dangers of atrial fibrillation remain, and many such patients are discovered by chance during a physical examination or even when they have a stroke. To facilitate follow-up of AF patients, AF symptoms have been quantified internationally according to the severity of AF-related symptoms, known as the EHRA score.