The three main dangers of atrial fibrillation are: cerebral infarction (stroke), heart failure and reduced quality of life, in addition to the fact that the mortality rate of patients with atrial fibrillation is twice as high as that of the normal population. Loss of atrial systolic function and prolonged heart rate increase in atrial fibrillation can lead to heart enlargement and heart failure, which can easily develop; more dangerously, atrial fibrillation can greatly increase the risk of blood clots and cerebral infarction. As the atria lose their full and effective ejection function, blood tends to stagnate in the atria, which in turn can form thrombi that can cause embolism in various parts of the body, such as the brain (stroke, hemiplegia), limbs (in severe cases, even requiring amputation), and intestines (abdominal pain, blood in the stool). More than 80% of severe cerebral infarcts seen in neurology are caused by atrial fibrillation; rapid heart rate and irregular heart rhythm in atrial fibrillation can cause palpitations, chest tightness, dizziness, and even fainting, seriously affecting the quality of life.