Early signs of sudden cardiac death include palpitations and chest pain, or there may be no signs at all. Days to months before sudden cardiac death, some patients may experience palpitations, fatigue, shortness of breath, chest pain, or aggravation of pre-existing angina and heart failure symptoms. However, these symptoms are not specific and only indicate the risk of cardiovascular disease, but do not predict the occurrence of sudden cardiac death. In some patients, sudden cardiac arrest occurs without warning. The vast majority of sudden cardiac deaths occur in patients with organic heart disease. In Western countries, 80% of sudden cardiac deaths are caused by coronary heart disease and its complications, and 5% to 15% of sudden cardiac deaths are caused by various cardiomyopathies, which are the main causes of sudden cardiac deaths before the age of susceptibility to coronary heart disease (<35 years old). Extreme emotional changes and mental stimulation can lead to sudden cardiac arrest by excitation of the sympathetic nerve and inhibition of the vagus nerve. Patients with organic heart disease should go to the hospital in time for standardized treatment when the above symptoms occur.