Coronary heart disease usually refers to coronary atherosclerotic heart disease, also known as ischemic heart disease. Coronary heart disease is a heart disease caused by atherosclerotic plaque formation in the walls of coronary arteries, which causes narrowing of the coronary artery lumen or localized thrombosis blocking the blood vessels, resulting in myocardial ischemia and hypoxia. The main risk factors are hypertension, hyperlipidemia, diabetes, smoking, obesity, age, gender and family history of early-onset coronary artery disease. Coronary heart disease has different clinical manifestations due to the location, extent and degree of coronary artery lesions. 1979 World Health Organization classified coronary heart disease into five types: angina pectoris, myocardial infarction, ischemic cardiomyopathy, occult coronary heart disease and sudden death. Angina pectoris and myocardial infarction are the most familiar types of coronary heart disease in daily life. If the ischemia and hypoxia are short, it manifests as angina; if the ischemia and hypoxia are long, it leads to myocardial necrosis and acute heart attack. The main symptoms of coronary heart disease are chest tightness and chest pain. The typical site of chest pain is behind the sternum, which can radiate to the left chest, the back of the left shoulder, the front inner side of the left upper arm; it can also radiate to the neck, throat, jaw and head; the nature of pain is typically pressure-like, mostly accompanied by obvious chest tightness, and some patients have a sense of near death, which often forces patients to stop activities immediately. The onset of symptoms is mostly triggered by such factors as going upstairs, fast walking, exertion, full meal, cold, emotional excitement, etc. The symptoms can be relieved by quiet rest. Some patients have atypical symptoms, such as the presence of epigastric pain and subxiphoid discomfort.