In clinical practice, patients are often diagnosed with “insufficient myocardial blood supply”, which is a relatively vague diagnosis and a generalized concept that can be understood and accepted by the general public. The other term is “myocardial ischemia”, a concept that covers a wide range of conditions. Myocardial ischemia is the most common manifestation of ischemic heart disease. The most common disease is coronary atherosclerotic heart disease, or coronary heart disease. Some other diseases or conditions can also present with myocardial ischemia, such as immune diseases like rheumatoid and lupus, congenital anomalies of the heart structure, coronary artery spasm, capillary dysfunction, and severe hypotension. Some are persistent and some are transient for a short period of time. Therefore, the diagnosis of “insufficient myocardial blood supply” is a functional diagnosis. Some of the causes are clear and some are unclear. When the cause is not clear, the diagnosis is usually made. Therefore, although all of them are “inadequate myocardial blood supply”, the cause may be different, and it is best to clarify the cause as much as possible. The risk varies from cause to cause, and the prognosis is very different.