The severity of cardiac insufficiency is determined by its primary cause. If the patient has secondary insufficiency of blood supply to the heart and the insufficiency of blood supply to the heart is in the initial state, it is not a serious condition. However, if the insufficiency of blood supply is due to an obvious organic lesion of the heart, and the insufficiency of blood supply occurs for a long period of time and leads to inadequate perfusion of vital organs, such as the heart, kidneys, and brain, it is a serious condition. For example, in the case of unstable angina pectoris with coronary atherosclerotic heart disease, the coronary arteries may become insufficiently supplied with blood, and arterial stenosis, ischemia and spasm may occur due to insufficient blood supply, which is a very serious condition because it may induce arrhythmia and even acute coronary syndrome.