Whether diagonal stenosis is life-threatening or not cannot be generalized, but should be judged according to the degree of stenosis. Diagonal branch stenosis is usually due to the patient’s own underlying coronary artery disease, mostly in the elderly or people with hypertension, hyperlipidemia, diabetes, the specific severity of the disease depends on the patient’s degree of illness. If the symptoms are not very obvious or the diagonal branch stenosis is not serious, generally not life-threatening, can be under the guidance of the doctor for drug treatment. These include antiplatelet agents such as aspirin and clopidogrel; anti-atherosclerotic agents such as atorvastatin; beta-blockers such as metoprolol tartrate; and calcium channel blockers such as nifedipine. If the diagonal branch stenosis is severe and the conservative treatment is not satisfactory, it may further deteriorate and lead to infarction, and then it is necessary to cooperate with the doctor to take cardiac stent or bypass surgery. If patients have found the diagonal branch stenosis lesions, it is recommended to consult the cardiovascular department of regular hospitals in a timely manner to assess the condition and follow the doctor’s instructions for treatment.