Whether or not a first diagonal stenosis is dangerous depends primarily on the size of the first diagonal branch and the severity of the stenosis. If the first diagonal branch is large and the opening is severely narrowed, it will have a greater impact on heart function because it will supply a larger area of myocardium than if the first diagonal branch is small and distal to the stenosis. If the first diagonal branch is thin and the opening is mildly narrowed, the impact on myocardial blood supply and cardiac function is less. Generally do not need to use stent treatment, regular drug treatment can be, such as taking aspirin, resuvastatin and other drugs, long-term blood pressure, blood fat, blood sugar control in the normal range. Patients should pay attention to low-fat diet light, do not eat spicy and stimulating food, at the same time to quit smoking and alcohol, maintain good habits, appropriate exercise. If discomfort occurs, they should go to the hospital in time.