Once Kawasaki disease develops in young children, damage to the coronary arteries, such as coronary aneurysms or narrowing, occlusion, or dilation of the coronary arteries, usually occurs within two weeks of the onset of the disease. In particular, children with persistent fever with clinical myocarditis at a relatively young age of onset have a greater chance of coronary artery injury. Once this occurs, prompt and aggressive treatment is required, such as the application of high-dose aspirin or immunoglobulin therapy, and later maintenance therapy with anti-platelet aggregation doses of aspirin.