during this time, and the risk for sudden death is highest. The convalescent stage begins when all clinical signs of illness have disappeared, and continues until the sedimentation rate returns to normal, usually at six to eight weeks after the onset of illness. Adult onset of Kawasaki disease is rare. The presentation differs between adults and children: in particular, it seems that adults more often have cervical lymphadenopathy, hepatitis, and arthralgia. Some children, especially young infants, have atypical presentations without the classic set of symptoms. Such presentations are associated with a higher risk of cardiac artery aneurysms. Cardiac Heart complications are the most important aspect of Kawasaki disease, which is the leading cause of heart disease acquired in childhood in the United States and Japan. In developed nations, it appears to have replaced acute rheumatic fever as the most common cause of acquired heart disease in children. Coronary artery aneurysms occur as a sequela of the vasculitis in 20–25% of untreated children. It is first detected at a mean of 10 days of illness and the peak frequency of coronary artery dilation or aneurysms occurs within four weeks of onset. Aneurysms are classified into small (internal diameter of vessel wall <5 mm), medium (diameter ranging from 5–8 mm), and giant (diameter > 8 mm). Saccular and fusiform aneurysms usually develop between 18 and 25 days after the onset of illness. Even when treated with high-dose IVIG regimens within the first 10 days of illness, 5% of children with Kawasaki disease develop at the least transient coronary artery dilation and 1% develop giant aneurysms. Death can occur either due to myocardial infarction secondary to blood clot formation in a coronary artery aneurysm or to rupture of a large coronary artery aneurysm. Death is most common two to 12 weeks after the onset of illness. Many risk factors predicting coronary artery aneurysms have been identified, including persistent fever after IVIG therapy, low hemoglobin concentrations, low albumin concentrations, high white-blood-cell count, high band count, high CRP concentrations, male sex, and age less than one year. Coronary artery lesions resulting from Kawasaki disease change dynamically with time. Resolution one to two years after the onset of the disease has been observed in half of vessels with coronary aneurysms. Narrowing of the coronary artery, which occurs as a result of the healing process of the vessel wall, often leads to significant obstruction of the blood