**5.2 Systemic vessels**

It is well known that vascular stiffness increases in the atherosclerotic vasculature. Patients with KD have systemic vasculitis because inflammation occurs in mediumsized muscular arteries throughout the body. While some KD patients show vessel lesions throughout the body, the association between KD vasculitis in the acute phase and atherosclerosis in long-term follow-up remains unclear.

The relationship between atherosclerotic lesions and the development of myocardial infarction has long been established in adult patients. It has also been reported that increased aortic stiffness is associated with coronary atherosclerosis, as such, this could be an important predictive marker for cardiovascular events [26]. Given these findings, KD patients with CAL may be at risk of developing atherosclerosis.

It is well known that functional impairment of vascular endothelial cells exists before morphological changes such as vascular intima-media thickening. Recently, the importance of assessment of vascular function has been suggested for vascular health. Although several evaluation methods have been reported, these parameters have mainly been published to understand the pathophysiology of vascular dysfunction in KD. In the future, these indices should be implemented in clinical practice and used for the appropriate follow-up of patients with KD. The following is an overview of each indicator:
