Risk category

Aortic Augmentation Index (Aix)

I

Optimal

Aix < 30%

No signs of endothelial dysfunction

II

Normal

−30% < Aix < −10%

No signs of endothelial dysfunction

III

Increased

−10% < Aix < 10%

Signs of endothelial dysfunction

IV

Abnormal

Aix > 10%

Clearly endothelial dysfunction