The aortic size index (ASI) is a means of adjusting the absolute aortic diameter to take into account the patient's physical size. This can help to identify a patient with an aortic aneurysm who is at increased risk for complications. The authors are fromo Yale University.



(1) aortic diameter in cm

(2) body surface area in square meters



= (aortic diameter in cm) / (BSA)


Units: cm per square meter BSA


For a patient with a thoracic aortic aneurysm, the ASI correlated with the risk of major complications (rupture, dissection and/or death).



Risk of Outcome

< 2.75

low (4% per year)

2.75 to 4.24

moderate (8% per year)

> 4.24

high (20% per year)


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