Modelling of predissection aortic size in acute descending aortic dissection

Area of Science:

• Cardiovascular Medicine
• Radiology
• Medical Imaging

Background:

• A large aortic diameter is often presumed to cause aortic dissection.
• This assumption is based on post-dissection imaging, which can be misleading due to dissection-induced aortic expansion.
• Recent findings indicate acute dissection increases descending aortic diameter by 23%.

Purpose of the Study:

• To estimate the aortic diameter before acute descending aortic dissection.
• To challenge the assumption that a large aortic diameter is the primary cause of aortic dissection.

Main Methods:

• Utilized computed tomography angiography scans from 165 non-Marfan patients who experienced acute descending aortic dissection between 2003 and 2017.
• Measured maximum postdissection aortic diameter at the mid-descending aorta.
• Modeled predissection aortic diameter by dividing the postdissection measurement by 1.23.

Main Results:

• The median modeled predissection descending aortic diameter was 30.5 mm.
• Predissection aortic diameter was higher in men and associated with age.
• 98.8% of patients had a modeled predissection aortic diameter <55 mm, and 84.8% had <40 mm.
• 50% of patients had a non-dilated descending aorta before dissection.

Conclusions:

• Over 80% of patients with acute descending aortic dissection had a descending aorta <40 mm prior to the event.
• Less than 1% met criteria for elective repair (≥55 mm).
• The role of a large aortic diameter as a predictor for descending aortic dissection may be overestimated.