Modelling of predissection aortic size in acute descending aortic dissection

Large aortic diameter is considered the most frequent cause of aortic dissection. However, this assumption relies on postdissection imaging of the aorta. We recently showed that acute dissection leads to a 23% increase in the descending aortic diameter. Our aim was to model the diameter of the aorta before the acute descending aortic dissection occurred.

Between 2003 and 2017, a total of 190 patients developed acute descending aortic dissection. In total, 165 non-Marfan patients were included, whose computed tomography angiography scans were available and taken within 6 h after the occurrence of acute descending aortic dissection [67 (first quartile 58-third quartile 75) years, 69% males]. The maximum postdissection aortic diameter was measured at the level of the mid-descending aorta. Modelling was performed by dividing the postdissection aortic diameter by the factor 1.23.

The median modelled predissection descending diameter measured in the mid-descending aorta was 30.5 (27.3-35.4) mm. The median predissection descending diameter was higher in men (P = 0.021) and associated with age (P < 0.001) but not with body surface area. The modelled diameter of the predissected descending aorta revealed that 98.8% (163/165) of patients had an aortic diameter measuring <55 mm and 84.8% (140/165) <40 mm. In other words, 50% of these patients had a non-dilated descending aorta prior to dissection onset.

Modelling indicated that more than 80% of patients who suffered an acute descending aortic dissection had a descending aorta <40 mm before dissection onset. Only 1% of them would have met the guideline criteria (aortic diameter ≥55 mm) for elective descending aortic repair. The role of an excessively large aortic diameter as a predictor of descending aortic dissection might be overrated.