Modelling of predissection aortic size in acute descending aortic dissection

Abstract

OBJECTIVES: 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. METHODS: 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. RESULTS: 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 <55mm and 84.8% (140/165) <40mm. In other words, 50% of these patients had a non-dilated descending aorta prior to dissection onset. CONCLUSIONS: Modelling indicated that more than 80% of patients who suffered an acute descending aortic dissection had a descending aorta <40mm 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.