Predicting the Risk for Acute Type B Aortic Dissection in Hypertensive Patients Using Anatomic Variables
Are anatomic characteristics of the aorta associated with risk of type B acute aortic dissection (AAD)?
This single-center retrospective study compared computed tomographic angiography (CTA) findings between nonhypertensive patients without AAD (group 1, n = 35), hypertensive patients without AAD (group 2, n = 37), and hypertensive patients with AAD (group 3, n = 37). Anatomic characteristics of the aorta on CTA in groups 2 and 3 were compared to group 1, including length, diameter, volume, tortuosity, and angulation of arch vessels. Stepwise logistic regression was used to identify variables independently associated with risk of type B AAD.
Groups 1, 2, and 3 were not significantly different in male gender (46%, 65%, and 65%, respectively; p = 0.17), whereas a difference was noted in mean age (53 ± 18, 60 ± 16, and 60 ± 12, respectively; p = 0.01). On univariate analysis, significant differences were observed between groups in regards to proximal and total aortic length; proximal and total aortic volume; total aortic tortuosity; brachiocephalic head vessel angle; and aortic diameters in the root, ascending aorta, and aortic arch (p < 0.01 for each). On multivariable analysis, variables independently associated with risk of AAD were aortic arch diameter, total aortic length, and brachiocephalic artery angulation. On bootstrap analysis, the estimated area under the receiver-operator curve was 0.97.
Anatomic characteristics of the aorta on CTA are associated with risk of type B AAD in patients with hypertension. Using a model that incorporates three simple anatomic variables, it may be possible to identify patients at increased risk of AAD.
While type B AAD is associated with high morbidity and mortality, it has been difficult to identify which patients are at increased risk for this disease. This study examines multiple potential variables that may be associated with AAD, and on multivariable analysis identifies three easily performed variables that are independently associated with risk: aortic arch diameter, total aortic length, and brachiocephalic artery angulation. If these findings are validated in larger subsequent studies, these variables may provide a simple approach to improve our ability to discriminate individuals at risk of future type B AAD.
Keywords: Hypertension, Logistic Models
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