Date of Award

January 2026

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

John A. Elefteriades

Abstract

Objectives: Acute type A (TAAD) and type B (TBAD) aortic dissections are catastrophic disorders associated with high mortality and morbidity rates. Current guidelines recommend a threshold diameter of 5.0-5.5 cm for surgery for ascending thoracic aortic aneurysms and for descending thoracic aortic aneurysms with additional risk factors, irrespective of sex. Although men are more affected than women, the distribution of aortic diameters at the time of TAAD or TBAD stratified by sex remains understudied.

Methods: Maximal ascending or descending aortic size at the time of naturally occurring acute flap-type TAAD or TBAD was measured in 478 patients presenting between 1983-2023 with still-available radiographic images of sufficient quality to permit size measurement. Demographic and comorbidity data were extracted from electronic medical records. Aortic size was re-measured from CT or MRI images in a standardized method. We compared the ascending or descending aortic diameter at time of dissection between male and female patients for TAAD or TBAD, respectively. Aortic diameters were indexed to height and body surface area (BSA), and histograms were constructed to display the raw and indexed aortic size at time of dissection. Logistic regression models were used to identify predictors associated with the likelihood of undergoing aortic dissection at an aortic diameter less than 5 cm.

Results: Among 295 patients with TAAD measurable on imaging studies (median age 63 years [IQR 53, 73]; 34% (N=99) female), the average maximal ascending aortic diameter was 5.02 cm [4.6, 5.6]. Male patients were taller (178 cm vs 163 cm, p<0.001), had a higher BMI (28 kg/m2 vs. 25 kg/m2, p=0.002), and had lower rates of COPD than women (8.8% (N=15/199) vs. 18% (N=16/99), p=0.03). Other comorbidities were comparable. Women had a smaller ascending aortic diameter (4.92 vs. 5.10 cm, p=0.012) and presented at an older age than men (68 vs. 61, p=0.006). After normalizing the ascending aortic diameter to the patient’s height, the difference in ascending aortic diameter between women and men disappeared (2.97 cm/m vs. 2.84 cm/m, p=0.1), whereas female patients had a larger aortic size after indexing to BSA compared to male patients (2.84 cm/m2 vs. 2.40 cm/m2, p<0.001). Among 183 patients with measurable TBAD (median age 65 years [IQR 53, 76], 41% (N=75) female), the average maximal descending aortic diameter was 4.2 cm [3.6, 4.9]. Male patients were taller (178 cm vs. 164 cm, p<0.001) and had higher BMI (29 kg/m2 vs. 26 kg/m2, p=0.005) than female patients. There were no differences between absolute, height-indexed, or BSA-indexed descending aortic diameters between male and female patients. On multivariable modeling, female sex was associated with higher odds of undergoing TAAD at an aortic diameter of less than 5 cm (OR: 1.79, p=0.043). Female sex was not associated with increased odds of presenting with a TBAD at aortic diameters less than 5 cm.

Conclusions: Our study demonstrated significant sex-based differences in age at presentation among all patients with aortic dissection and aortic diameter at time of dissection among patients with type A aortic dissection. An earlier intervention criterion below 5.0 cm may prove to be appropriate for female patients. Indexing aortic diameter to patient height reduces the size disparity and risk for female patients, endorsing the use of aortic diameter indexing when determining patient risk for TAAD. Female patients were almost a decade older at presentation for both TAAD and TBAD; the pathophysiologic reasons for this age difference remain to be clarified.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 07/14/2028

Download

Share

COinS