Role of aortic distensibility and stiffness in ascending thoracic aneurysm outcomes

Ascending thoracic aortic aneurysms pose a risk of acute dissection. Although diameter guides elective repair, complications often occur below surgical thresholds. Aortic distensibility and stiffness have been proposed as alternative risk markers. We aimed to evaluate the association of deformation indices with all-cause mortality in patients with dilated aortas and ascending thoracic aortic aneurysms.

Retrospective study of patients with ascending aortic diameter ≥4.0 cm who had a multiphasic electrocardiogram-gated computed tomography angiogram within 3 years of death or between 2021 and 2024. Diameter- and area-based distensibility and stiffness indices were calculated 3 cm above the annulus using dynamic aortic measurements across the cardiac cycle. Differences by mortality status and aortic valve phenotype were assessed using the Wilcoxon rank-sum test.

We included 319 veterans with median age of 75 years (interquartile range, 7.0 years), of whom 35 (11.0%) died within 3 years. Aortic diameter was larger in the mortality group (4.50 vs 4.40 cm; P = .005). Bicuspid aortic valve was present in 12 patients (3.8%). No differences in diameter-based distensibility (0.56 vs 0.64 × 10^-6 cm²/dyne; P = .38) or stiffness index (23.5 vs 23.5; P = .34) were observed by mortality status. Patients with bicuspid aortic valve had higher unadjusted distensibility (1.23 vs 0.63 × 10^-6 cm²/dyne; P = .046) and lower stiffness index (12.5 vs 24.4; P = .05) compared with tricuspid valves. Area-based metrics were similar.

Aortic distensibility and stiffness index were not associated with all-cause mortality. Deformation indices varied by valve morphology in unadjusted analyses but were attenuated after adjustment. Further studies are needed to evaluate aortic deformation indices with regard to ascending thoracic aortic aneurysm risk stratification.