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. 2025 Aug 21:S1936-878X(25)00371-7.
doi: 10.1016/j.jcmg.2025.06.019. Online ahead of print.

Ascending Aortic Dimensions and Body Size: Allometric Scaling, Normative Values, and Prognostic Performance

Hamed Tavolinejad  1 , Cameron Beeche  2 , Marie-Joe Dib  1 , Bianca Pourmussa  1 , Scott M Damrauer  3 , John DePaolo  4 , Joe David Azzo  1 , Oday Salman  1 , Jeffrey Duda  5 , James Gee  5 , Seavmeiyin Kun  1 , Walter R Witschey  5 ; Penn Medicine BioBank; Julio A Chirinos  6
Collaborators, Affiliations

Ascending Aortic Dimensions and Body Size: Allometric Scaling, Normative Values, and Prognostic Performance

Hamed Tavolinejad et al. JACC Cardiovasc Imaging. .

Abstract

Background: Ascending aortic (AscAo) dimensions partially depend on body size. Ratiometric (linear) indexing of AscAo dimensions to height and body surface area (BSA) are currently recommended, but it is unclear whether these allometric relationships are indeed linear.

Objectives: This study aimed to evaluate allometric relations, normative values, and the prognostic performance of AscAo dimension indices.

Methods: We studied UK Biobank (UKB) (n = 49,271) and Penn Medicine BioBank (PMBB) (n = 8,426) participants. A convolutional neural network was used to segment the thoracic aorta from available magnetic resonance and computed tomography thoracic images. Normal allometric exponents of AscAo dimensions were derived from log-log models among healthy reference subgroups. Prognostic associations of AscAo dimensions were assessed with the use of Cox models.

Results: Among reference subgroups of both UKB (n = 11,310; age 52 ± 8 years; 37% male) and PMBB (n = 799; age 50 ± 16 years; 41% male), diameter/height, diameter/BSA, and area/BSA exhibited highly nonlinear relationships. In contrast, the allometric exponent of the area/height index was close to unity (UKB: 1.04; PMBB: 1.13). Accordingly, the linear ratio of area/height index did not exhibit residual associations with height (UKB: R2 = 0.04 [P = 0.411]; PMBB: R2 = 0.08 [P = 0.759]). Across quintiles of height and BSA, area/height was the only ratiometric index that consistently classified aortic dilation, whereas all other indices systematically underestimated or overestimated AscAo dilation at the extremes of body size. Area/height was robustly associated with thoracic aorta events in the UKB (HR: 3.73; P < 0.001) and the PMBB (HR: 1.83; P < 0.001).

Conclusions: Among AscAo indices, area/height was allometrically correct, did not exhibit residual associations with body size, and was consistently associated with adverse events.

Keywords: allometric relations; aneurysm; aorta; ascending aorta; dissection; rupture.

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Conflict of interest statement

Funding Support and Author Disclosures This research was conducted using the UKB Resource under application number 81032. The PMBB is approved under IRB protocol number 813913 and supported by Perelman School of Medicine at University of Pennsylvania, a gift from the Smilow family, and the National Center for Advancing Translational Sciences of the National Institutes of Health under CTSA award number UL1TR001878. This work was partially funded by grant K24-AG070459 (to Dr Chirinos). Dr Chirinos was supported by National Institutes of Health grants U01-TR003734, U01-TR003734-01S1, UO1-HL160277, R33-HL-146390, R01-HL153646, K24-AG070459, R01-AG058969, R01-HL157108, R01-HL155599, R01-HL104106, and R01HL155764; has consulted for Bayer, Fukuda-Denshi, Bristol-Myers Squibb, Biohaven Pharmaceuticals, Johnson & Johnson, Edwards Life Sciences, Merck, NGM Biopharmaceuticals, S2N Health, Health Advances, Emory University, and University of Delaware; has received University of Pennsylvania research grants from the National Institutes of Health, Fukuda-Denshi, Bristol-Myers Squibb, Microsoft, and Abbott; is named as inventor in a University of Pennsylvania patent for the use of inorganic nitrates/nitrites for the treatment of heart failure and preserved ejection fraction and for the use of biomarkers in heart failure with preserved ejection fraction; has received payments for editorial roles from the American Heart Association, the American College of Cardiology, Elsevier, and Wiley, and for academic roles from the University of Texas, Boston University, Rochester Regional Health, Virginia Commonwealth University, and the Korean Vascular Society; and has received research device loans from Atcor Medical, Fukuda-Denshi, Unex, Uscom, NDD Medical Technologies, Microsoft, and MicroVision Medical. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

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