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

Last updated:

19 November 2025

Author(s):

Hamed Tavolinejad, Cameron Beeche, Marie-Joe Dib, Bianca Pourmussa, Scott M. Damrauer, John DePaolo, Joe David Azzo, Oday Salman, Jeffrey Duda, James Gee, Seavmeiyin Kun, Walter R. Witschey, Penn Medicine BioBank, Daniel J. Rader, Marylyn D. Ritchie, JoEllen Weaver, Nawar Naseer, Giorgio Sirugo, Afiya Poindexter, Yi-An Ko, Kyle P. Nerz, Meghan Livingstone, Fred Vadivieso, Stephanie DerOhannessian, Teo Tran, Julia Stephanowski, Salma Santos, Ned Haubein, Joseph Dunn, Anurag Verma, Colleen Morse Kripke, Marjorie Risman, Renae Judy, Colin Wollack, Shefali S. Verma, Scott Damrauer, Yuki Bradford, Scott Dudek, Theodore Drivas, Julio A. Chirinos

Publish date:

21 August 2025

Journal:

JACC Cardiovascular Imaging

PubMed ID:

40844449

DOI:

10.1016/j.jcmg.2025.06.019

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.