A model developed to predict aortic surgery in patients with an ascending aortic aneurysm (AsAA), in which wall shear stress and circulating biomarkers of aortic strain are taken into account, may benefit decision-making in this patient population, according to a study published in the Annals of Thoracic Surgery.

In this study, 125 patients with AsAA and different aortic valve morphotypes who were referred to an Italian hospital for aneurysm size evaluation by echocardiography and computed tomography angiography, were included. Participants were categorized based on valve phenotype: bicuspid aortic valve (BAV) AsAA (n=42; mean age, 57.8±11.4 years) and tricuspid aortic valve (TAV) AsAA (n=83; mean age, 64.6±10.5 years; P =.002). A total of 47 circulating microRNAs and 14 protein biomarkers were measured from plasma samples. In addition, 8 hemodynamic variables were estimated with computational flow analysis, and 4 aortic wall strain and 7 anatomic parameters were measured.

No significant differences were found between the 2 groups in terms of aortic diameters or pressure-strain modulus. Aortic flow was greater in the BAV AsAA vs TAV AsAA group (1.9±0.7 m/s vs 1.4±0.4 m/s; P =.001).

Patients with BAV AsAA vs TAV AsAA had reduced expression levels of miR-133a (P =.038), miR-320a (P =.014), and miR-34a (P =.010), suggesting that valve morphotype may influence the differing circulating exosomal expression of these miRNAs.


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In the analysis of the proximal ascending aorta, matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of matrix metalloproteinase 1 (TIMP-1) plasma levels were positively correlated with peak systolic wall shear stress (P =.005) and time-average wall shear stress (TAWSS; P <.001), respectively. The matrix metalloproteinase-2 MMP-2 was positively correlated with TAWSS (P <.001). In patients categorized as BAV AsAA, there were positive associations between aortic wall strain at the mid-ascending aorta with plasma levels of miR-320a (P <.001) and miR-26a (P =.041).

Bicuspid-induced wall shear stress correlated with levels of MMP-7 (P <.001), and pressure-strain modulus\correlated with levels of MMP-7 (P =.004). Receiver-operating characteristics curves indicated that a combination of wall shear stress, MMP-1, TIMP-1, and matrix metalloproteinase-12 circulating biomarkers was predictive of the event of AsAA surgery (area under the curve, 0.898).

Limitations of the analysis included the small sample size and the short follow up.

”[W]e reported direct relationships of both shear stress and strain exerted on the aneurysmal aortic wall with circulating exosomal miRNAs and protein proteolytic activity. We also demonstrated the feasibility to combine imaging-derived metrics and circulating biomarkers to predict the risk of aortic surgery in a holistic and personalized decision-making process of the aortic wall disease,” concluded the study authors.

Reference

Pasta S, Agnese V, Gallo A, et al. Shear stress and aortic strain associations with biomarkers of ascending thoracic aortic aneurysm [published online April 11, 2020]. Ann Thorac Surg. doi:10.1016/j.athoracsur.2020.03.017