Anatomical variations in the arch of the aorta have been presumptively involved in aneurysm formation, because they lead to alterations in the vascular morphology and hemodynamics. This systematic review with meta-analysis evaluated the occurrence of bovine arch and aberrant subclavian artery variations of the aortic arch and aneurysm formation rate. The structured search was conducted across seven databases, namely PubMed, Embase, Web of Science, Scopus, Cochrane Library, CINAHL, and ClinicalTrials.gov, by using Boolean operators and MeSH terms. The review followed the guidelines of PRISMA and applied PECOS frameworks for individuals with aortic arch variations, quantifying the incidence or risk of aneurysm formation. The review utilized ROBINS-I and SYRCLE tools to assess the quality and bias, and a GRADE certainty assessment was used. A random-effects model was used for the meta-analysis, and sensitivity analyses were carried out to find out the robustness of the conclusion.
A total of seven studies were included, comprising both clinical cohort studies and animal research. The analysis indicated that individuals with anatomical variations such as the bovine arch had a higher mean difference (MD) of aneurysm risk compared to those without variations (MD 0.90 (0.63, 1.17); p < 0.00001). Vessel dimensions were significantly greater in those with anatomical variations associated with increased aneurysm risk (MD 9.00 (7.96, 10.04); p < 0.00001). Additionally, a comparison between patients with thoracic aortic aneurysms and healthy controls showed a notable increase in aortic arch dimensions in the aneurysm group (MD 11.46 (6.85, 16.08); p < 0.00001). The presence of specific anatomical variations in the aortic arch, particularly the bovine arch and aberrant subclavian artery, was associated with an increased risk of aneurysm formation. Variability in outcomes across age groups and study designs indicated that both anatomical and hemodynamic factors contribute to aneurysm formation risk. These findings emphasize the importance of individualized assessment of aortic arch anatomy in clinical practice for aneurysm risk stratification.
