Association between the Loss of Ambulation and the Distal Aortic Diameter in Male Patients with Muscular Dystrophy: A CT-based Observational Study.

Objective Muscular dystrophy (MD) is a rare neuromuscular disorder characterized by progressive muscle weakness and the loss of ambulation (LoA). Although vascular involvement has been suggested, the determinants of the aortic morphology in MD remain unclear. We hypothesized that the distal aortic diameters are smaller in patients with earlier LoA, potentially reflecting a reduced lower limb activity. Methods We retrospectively analyzed data of 31 male patients with MD who had undergone chest-to-pelvis computed tomography. The aortic diameters were measured at ten anatomical levels from the ascending to the terminal aorta. The primary outcome was the terminal aortic diameter; exploratory outcomes included diameters at nine additional levels. Correlations between age at LoA and aortic diameters were assessed using either Pearson or Spearman tests. Multivariable linear regression evaluated the association between the terminal aortic diameter and age at LoA, adjusting for age, the duration since LoA, systolic blood pressure, height, and MD subtype. Results The aortic diameter progressively decreased in the distal segments. Strong positive correlations were observed between the age at LoA and distal aortic diameters, including the terminal aorta (r=0.82). The age at LoA was independently associated with the terminal aortic diameter after multivariate adjustment. Conclusion This association is consistent with a potential link between a reduced lower limb activity and region-specific vascular remodeling, whereas the proximal segments supplying major abdominal organs appear to be relatively preserved. These findings highlight the potential influence of mobility-related factors on arterial morphology in neuromuscular disorders and support the need for further longitudinal studies.