Comparison of microstructural alterations in the proximal aorta between aortic stenosis and regurgitation

Objective: We aimed to analyze the association among flow patterns, gene expression, and histologic alterations of the proximal aorta in patients with aortic valve disease.

Methods: A total of 131 patients referred for aortic valve replacement were grouped by valve dysfunction (aortic stenosis vs aortic regurgitation) and valve morphology (bicuspid vs tricuspid). On the basis of magnetic resonance imaging, aortic tissue from outer and inner curvature was collected for gene expression and histologic analysis. To identify differences in aortic remodeling, age- and sex-adjusted data for inflammation (CCL2, VCAM1, inflammation and atherosclerosis) and medial degeneration (COL1A1, ELN, fibrosis, elastin fragmentation, and cystic medial necrosis) were compared.

Results: First, we compared all patients with aortic regurgitation (n = 64) and patients with aortic stenosis (n = 67). In patients with aortic regurgitation, COL1A1 expression and all histologic markers were significantly increased. With respect to aortic diameter, all subsequent analyses were refined by considering only individuals with aortic diameter 40 mm or greater. Second, patients with bicuspid aortic valve were compared, resulting in a similar aortic diameter. Although patients with aortic regurgitation were younger, no differences were found in gene expression or histologic level. Third, valve morphology was compared in patients with aortic regurgitation. Although aortic diameter was similar, patients with regurgitant bicuspid aortic valve were younger than patients with regurgitant tricuspid aortic valve. Inflammatory markers were similar, whereas markers for medial degeneration were increased in patients with regurgitant tricuspid aortic valve.

Conclusions: Our results indicate that the proximal aorta in patients with aortic regurgitation showed an increased inflammation and medial degeneration compared with patients with aortic stenosis. Refining both groups by valve morphology, in patients with bicuspid aortic valve, no difference except age was detected between aortic regurgitation and aortic stenosis. In patients with aortic regurgitation, tricuspid aortic valve revealed increased markers for medial degeneration but no differences regarding inflammatory markers.