Clinical and Histological Predictors of Aortic Distensibility in Patients with Thoracic Aortic Aneurysms

Background: Low aortic distensibility has been associated with an increased risk for aortic dissection. To improve our understanding of aortic distensibility, we aimed to identify clinical and histopathological parameters that are associated with reduced distensibility.

Methods: Patients who underwent thoracic aortic surgery at our center were included in our prospective aortic registry after informed consent. Aortic tissue alterations in paraffin sections of intraoperatively excised aortic tissue samples were characterized according to established guidelines on aortic pathology. Aortic distensibility was measured prior to surgery using transthoracic echocardiography. Finally, clinical and tissue alteration parameters (i.e., media degeneration, fibrosis, elastic fiber degeneration, and others) were tested for correlation with reduced aortic distensibility using linear regression analysis.

Results: Between 12/2020 and 12/2022, 80 patients were included in the analysis. The mean age was 63.0 ± 12.6 years. Five (6.3%) patients showed Marfan syndrome and 26 (32.9%) patients had a bicuspid aortic valve. The mean diameter of the ascending aorta was 5.6 ± 1.1 cm. The histological analysis of aortic tissue revealed severe elastic fiber thinning in 51.9% (n = 41), aortitis in 53.2% (n = 42), severe media fibrosis in 42.5% (n = 34), adventitia fibrosis in 41.8% (n = 33), extensive elastic fiber fragmentation in 40.5% (n = 32), severe overall media degeneration in 30.8% (n = 24), and extensive loss of smooth muscle cells in 22.8% (n = 18). At least moderate aortic regurgitation (regression coefficient [RC]: −0.006, p < 0.001), positive family history (RC: −0.006, p = 0.004), distribution of vascular smooth muscle cell loss (RC: −0.001, p = 0.035), and grade of medial fibrosis (RC: −0.002, p = 0.018) were independently associated with a reduced aortic distensibility. In contrast, statin therapy (RC: 0.003, p = 0.012) and grade of elastic fiber fragmentation and/or loss (RC: 0.002, p = 0.041) were identified as independent predictors of increased distensibility.

Conclusion: We identified both clinical and histological predictors of altered aortic distensibility in the ascending aorta. Future studies should focus on the mechanistic pathways linking these predictors to aortic distensibility and explore potential interventions to preserve or restore this crucial property of the aorta.

Publication History

Article published online:
11 February 2025