Histopathological grading of ascending aortic aneurysm: Comparison of patients with bicuspid versus tricuspid aortic valve

Background and aims of the study: Bicuspid aortic valve (BAV) is a common inherited condition that is often accompanied by ascending aortic aneurysm. A high level of histological wall abnormalities was reported to be present in non-dilated aortas of patients with BAV. In patients with tricuspid aortic valve, there appears to exist a direct relationship between the diameter of the ascending aorta and degree of histopathological aortic wall abnormalities. Whether this situation exists in patients with BAV has not yet been investigated. Methods: Surgical and medical records of all patients undergoing surgery of the ascending aorta were reviewed. A total of 65 patients was identified in whom an aortic wall specimen was obtained intraoperatively. These specimens were systematically re-evaluated, and graded according to the severity of seven histopathological conditions: fibrosis, atherosclerosis, medionecrosis, cystic medial necrosis, smooth muscle cell orientation, elastic fiber fragmentation, and inflammation. Results: BAVs were present in 26 patients (40%). Patients with BAV had significantly less aortic wall alterations than patients with tricuspid aortic valves (p <0.001) in all variables examined. The severity of aortic wall abnormalities was significantly dependent on aortic diameter in patients with BAV as well as tricuspid aortic valve (p = 0.036 and 0.019), but dependent on age (p = 0.009) only in patients with tricuspid aortic valve. Conclusion: The study results provide evidence that ascending aortic aneurysm in patients with BAV differs clinically and histologically from that in patients with tricuspid aortic valve. Further studies are needed to elucidate the impact of inherited and acquired aortic wall abnormalities on the development of aneurysms.