Clinicopathological characteristics of severe aortic valve regurgitation caused by Behçet's syndrome.

Objectives: Aortic valve regurgitation (AR) caused by Behçet's syndrome (BS) has high mortality. Preoperative biologics reduced systemic inflammation, but their effect on lesion inflammation remains unclear.

Methods: Twenty-two BS patients with severe AR who underwent cardiac surgery with retained pathological specimens were included. The pathology of the aortic wall and/or valve was re-analysed based on their preoperative disease activity and treatment strategy. Immunohistochemistry (IHC) assessed the distribution of CD4+, CD8+, CD20+ and CD68+ cells.

Results: The mean diagnosis age was 39.6±13.1 years, with a median disease duration of 9 (3-35) years. Seven (31.8%) underwent cardiac surgery during the active phase due to uncontrollable disease progression, while 15 (68.2%) were in remission. Pathologically, severe AR caused by BS is characterised by mixed inflammatory cell infiltration in the aortic wall. Active cases showed significantly more diffuse infiltration of CD4+ (100% vs. 8.3%, p=0.0002) and CD8+ (71.4% vs. 20%, p=0.058) T cells in the aortic adventitia, with more neutrophil infiltration in the aortic valve (60% vs. 7.7%, p=0.044). Notably, less CD68+ macrophage infiltration (57.2% vs. 0%, p=0.045), CD4+ T cell diffusion (57.1% vs. 0%, p=0.045), and vasa vasorum mucoid degeneration (85.7% vs. 20%, p=0.017) were observed in the aortic adventitia of patients receiving preoperative biologics, together with less aortic valve necrosis (71.4% vs. 0%, p=0.023).

Conclusions: Overall, our study provides valuable insights into the pathology of severe AR caused by BS as a mixed inflammatory infiltration and provides the first pathological rationale for achieving preoperative remission and early biologics to improve the prognosis.