E173 Isolated inflammatory aneurysmal aortitis: should immunosuppression be used or is endovascular repair sufficient? A retrospective cohort study from a tertiary centre

Background/Aims Inflammatory aneurysmal aortitis (IAA) is a clinically significant variant of large vessel vasculitis (LVV), with aortic wall inflammation and periaortic fibrosis. Although patients with aortic aneurysms are generally referred to vascular surgery for endovascular aneurysm repair (EVAR), those with inflammatory features need rheumatology review to exclude LVV/IAA to determine if immunosuppression is indicated. This study evaluates radiological, biochemical, and survival outcomes in patients with EVAR-treated IAA, with/without corticosteroid therapy, to determine if immunosuppressant intervention is needed. Methods Retrospective data were collected on EVAR patients at a tertiary centre from 2019 to 2023. Radiology databases searched “aortitis,” “vessel wall thickening,” “periaortic fat stranding.” Data were collected on demographic, clinical, and laboratory data, comorbidities, pre/post-procedure CRP, imaging features, steroid use, and survival. Post-EVAR CT scans were reviewed for interval inflammatory change (improvement, stability, worsening). CRP change and radiological response were compared between steroid-treated and untreated groups. Results Of 24 patients identified, 8 were excluded (likely infection) and 16 met inclusion criteria (median age 73 years, range 52-90; 81% male), with cardiovascular comorbidity (75%), heart disease (63%), diabetes (19%) and chronic kidney disease (19%). Corticosteroids were given to 3 patients (19%), 2 for retroperitoneal fibrosis, 1 for widespread LVV on PET-CT. Median pre-EVAR CRP was 25.5 mg/L (range 4.9-276), CRP normalised in 81% (13/16) with no worsening during follow-up. Post-procedure imaging was available in 81% (n = 13): 38% (n = 5) demonstrated improvement and 62% (n = 8) remained stable irrespective of corticosteroid use. 30-day mortality was 0%. Surveillance over median 52 months (range 13-72) showed no patient required steroid initiation or further immunosuppression after EVAR. (Table 1) Conclusion Although corticosteroids are conventionally used in LVV, our findings suggest that EVAR alone for IAA achieves biochemical and radiological stability irrespective of corticosteroid use. Immunosuppression should be reserved for patients with systemic LVV or concomitant retroperitoneal fibrosis. The absence of early mortality and relapse underscores EVAR’s safety and durability. Limitations include small sample size, retrospective design, and incomplete imaging follow-up. Future multicentre studies incorporating PET-CT and longer-term immunological follow-up are warranted to refine management algorithms for this rare and under-recognised condition. Disclosure G. Sukhija: None. K. Thompson: None. N. Arumalla: None. K. Quazi: None. B. Azhar: None. R. Morgan: None. A. Kaul: None.