Comparison of idiopathic (isolated) aortitis and giant cell arteritis-related aortitis. A French retrospective multicenter study of 117 patients.

Objectives: The aim of the study was to compare clinical/imaging findings and outcome in patients with idiopathic (isolated aortitis, IA) and with giant cell arteritis (GCA)-related aortitis.
Methods: Patients from 11 French internal medicine departments were retrospectively included. Aortitis was defined by aortic wall thickening >2mm and/or an aortic aneurysm on CT-scan, associated to inflammatory syndrome. Patients with GCA had at least 3 ACR criteria. Aortic events (aneurysm, dissection, aortic surgeries) were reported, and free of aortic events-survival were compared.
Results: Among 191 patients with non-infectious aortitis, 73 with GCA and 44 with IA were included. Patients with IA were younger (65 vs 70 years, p=0.003) and comprised more past/current smokers (43 vs 15%, p=0.0007). Aortic aneurisms were more frequent (38% vs 20%, p=0.03), and aortic wall thickening was more pronounced in IA. During follow-up (median=34 months), subsequent development of aortic aneurysm was significantly lower in GCA when compared to IA (p=0.009). GCA patients required significantly less aortic surgery during follow-up than IA patients (p=0.02). Mean age, sex ratio, inflammatory parameters, and free of aortic aneurism survival were equivalent in patients with IA ≥ 60 years when compared to patients with GCA-related aortitis.
Conclusions: IA is more severe than aortitis related to GCA, with higher proportions of aortic aneurism at diagnosis and during follow-up. IA is a heterogeneous disease and its prognosis is worse in younger patients <60 years. Most patients with IA ≥ 60 years share many features with GCA-related aortitis.
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