Aortitis accelerates the growth rate of thoracic aortic aneurysms.

Thoracic aortic aneurysms (TAA) are predominantly degenerative. Non-infectious inflammatory aortitis, including giant cell arteritis (GCA), Takayasu arteritis and clinically isolated aortitis (CIA), represents a less understood aetiology with poorly characterised growth patterns. While GCA is linked to higher TAA risk, preoperative growth data for inflammatory TAA are scarce. This study compares growth rates in histologically proven inflammatory aortitis. We conducted a retrospective case-control study, including patients with histologically proven aortitis and matched controls with degenerative TAA. Cases and controls were matched for age, sex, surgical year and procedure type. Aneurysm growth rate (mm/month) was calculated from serial imaging. This study included 23 patients with histologically confirmed aortitis (13 GCA, 9 CIA) and 42 matched controls with degenerative TAA. The mean growth rate was significantly higher in the aortitis group (0.177±0.01 mm/month; 2.12 mm/year) compared with controls (0.039±0.02 mm/month; 0.47 mm/year), representing a 4.5-fold acceleration (p<0.001). Among inflammatory etiologies, CIA demonstrated faster growth (0.338±0.06 mm/month; 4.06 mm/year) than GCA (2.1 mm/year; p<0.01). Patients with CIA more frequently required Bentall procedures (33% vs 0%, p=0.047). No differences were observed in baseline demographics, cardiovascular risk factors or baseline aortic diameters between groups. Histologically, 70% of aortitis cases exhibited granulomatous inflammation. Inflammatory aortitis is associated with a 4.5-fold faster preoperative TAA growth rate compared with degenerative aneurysms, with CIA exhibiting two times the growth rate of GCA. Prospective studies are warranted to validate these results and optimise surveillance and management strategies for this high-risk population.