The influence of baseline aortitis on aortic dilation risk in GCA: a multicentre imaging study

OBJECTIVES: To assess the prevalence of aortitis and aortic dilation at diagnosis, estimate the progression of aortic diameter over time, and identify predictors of incident aortic dilation development in patients with newly diagnosed GCA. METHODS: We conducted a retrospective cohort study involving 157 patients with new-onset GCA from two European centres. All patients underwent baseline thoracic aortic imaging within 6 months of diagnosis and at least one follow-up imaging ≥6 months later. Outcomes included baseline aortic diameter, aortic expansion (cm2/year), and incident aortic dilation. Multivariable regression models were adjusted for sex and age. RESULTS: Aortitis was present in 60.4% of patients at baseline. Baseline aortic dilation was identified in 19.6% of patients, predominantly in the mid-ascending aorta. Aortitis was associated with larger aortic diameters and higher odds of baseline aortic dilation (adjusted odds ratio 2.3; 95% CI: 1.0, 5.1). Over a median follow-up of 30 months, incident aortic dilation developed in 9.8% of patients. Baseline aortic diameter was the strongest predictor of aortic expansion (β = 0.088; P = 0.006) and incident aortic dilation (adjusted hazard ratio 3.9; 95% CI: 2.0, 7.3). CONCLUSION: Aortic involvement is common at the time of GCA diagnosis, and baseline aortic diameter is the strongest predictor of future dilation in our cohort. These findings highlight the importance of early imaging assessment and longitudinal monitoring of aortic dimensions in patients with newly diagnosed GCA.