Background Necroscopic and surgical studies have suggested that giant cell arteritis (GCA) may target the aorta and its main branches. Imaging techniques are able to detect large vessel vasculitis (LVV) non-invasively in patients, but the prevalence of LVV in GCA has not been clearly established.

Objective To assess prospectively the prevalence, characteristics and topography of LVV in patients with newly diagnosed GCA and to determine the associated clinical and laboratory features.

Methods CT angiography (CTA) was performed in 40 consecutive patients with newly diagnosed biopsy-proven GCA. Patients were treatment-naïve or had been treated with corticosteroids for <3 days. Vessel wall thickness and vessel diameter (dilation or stenoses) at four aortic segments (ascending aorta, aortic arch, descending thoracic and abdominal aorta) and at the main aortic branches were evaluated.

Results LVV was detected in 27 patients (67.5%). The vessels involved were as follows: aorta (26 patients, 65%), brachiocephalic trunk (19 patients, 47.5%), carotid arteries (14 patients, 35%), subclavian arteries (17 patients, 42.5%), axillary arteries (7 patients, 17.5%), splanchnic arteries (9 patients, 22.5%), renal arteries (3 patients, 7.5%), iliac arteries (6 patients, 15%) and femoral arteries (11 patients, 30%). Dilation of the thoracic aorta was already present in 6 patients (15%). Cranial ischaemic events were significantly less frequent in patients with LVV (p=0.029). Treatment-naïve patients had a higher frequency of LVV (77% vs 29%, p=0.005).

Conclusions CTA-defined LVV occurs in two-thirds of patients with GCA at the time of diagnosis and aortic dilation is already present in 15%. Previous corticosteroid treatment may decrease CTA-detected LVV.