BACKGROUND:Aortic structural damage (ASD) may complicate the course of patients with giant cell arteritis (GCA). However the frequency and outcome of ASD has not been assessed in long term prospective studies. METHODS:In a previous screening of 54 biopsy proven GCA patients, significant ASD was detected in 12 (22.2%) after a median follow-up of 5.4 years. These patients were periodically evaluated (every 4 years) over a median of 10.3 years (range 4-16.6 years) in order to investigate the development of new ASD and the outcome of previously detected abnormalities. RESULTS:18 of the 54 patients abandoned the study due to death or other reasons. The remaining 36 patients were subjected to a second screening and 14 to a third screening. 12 (33.3%) of the 36 patients re-screened and 16 (29.6%) of the initial cohort developed ASD, all but one in the thoracic aorta. Aortic diameters at the ascending and descending aorta significantly increased over time. One patient (1.9% of the initial cohort) died from aortic dissection. Surgery was advised in eight (50%) patients with ASD but could only be performed in three patients (37.7%). The development of ASD was not associated with persistence of detectable disease activity. CONCLUSIONS:The incidence of ASD is maximal within the first 5 years after diagnosis but continues developing over time, affecting up to 33.3% of individuals after long term follow-up. Once ASD occurs, dilatation increases over time, underlining the need for periodic evaluation. Surgical repair is feasible in about one-third of candidates.