Background/Purpose: Aortitis, characterized by inflammation of the aorta, is broadly divided into infectious and non-infectious aortitis (NIA); the latter group consists of a number of inflammatory conditions (most commonly giant cell arteritis [GCA] and rheumatoid arthritis [RA]) and idiopathic aortitis (IA), when an underlying inflammatory cause cannot be identified. Retrospective data depicts a high rate of development of subsequent vascular complications in NIA, but corresponding prospective studies are lacking.

Methods: We analyzed patients enrolled in a prospective observational cohort of patients with histologic aortitis, who were diagnosed at The Ottawa Hospital between 2013-2017 following surgical repair of thoracic aortic aneurysms or dissections. Upon referral, triggered by a positive histopathologic specimen, patients were assessed for evidence of inflammatory or infectious disease and presence of additional vascular lesions. Consenting patients with NIA were followed prospectively with periodic clinical assessments and laboratory and radiographic studies. Aortic outcomes during follow-up included ‘significant events’, defined as new thoracic or abdominal aortic aneurysms, dissection/rupture, or need for further surgery, as well as aortic branch ectasias, aneurysms, and stenosis. Fisher’s exact and the Mann-Whitney tests were used for significance calculations.

Results: Sixteen patients were included; 9 had IA and 7 had secondary aortitis (SA), specifically GCA (5) and RA (2). IA patients were more likely to have smoked (100% vs. 43%, p=0.02), and had more associated arch or descending aortic aneurysms on pre-operative baseline imaging compared to SA (6 vs. 0, p=0.01). At median 3.6-years of follow-up, 8 patients had 13 significant aortic events (9 and 4 events in 5 IA and 3 SA patients, respectively) (Table 1). The incidence of aortic dissection or second intervention, and the average annual rate of growth of descending aortic aneurysms, was higher in the first year post-surgery, compared to subsequent years. Immunosuppressive therapy did not seem to affect the outcomes, while elevated inflammatory markers during follow-up seemed to correlate with accumulation of severe aortic damage. No IA patients were diagnosed with a defined inflammatory condition at follow-up.

Conclusion: This is the first reported prospective study in patients with surgically diagnosed aortitis. Within the statistical limitations of a small cohort, we report a high incidence of aortic complications, especially in the early post-surgical period, and unaltered by immunosuppression. Studies of larger sample size and longer follow-up will be needed to corroborate these findings.

Table 1. Cumulative number of patients with (and total number of) aortic events over entire duration of follow-up.

*’Significant aortic events’ is a composite outcome that includes new aneurysms, dissection/rupture, or further interventions.