Increased Risk for Relapse in GCA-Related Aortitis Linked to Positivity on Imaging

In patients with giant cell arteritis (GCA)-associated aortitis, positivity on both fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and CT angiography (CTA) is associated with an elevated risk for relapse, according to the results of a multicenter retrospective study published in Seminars in Arthritis and Rheumatism.

Because of the risk for complications associated with aortitis, including aneurysm and dissection, the use of CTA imaging has been recommended for GCA diagnosis. Currently, the main aortic imaging modalities used include ¹⁸fluorine FDG (¹⁸FDG)-PET/CT scans and magnetic resonance angiography.

Researchers sought to compare the risk for relapse among individuals with GCA-related aortitis, as observed on FDG-PET/CT scans and CTA.

Patients diagnosed retrospectively from 2008 to 2020 at 13 tertiary care centers in the French Study Group for Large Vessel Vasculitis were included in the analysis. Eligible patients had GCA with at least 3 of the 5 American College of Rheumatology (ACR) diagnostic criteria or were aged older than 50 years, along with a C-reactive protein (CRP) levels of at least 10 mg/L and large-vessel vasculitis (LVV).

Aortitis was defined as a circumferential wall thickening 2.2 mm or greater away from atheroma on CTA or on PET/CT, with a grade 2 or 3 aortic wall ¹⁸FDG-uptake. Relapses of GCA were defined by “a combination of recurrence of clinical manifestations, inflammatory syndrome (CRP ≥10 mg/dL) and/or radiologic evidence of LVV progression.” Relapse was considered to be positive if participants presented with at least 2 of the 3 features concomitantly during the follow-up period.

A total of 82 patients were enrolled in the study, with mean age of participants being 67±8 years; 77% were women.

Study results showed that 78% of the participants had CTA and PET/CT scans that were positive for aortitis (Ao-CTA+/PET+ group). In addition, 21% of the participants had a positive PET/CT scan for aortitis and a negative CTA for aortitis (Ao-CTA-/PET+ group). One study participant had a positive CTA and no evidence of aortitis on the PET/CT scan.

All participants received initial treatment with glucocorticoids. A total of 94% in the Ao-CTA+/PET+ group vs 76% in the Ao-CTA-/PET+ group underwent CTA imaging before glucocorticoid use (P =.06), and 80% vs 76%, respectively, underwent PET/CT before glucocorticoid onset (P =.75).

During follow-up, 63% of the participants experienced a relapse — 70% of those in Ao-CTA+/PET+ group and 29% in the Ao-CTA-/PET+ group (P =.004). Overall, 44% of participants in the Ao-CTA+/PET+ group and 12% of participants in the Ao-CTA/PET+ group experienced a single relapse (P =.02), whereas 27% and 18%, respectively, experienced multiple relapses (P= .54). Relapse-free survival was significantly lower in the Ao-CTA+/PET+ group compared with the Ao-CTA-/PET+ group (log-rank test, P =.019).

According to multivariate analysis, aortitis on CTA was the only independent risk factor significantly associated with an elevated risk for relapse (hazard ratio, 2.90; 95% CI, 1.11-7.63; P =.03).

Study limitations included the retrospective design; the enrollment of patients who underwent both the imaging procedures at GCA diagnosis, which may have introduced a selection bias; and that treatment and follow-up therapeutic modalities were not standardized at the various centers.

“In this study, aortic wall thickening was associated with an increased risk of relapse,” the researchers indicated. However, “Further studies are needed to define the appropriate therapeutic approach for these patients,” they concluded.