LAUSR

Background The European League Against Rheumatism (EULAR) recently recommended the use of ultrasound for the detection of inflamed artery walls in giant cell arteritis (GCA) for diagnostic purposes. Intima media thickness (IMT) values, defining the “halo” sign in acute GCA patients, have also recently been proposed. In patients with chronic GCA, already receiving a treatment, the ultrasound appearance of inflamed artery walls changes and becomes difficult to detect.(1-4) IMT measurement may help to identify patients with chronic large-vessel GCA (LV-GCA) by assessing the axillary arteries; however, a cut-off for distinguishing between chronically affected arteries and unaffected ones is not yet available. Objectives To determine an ultrasound IMT cut-off value for axillary arteries in patients with chronic LV-GCA. Methods Ultrasound of temporal and axillary arteries was performed in 127 GCA patients at the time of diagnosis and at one or two follow-up visits. Axillary arteries of GCA patients with sonographic signs of inflammation at the time of diagnosis were compared to unaffected axillary arteries of GCA patients and to axillary arteries of healthy controls. Receiver operating curves (ROC) were calculated using follow-up data to identify the optimal IMT cut-off. Results 148 axillary arteries of GCA patients showed signs of ultrasound inflammation at baseline (=LV-GCA group). The control group consisted of 162 axillary arteries, including 82 (50.6%) axillary arteries of GCA patients without signs of ultrasound inflammation at baseline or follow-up exam and 80 (49.4%) axillary arteries of 40 healthy controls. The mean age and gender distribution of the two groups at follow-up were 71 years (S.D. 7.9) with 69.9% females, respectively in the chronic LV-GCA group and 74 years (S.D. 6.9) with 59.8% females, respectively in the control group. The mean IMT values in the LV-GCA group were 1.14 (S.D. 0.38, n=78) for the right and 1.18 (S.D. 0.47, n=70) for the left axillary arteries as compared to 0.60 (S.D. 0.11, n=77) for the right and 0.62 (S.D. 0.11, n=85) for the left axillary arteries in the control group. Intervals from diagnosis to follow-up were 0.5-3 years, 3-6 years and >6years, with a distribution of 96 (65%), 32 (22%) and 20 (13%) exams in the LV-GCA group and 29 (35%), 41 (50%) and 12 (15%) exams in the control group (excluding healthy controls), respectively. The optimal IMT cut-off value for the axillary arteries in patients with chronic LV-GCA was 0.87 mm with 75.0% sensitivity and 99.4% specificity (see figure 1). Sensitivity analysis (comparing patients with and without an involvement of the temporal artery at the time of diagnosis) validated this cut-off value. Conclusion An ultrasound IMT cut-off value for the axillary arteries can distinguish between patients with chronic LV-GCA and patients without chronic large vessel involvement. References [1] Dejaco C, Ramiro S, Duftner C, et al. EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice. Ann Rheum Dis2018;77:636-43. [2] Schäfer VS, Juche A, Ramiro S, et al. Ultrasound cut-off values for intima-media thickness of temporal, facial and axillary arteries in giant cell arteritis. Rheumatology2017;56:1479-83. [3] De Miguel E, Beltran LM, Monjo I, et al. Atherosclerosis as a potential pitfall in the diagnosis of giant cell arteritis. Rheumatology2017;57:318-21. [4] Czihal M, Schrottle A, Baustel K, et al. B-mode sonography wall thickness assessment of the temporal and axillary arteries for the diagnosis of giant cell arteritis: a cohort study. Clin Exp Rheumatol2017;35Suppl 103:128-33.Figure 1 Receiver operating curve for the axillary artery cut-off in chronic large-vessel giant cell arteritis. Disclosure of Interests Philipp Bosch: None declared, Christian Dejaco Speakers bureau: MSD, Pfizer, UCB, AbbVie, Roche, Novartis, Lilly, Celgene, Merck, Sandoz, Wolfgang A. Schmidt: None declared, Andreas Krause Consultant for: Pfizer, Speakers bureau: Pfizer, Kenny-Davis Schlüter: None declared, Valentin S. Schäfer: None declared