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FRI0393 Cut-Off Values for Intima-Media Thickness of Temporal, Facial and Axillary Arteries in Giant Cell Arteritis

Background Ultrasound (US) is increasingly used in the diagnosis of giant cell arteritis (GCA). US findings mainly rely on morphology (“halo-sign” and “compression sign”). Increasing resolution of modern US probes allows exact intima-media thickness (IMT) measurement of normal and vasculitic temporal arteries. No data have yet been published on IMT of temporal, facial and axillary arteries in GCA patients compared to healthy controls. Objectives To evaluate the mean IMT thickness of arteries commonly involved in GCA in GCA patients and controls, and to determine if cut-off values can define pathology. Methods Fourty newly diagnosed GCA patients of a fast-track GCA clinic and 40 age- and sex-matched controls were included between October 2014 and December 2015. The diagnosis of GCA was established by two very experienced rheumatologists (WAS or AJ) on the basis of clinical presentation, laboratory tests and US results. The diagnosis was confirmed after 6 months in patients who were included until July 2015. IMT measurement was performed at or within 24 hours after the first visit. The common superficial temporal arteries with their frontal and parietal branches and the facial arteries were bilaterally examined with a 10–22 MHz probe (Esaote MyLab Twice). A 6–18 MHz probe was used for both axillary arteries. In total, IMT measurement was performed at 800 sites. The mean IMT values of the different arteries were compared between controls and patients with active vasculitis of the corresponding artery by means of a Mann-Whitney test. ROC analysis was performed to determine the best cut-off value, balancing sensitivity and specificity, to discriminate between a normal and a vasculitic artery. Results Both groups of 40 participants, each, included 27 females. The mean age was 72 years (SD 9). Of the 40 GCA patients, 22 (55%) had indurated temporal arteries on clinical examination, 16 (40%) had symptoms of polymyalgia rheumatica. The mean duration of symptoms was 15 weeks (SD 19). Five patients (13%) had visual impairment (anterior ischaemic optic neuropathy, 3; amaurosis fugax, 1; diplopia, 1). Twenty-eight patients (70%) described headache; and 17 (43%) had jaw claudication. The mean ESR was 82 mm/h (SD ± 28); and the mean CRP was 107 mg/dL (SD 79). In 26 patients (65%) the axillary arteries were involved of whom 9 had no involvement of temporal arteries. Table 1 shows IMT of affected arteries in GCA patients compared to controls and cut-off values for distinguishing normal from inflamed arteries. Maximum IMT of controls and minimum IMT of vasculitic segments in GCA was 0.34 mm/0.42 mm for the common superficial temporal arteries, 0.32 mm/0.34 mm for the frontal branch, 0.31 mm/0.24 mm for the parietal branch, 0.42 mm/0.31 mm for the facial artery and 0.86 mm/1.0 mm in the axillary arteries, i.e. no overlap occurred in the common superficial temporal arteries, the frontal branch and the facial arteries. Conclusions IMT measurement of temporal, facial and axillary arteries can correctly distinguish vasculitic from normal arteries in suspected GCA in addition to morphological parameters. Data for wall diameters are needed for future longitudinal trials to monitor GCA treatment. Disclosure of Interest None declared