P191 Giant cell arteritis relapses occur in a different arterial territory as compared to diagnosis

Abstract

Abstract Background/Aims Ultrasonography (US) for diagnosis of large vessel vasculitis (LVV) is a recommended first line diagnostic procedure. We have been running an US led diagnostic pathway in our centre since January 2017. This pathway is also used to diagnose relapsing disease. We present US defined anatomical distribution of relapses in consecutive patients. Methods Patients in whom new and relapsing disease was diagnosed using US were included. Protocolised US examination of the common carotid system (segments of common carotid, external carotid and branches) and those of the subclavian system (segments from origin of subclavian to end of axillary artery and branches) were carried out at diagnosis and relapse. Halo sign in at least two different arteries was needed for establishing new or relapsing disease. Disease characterisation was classified as being in the carotid system, subclavian system, or both. The nature of the disease at relapse was compared to that at diagnosis. Results 279 patients were diagnosed with LVV using US since Jan 2017. 57 (20%) were diagnosed as having a relapse using US. 43/57 (75%) and 28/57 (49%) had involvement of the carotid system at baseline and relapse respectively. 22/57 (39%) and 44/57 (77%) had involvement of the subclavian system at baseline and relapse respectively. A comparison of the disease involvement is as in Figure 1. Conclusion The branches of the common carotid artery (external carotid artery) are commonly involved at diagnosis, but relapse occurs more frequently in the subclavian artery branches. This is especially true when disease affects the carotid system at baseline. The presentation of patients with subclavian system disease is often with only constitutional symptoms and with shoulder girdle pain and stiffness. This may be mistaken for being a polymyalgia rheumatica relapse. It is essential to examine the subclavian system of arteries in patients with LVV before diagnosing polymyalgia rheumatic relapse. Disclosure S. Alanoor: None. G. Ducker: None. C.B. Mukhtyar: None.