[Giant-cell arteritis and Takayasu arteritis: epidemiological, diagnostic and treatment aspects]

Abstract

Giant-cell arteritis (GCA) and Takayasu arteritis (TAK) are primary systemic granulomatous large-vessel vasculitides. Whether both entities represent distinct phenotypic expressions of a shared etiopathogenic process remains hypothetical. GCA more commonly affects subjects of northern European background while the clinical observation that TAK might be more common in populations of Asian or African ancestry needs to be confirmed by epidemiological studies. Distinct human leukocyte antigen class II associations were identified as genetic risk factors of GCA and TAK. The increasing incidence of GCA also suggests an environmental cause. Temporal artery biopsy is the main diagnostic test for GCA, although MRI and Doppler ultrasonography of the temporal or occipital arteries may also reveal vessel wall inflammation. MRI, CT and positron emission tomography with 18F fluodeoxyglucose have progressively replaced conventional invasive imaging modalities for study of large-vessel disease. The diagnostic accuracy of these 3 imaging modalities seems equivalent, but their value in the follow-up of GCA and TAK is less clear. According to studies based on modern imaging techniques, 70-80% of patients with newly diagnosed GCA show an involvement of the aorta and/or the major branches of the aorta. Glucocorticoids are the reference therapy for GCA. Adjunctive therapy, notably with methotrexate, appears to enhance disease control and reduce glucocorticoid exposure. IL-6 blockade has hope as a new treatment option for GCA. Principles of therapy for TAK are similar to those of GCA, except that TNFα blockers, particularly infliximab, seem to show good results in TAK and revascularization procedures are an important part of the TAK therapy.