Large Vessel Vasculitis Revisited: Mechanistic Insights and Advances in Diagnosis and Management

Systemic vasculitides are complex multisystem immune-mediated inflammatory diseases, classified by the affected vessel size, which are associated with a wide range of clinical manifestations and complications. The most common forms of large vessel vasculitis (LVV) are giant cell arteritis and Takayasu arteritis, although other more rare causes exist. Cranial giant cell arteritis is the most commonly diagnosed form of LVV, affects older adults and can result in sudden visual loss and stroke. Up to 80% of individuals with giant cell arteritis have LV involvement, which can exist with or without cranial involvement. Takayasu arteritis usually occurs in those under the age of 60 years, resulting in progressive injury of the aorta and its main branches. LVV may also affect the coronary and pulmonary circulations, as well as the pericardium and myocardium resulting in a range of cardiovascular pathologies. Diagnosing LVV can be challenging in the absence of a disease-specific laboratory biomarker, and relies on a combination of inflammatory markers, imaging, and temporal artery biopsy when required. Noninvasive multimodality imaging techniques are advancing and provide new avenues for diagnosis and disease monitoring. High-resolution ultrasound, magnetic resonance imaging, and computed tomography can survey the pattern and extent of arterial involvement and reveal signs of active inflammation. Positron emission tomography imaging with ¹⁸F-fluorodeoxyglucose and novel radiotracers provide more sensitive measures of vascular inflammation of the large vessels. Ultimately, these imaging tests can be used to guide therapeutic interventions and inform the clinical use of new targeted disease modifying therapies for LVV.