Radiation-induced Carotid Stenotic Lesions have a more Stable Phenotype than De Novo Atherosclerotic Plaques

Abstract Objective To identify plaque characteristics of carotid artery radiation-induced stenosis. Materials and methods Nineteen carotid plaques were obtained during carotid endarterectomy (CEA) in 17 consecutive patients with prior cervical radiation therapy (XRT) (median interval 10 years) and compared with 95 matched control carotid plaques of patients without a history of XRT. The following histopathological factors were assessed: calcification, collagen, macrophages, smooth muscle cells, atheroma, microvessels and intraplaque haemorrhage. Association of individual histological parameters with XRT plaque was analysed through a multivariable regression model. Results Less infiltration of macrophages (6/19 versus 60/95, adjusted p  = 0.003) and a smaller lipid core size (Atheroma >10%: 10/19 versus 80/95, adjusted p  = 0.006) were independently associated with XRT plaque, compared to non-XRT plaques. Conclusions Carotid stenotic lesions in patients with previous cervical radiation are less inflammatory and more fibrotic than carotid atherosclerotic lesions in non-radiated patients.