Histological and Immunohistochemical Characteristics of Eccentric Coronary Artery Lesions Retrieved by Atherectomy from Cardiac Transplant Recipients

The lesions of cardiac allograft vasculopathy are thought to be strongly related to an immune inflammatory process. Little is known about the biology of these eccentric lesions. However, transplant patients may present with focal disease. Coronary atherectomy provides a unique opportunity to study these clinically relevant lesions in surviving transplant patients. In this series we characterized the features of four lesions (two restenotic and two primary) from three cardiac transplant recipients who underwent coronary atherectomy. The histologic characteristics of the lesions were analyzed and immunohistochemistry was used to assess qualitatively the presence of specific markers of inflammation and the extracellular matrix component fibronectin. Histology showed cholesterol clefts, calcium deposits, and foam cells with low to moderate cellularity and moderate to high fibrosis. Interleukin (IL)-1β was present in two lesions, but tumor necrosis factor (TNF)-α was absent. The adhesion molecules intercellular adhesion molecule (ICAM)-1 and vascular cellular adhesion molecule (VCAM)-1 and the integrins α5β1 and α4 were present in all lesions. There was mild to moderate accumulation of fibronectin. Thus, atheroscleroticlike features were present with only low to moderate degrees of immune inflammation. Our findings suggest that eccentric focal plaques in cardiac allograft vasculopathy are less likely to be primarily related to a prominent immune inflammatory process and are similar to atherosclerosis. We speculate that these eccentric lesions that resemble atherosclerosis may be more related to the conventional risk factors for coronary artery disease frequently seen in this population.