Correlation of thin fibrous cap possessing adipophilin-positive macrophages and intraplaque hemorrhage with high clinical risk for carotid endarterectomy

OBJECT: Preoperative clinical risk classification of carotid artery (CA) stenosis anticipates the outcome of CA intervention. A higher incidence of neurological morbidity was noted after CA stenting (CAS) in patients with medical risks than in those without risks. However, little is known about the correlation between clinical risks and plaque composition. The purpose of this study was to characterize the CA plaque histology in 3 groups of patients who were classified based on clinical risks for carotid endarterectomy (CEA). Furthermore, the authors examined whether the plaque with high embolic potential after CA intervention, particularly CAS, could be predicted based on clinical risks for CEA. METHODS: Patients were divided into 4 groups, according to the CEA risk classification system, and 3 groups with more than 10 cases were enrolled in this study as follows: absence of all angiographic, medical, and neurological risks (Grade I, 27 cases); presence of medical risk, but no neurological risk (Grade III, 31 cases); and presence of neurological risk (Grade IV, 17 cases). Histopathological characteristics of CA plaques, including fibrous cap thickness, plaque disruption, thrombus formation, intraplaque hemorrhage (IPH), and adipophilin expression were examined without information regarding clinical status. RESULTS: Plaques in patients in Grades III and IV demonstrated a thin fibrous cap and enhanced IPH, compared with those in Grade I. Plaques in patients in Grade IV showed more adipophilin-expressing macrophages in the fibrous cap than in those of the other groups. CONCLUSIONS: Plaques in Grades III and IV patients were characterized by thin fibrous cap atheroma with IPH. Adipophilin-positive macrophage infiltration in the fibrous cap might be correlated with instability in neurological status. The plaque morphology in patients with medical and neurological risks needs to be examined carefully with the aid of imaging modalities. In plaques demonstrating a thin fibrous cap and IPH, the CAS procedure should be avoided and CEA should be performed instead.