Abstract 2994: Atherosclerotic Plaque Histology Predicts Restenosis after Carotid Endarterectomy: a Prospective Cohort Study in 500 Patients.

Abstract

Introduction: Many studies have addressed clinical and angiographic risk factors for restenosis development after vascular interventions, but the composition of the atherosclerotic plaque at the intervention site has not been studied as a determinant of luminal re-narrowing after intervention. The aim of this study was to investigate the association between atherosclerotic plaque histology at baseline and restenosis development after carotid endarterectomy. Methods: Patients undergoing carotid endarterectomy were included in a longitudinal vascular biobank study. After surgical excision, the plaques were subjected to histological examination. The patients were prospectively followed-up with duplex ultrasound to assess restenosis (cut-off points: >50% and >70% renarrowing) one year after the intervention. The risk of restenosis was related to predefined plaque histological characteristics (macrophage and smooth muscle cell infiltration, collagen, calcifications, intra-plaque bleeding, luminal thrombus and lipid core size) adjusted for clinical characteristics (multivariable logistic regression analysis). Measurements of vessel diameter and intima-media thickness were performed using B-mode ultrasound in a subgroup of patients to discriminate between the roles of geometric vascular remodeling and neointima formation during follow-up. Results: In 500 consecutive patients (April 2002 – April 2007), plaque macrophage infiltration and a large lipid core were strongly associated with decreased risk of >50% restenosis (adjusted odds ratio = 0.43 [0.26 – 0.70]; 0.38 [0.19 – 0.70]) and >70% restenosis during follow-up (adjusted odds ratio = 0.36 [0.18 – 0.74]; 0.42 [0.17–1.03]), independent of clinical characteristics. The other histological characteristics were not related with restenosis. Duplex measurements (n=50) showed that vessels holding macrophage rich plaques revealed increased expansive geometric vascular remodeling during 1 year follow-up (+1.19 mm [0.03 – 2.36]). Conclusions: The absence of plaque macrophages and lipid core are powerful independent predictors of restenosis development after carotid endarterectomy. Plaque composition is linked with restenosis via geometric vascular remodeling.