Delay to carotid endarterectomy in patients with symptomatic carotid artery stenosis.

OBJECTIVE: In patients with recently symptomatic carotid artery stenosis, guidelines recommend carotid revascularization within 2 weeks of the index event. The "index event" may be defined as either the first or the most recent event. The delay between the index event and carotid endarterectomy (CEA) over a period of 6 years in a single centre was evaluated and the effect of defining the index event as either the first or the most recent event was assessed. DESIGN: Observational study. METHODS: 555 consecutive patients with symptomatic carotid stenosis ≥ 50% treated with CEA between 2007 and 2012 were assessed. In 2010, changes to the in-hospital process of care to reduce delays in referral and CEA were introduced. These changes included, for example, improving access to physicians, imaging, and operating rooms. The delay from symptoms to surgery was expressed in days. RESULTS: The median time between the first event and surgery was reduced from 53 days (interquartile range [IQR] 30-78) in 2007 to 21 days (IQR 12-45) in 2012, and between the most recent event and CEA from 45 days (IQR 28-67) to 17 days (IQR 9-28). Patients referred directly by their general practitioner more often underwent CEA within 2 weeks than patients referred by specialists from other hospitals. Compared to patients with transient ischaemic attack or ocular symptoms, patients with ischaemic stroke more often underwent CEA within 2 weeks. CONCLUSIONS: A small change in the process of care significantly reduced the delay from the index event to CEA, but in 2012 it still exceeded 14 days in the majority of patients. The definition of the "index event" has a large impact on the total duration of delay, and should therefore be uniform across studies.

Current status of clinical magnetic resonance imaging for plaque characterisation in patients with carotid artery stenosis.

OBJECTIVE: The article aims to provide an overview of the literature that assessed the agreement between magnetic resonance imaging (MRI) and histology for specific carotid plaque characteristics associated with vulnerability in terms of sensitivity and specificity. METHODS: A systematic search strategy was conducted in MEDLINE and EMBASE databases resulting in 1084 articles. Finally, we included 17 papers. Due to variation in presentation, especially in MRI and histology methods, a pooled analysis could not be performed. RESULTS: Two studies were performed on a 3.0-T MRI scanner; all other studies were performed on a 1.5-T scanner. Most performed sequences were two-dimensional (2D) and three-dimensional (3D) T1-weighted and all histology protocols varied slightly. Our results indicate that calcification, fibrous cap, intraplaque haemorrhage and lipid-rich necrotic cores can be identified with moderate-to-good sensitivity and specificity. CONCLUSIONS: Based on current literature, it appears premature for routine application of MRI as an imaging modality to assess carotid plaque characteristics associated with plaque vulnerability. Although MRI still holds promise, clinical application for plaque characterisation would require consensus regarding MRI settings and confirmation by histology. Predefined protocols for histology and MR imaging need to be established.

Asymptomatic carotid artery stenosis: identification of subgroups with different underlying plaque characteristics.

OBJECTIVES: Optimal surgical treatment of patients with asymptomatic carotid artery stenosis (ACAS) remains a matter of debate. Established definitions of ACAS include: (1) patients who never suffered from ipsilateral cerebrovascular events (group 1) or (2) patients who suffered from ipsilateral cerebrovascular events more than 6 months prior to revascularisation (group 2). Cerebrovascular symptoms are closely related to underlying carotid plaque composition and therefore we investigated potential plaque differences between these definition-based subgroups. DESIGN: Cross-sectional analysis of a longitudinal prospective biobank study. MATERIAL AND METHODS: Carotid atherosclerotic plaques from 264 asymptomatic patients were harvested during endarterectomy, and subjected to histopathological examination. Patients were divided into two groups: group 1: truly asymptomatic (n = 182), and group 2: patients with ipsilateral events more than 6 months before carotid endarterectomy (CEA) (n = 82). RESULTS: Patients in group 1 had relatively more stable plaque characteristics as compared with patients in group 2, with a higher median plaque smooth muscle cell content (2.1 (0.0-18.7) vs. 1.6 (0.0-14.4); P = 0.036), a higher proportion of heavily calcified plaques (67.7% (123/182) vs. 48.8% (40/82); P = 0.005) and less frequently intraplaque haemorrhages (11.5% (21/182) vs. 30.5% (25/82); P = 0.001). CONCLUSION: Different plaque characteristics within subgroups of ACAS patients can be identified based on reported past ipsilateral events, which might result in adjusted future treatment strategies.

Radiation-induced carotid stenotic lesions have a more stable phenotype than de novo atherosclerotic plaques.

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.

Prevalence and clinical consequences of carotid artery residual defects following endarterectomy: a prospective CT angiography evaluation study.

OBJECTIVES: It is still unclear whether residual defects seen after carotid endarterectomy (CEA) have clinical consequences. We investigated prevalence of residual defects in the carotid artery and their possible impact on clinical and Duplex ultrasound (DUS) follow-up. MATERIALS AND METHODS: Sixty-five patients who had undergone CEA were prospectively examined with 1-3 month postoperative computed tomographic angiography (CTA), clinical and DUS follow-up. Defects in common (CCA), external (ECA) and internal carotid artery (ICA) were scored as clamp marks, intimal step or flap, mural thrombus, kink, microdehiscence suture or residual stenosis. RESULTS: Fifty-eight patients (89.2%) had residual defects in CCA, ECA or ICA (143 defects). Intimal steps (n = 39) and residual stenosis (n = 17) were most noted defects. Only residual defects in ECA were significantly associated with significant higher PSV values both at short-term and long-term follow-up (1990 vs. 1400 mm s(-1) at 1 year and 2000 vs. 1230 mm s(-1) at 2 years, P-values 0.031 and 0.016). CONCLUSION: Carotid artery residual defects on CTA after CEA are very common, simple fingerprints of the operative procedure, have no clear consequence. When CTA is performed clinically after CEA, knowledge of high prevalence and type of defects detected on CTA may be of importance for radiologists and clinicians.

PLACD-7T Study: Atherosclerotic Carotid Plaque Components Correlated with Cerebral Damage at 7 Tesla Magnetic Resonance Imaging.

INTRODUCTION: In patients with carotid artery stenosis histological plaque composition is associated with plaque stability and with presenting symptomatology. Preferentially, plaque vulnerability should be taken into account in pre-operative work-up of patients with severe carotid artery stenosis. However, currently no appropriate and conclusive (non-) invasive technique to differentiate between the high and low risk carotid artery plaque in vivo is available. We propose that 7 Tesla human high resolution MRI scanning will visualize carotid plaque characteristics more precisely and will enable correlation of these specific components with cerebral damage. STUDY OBJECTIVE: The aim of the PlaCD-7T study is 1: to correlate 7T imaging with carotid plaque histology (gold standard); and 2: to correlate plaque characteristics with cerebral damage ((clinically silent) cerebral (micro) infarcts or bleeds) on 7 Tesla high resolution (HR) MRI. DESIGN: We propose a single center prospective study for either symptomatic or asymptomatic patients with haemodynamic significant (70%) stenosis of at least one of the carotid arteries. The Athero-Express (AE) biobank histological analysis will be derived according to standard protocol. Patients included in the AE and our prospective study will undergo a pre-operative 7 Tesla HR-MRI scan of both the head and neck area. DISCUSSION: We hypothesize that the 7 Tesla MRI scanner will allow early identification of high risk carotid plaques being associated with micro infarcted cerebral areas, and will thus be able to identify patients with a high risk of periprocedural stroke, by identification of surrogate measures of increased cardiovascular risk.