Preoperative magnetic resonance plaque imaging and carotid artery stenting: a review

Intraplaque neovascularisation is associated with ischaemic events after carotid artery stenting: an observational prospective study

Background

Intraplaque neovascularisation (IPN) is a component of vulnerable atherosclerotic plaque, which is a biomarker of cardiovascular events. However, the identification of patients with high probability of ischaemic events after carotid artery stenting (CAS) is mainly based on vascular risk factors. Prospective studies on the development of plaques are lacking.

Objectives

The purpose of this study was to investigate whether IPN detected by contrast-enhanced ultrasound is related to the occurrence of ischaemic events after CAS.

Methods

Sixty consecutive patients receiving CAS were prospectively enrolled in our centre. The patients were evaluated using contrast-enhanced ultrasound before CAS. According to the degree of microbubble enhancement, IPN was graded from 0 to 2. Endpoint events, including ischaemic stroke and other cardiovascular events, were recorded during follow-up. Kaplan-Meier survival curves and Cox proportional-hazards models were used to evaluate the risk factors for endpoint events. At a median follow-up of 30 months, 13 patients (28.9%) experienced endpoint events. Kaplan-Meier survival curves showed that patients with grade 2 IPN had a higher risk of future ischaemic events than those with grade 0 or 1 IPN (p < 0.05). Cox proportional-hazards models showed that grade 2 IPN [adjusted hazard ratio (HR), 4.049; 95% confidence interval (CI), 1.078-15.202] was a significant predictor of endpoint events (p < 0.05).

Conclusion

Grade 2 IPN evaluated by contrast-enhanced ultrasound has predictive value for ischaemic events in patients after CAS and may help clinicians identify high-risk patients who need close follow-up.

Plain Language Summary

Neovascularisation and carotid artery stenting Introduction: Introduction: It is unclear whether intraplaque neovascularisation (IPN) can be used as an biomarker of high probability ischemic events after carotid artery stenting (CAS).Materials and methods: We enrolled 60 patients who underwent CAS, all of whom underwent CEUS before CAS. We recorded ischaemic events during follow-up. Cox proportional-hazards models were used to evaluate the risk factors for ischaemic events.Results: We found that grade 2 IPN was an independent predictor (hazard ratio, 4.049; 95% confidence interval, 1.078-15.202; p < 0.05) of ischaemic events in patients after CAS.Conclusion: This may help clinicians identify high-risk patients who need close follow-up.

Carotid intraplaque haemorrhage: pathogenesis, histological classification, imaging methods and clinical value

Vulnerable carotid atherosclerotic plaques are characterised by several risk factors, such as inflammation, neovascularization and intraplaque haemorrhage (IPH). Vulnerable plaques can lead to ischemic events such as stroke. Many studies reported a relationship between IPH, plaque rupture, and ischemic stroke. Histology is the gold standard to evaluate IPH, but it required carotid endarterectomy (CEA) surgery to collect the tissue sample. In this context, several imaging methods can be used as a non-invasive way to evaluate plaque vulnerability and detect IPH. Most imaging studies showed that IPH is associated with plaque vulnerability and stroke, with magnetic resonance imaging (MRI) being the most sensitive and specific to detect IPH as a predictor of ischemic events. These conclusions are however still debated because of the limited number of patients included in these studies; further studies are required to better assess risks associated with different IPH stages. Moreover, IPH is implicated in plaque vulnerability with other risk factors which need to be considered to predict ischemic risk. In addition, MRI sequences standardization is required to compare results from different studies and agree on biomarkers that need to be considered to predict plaque rupture. In these circumstances, IPH detection by MRI could be an efficient clinical method to predict stroke. The goal of this review article is to first describe the pathophysiological process responsible for IPH, its histological detection in carotid plaques and its correlation with plaque rupture. The second part will discuss the benefits and limitations of imaging the carotid plaque, and finally the clinical interest of imaging IPH to predict plaque rupture, focusing on MRI-IPH.

Staged carotid artery stenting in patients with severe carotid stenosis: Multicenter experience

Cerebral hyperperfusion syndrome (CHS) is serious complication after carotid artery stenting (CAS) caused by decreased cerebral vasoreactivity (CVR) due to long standing hypoperfusion of the brain. We hypothesized that partial dilatation of carotid stenosis would allow the recovery of CVR, and prevent CHS when definitive angioplasty with stent is performed afterward. In this study, we aimed to evaluate the safety and efficacy of staged CAS in patients with severe carotid artery stenosis with evident hemodynamic compromise in regard to preventing hyperperfusion syndrome. From January 2005 to February 2016, 53 patients with 55 severe carotid artery stenosis lesions showing decreased CVR and/or cerebral basal flow at the perfusion studies underwent staged CAS in three institutes. The procedure consisted of initial partial balloon angioplasty (BA), recovery period, and delayed definitive stenting (DS). We analyzed immediate results, complications, recoil and CHS related to staged CAS. We experienced no symptomatic manifestation of CHS except self-limited headache after the procedures. The median of intervals between BA and DS stages were 10 days. There was no case of severe recoil during the interval between BA and DS stage. Where perfusion imaging data was available, hyperperfusion was present in three and one patients after BA and DS stage, respectively, with no clinical symptom of CHS. In conclusion, staged CAS was feasible in patients with severe carotid artery stenosis and hemodynamic compromise, without inducing severe complication of CHS such as intracranial hemorrhage.

The association between carotid intraplaque hemorrhage and outcomes of carotid stenting: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

The purpose of this systematic review and meta-analysis was to determine whether carotid stenting patients with intraplaque hemorrhage (IPH) identified on preoperative MRI were more likely to suffer perioperative ischemic complications compared with patients without IPH.

METHODS

We conducted a comprehensive literature search of studies published between January 1, 2005 and December 31, 2015 reporting perioperative outcomes of carotid stenting among patients with and without IPH on hemorrhage sensitive carotid MRI sequences. Clinical outcomes included perioperative (≤30 days post-stenting) minor stroke, major stroke, death, and a composite outcome combining stroke, death, and myocardial infarction (MI). We also compared the rate of silent ischemia on diffusion weighted imaging (DWI) between groups. Statistical analysis was performed using a random effects meta-analysis.

RESULTS

9 studies with 491 unique patients (198 in the IPH group and 293 in the non-IPH group) were included. The rate of the composite outcome of any stroke, death, or MI within 30 days was 8.1% (13/160) in the IPH group and 2.1% (5/239) in the non-IPH group (OR=4.45, 95% CI 1.61 to 12.30, p<0.01). There were no significant differences between groups in the rates of minor stroke, major stroke, or death when considered individually. The rate of postoperative infarct on DWI was 49.7% (75/161) for the IPH group and 33.6% (81/241) for the non-IPH group (OR=2.01, 95% CI 1.31 to 3.09, p<0.01).

CONCLUSIONS

Our systematic review and meta-analysis demonstrated that patients with IPH on pre-carotid stenting MRI had higher rates of silent ischemia as well as of a composite outcome of perioperative stroke, death, and MI compared with those without IPH.