Department of Neurology, Inselspital, University of Bern, Bern, Switzerland.
Cerebrovasc Dis. 2012;34(5-6):343-50. doi: 10.1159/000343227. Epub 2012 Nov 14.
The optimal treatment of asymptomatic carotid stenosis (ACS) is controversial. To optimize the risk-benefit ratio of carotid artery revascularization, it is crucial to identify ACS patients who are at increased stroke risk. Recent data suggest that plaque vulnerability depends on its composition. Therefore, we assessed plaque composition in ACS to determine predictors for ipsilateral cerebrovascular events.
62 patients with 65 ACS ≥50% underwent 3-T MRI of the carotid bifurcation (TOF, special dark-blood weighted noncontrast and contrast-enhanced T(1) and T(2) images) and of the brain. The different plaque components (lipid core, intraplaque hemorrhage, calcification and the status of the fibrous cap) were assessed. Furthermore, the plaque volume and the volume of clinically silent cortical and subcortical infarcts in the territory of the stenosed carotid artery as seen on FLAIR images were determined by using a semi-automated software. Carotid stenosis was considered asymptomatic if there had not been any clinically apparent ischemic events in the corresponding vascular territory within the previous 6 months. During follow-up, information on the occurrence of cerebrovascular events, medical treatment and sonographic changes of the stenosis was collected.
At baseline, 24 ACS (37%) were classified as high grade. A lipid-rich necrotic core was the dominant plaque component in 16 ACS (25%). The plaque volume was higher in ACS with a lipid-rich necrotic core as dominant plaque component (p = 0.002) and in patients with prior stroke/TIA (p = 0.010). After a median follow-up of 18.9 months (interquartile range 3.5-30.1) there were 2 ipsilateral strokes and 3 ipsilateral TIAs. The average annual event rate was 7.7%. A lipid-rich necrotic core (HR 7.21; 95% CI 1.12-46.28; p = 0.037), sonographic progression of the stenosis (HR 7.00; 95% CI 1.13-41.34; p = 0.036), history of stroke (HR 11.03; 95% CI 1.23-99.36; p = 0.032), and the volume of clinically asymptomatic ischemic brain lesions (HR 1.14/cm(3); 95% CI 1.03-1.25; p = 0.008) predicted cerebrovascular events. Patients on statin therapy at follow-up were at lower risk of events (HR 0.17; 95% CI 0.03-1.00; p = 0.05).
In addition to medical history and sonographic findings, a lipid-rich necrotic core within the plaque turned out as a predictor of cerebrovascular events. Therefore, MR imaging of carotid plaques deserves further attention and might be helpful to improve risk stratification of asymptomatic carotid disease. The identified predictors could be combined in a risk model and tested in larger prospective studies.
无症状性颈动脉狭窄（ACS）的最佳治疗方法存在争议。为了优化颈动脉血运重建的风险效益比，识别发生卒中风险增加的 ACS 患者至关重要。最近的数据表明，斑块易损性取决于其组成。因此，我们评估了 ACS 中的斑块成分，以确定同侧脑血管事件的预测因子。
62 例 65 处狭窄≥50%的 ACS 患者接受了颈动脉分叉处（TOF，特殊暗血非对比和对比增强 T1 和 T2 图像）和脑部的 3-T MRI 检查。评估了不同的斑块成分（脂质核心、斑块内出血、钙化和纤维帽的状态）。此外，通过使用半自动软件确定狭窄颈动脉供血区域内 FLAIR 图像上可见的临床无症状皮质和皮质下梗死的斑块体积和体积。如果在过去 6 个月内相应血管区域没有任何临床明显的缺血事件，则将颈动脉狭窄视为无症状。在随访期间，收集了关于脑血管事件的发生、治疗和狭窄的超声变化的信息。
基线时，24 例 ACS（37%）被归类为高级别。16 例 ACS（25%）中以富含脂质的坏死核心为主要斑块成分。富含脂质的坏死核心为主的斑块成分（p=0.002）和有既往卒中和 TIA 病史的患者（p=0.010）的斑块体积较高。在中位随访 18.9 个月（四分位距 3.5-30.1）后，有 2 例同侧卒中和 3 例同侧 TIA。平均年事件发生率为 7.7%。富含脂质的坏死核心（HR 7.21；95%CI 1.12-46.28；p=0.037）、狭窄的超声进展（HR 7.00；95%CI 1.13-41.34；p=0.036）、卒中病史（HR 11.03；95%CI 1.23-99.36；p=0.032）和临床无症状性缺血性脑病变的体积（HR 1.14/cm3；95%CI 1.03-1.25；p=0.008）预测了脑血管事件。随访时接受他汀类药物治疗的患者发生事件的风险较低（HR 0.17；95%CI 0.03-1.00；p=0.05）。
除了病史和超声发现外，斑块内富含脂质的坏死核心也是脑血管事件的预测因子。因此，颈动脉斑块的磁共振成像值得进一步关注，并可能有助于改善无症状性颈动脉疾病的风险分层。确定的预测因子可以组合在一个风险模型中，并在更大的前瞻性研究中进行测试。
