Risk of intracranial hemorrhage after carotid artery stenting versus endarterectomy: a population-based study

OBJECTIVEIntracranial hemorrhage (ICH) associated with cerebral hyperperfusion syndrome is a rare but major complication of carotid artery revascularization. The objective of this study was to compare the rate of ICH after carotid artery stenting (CAS) with that after endarterectomy (CEA).METHODSThe authors performed a retrospective population-based cohort study of patients who underwent carotid artery revascularization in the province of Ontario, Canada, between 2002 and 2015. The primary outcome was the rate of ICH that occurred within 90 days after carotid artery intervention among patients who underwent CAS versus that of those who underwent CEA. The authors used inverse probability of treatment weighting and propensity scores to account for selection bias. In sensitivity analyses, patients who had postprocedure ischemic stroke were excluded, and the following subgroups were examined: patients with symptomatic and asymptomatic carotid artery stenosis, patients treated between 2010 and 2015, and patients aged ≥ 66 years (to account for antiplatelet and anticoagulant use).RESULTSA total of 16,688 patients underwent carotid artery revascularization (14% CAS, 86% CEA). Patients with more comorbid illnesses, symptomatic carotid artery stenosis, or cardiac disease and those who were taking antiplatelet agents or warfarin before surgery were more likely to undergo CAS. Among the overall cohort, 80 (0.48%) patients developed ICH within 90 days (0.85% after CAS, 0.42% after CEA). The 180-day mortality rate after ICH in the overall cohort was 2.7%, whereas the 180-day mortality rate among patients who suffered ICH was 42.5% (40% for CAS-treated patients, 43.3% for CEA-treated patients). In the adjusted analysis, patients who underwent CAS were significantly more likely to have ICH than those who underwent CEA (adjusted OR 1.77; 95% CI 1.32-2.36; p < 0.001). These results were consistent after excluding patients who developed postprocedure ischemic stroke (adjusted OR 1.90; 95% CI 1.41-2.56) and consistent among symptomatic (adjusted OR 1.74; 95% CI 1.16-2.63) and asymptomatic (adjusted OR 1.75; 95% CI 1.16-2.63) patients with carotid artery stenosis, among patients treated between 2010 and 2015 (adjusted OR 2.21; 95% CI 1.45-3.38), and among the subgroup of patients aged ≥ 66 years (adjusted OR 1.53; 95% CI 1.05-2.24) after adjusting for medication use.CONCLUSIONSCAS is associated with a rare but higher risk of ICH relative to CEA. Future research is needed to devise strategies that minimize the risk of this serious complication after carotid artery revascularization.

Association between low levels of serum miR-638 and atherosclerotic plaque vulnerability in patients with high-grade carotid stenosis

OBJECTIVE

Carotid artery atherosclerosis is a major cause of ischemic stroke. However, reliable criteria to identify patients with high-risk carotid plaques beyond the severity of stenosis are still lacking. Circulating microRNAs (miRNAs) are being postulated as biomarkers for a variety of vascular immune-inflammatory diseases. The authors investigated whether cell-free circulating miR-638, highly expressed in vascular smooth muscle cells and implicated in proliferative vascular diseases, is associated with vulnerable atherosclerotic plaques in high-risk patients with advanced carotid artery stenosis undergoing carotid endarterectomy (CEA).

METHODS

The authors conducted a prospective study in 22 consecutive symptomatic patients with high-grade carotid stenosis undergoing CEA and 36 age- and sex-matched patients without ischemic stroke history or carotid atherosclerosis (control group). In addition, they reviewed data from a historical group of 9 CEA patients who underwent long-term follow-up after revascularization. Total RNA was isolated from all serum samples, and relative miR-638 expression levels were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and compared among groups. A correlation analysis of serum miR-638 levels with vascular risk factors and treatments, and with plaque features, was performed. The ability of serum miR-638 to discriminate between the non-CEA control group and the different CEA groups was assessed by receiver operating characteristic evaluation. A logistic regression model was employed to examine the association between stratified CEA patients and serum miR-638 levels.

RESULTS

Serum levels of miR-638 were significantly lower in symptomatic CEA patients (p = 0.009) and particularly in the subgroup of CEA patients who had experienced stroke (p = 0.0006) than in non-CEA controls. Discrimination of high-risk plaques was accurate (area under the curve [AUC] 0.66 for symptomatic CEA patients in general and 0.76 for those who had experienced stroke). When only patients with high cardiovascular risk were considered, the diagnostic value of serum miR-638 from symptomatic CEA patients and CEA patients who had experienced stroke improved (AUC 0.79 and 0.85). Moreover, serum miR-638 was negatively correlated with the occurrence of stroke, smoker status, presence of bilateral pathology, coronary artery disease, and cholesterol treatment; and with the high-risk fibroatheroma plaques extracted from CEA patients. Multivariate logistic regression analysis demonstrated that serum miR-638 was an independent predictor of plaque instability. Furthermore, serum miR-638 appeared to attain good discrimination for atherosclerotic stenosis in CEA patients based on analysis of blood samples obtained in the historical group before and 5 years after intervention (p = 0.04) (AUC = 0.79).

CONCLUSIONS

According to this preliminary proof-of-concept study, serum miR-638 might constitute a promising noninvasive biomarker associated with plaque vulnerability and ischemic stroke, particularly in individuals with elevated cardiovascular risk.

Systematic review of health economic studies in cranial neurosurgery

OBJECTIVE As the cost of health care continues to increase, there is a growing emphasis on evaluating the relative economic value of treatment options to guide resource allocation. The objective of this systematic review was to evaluate the current evidence regarding the cost-effectiveness of cranial neurosurgery procedures. METHODS The authors performed a systematic review of the literature using PubMed, EMBASE, and the Cochrane Library, focusing on themes of economic evaluation and cranial neurosurgery following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Included studies were publications of cost-effectiveness analysis or cost-utility analysis between 1995 and 2017 in which health utility outcomes in life years (LYs), quality-adjusted life years (QALYs), or disability-adjusted life years (DALYs) were used. Three independent reviewers conducted the study appraisal, data abstraction, and quality assessment, with differences resolved by consensus discussion. RESULTS In total, 3485 citations were reviewed, with 53 studies meeting the inclusion criteria. Of those, 34 studies were published in the last 5 years. The most common subspecialty focus was cerebrovascular (32%), followed by neurooncology (26%) and functional neurosurgery (24%). Twenty-eight (53%) studies, using a willingness to pay threshold of US$50,000 per QALY or LY, found a specific surgical treatment to be cost-effective. In addition, there were 11 (21%) studies that found a specific surgical option to be economically dominant (both cost saving and having superior outcome), including endovascular thrombectomy for acute ischemic stroke, epilepsy surgery for drug-refractory epilepsy, and endoscopic pituitary tumor resection. CONCLUSIONS There is an increasing number of cost-effectiveness studies in cranial neurosurgery, especially within the last 5 years. Although there are numerous procedures, such as endovascular thrombectomy for acute ischemic stroke, that have been conclusively proven to be cost-effective, there remain promising interventions in current practice that have yet to meet cost-effectiveness thresholds.

Combined interventional and surgical treatment of tandem middle cerebral artery embolus and internal carotid artery occlusion: case report

Tandem internal carotid artery (ICA) origin occlusion and middle cerebral artery (MCA) thromboembolism is a life-threatening condition with poor neurological outcome. The authors report on a patient presenting with acute ischemic stroke from a tandem ICA and MCA occlusion with penumbra. Emergency MCA mechanical thrombectomy was performed through percutaneous cervical ICA access due to the inability to cross the cervical carotid occlusion. Emergency carotid endarterectomy to reperfuse the poorly collateralized hemisphere and repair the ICA access site was performed 2 hours after completion of tissue plasminogen activator (tPA) infusion. This case illustrates the shortest reported interval between tPA infusion and open surgical intervention for carotid revascularization, as well as the role of direct carotid artery access for mechanical thrombectomy. The authors also describe the use of a temporizing femoral artery-to-ICA shunt to maintain cerebral perfusion in the setting of ICA occlusion.

Predicting ischemic stroke after carotid artery stenting based on proximal calcification and the jellyfish sign

OBJECTIVE Carotid artery stenting (CAS) has been considered to prevent ischemic strokes caused by stenosis of the cervical carotid artery. The most common complication of CAS is new cerebral infarction. The authors have previously reported that the jellyfish sign-the rise and fall of the mobile component of the carotid plaque surface detected by carotid ultrasonography-suggests thinning and rupture of the fibrous cap over the unstable plaque content, such as the lipid-rich necrotic core or internal plaque hemorrhage. The authors' aim in the present study was to evaluate the risk of a new ischemic lesion after CAS by using many risk factors including calcification (size and location) and the jellyfish sign. METHODS Eighty-six lesions (77 patients) were treated with CAS. The presence of ischemic stroke was determined using diffusion-weighted imaging (DWI). Risk factors included calcification of the plaque (classified into 5 groups for size and 3 groups for location) and the jellyfish sign, among others. Multiple linear regression analysis (stepwise analysis and partial least squares [PLS] analysis) was conducted, followed by a machine learning analysis using an artificial neural network (ANN) based on the log-linearized gaussian mixture network (LLGMN). The additive effects of the jellyfish sign and calcification on ischemic stroke after CAS were examined using the Kruskal-Wallis test, followed by the Steel-Dwass test. RESULTS The stepwise analysis selected the jellyfish sign, proximal calcification (proximal Ca), low-density lipoprotein (LDL) cholesterol, and patient age for the prediction model to predict new DWI lesions. The PLS analysis revealed the same top 3 variables (jellyfish sign, proximal Ca, and LDL cholesterol) according to the variable importance in projection scores. The ANN was then used, showing that these 3 variables remained. The accuracy of the ANN improved; areas under the receiver operating characteristic curves of the stepwise analysis, the PLS analysis, and the ANN were 0.719, 0.727, and 0.768, respectively. The combination of the jellyfish sign and proximal Ca indicates a significantly increased risk for ischemic stroke after CAS. CONCLUSIONS The jellyfish sign, proximal Ca, and LDL cholesterol were considered to be important predictors for new DWI lesions after CAS. These 3 factors can be easily determined during a standard clinical visit. Thus, these 3 variables-especially the jellyfish sign and proximal Ca-may be useful for reducing the ischemic stroke risk in patients with stenosis of the cervical carotid artery.

Stent technology in ischemic stroke

Atherosclerotic disease of the cerebral vasculature is a major cause of stroke worldwide. Atherosclerosis that is refractory to best medical management may require revascularization. In these instances, endovascular treatment provides a popular and safe alternative to open surgical techniques. The authors provide an overview of stent technology in the treatment of ischemic stroke, discussing the major studies evaluating stenting for extracranial carotid artery, vertebral artery, and intracranial atherosclerotic disease. The authors describe the commonly used stents with respect to their individual characteristics and technical limitations. Current and future developments in stent technology are also discussed, with areas for further innovation and clinical research.

Impact of subclinical coronary artery disease on the clinical outcomes of carotid endarterectomy

OBJECTIVE Controversy persists regarding the optimal management of subclinical coronary artery disease (CAD) prior to carotid endarterectomy (CEA) and the impact of CAD on clinical outcomes after CEA. This study aimed to evaluate the short-term surgical risks and long-term outcomes of patients with subclinical CAD who underwent CEA. METHODS The authors performed a retrospective study of data from a prospective CEA registry. They analyzed a total of 702 cases involving patients without a history of CAD who received preoperative cardiac risk assessment by radionuclide myocardial perfusion imaging (MPI) and underwent CEA over a 10-year period. The management strategy (the necessity, sequence, and treatment modality of coronary revascularization and optimal perioperative medical treatment) was determined according to the presence, severity, and extent of CAD as determined by preoperative MPI and additional coronary computed tomography angiography and/or coronary angiography. Perioperative cardiac damage was defined on the basis of postoperative elevation of the blood level of cardiac troponin I (0.05-0.5 ng/ml) in the absence of myocardial ischemia. The primary endpoint was the composite of any stroke, myocardial infarction, or death during the perioperative period and all-cause mortality within 4 years of CEA. The associations between clinical outcomes after CEA and subclinical CAD were analyzed. RESULTS Concomitant subclinical CAD was observed in 81 patients (11.5%). These patients did have a higher incidence of perioperative cardiac damage (13.6% vs 0.5%, p < 0.01), but they had similar primary endpoint incidences during the perioperative period (2.5% vs.1.8%, p = 0.65) and similar estimated 4-year primary endpoint rates (13.6% vs 12.4%, p = 0.76) as the patients without subclinical CAD. Kaplan-Meier survival analysis showed that the 2 groups had similar rates of overall survival (p = 0.75). CONCLUSIONS Patients with subclinical CAD can undergo CEA with acceptable short- and long-term outcomes provided they receive selective coronary revascularization and optimal perioperative medical treatment.

Contemporary carotid imaging: from degree of stenosis to plaque vulnerability

Carotid artery stenosis is a well-established risk factor of ischemic stroke, contributing to up to 10%-20% of strokes or transient ischemic attacks. Many clinical trials over the last 20 years have used measurements of carotid artery stenosis as a means to risk stratify patients. However, with improvements in vascular imaging techniques such as CT angiography and MR angiography, ultrasonography, and PET/CT, it is now possible to risk stratify patients, not just on the degree of carotid artery stenosis but also on how vulnerable the plaque is to rupture, resulting in ischemic stroke. These imaging techniques are ushering in an emerging paradigm shift that allows for risk stratifications based on the presence of imaging features such as intraplaque hemorrhage (IPH), plaque ulceration, plaque neovascularity, fibrous cap thickness, and presence of a lipid-rich necrotic core (LRNC). It is important for the neurosurgeon to be aware of these new imaging techniques that allow for improved patient risk stratification and outcomes. For example, a patient with a low-grade stenosis but an ulcerated plaque may benefit more from a revascularization procedure than a patient with a stable 70% asymptomatic stenosis with a thick fibrous cap. This review summarizes the current state-of-the-art advances in carotid plaque imaging. Currently, MRI is the gold standard in carotid plaque imaging, with its high resolution and high sensitivity for identifying IPH, ulceration, LRNC, and inflammation. However, MRI is limited due to time constraints. CT also allows for high-resolution imaging and can accurately detect ulceration and calcification, but cannot reliably differentiate LRNC from IPH. PET/CT is an effective technique to identify active inflammation within the plaque, but it does not allow for assessment of anatomy, ulceration, IPH, or LRNC. Ultrasonography, with the aid of contrast enhancement, is a cost-effective technique to assess plaque morphology and characteristics, but it is limited in sensitivity and specificity for detecting LRNC, plaque hemorrhage, and ulceration compared with MRI. Also summarized is how these advanced imaging techniques are being used in clinical practice to risk stratify patients with low- and high-grade carotid artery stenosis. For example, identification of IPH on MRI in patients with low-grade carotid artery stenosis is a risk factor for failure of medical therapy, and studies have shown that such patients may fair better with carotid endarterectomy (CEA). MR plaque imaging has also been found to be useful in identifying revascularization candidates who would be better candidates for CEA than carotid artery stenting (CAS), as high intraplaque signal on time of flight imaging is associated with vulnerable plaque and increased rates of adverse events in patients undergoing CAS but not CEA.

Communication of inwardly projecting neovessels with the lumen contributes to symptomatic intraplaque hemorrhage in carotid artery stenosis

OBJECT

Recent studies have demonstrated that plaque morphology can contribute to identification of patients at high risk of carotid artery atherosclerosis as well as the degree of stenosis in those with carotid atherosclerosis. Neovascularization of carotid plaques is associated with plaque vulnerability. However, the mechanism of neovascularization in intraplaque hemorrhage (IPH) and its clinical contribution remain undetermined. In this study, the authors aimed to clarify the characteristics of neovessel appearance with a focus on inwardly projecting neovessels, which are reportedly important in plaque advancement.

METHODS

Consecutive patients with moderate to severe carotid atherosclerosis who underwent carotid endarterectomy were prospectively analyzed from 2010 to 2014. The neovessel appearance was categorized into 3 groups based on intraoperative indocyanine green (ICG) videoangiography: early appearance of neovessels from the endothelium (NVe), late appearance of neovessels from the vasa vasorum (NVv), and no appearance of vessels. Each neovessel pattern was evaluated with respect to clinical, radiological, and pathological findings including IPH, neovascularization, hemosiderin spots, and inflammation.

RESULTS

Of 57 patients, 13 exhibited NVe, 33 exhibited NVv, and 11 exhibited no neovessels. Overall, the interobserver and intraobserver reproducibilities of neovessel appearance were substantial for ICG videoangiography (κ=0.76) and at 7 days postoperatively (κ=0.76). There were no significant differences in baseline characteristics among the 3 groups, with the exception of a higher percentage of symptomatic presentations in patients with NVe (artery-to-artery embolic infarction in 61.5% and transient ischemic attack in 23.1%). Moreover, patients with NVe exhibited larger infarctions than did those with NVv (9675.0±5601.9 mm3 vs 2306.6±856.9 mm3, respectively; p=0.04). Pathologically, patients with NVe had more severe IPH (47.2±8.3 mm2 vs 19.8±5.2 mm2, respectively; p<0.01), hemosiderin spots (0.5±0.2 mm2 vs 0.2±0.1 mm2, respectively; p=0.04), neovessels (0.4±0.7 mm2 vs 0.1±0.4 mm2, respectively; p=0.11), and inflammation (1.0±1.1 mm2 vs 0.6±0.9 mm2, respectively; p=0.26) around the endothelium than did patients with NVv, and all of these parameters were correlated with hyperintensity on time-of-flight MRI. However, the neovessel and inflammation differences were nonsignificant. Interestingly, inflammation was significantly correlated with neovessel formation (r=0.43, p=0.0008), hemosiderin spots (r=0.62, p<0.0001), and IPH (r=0.349, p=0.0097), suggesting that inflammation may be a key factor in plaque vulnerability.

CONCLUSIONS

Communication of inwardly projecting neovessels with the lumen and inflammation synergistically contribute to IPH and symptomatic presentations in patients with carotid stenosis and are more specific than the vasa vasorum. This condition could be a new therapeutic target, and regression of luminal neovessel sprouting and inflammation may help to prevent IPH development and a symptomatic presentation.

Omnidirectional retractor-supporting ring as a new device for carotid endarterectomy

In carotid endarterectomy (CEA), the traditional retractors are often difficult to use because they tend to obstruct surgical manipulations, especially in the deep operative field on the rostral side. The authors have invented a new omnidirectional retractor-supporting ring (OD ring) to solve the problems of traditional retractors. The OD ring has an ellipsoid-shaped frame (major axis: 275 mm, minor axis: 192 mm) with 22 equally spaced outward protrusions. Rubber bands from which blunt mini-hooks are hung are twisted around the protrusions. The OD ring was placed on the operative area, and the skin edges were retracted by mini-hooks placed symmetrically. The hooks were moved gradually from the shallow to the deep operative field as surgical dissection continued to expose the carotid bifurcation and distal internal carotid artery (ICA). The OD ring was used in 158 consecutive CEAs in the authors' institute between July 2010 and October 2013. The OD ring provided a flatter surgical field and was less obstructive than traditional retractors, thereby facilitating surgical manipulation in the deep operative field such as at the distal ICA. Furthermore, because of its simpler shape, angiorrhaphy could be conducted more smoothly, with less tangled thread during closure of the arteriotomy. There were no technical complications related to the OD ring. As a new retractor system for CEA, the OD ring is less obstructive and provides a flatter surgical field than traditional retractors, thereby facilitating surgical manipulations in the deep operative field around the distal ICA.

64-detector CT angiography within 24 hours after carotid endarterectomy and correlation with postoperative stroke

OBJECT

Carotid endarterectomy (CEA) carries a small but not insignificant risk of stroke/transient ischemic attack (TIA), most frequently observed within 24 hours of surgery, which can lead to the need for urgent vascular imaging in the immediate postoperative period. However, distinguishing expected versus pathological postoperative changes may not be straightforward on imaging studies of the carotid artery early after CEA. The authors aimed to describe routine versus pathological anatomical findings on CTA performed within 24 hours of CEA, and to evaluate associations between these CTA findings and postoperative stroke/TIA.

METHODS

The authors reviewed 113 consecutive adult patients who underwent postoperative CTA within 24 hours of CEA at a single academic institution. Presence and location of arterial "flaps," luminal "step-off," intraluminal thrombus and hematoma were documented from postoperative CTA scans. Medical records were reviewed to determine the incidence of new postoperative neurological findings.

RESULTS

Postoperative CTA findings included common carotid artery (CCA) step-off (63.7%), one or more intraarterial flaps (27.4%), hematoma at the surgical site (15.9%), and new intraluminal thrombus (7.1%). Flaps were seen in the external carotid artery (ECA), internal carotid artery (ICA), and CCA in 18.6%, 9.7%, and 6.2% of patients, respectively. New postoperative neurological findings were present in 7.1% of patients undergoing CTA. Flaps (especially ICA/CCA) and/or intraluminal thrombi were more frequently seen in patients undergoing CTA for new postoperative stroke/TIA (85.7%) versus patients undergoing CTA for routine postoperative imaging (14.3%, p = 0.002).

CONCLUSIONS

CTA within 24 hours of CEA demonstrates characteristic anatomical findings. CCA step-offs and ECA flaps are relatively common and clinically insignificant, whereas ICA/CCA flaps and thrombi are less frequently seen and are associated with postoperative stroke/TIA.

Radiographic absence of the posterior communicating arteries and the prediction of cognitive dysfunction after carotid endarterectomy

OBJECT

Approximately 25% of patients exhibit cognitive dysfunction 24 hours after carotid endarterectomy (CEA). One of the purported mechanisms of early cognitive dysfunction (eCD) is hypoperfusion due to inadequate collateral circulation during cross-clamping of the carotid artery. The authors assessed whether poor collateral circulation within the circle of Willis, as determined by preoperative CT angiography (CTA) or MR angiography (MRA), could predict eCD.

METHODS

Patients who underwent CEA after preoperative MRA or CTA imaging and full neuropsychometric evaluation were included in this study (n = 42); 4 patients were excluded due to intraoperative electroencephalographic changes and subsequent shunt placement. Thirty-eight patients were included in the statistical analyses. Patients were stratified according to posterior communicating artery (PCoA) status (radiographic visualization of at least 1 PCoA vs of no PCoAs). Variables with p < 0.20 in univariate analyses were included in a stepwise multivariate logistic regression model to identify predictors of eCD after CEA.

RESULTS

Overall, 23.7% of patients exhibited eCD. In the final multivariate logistic regression model, radiographic absence of both PCoAs was the only independent predictor of eCD (OR 9.64, 95% CI 1.43-64.92, p = 0.02).

CONCLUSIONS

The absence of both PCoAs on preoperative radiographic imaging is predictive of eCD after CEA. This finding supports the evidence for an underlying ischemic etiology of eCD. Larger studies are justified to verify the findings of this study. Clinical trial registration no.: NCT00597883 ( http://www.clinicaltrials.gov ).

The impact of patient age and comorbidities on the occurrence of "never events" in cerebrovascular surgery: an analysis of the Nationwide Inpatient Sample

OBJECT

As health care administrators focus on patient safety and cost-effectiveness, methodical assessment of quality outcome measures is critical. In 2008 the Centers for Medicare and Medicaid Services (CMS) published a series of "never events" that included 11 hospital-acquired conditions (HACs) for which related costs of treatment are not reimbursed. Cerebrovascular procedures (CVPs) are complex and are often performed in patients with significant medical comorbidities.

METHODS

This study examines the impact of patient age and medical comorbidities on the occurrence of CMS-defined HACs, as well as the effect of these factors on the length of stay (LOS) and hospitalization charges in patients undergoing common CVPs.

RESULTS

The HACs occurred at a frequency of 0.49% (1.33% in the intracranial procedures and 0.33% in the carotid procedures). Falls/trauma (n = 4610, 72.3% HACs, 357 HACs per 100,000 CVPs) and catheter-associated urinary tract infections (n = 714, 11.2% HACs, 55 HACs per 100,000 CVPs) were the most common events. Age and the presence of ≥ 2 comorbidities were strong independent predictors of HACs (p < 0.0001). The occurrence of HACs negatively impacts both LOS and hospital costs. Patients with at least 1 HAC were 10 times more likely to have prolonged LOS (≥ 90th percentile) (p < 0.0001), and 8 times more likely to have high inpatient costs (≥ 90th percentile) (p < 0.0001) when adjusting for patient and hospital factors.

CONCLUSIONS

Improved quality protocols focused on individual patient characteristics might help to decrease the frequency of HACs in this high-risk population. These data suggest that risk adjustment according to underlying patient factors may be warranted when considering reimbursement for costs related to HACs in the setting of CVPs.