Asymptomatic carotid stenosis: What we can learn from the next generation of randomized clinical trials

Patient-Tailored Stenting versus Endarterectomy for the Treatment of Asymptomatic Carotid Artery Stenosis

Carotid artery stenosis is a major cause of acute ischemic strokes in adults. Given the consequences and sequelae of an acute ischemic stroke, intervention while patients are still asymptomatic is a key opportunity for stroke prevention. Although carotid endarterectomy has been the gold standard of treatment for carotid stenosis for many years, recent advances in carotid stenting technology, practitioner experience, and dual antiplatelet therapy have expanded the use for treatments other than endarterectomy. Review of the current literature has demonstrated that endarterectomy and carotid artery stenting produce overall similar results for the treatment of asymptomatic carotid stenosis, but certain factors may help guide physicians and patients in choosing one treatment over the other. Age 70 years and older, renal disease, poor medication compliance, and unstable plaque features all portend better outcomes from endarterectomy, whereas age under 70 years, high cervical location of disease, cardiac disease, and reliable medication compliance favor stenting. The decision to pursue endarterectomy versus stenting is therefore complex, and although large studies have demonstrated similar outcomes, the approach to treatment of asymptomatic carotid stenosis must be optimized for each individual patient to achieve the best possible outcome.

Dysregulation Serum miR-19a-3p is a Diagnostic Biomarker for Asymptomatic Carotid Artery Stenosis and a Promising Predictor of Cerebral Ischemia Events

This study aims to identify the diagnostic potential of microRNA-19a-3p (miR-19a-3p) for asymptomatic carotid artery stenosis (CAS) and clinical predictive potential for cerebral ischemia events (CIEs). Serum samples from 101 asymptomatic CAS patients and 98 healthy controls were collected. And it was found that serum miR-19a-3p in asymptomatic CAS patients was generally elevated (P < .05). Increased miR-19a-3p in asymptomatic CAS was associated with severe CAS (odds ratio  = 3.920, 95% confidence interval [CI] = 1.482-10.372, P < .01). The area under the receiver operating characteristic (ROC) curve (AUC) was 0.905, indicating that the level of miR-19a-3p was statistically significant for the diagnosis of asymptomatic CAS. Furthermore, the level of serum miR-19a-3p (hazard ratio [HR] = 8.507, 95% confidence interval [CI] = 2.239-32.328, P = .002) and degree of artery stenosis (HR = 3.695, 95% CI = 1.127-12.109, P = .031) were independent predictors of occurrence of CIE. Moreover, patients with elevated miR-19a-3p levels were more likely to experience CIE than patients with low levels. Upregulated miR-19a-3p can be used as a diagnostic biomarker for asymptomatic CAS patients and as an independent predictor of CIE.

Multivariable Analysis of Patients With Severe Persistent Postprocedural Hypotension After Carotid Artery Stenting

Purpose: To assess the incidence and predictors of severe, persistent postprocedural hypotension (PPH) after carotid artery stenting (CAS). Materials and Methods: A total of 146 patients (mean age 72.8 years; 104 men) who underwent 160 CAS procedures using a standardized protocol at 3 vascular centers were retrospectively analyzed. The primary endpoint was postprocedural hypotension, defined as a reduction in systolic blood pressure (SBP) >40 mm Hg from baseline or an SBP of <90 mm Hg sustained for >1 hour after CAS. Potential prognostic factors for postprocedural hypotension were identified and subjected to logistic regression analyses; outcomes are presented as the odds ratios (ORs) with 95% confidence intervals (CIs). Results: PPH developed in 36 (24.7%) patients after 37 (23.1%) CAS procedures. These patients had significantly longer intensive care unit and hospital stays than those who did not develop hypotension (p<0.001). PPH was associated with severe lesion calcification (OR 6.28, 95% CI 1.81 to 21.98, p=0.004) and contrast volume (OR 1.02, 95% CI 1.01 to 1.02, p<0.001). A 4-fold increase in the risk of PPH (OR 4.22, 95% CI 1.38 to 13.33, p=0.012) was found between the embolic protection device most associated with PPH (Angioguard) and the device least associated with PPH (Emboshield NAV6). A similar trend was also observed for the Precise vs Xact stents (OR 6, 95% CI 2.08 to 17.6, p=0.001). Bootstrapped multivariable modeling identified the Precise stent and contrast volume as significant predictors of persistent postprocedural hypotension. Further investigation of the contrast volume revealed associations with sex, severe calcification, arch type, previous coronary artery bypass surgery, and primary stenting, suggesting that the contrast volume reflects the complexity of the procedure. Conclusion: The complexity of the procedure and type of stent may play a role in the development of postprocedural hypotension after CAS.

Regional variation in patient outcomes in carotid artery disease treatment in the Vascular Quality Initiative

OBJECTIVE

Quality metrics were developed to improve outcomes after carotid artery revascularization; however, few studies have evaluated regional differences in perioperative outcomes. This study aimed to evaluate regional variation in mortality and perioperative outcomes after carotid endarterectomy (CEA) and carotid artery stenting (CAS).

METHODS

We identified all patients who underwent CEA or CAS from 2009 to 2016 in the Vascular Quality Initiative. Patients were analyzed on the basis of their symptom status. We assessed variation in perioperative outcomes using χ² analysis, Fisher exact test, and t-test, where appropriate.

RESULTS

A total of 78,467 carotid interventions were identified; 85% were CEAs, with 69% of those asymptomatic. Within CAS, 39% were asymptomatic. Perioperative stroke/death varied across regions within both CAS groups (asymptomatic, 0%-5.8% [P = .03]; symptomatic, 2.4%-8.1% [P = .1]), and several regions did not meet the American Heart Association (AHA) guidelines of 3% for asymptomatic patients and 6% for symptomatic patients, which persisted after risk adjustment. For CEA, the stroke/death rates fell within the standards set by the AHA guidelines in all regions for both the unadjusted and risk-adjusted models; however, there was significant regional variation in the cohorts (asymptomatic, 0.9%-3.1% [P < .01]; symptomatic, 1.3%-4.9% [P < .01]). Variation in 30-day mortality was significant in symptomatic patients (asymptomatic: CEA, 0%-1.3% [P = .2], CAS, 0%-2.4% [P = .2]; symptomatic: CEA, 0%-1.8% [P < .01], CAS, 0%-4.6% [P = .01]). Rates of in-hospital stroke, postoperative myocardial infarction, prolonged length of stay (>2 days), and use of intravenous blood pressure medications all varied significantly across the regions. After CEA, there was significant variation in the rates of cranial nerve injuries (asymptomatic, 0.9%-4.9% [P < .01]; symptomatic, 1.5%-7.7% [P < .01]), return to the operating room (asymptomatic, 0.9%-3.4% [P < .01]; symptomatic, 0.6%-3.4% [P = .02]), and discharge on antiplatelet and statin (asymptomatic, 75%-87% [P < .01]; symptomatic, 78%-91% [P < .01]). After CAS, significant variation was found in the rates of access site complications (asymptomatic, 2.3%-18.2% [P < .01]; symptomatic, 1.4%-16.9% [P < .01]) and discharge on dual antiplatelet therapy (asymptomatic, 79%-94% [P < .01]; symptomatic, 83%-93% [P < .01]).

CONCLUSIONS

Unwarranted regional variation exists in outcomes after carotid artery revascularization across the regions of the VQI. Significant variation was seen in a number of outcomes for which quality metrics currently exist, such as length of stay and discharge medications. In addition, after CAS, several regions failed to meet the AHA guidelines for stroke and death. Given these results, quality improvement projects should be targeted to improve adherence to current guidelines to promote best practices.

Stroke Caused by Extracranial Disease

Extracranial internal carotid artery atherosclerotic occlusive disease is a common ischemic stroke mechanism. Vascular risk factor control remains the cornerstone of stroke prevention in patients with both asymptomatic and symptomatic carotid occlusive diseases. Intensive medical therapy refers to the contemporary approach of antiplatelet therapy, blood pressure control, low-density lipoprotein reduction, and lifestyle modification to reduce stroke risk. Carotid revascularization with endarterectomy or angioplasty and stenting are established treatments for patients with symptomatic carotid stenosis ≥70%. Previously accepted ischemic stroke preventative strategies, such as carotid revascularization for asymptomatic carotid stenosis, require reassessment given advances in both medical therapy and surgical techniques. The purpose of this review is to describe contemporary approaches to the management of extracranial carotid atherosclerotic occlusive disease and the basis of these recommendations. Results from recently published clinical trials will be highlighted in addition to updated information from clinical trials addressing knowledge gaps in prevention of stroke caused by extracranial disease.

Regional variation in patient selection and treatment for carotid artery disease in the Vascular Quality Initiative

OBJECTIVE

Previous studies involving large administrative data sets have revealed regional variation in the demographics of patients selected for carotid endarterectomy (CEA) and carotid artery stenting (CAS) but lacked clinical granularity. This study aimed to evaluate regional variation in patient selection and operative technique for carotid artery revascularization using a detailed clinical registry.

METHODS

All patients who underwent CEA or CAS from 2009 to 2015 were identified in the Vascular Quality Initiative (VQI). Deidentified regional groups were used to evaluate variation in patient selection, operative technique, and perioperative management. χ² analysis was used to identify significant variation across regions.

RESULTS

A total of 57,555 carotid artery revascularization procedures were identified. Of these, 49,179 patients underwent CEA (asymptomatic: median, 56%; range, 46%-69%; P < .01) and 8376 patients underwent CAS (asymptomatic: median, 36%; range, 29%-51%; P < .01). There was significant regional variation in the proportion of asymptomatic patients being treated for carotid stenosis <70% in CEA (3%-9%; P < .01) vs CAS (3%-22%; P < .01). There was also significant variation in the rates of intervention for asymptomatic patients older than 80 years (CEA, 12%-27% [P < .01]; CAS, 8%-26% [P < .01]). Preoperative computed tomography angiography or magnetic resonance angiography in the CAS cohort also varied widely (31%-83%; P < .01), as did preoperative medical management with combined aspirin and statin (CEA, 53%-77% [P < .01]; CAS, 62%-80% [P < .01]). In the CEA group, the use of shunt (36%-83%; P < .01), protamine (32%-89%; P < .01), and patch (87%-99%; P < .01) varied widely. Similarly, there was regional variation in frequency of CAS done without a protection device (1%-8%; P < .01).

CONCLUSIONS

Despite clinical benchmarks aimed at guiding management of carotid disease, wide variation in clinical practice exists, including the proportion of asymptomatic patients being treated by CAS and preoperative medical management. Additional intraoperative variables, including the use of a patch and protamine during CEA and use of a protection device during CAS, displayed similar variation in spite of clear guidelines. Quality improvement projects could be directed toward improved adherence to benchmarks in these areas.

Simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) imaging: Comparison with contrast-enhanced MR angiography for measuring carotid stenosis

PURPOSE

To evaluate in a proof-of-concept study the feasibility of Simultaneous Noncontrast Angiography and intraPlaque hemorrhage (SNAP) imaging as a clinical magnetic resonance angiography (MRA) technique for measuring carotid stenosis. There is a growing interest in detecting intraplaque hemorrhage (IPH) during the clinical management of carotid disease, yet luminal stenosis has remained indispensable during clinical decision-making. SNAP imaging has been proposed as a novel IPH imaging technique that provides carotid MRA with no added scan time. Flowing blood shows negative signal on SNAP because of phase-sensitive inversion recovery.

MATERIALS AND METHODS

In all, 58 asymptomatic subjects with 16-79% stenosis on ultrasound were scanned at 3T by SNAP with 0.8 mm isotropic resolution and 16 cm longitudinal coverage. Two readers measured luminal stenosis of bilateral carotid arteries (n = 116) on minimum intensity projections of SNAP using the NASCET criteria. In the subset (48 arteries) with contrast-enhanced (CE) MRA available for comparison, luminal stenosis was also measured on maximum intensity projections of CE-MRA.

RESULTS

Intraclass correlation coefficients (ICCs) with 95% confidence intervals were 0.94 (0.90-0.96) and 0.93 (0.88-0.96) for intra- and interreader agreement on stenosis measurements, respectively. Corresponding kappas for grading stenosis (0-29%, 30-69%, 70-99%, and 100%) were 0.79 (0.67-0.89) and 0.80 (0.68-0.90). Agreement between SNAP and CE-MRA was high (ICC: 0.95 [0.90-0.98]; kappa: 0.82 [0.71-0.93]).

CONCLUSION

As a dedicated IPH-imaging sequence, SNAP also provided carotid stenosis measurement that showed high intra- and interreader consistency and excellent agreement with CE-MRA. Further comparisons with digital subtraction angiography and other noninvasive techniques are warranted.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1045-1052.

The association between ankle-brachial index and asymptomatic cranial-carotid stenosis: a population-based, cross-sectional study of 5440 Han Chinese

BACKGROUND AND PURPOSE

Routine screening for asymptomatic cranial-carotid stenosis (ACCS) is controversial and recommendation in clinical practice is vague. The ankle-brachial index (ABI) is reported as a predictor for cardiovascular disease. However, there is a scarcity of data about the association between abnormal ABI and ACCS. A population-based cross-sectional study was conducted to explore the relationship between ABI and ACCS.

METHODS

A sample of 5440 Chinese adults aged 40-94 years old was recruited from 2010 to 2011. The ABI was measured using a portable Doppler device and ACCS was evaluated by bilateral carotid duplex ultrasound and portable examination devices. A logistic regression model was used to analyse the association between ABI and ACCS after adjusting for potential confounding factors.

RESULTS

A low ABI was associated with ACCS [odds ratio (OR) 1.95, 95% confidence interval (CI) 1.42-2.67] after adjusting for potential confounders. When the data were stratified by age and sex, the correlation remained statistically significant in the male (OR 2.32, 95% CI 1.60-3.37) and elderly (OR 3.07, 95% CI 1.97-4.78) subgroups compared to the female (OR 1.26, 95% CI 0.67-2.39) and middle-aged groups (OR 1.27, 95% CI 0.77-2.12), respectively.

CONCLUSION

This study demonstrated that low ABI is a significant risk factor for ACCS in male and elderly Chinese adults.

The relationship between carotid artery plaque stability and white matter ischemic injury

Higher local carotid artery strain has previously been shown to be a characteristic of unstable carotid plaques. These plaques may be characterized by microvascular changes that predispose to intraplaque hemorrhage, increasing the likelihood of embolization. Little is known however, about how these strain indices correspond with imaging markers of brain health and metrics of brain structure. White matter hyperintensities (WMHs), which are bright regions seen on T2-weighted brain MRI imaging, are postulated to result from cumulative ischemic vascular injury. Consequently, we hypothesized that plaques that are more prone to microvascular changes and embolization, represented by higher strain indices on ultrasound, would be associated with an increased amount of WMH lesion volume. This relationship would suggest not only emboli as a cause for the brain degenerative changes, but more importantly, a common microvascular etiology for large and small vessel contributions to this process. Subjects scheduled to undergo a carotid endarterectomy were recruited from a neurosurgery clinic. Prior to surgery, participating subjects underwent both ultrasound strain imaging and brain MRI scans as part of a larger clinical study on vascular health and cognition. A linear regression found that maximum absolute strain and peak to peak strain in the surgical side carotid artery were predictive of WMH burden. Furthermore, the occurrence of microembolic signals monitored using transcranial Doppler (TCD) ultrasound examinations also correlated with increasing lesion burden. It is becoming increasingly recognized that cognitive decline is often multifactorial in nature. One contributing extra-brain factor may be changes in the microvasculature that produce unstable carotid artery plaques. In this study, we have shown that higher strain indices in carotid artery plaques are significantly associated with an increased WMH burden, a marker of vascular mediated brain damage.

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We examine how carotid artery plaque strain indices correspond with MRI metrics.

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Strain in the ICA predicts increased white matter hyperintensity lesion burden.

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Subjects with embolizing plaques have greater white matter lesion burden.

Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of stroke among individuals who have not previously experienced a stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches to atherosclerotic disease of the cervicocephalic circulation, and antithrombotic treatments for preventing thrombotic and thromboembolic stroke. Further recommendations are provided for genetic and pharmacogenetic testing and for the prevention of stroke in a variety of other specific circumstances, including sickle cell disease and patent foramen ovale.

Management of vascular risk factors in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST)

Background

The Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) is a multicenter randomized trial of stenting versus endarterectomy in patients with symptomatic and asymptomatic carotid disease. This study assesses management of vascular risk factors.

Methods and Results

Management was provided by the patient's physician, with biannual monitoring results collected by the local site. Therapeutic targets were low‐density lipoprotein, cholesterol <100 mg/dL, systolic blood pressure <140 mm Hg, fasting blood glucose <126 mg/dL, and nonsmoking status. Optimal control was defined as achieving all 4 goals concurrently. Generalized estimating equations were used to compare risk factors at baseline with those observed in scheduled follow‐up visits for up to 48 months. In the analysis cohort of 2210, significant improvements in risk‐factor control were observed across risk factors for all follow‐up visits compared with baseline. At 48 months, achievement of the low‐density lipoprotein cholesterol goal improved from 59.1% to 73.6% (P<0.001), achievement of the systolic blood pressure goal improved from 51.6% to 65.1% (P<0.001), achievement of the glucose goal improved from 74.9% to 80.7% (P=0.0101), and nonsmoking improved from 74.4% to 80.9% (P<0.0001). The percentage with optimal risk‐factor control also improved significantly, from 16.7% to 36.2% (P<0.001), but nearly 2 of 3 study participants did not achieve optimal control during the study.

Conclusions

Site‐based risk‐factor control improved significantly in the first 6 months and over the long term in CREST but was often suboptimal. Intensive medical management should be considered for future trials of carotid revascularization.

Clinical Trial Registration

URL: ClinicalTrials.gov. Unique identifier: NCT00004732.