Prevalence and outcome of asymptomatic carotid stenosis: a population-based ultrasonographic study

A Radiomics-Based Nomogram Using Ultrasound Carotid Plaque Evaluation For Predicting Cerebro-Cardiovascular Events In Asymptomatic Patients

RATIONALE AND OBJECTIVES

This study aims to assess whether a radiomics-based nomogram correlates with a higher risk of future cerebro-cardiovascular events in patients with asymptomatic carotid plaques. Additionally, it investigates the nomogram's contribution to the revised Framingham Stroke Risk Profile (rFSRP) for predicting cerebro-cardiovascular risk.

MATERIALS AND METHODS

Predictive models aimed at identifying an increased risk of future cerebro-cardiovascular events were developed and internally validated at one center, then externally validated at two other centers. Survival curves, constructed using the Kaplan-Meier method, were compared through the log-rank test.

RESULTS

This study included a total of 2009 patients (3946 images). The final nomogram was generated using multivariate Cox regression variables, including dyslipidemia, lumen diameter, plaque echogenicity, and ultrasonography (US)-based radiomics risk. The Harrell's concordance index (C-index) for predicting events-free survival (EFS) was 0.708 in the training cohort, 0.574 in the external validation cohort 1, 0.632 in the internal validation cohort, and 0.639 in the external validation cohort 2. The final nomogram showed a significant increase in C-index compared to the clinical, conventional US, and US-based radiomics models (all P < 0.05). Furthermore, the final nomogram-assisted method significantly improved the sensitivity and accuracy of radiologists' visual qualitative score of plaque (both P < 0.001). Among 1058 patients with corresponding 1588 plaque US images classified as low-risk by the rFSRP, 75 (7.1%) patients with corresponding 93 (5.9%) carotid plaque images were appropriately reclassified to the high-risk category by the final nomogram.

CONCLUSION

The radiomics-based nomogram demonstrated accurate prediction of cerebro-cardiovascular events in patients with asymptomatic carotid plaques. It also improved the sensitivity and accuracy of radiologists' visual qualitative score of carotid plaque and enhanced the risk stratification ability of rFSRP.

SUMMARY

The radiomics-based nomogram allowed accurate prediction of cerebro-cardiovascular events, especially ipsilateral ischemic stroke in patients with asymptomatic carotid atherosclerotic plaques.

KEY RESULTS

The radiomics-based nomogram allowed accurate prediction of cerebro-cardiovascular events, especially ipsilateral ischemic stroke in patients with asymptomatic carotid atherosclerotic plaques. The radiomics-based nomogram improved the sensitivity and accuracy of radiologists' visual qualitative score of carotid plaque. The radiomics-based nomogram improved the discrimination of high-risk populations from low-risk populations in asymptomatic patients with carotid atherosclerotic plaques and the risk stratification capability of the rFSRP.

Carotid disease, cognition, and aging: time to redefine asymptomatic disease?

There is an increasing appreciation of the vascular contributions in the development of age-related cognitive impairment and dementia^1,2. Identifying risk and maintaining cognitive health for successful aging is ever relevant in our aging population. Carotid disease, a well-established risk factor for stroke and often a harbinger of other vascular disease states, is also emerging as another vascular risk factor for age-related cognitive decline. When combined with vascular risk factors, the incidence of age-related carotid disease can be as high as 70%^3,4. Historically, carotid disease has been dichotomized into two large groups in trial design, outcome measurements, and treatment decisions: symptomatic and asymptomatic carotid artery stenosis. The dichotomous distinction between asymptomatic and symptomatic carotid stenosis based on existing definitions may be limiting the care we are able to provide for patients classified as "asymptomatic" from their carotid disease. Medically, we now know that these patients should be treated with the same intensive medical therapy as those with "symptomatic" carotid disease. Emerging data also shows that hypoperfusion from asymptomatic disease may lead to significant cognitive impairment in the aging population, and it is plausible that most "age-related" cognitive changes may be reflective of vascular impairment and neurovascular dysfunction. While over the past 30 years medical, surgical, and radiological advances have pushed the field of neurovascular disease to significantly reduce the number of ischemic strokes, we are far from any meaningful interventions to prevent vascular cognitive impairment. In addition to including cognitive outcome measures, future studies of carotid disease will also benefit from including advanced neuroimaging modalities not currently utilized in standard clinical imaging protocols, such as perfusion imaging and/or functional connectivity mapping, which may provide novel data to better assess for hypoxic-ischemic changes and neurovascular dysfunction across diffuse cognitive networks. While current recommendations advise against widespread population screening for asymptomatic carotid stenosis, emerging evidence linking carotid stenosis to cognitive impairment prompts us to re-consider our approach for older patients with vascular risk factors who are at risk for cognitive decline.

Asymptomatic carotid artery stenosis is associated with cerebral hypoperfusion

OBJECTIVE

We have shown that almost 50% of patients with asymptomatic carotid stenosis (ACS) will demonstrate cognitive impairment. Recent evidence has suggested that cerebral hypoperfusion is an important cause of cognitive impairment. Carotid stenosis can restrict blood flow to the brain, with consequent cerebral hypoperfusion. In contrast, cross-hemispheric collateral compensation through the Circle of Willis, and cerebrovascular vasodilation can also mitigate the effects of flow restriction. It is, therefore, critical to develop a clinically relevant measure of net brain perfusion in patients with ACS that could help in risk stratification and in determining the appropriate treatment. To determine whether ACS results in cerebral hypoperfusion, we developed a novel approach to quantify interhemispheric cerebral perfusion differences, measured as the time to peak (TTP) and mean transit time (MTT) delays using perfusion-weighted magnetic resonance imaging (PWI) of the whole brain. To evaluate the utility of using clinical duplex ultrasonography (DUS) to infer brain perfusion, we also assessed the relationship between the PWI findings and ultrasound-based peak systolic velocity (PSV).

METHODS

Structural and PWI of the brain and magnetic resonance angiography of the carotid arteries were performed in 20 patients with ≥70% ACS. DUS provided the PSV, and magnetic resonance angiography provided plaque geometric measures at the stenosis. Volumetric perfusion maps of the entire brain from PWI were analyzed to obtain the mean interhemispheric differences for the TTP and MTT delays. In addition, the proportion of brain volume that demonstrated a delay in TTP and MTT was also measured. These proportions were measured for increasing severity of perfusion delays (0.5, 1.0, and 2.0 seconds). Finally, perfusion asymmetries on PWI were correlated with the PSV and stenosis features on DUS using Pearson's correlation coefficients.

RESULTS

Of the 20 patients, 18 had unilateral stenosis (8 right and 10 left) and 2 had bilateral stenoses. The interhemispheric (left-right) TTP delays measured for the whole brain volume identified impaired perfusion in the hemisphere ipsilateral to the stenosis in 16 of the 18 patients. More than 45% of the patients had had ischemia in at least one half of their brain volume, with a TTP delay >0.5 second. The TTP and MTT delays showed strong correlations with PSV. In contrast, the correlations with the percentage of stenosis were weaker. The correlations for the PSV were strongest with the perfusion deficits (TTP and MTT delays) measured for the whole brain using our proposed algorithm (r = 0.80 and r = 0.74, respectively) rather than when measured on a single magnetic resonance angiography slice as performed in current clinical protocols (r = 0.31 and r = 0.58, respectively).

CONCLUSIONS

Interhemispheric TTP and MTT delay measured for the whole brain using PWI has provided a new tool for assessing cerebral perfusion deficits in patients with ACS. Carotid stenosis was associated with a detectable reduction in ipsilateral brain perfusion compared with the opposite hemisphere in >80% of patients. The PSV measured at the carotid stenosis using ultrasonography correlated with TTP and MTT delays and might serve as a clinically useful surrogate to brain hypoperfusion in these patients.

Why are we still debating criteria for carotid artery stenosis?

The risk of new or recurrent stroke is high among patients with extracranial carotid artery stenosis and the benefit of carotid revascularization is associated to the degree of luminal stenosis. Catheter-based digital subtraction angiography (DSA) as the diagnostic gold-standard for carotid stenosis (CS) has been replaced by non-invasive techniques including duplex ultrasound, computed-tomography angiography, and magnetic resonance angiography (MRA). Duplex ultrasound is the primary noninvasive diagnostic tool for detecting, grading and monitoring of carotid artery stenosis due to its low cost, high resolution, and widespread availability. However, as discussed in this review, there is a wide range of practice patterns in use of ultrasound diagnostic criteria for carotid artery stenosis. To date, there is no internationally accepted standard for the gradation of CS. Discrepancies in ultrasound criteria may result in clinically relevant misclassification of disease severity leading to inappropriate referral, or lack of it, to revascularization procedures, and potential for consequential adverse outcome. The Society of Radiologists in Ultrasound (SRU), either as originally outlined or in a modified form, are the most common criteria applied. However, such criteria have received criticism for relying primarily on peak systolic velocities, a parameter that when used in isolation could be misleading. Recent proposals rely on a multiparametric approach in which the hemodynamic consequences of carotid narrowing beyond velocity augmentation are considered for an accurate stenosis classification. Consensus criteria would provide standardized parameters for the diagnosis of CS and considerably improve quality of care. Accrediting bodies around the world have called for consensus on unified criteria for diagnosis of CS. A healthy debate between professionals caring for patients with CS regarding optimal CS criteria still continues.

Evaluation and Management of Atherosclerotic Carotid Stenosis

Medical therapies for the prevention of stroke have advanced considerably in the past several years. There can also be a role for mechanical restoration of the lumen by endarterectomy or stenting in selected patients with high-grade atherosclerotic stenosis of the extracranial carotid artery. Endarterectomy is generally recommended for patients with high-grade symptomatic carotid stenosis. Stenting is considered an option for patients at high risk of complications with endarterectomy. Whether revascularization is better than contemporary medical therapy for asymptomatic extracranial carotid stenosis is a subject of several ongoing randomized clinical trials in the United States and internationally.

Is anti-platelet therapy always necessary in asymptomatic 30-40% carotid stenosis?

Asymptomatic mild carotid artery stenosis is relatively frequent and associated with an increased risk of cardiovascular events. Its recognition is clinically relevant for appropriate prevention strategies. These include a healthy lifestyle approach and a careful pharmacologic control of cardiovascular risk factors, such as hypertension, hypercholesterolemia, and diabetes. Furthermore, interventions able to reduce the risk of atherothrombotic events, such as antiplatelet drugs, should be considered. Noninvasive imaging of carotid artery plaque and stenosis severity and morphology may add relevant information for the risk stratification of these subjects.

Rapid High-Volume Population Screening for Three Major Risk Factors of Future Stroke: Phase I Results

Three proximate risk factors for stroke are carotid stenosis, atrial fibrillation, and hypertension. Phase I of this prospective study was designed to establish the prevalence of these conditions among a population of health maintenance organization beneficiaries by using a rapid screening protocol in order to risk-stratify patients for appropriate management and subsequent cohort analysis. Patients at a tertiary care medical center were screened for stroke risk by using directed history, a 3-minute carotid “quick-scan” protocol, an EKG lead II rhythm strip, and bilateral arm blood pressures. Patients with any abnormal result underwent specific diagnostic consultation with vascular surgery, cardiology, or primary care. These evaluations included formal carotid duplex ultrasound, 12-lead EKG ± Holter monitor, and 5-day blood pressure check. Patients were then stratified into risk cohorts for appropriate management and future analysis of stroke incidence and outcomes. In 8 hours on a single day in October 2002, 294 patients (mean age 69) were screened. Combining history with results of screening and diagnostic tests, the overall prevalence of carotid stenosis was 6% (n= 17/294), atrial fibrillation 7% (n= 21/294), and severe hypertension 5% (n= 16/294). Fifty-nine patients (20%) screened positive for carotid stenosis by “quick-scan,” and 29% (n= 17/59) of these had confirmed stenosis (>50%) in 1 or both arteries by formal duplex. The prevalence of confirmed carotid stenosis was 37% among those screening positive for 1 artery (odds ratio [OR] 14.6; p <0.001) and 75% among those screening positive for both (OR 74.7; p <0.001). Significant independent predictors of carotid stenosis by multivariate analysis included coronary artery disease or myocardial infarction, smoking, stroke or transient ischemic attack, male gender, and white race (all p <0.05). The prevalence of confirmed stenosis was 10% with any 3 predictors alone (OR 2.5; p <0.05), 31% with any 4 (OR 21.2; p <0.001), and 50% with all 5 (OR 46.5; p <0.001). Thirty-three patients (11%) were found to have a previously unidentified and untreated arrhythmia, and 12% (n= 4/33) of these had confirmed new atrial fibrillation; 158 patients (54%) had moderate hypertension and 16 (5%) had severe hypertension (>180/100). Overall, 82% (n= 242/294) of patients screened required additional diagnostic tests. Based on these results, 11% (n= 31/294) of patients were stratified as high risk, 64% (n= 188/294) as moderate risk, and 25% (n= 75/294) as low risk for future stroke. Rapid and efficient screening of a large population for stroke risk factors is feasible. The prevalence of undiagnosed, unsurveilled, and untreated carotid stenosis, atrial fibrillation, and severe hypertension is significant, as 75% of patients screened had 1 or more confirmed major risk factors for stroke. Phase II of this study will investigate the degree of stroke risk reduction possible with a multidisciplinary approach to early identification and aggressive treatment of these risks.

Red cell distribution width and mortality in carotid atherosclerosis

BACKGROUND

Red cell distribution width (RDW) is associated with morbidity and mortality in chronic cardiac disease. The aim of the present study was to investigate the role of RDW as a predictor of adverse outcome in patients with carotid atherosclerosis.

MATERIALS AND METHODS

We prospectively studied 1065 of 1286 consecutive patients with neurological asymptomatic carotid artery stenosis as assessed by duplex Doppler sonography. The study end points were all-cause mortality and cardiovascular mortality respectively.

RESULTS

During a median follow-up time of 6·2 years (interquartile range 5·9-6·6), corresponding to 5551 overall person-years, 275 patients (25·8%) died. Of them, 182 patients (66·2%) died due to cardiovascular causes. RDW was significantly associated with adverse outcome. In a continuous multivariate Cox regression analysis, the adjusted hazard ratio for each per cent increase in RDW was 1·39 (95% CI 1·27-1·53; P < 0·001) for all-cause and 1·43 (95% CI 1·28-1·60; P < 0·001) for cardiovascular mortality respectively. Kaplan-Meier estimates showed a gradual relationship between increasing quartiles of RDW and death (log rank P < 0·001). Adjusted hazard ratios for all-cause death ranged from 0·89 to 1·94 for the highest vs. the lowest quartile (P < 0·001 for trend) and for cardiovascular death from 1·08 to 2·34 for the highest vs. the lowest quartile (P < 0·001 for trend) respectively.

CONCLUSIONS

Red cell distribution width was significantly and independently associated with all-cause and cardiovascular death in patients with asymptomatic carotid atherosclerosis.

Pathophysiology and Medical Treatment of Carotid Artery Stenosis

Stroke is the third leading cause of mortality. Approximately 80 to 85% strokes are ischemic due to carotid artery stenosis (CAS). The prevalence of significant CAS is 7% in women and 9% in men. Severe asymptomatic CAS varies from 0 to 3.1%. Prevalence of symptomatic CAS is high in patients with peripheral arterial disease. CAS is due to atherosclerosis, the major risk factors for which include dyslipidemia, hypertension, diabetes, obesity, cigarette smoking, advanced glycation end products (AGEs) and its receptors (RAGE, soluble RAGE [sRAGE]), lack of exercise and C-reactive protein (CRP). This article discusses the basic mechanism of atherosclerosis and the mechanisms by which these risk factors induce atherosclerosis. The role of AGEs and its receptors in the development and progression of CAS has been discussed in detail. Lifestyle changes and medical treatment of CAS such as lifestyle changes, lipid-lowering agents, antihypertensive agents, antidiabetic drugs, anti-AGE therapy, measures to elevate soluble receptors of AGE (sRAGE, esRAGE). CRP-lowering agents have been discussed in detail. The drugs especially lipid-lowering agents, and antihypertensive and antidiabetic drugs suppress, regress, and slow the progression of CAS. The possible role of lowering the levels of AGEs and raising the levels of sRAGE in the treatment of CAS has been proposed. Lifestyle changes besides medical treatment have been stressed. Lifestyle changes and medical treatment not only would slow the progression of CAS but would also regress the CAS.

Retinal artery occlusion and the 3-year risk of stroke in Taiwan: a nationwide population-based study

PURPOSE

To verify the association between retinal artery occlusion (RAO) and stroke with a large-scale nationwide study.

DESIGN

Retrospective nationwide population-based administrative database study.

METHODS

Data were collected from the Longitudinal Health Insurance Database 2000 (LHID2000), which contains claim data from 1 million randomly selected beneficiaries among Taiwan's 23 million residents. The study cohort consisted of all patients with a diagnosis of RAO from January 1999 through December 2006 (n = 464). The control group consisted of randomly selected patients (n = 2748) matched with the study group by age, sex, date of index medical care, and comorbid hypertension. Patients were tracked from their index date for 3 years. The Kaplan-Meier method was used to compute the stroke-free survival rate. Cox proportional hazard regressions were used to compute the adjusted stroke-free survival rate after adjusting for possible confounding factors.

RESULTS

Ninety-one RAO patients (19.61%) and 280 controls (10.05%) had a stroke (P < .0001) during the 3-year follow-up period. Compared with the controls, the incidence rate ratios of stroke in RAO patients were 9.46 at 0-1 month, 5.57 at 1-6 months, and 2.16 at 0-3 years after RAO (P < .0001). After adjusting for age, sex, and selected comorbid disorders, the hazard ratio of having a stroke for RAO patients was still 2.07 times higher than that of controls and 3.34 times higher in the ≤60-year-old subgroup.

CONCLUSIONS

RAO increases the risk for subsequent stroke. Early neurologic evaluation and secondary prevention for stroke are recommended for RAO patients.

Carotid stenosis: what is the high-risk population?

OBJECTIVE

Prevention is the best treatment for cerebrovascular disease, which is why early diagnosis and the immediate treatment of carotid stenosis contribute significantly to reducing the incidence of stroke. Given its silent nature, 80% of stroke cases occur in asymptomatic individuals, emphasizing the importance of screening individuals with carotid stenosis and identifying high-risk groups for the disease. The aim of this study was to determine the prevalence and the most frequent risk factors for carotid stenosis.

METHODS

A transversal study was conducted in the form of a stroke prevention campaign held on three nonconsecutive Saturdays. During the sessions, carotid stenosis diagnostic procedures were performed for 500 individuals aged 60 years or older who had systemic arterial hypertension and/or diabetes mellitus and/or coronary heart disease and/or a family history of stroke.

RESULTS

The prevalence of carotid stenosis in the population studied was 7.4%, and the most frequent risk factors identified were mean age of 70 years, carotid bruit, peripheral obstructive arterial disease, coronary insufficiency and smoking. Independent predictive factors of carotid stenosis include the presence of carotid bruit or peripheral obstructive arterial disease [corrected] and/or coronary insufficiency.

CONCLUSIONS

The population with peripheral obstructive arterial disease [corrected] and/or coronary insufficiency and carotid bruit should undergo routine screening for carotid stenosis.

Symptomatic and asymptomatic carotid artery plaque

Carotid atherosclerotic plaques represent both stable and unstable atheromatous lesions. Atherosclerotic plaques that are prone to rupture owing to their intrinsic composition such as a large lipid core, thin fibrous cap and intraplaque hemorrhage are associated with subsequent thromboembolic ischemic events. At least 15-20% of all ischemic strokes are attributable to carotid artery atherosclerosis. Characterization of plaques may enhance the understanding of natural history and ultimately the treatment of atherosclerotic disease. MRI of carotid plaque and embolic signals during transcranial Doppler have identified features beyond luminal stenosis that are predictive of future transient ischemic attacks and stroke. The value of specific therapies to prevent stroke in symptomatic and asymptomatic patients with severe carotid artery stenosis are the subject of current research and analysis of recently published clinical trials that are discussed in this article.

Strategies for asymptomatic carotid artery stenosis

The treatment of asymptomatic carotid artery stenosis (ACAS) has continued to evolve for the past 3 decades. With rapidly advancing technology, the results of old trials have become obsolete. While there has been little change in the efficacy of carotid endarterectomy, there have been vast improvements in both medical management and carotid angioplasty with stenting. Finding the best therapy for a given patient can therefore be difficult. In this article, the authors review the current literature regarding treatment options for ACAS and the methods available for stratifying patients who would benefit from surgical versus medical treatment.

Evidence-based review of primary and secondary ischemic stroke prevention in adults: a neurosurgical perspective

In this paper, the authors' aim is to provide an evidence-based review of primary and secondary ischemic stroke prevention guidelines covering most of the common risk factors and stroke etiologies for the practicing neurosurgeon. The key to stroke prevention is in the identification and treatment of the major risk factors for stroke. These include hypertension, heart disease, diabetes mellitus, dyslipidemia, and tobacco smoking. An updated approach to secondary prevention of stroke in the setting of intracranial and extracranial large vessel atherosclerosis and cardioembolism is provided along with a brief overview of pertinent clinical trials. Novel pharmacological options for prevention of cardioembolic strokes, such as new alternatives to warfarin, are addressed with recommendations for interruption of therapy for elective surgical procedures. In addition, the authors have reviewed the anticoagulation guidelines and the risk of thromboembolic complications of such therapies in the perioperative period, which is an invaluable piece of information for neurosurgeons. Less common etiologies such as arterial dissections and patent foramen ovale are also briefly discussed. Finally, the authors have outlined the quality measures in the Medicare Physician Quality Reporting System and essential guidelines for Primary Stroke Center certification, which have implications for day-to-day neurosurgical practice.

Carotid stenting vs endarterectomy: new results in perspective

Carotid artery stenosis is a major risk factor for stroke, and treatments for this condition to decrease the risk of stroke include medical therapy, carotid endarterectomy (CEA), and, more recently, carotid angioplasty and stenting (CAS). Randomized controlled trials comparing the efficacy of CEA vs medical therapy showed a clear benefit for CEA in patients with symptomatic carotid artery stenosis of greater than 70% and a lesser benefit in patients with 50% to 69% stenosis. Treatments have evolved in the ensuing 20 years, and a new method, CAS, has emerged as a possible alternative to CEA. In early results, CAS proved feasible but did not compare favorably with CEA. Later and larger-scale studies comparing CAS to CEA failed to reach conclusions regarding a clear neurologic outcome advantage of one method over the other. This subject was of sufficient interest that 2 larger-scale randomized controlled trials comparing CAS and CEA, the Carotid Revascularization Endarterectomy vs Stenting Trial and the International Carotid Stenting Study, were undertaken to further explore this issue. This brief review places the new data arising from these studies in the context of prior efforts to address the problem of carotid artery stenosis and explores further opportunities for improvement and patient recommendations in light of these new findings.

Comparison between quantification methods of carotid artery stenosis and computed tomographic angiography

PURPOSE

The purpose of this study was to compare 3 percentage carotid artery measurement methods (the North American Symptomatic Carotid Endarterectomy Trial [NASCET], the European Carotid Surgery Trial [ECST], and the Carotid Stenosis Index [CSI]) and 1 millimeter method (direct millimeter measurement) to evaluate the difference and correlation between them.

MATERIALS AND METHODS

Seven hundred ninety-two patients (591 men; age: mean, 63 years; range, 32-91 years) studied by using a multi-detector row computed tomographic scanner for a total of 1584 carotid arteries were retrospectively analyzed. Each carotid stenosis was measured according to 4 measurement methods (the NASCET, the ECST, the CSI, and the direct millimeter measurement). Carotid arteries with near-occlusion condition were excluded. The Kolmogorov-Smirnov Z test was used to test the normality of continuous variable groups. Comparison of derived ratio-percent methods was performed by using the Bland-Altman plots, and receiver operating characteristic curves were calculated. Correlation coefficients were also calculated by using a nonparametric Spearman correlation. A P < 0.05 was considered to mean statistical significance.

RESULTS

Four hundred sixteen carotid arteries were excluded, and in the remaining 1168 ones, a strength correlation according to quadratic regression between the NASCET and ECST methods was observed (Spearman rho coefficient, 0.948; P < 0.0001). An inverse correlation according to linear regression was observed between the NASCET and the direct millimeter measurement (Spearman rho coefficient, -0.972; P < 0.0001); the CSI shows a quadratic regression with the NASCET, a linear regression with the ECST, and an inverse linear regression with the direct millimeter measurement (Spearman rho coefficient, 0.946, 0.932, and -0.939 respectively). The cutoff values for 50% and 70% NASCET stenosis were 2.36 and 1.51, respectively.

CONCLUSIONS

Our study results indicate that the direct millimeter measurement of stenosis, by using appropriate equations, can reliably predict NASCET-, ECST-, and CSI-type percent stenoses. The use of direct millimeter measurement may remove the pitfalls and the discrepancies deriving from the use of different ratio-percent methods.

Medical (Nonsurgical) Intervention Alone Is Now Best for Prevention of Stroke Associated With Asymptomatic Severe Carotid Stenosis

Significant advances in vascular disease medical intervention since large randomized trials for asymptomatic severe carotid stenosis were conducted (1983–2003) have prompted doubt over current expectations of a surgical benefit. In this systematic review and analysis of published data it was found that rates of ipsilateral and any-territory stroke (+/−TIA), with medical intervention alone, have fallen significantly since the mid-1980s, with recent estimates overlapping those of operated patients in randomized trials. However, current medical intervention alone was estimated at least 3 to 8 times more cost-effective. In conclusion, current vascular disease medical intervention alone is now best for stroke prevention associated with asymptomatic severe carotid stenosis given this new evidence, other cardiovascular benefits, and because high-risk patients who benefit from additional carotid surgery or angioplasty/stenting cannot be identified.

[Cerebrovascular diseases]

In the majority of the cases cerebrovascular disease is caused by atherosclerosis. Duplexsonography is the diagnostic tool of first choice. Management of cardiovascular risk factors is of paramount importance in secondary prevention of atherosclerotic vascular complications. Patients with a symptomatic internal carotid artery stenosis >70% have a clear indication for revascularization. Asymptomatic patients with >60% stenosis benefit from revascularisation if the perioperative risk for death or stroke is below 3%. The optimal revascularization strategy highly depends on the expertise of the local surgeon or endovascular specialist. In younger patients with cerebrovascular disease rare causes such as dissection, large vessel arteritis, fibromuscular dysplasia or vasospasms have to be considered.

Prevalence of asymptomatic carotid artery stenosis according to age and sex: systematic review and metaregression analysis

BACKGROUND AND PURPOSE

In the discussion on the value of population-wide screening for asymptomatic carotid artery stenosis (ACAS), reliable prevalence estimates are crucial. We set out to provide reliable age- and sex-specific prevalence estimates of ACAS through a systematic literature review and meta-regression analysis.

METHODS

We searched PubMed and EmBase until December 2007 for studies that reported the prevalence of ACAS in a population free of symptomatic carotid artery disease. Data were extracted with use of a standardized form on participants' characteristics, assessment method, study quality, and prevalence estimates for moderate (>or=50% stenosis) and severe (>or=70% stenosis) ACAS. Metaregression was used to investigate sources of heterogeneity.

RESULTS

Forty studies fulfilled the inclusion criteria. There was considerable variation among studies with respect to demographics, methods of grading stenosis, and stenosis cutoff point used. The pooled prevalence of moderate stenosis was 4.2% (95% CI, 3.1% to 5.7%). Prevalence of moderate stenosis among people age <70 years was 4.8% (95% CI, 3.1% to 7.3%) in men and 2.2% (95% CI, 0.9% to 4.9%) in women. Among those >or=70 years, prevalence increased to 12.5% (95% CI, 7.4% to 20.3%) in men and to 6.9% (95% CI, 4.0% to 11.5%) in women. Metaregression showed that both age and sex significantly affected the prevalence of moderate stenosis. No contribution of study size, publication year, geographic region, assessment method, and study quality was found. The pooled prevalence of severe stenosis was 1.7% (95% CI, 0.7% to 3.9%).

CONCLUSIONS

Prevalence of moderate stenosis increases with age in both men and women, but men at all ages have the higher prevalence estimates. The number of studies that allowed meaningful data synthesis of severe stenosis was limited.

[A case of nonarteritic anterior ischemic optic neuropathy with hypertension, diabetes mellitus, hyperlipidemia and severe stenosis of the internal carotid artery]

A 76 year-old man had had hypertension, diabetes mellitus and hyperlipidemia since 1985, and bruit in his left neck since 1993. He had abrupt decrease in left visual acuity on November 24, 2005, and visited an ophthalmologist. On November 28, his corrected visual acuity was 1.0 in the right and 0.1 in the left. The examination of optic fundi showed ear-side edema of the left optic disk. Fluorescence examination of the left optic fundus showed delay in early filling and later hyperfluorescence. Goldman visual field examination showed horizontal lower semiblindness. Since he did not complain of eye pain, his blood examination showed no reaction of inflammation, and he had hypertension, diabetes mellitus and hyperlipidemia, anterior ischemic optic neuropathy was diagnosed. The treatment with aspirin, alprostadil and prednisolone transiently improved the optic fundi and visual acuity, but his left visual acuity returned to 0.1. Carotid ultrasonography showed 95 percent stenosis in the left internal carotid artery. As there is no established treatment for ischemic optic neuropathy, the management of risk factors is most important.

A common VLDLR polymorphism interacts with APOE genotype in the prediction of carotid artery disease risk

The genetic factors associated with carotid artery disease (CAAD) are not fully known. Because of its role in lipid metabolism, we hypothesized that common genetic variation in the very low density lipoprotein receptor (VLDLR) gene is associated with severe CAAD (>80% stenosis), body mass index (BMI), and lipid traits in humans. VLDLR was resequenced for variation discovery in 92 subjects, and single nucleotide polymorphisms (tagSNPs) were chosen for genotyping in a larger cohort (n = 1,027). Of the 17 tagSNPs genotyped, one tagSNP (SNP 1226; rs1454626) located in the 5' flanking region of VLDLR was associated with CAAD, BMI, and LDL-associated apolipoprotein B (apoB). We also identified receptor-ligand genetic interactions between VLDLR 1226 and APOE genotype for predicting CAAD case status. These findings may further our understanding of VLDLR function, its ligand APOE, and ultimately the pathogenesis of CAAD in the general population.

Asymptomatic Carotid Artery Stenosis and the Risk of New Vascular Events in Patients With Manifest Arterial Disease

Background and Purpose— The frequency of asymptomatic carotid artery stenosis (CAS) increases with age from 0.5% in individuals below 50 years of age to 5% to 10% in individuals over 65 years of age in the general population. Its prognostic value has been examined in the general population but less often in patients with clinical manifestations of arterial disease other than retinal or cerebral ischemia. We examined the relationship between asymptomatic CAS and the risk of subsequent events in this specific group of patients.

Methods— This study involved 2684 consecutive patients with clinical manifestations of arterial disease or type 2 diabetes mellitus, but without a history of cerebral ischemia, enrolled in the SMART study (Second Manifestations of ARTerial disease). The degree of asymptomatic CAS was assessed with Duplex scanning and defined on the basis of the blood flow velocity patterns at baseline in both carotid arteries. None of the patients underwent carotid endarterectomy or endovascular intervention. During the follow-up period, vascular events (vascular death, ischemic stroke, and myocardial infarction) were documented in detail. Data were analyzed with Cox proportional hazards regression and adjusted for age, gender, and classic vascular risk factors.

Results— Asymptomatic CAS of 50% or greater was present in 221 (8%) patients. During a mean follow up of 3.6 years (SD=2.3), a first vascular event occurred in 253 patients (9%). The cumulative incidence rate for the composite of subsequent vascular events after 5 years was 12.3% (95% CI=10.7 to 13.9), for cerebral infarction 2.2% (95% CI=1.4 to 2.8), and for myocardial infarction 8.0% (95% CI=6.6 to 9.4). Adjusted for age and gender, asymptomatic CAS of 50% or greater was related to a higher risk of subsequent vascular events (hazard ratio=1.5, 95% CI=1.1 to 2.1), in particular of vascular death (hazard ratio=1.8, 95% CI=1.2 to 2.6). After additional adjustment for vascular risk factors, the hazard ratios remained essentially the same.

Conclusion— Asymptomatic carotid artery stenosis is an independent predictor of vascular events, especially vascular death, in patients with clinical manifestations of arterial disease or type 2 diabetes but without a history of cerebral ischemia.

Anästhesiologisches Management bei neuroendovaskulären Eingriffen

The endovascular treatment of diseases of intracranial and spinal vessels has become widely accepted in recent years. The patient is usually treated under general anesthesia and in choosing an appropriate anesthesia regimen and an optimized pre-interventional preparation, the anesthesiologist can influence the postinterventional result. The working environment in the angiography suite should address the requirements of a routine procedure and the necessities of complication management. Application of short-acting narcotics and relaxation of the patient if required, facilitate the intervention for both the neuroradiologist and the anesthesiologist. The patient should be supplied with everything needed before the intervention to avoid any waste of time in the case of an emergency (e.g., haemorrhage or fibrinolytic treatment). After the procedure the patient has to be monitored for at least 24 h. Peri-interventional and postinterventional complications, such as thrombo-embolism or hemorrhage, must be managed aggressively and consequently by the anesthesist to improve the postinterventional outcome. Therefore a close collaboration between the anesthesiologist and the neuroradiologist is essential.

Pulsatile ocular blood flow in patients with asymmetric internal carotid artery stenosis

BACKGROUND

The pulsatile ocular blood flow (POBF) of patients with asymmetric internal carotid artery (ICA) stenosis was measured bilaterally. The purpose of this study was to investigate the sensitivity of POBF assessments in screening for ICA stenosis.

METHODS

Seventeen subjects with asymmetric ICA stenosis confirmed with carotid duplex ultrasound were recruited. The diagnoses of ICA stenosis were categorised into less than 50 per cent, 50 to 69 per cent and 70 per cent or greater. Their POBF and ocular dimensions were measured after local anaesthesia. Twenty-three normal healthy subjects were recruited as the control. All of the subjects had an inter-ocular axial length difference of less than one millimetre.

RESULTS

There were 14 males and three females in the patient group with a median age of 74 years. Fourteen patients had reduced POBF to the eye ipsilateral on the side with greater ICA stenosis. The reduction in POBF ranged from 3.1 to 49.2 per cent. Two patients had reduced POBF contralateral to the side with greater ICA stenosis. One patient had similar POBF between the eyes. The control group included six males and 17 females with a median age of 65 years. The difference in their POBF between the eyes ranged from 0.3 to 13.0 per cent.

CONCLUSIONS

Stenosis of the internal carotid artery was found to reduce the POBF ipsilateral to the side with greater stenosis. The overlap in the difference in inter-ocular POBF between the patient and control groups led to a low sensitivity (calculated as 41.2 per cent) for screening ICA stenosis from an assessment of POBF. Therefore, POBF assessment is not a good diagnostic tool for screening for ICA stenosis.

Ex vivo measures of LDL oxidative susceptibility predict carotid artery disease

AIM

The purpose of the study was to assess whether ex vivo measures of low-density lipoprotein (LDL) oxidation improved prediction of carotid artery disease (CAAD) case-control status compared to standard lipid and smoking measures.

METHODS

One hundred and forty cases with a high degree of carotid artery stenosis aged 40-83 years and an equal number of controls without stenosis or other vascular disease were matched by censored age within 2 years. Matched logistic regression evaluated the significance of copper-induced oxidative measures with and without covariates. The relationship of LDL oxidation measures with statin use and current smoking was also evaluated.

RESULTS

Logistic regression demonstrated a significant effect of the three correlated measures of oxidative susceptibility (lag time, oxidation rate and maximal rate of oxidation) separately on disease prediction (all p<0.05). These oxidative measures remained significant predictors of case-control status when other cardiovascular disease predictors (age; LDL-C, HDL-C and ApoAI levels; current smoking, ever smoking and pack-years smoked) were jointly considered. This relationship was not attributable to the effects of statin use on LDL oxidation.

CONCLUSIONS

Ex vivo measures of oxidation improved the prediction of carotid artery disease status, suggesting that this is an important determinant of atherosclerotic risk in this older population.

Evaluation and management of asymptomatic carotid artery stenosis

Internal carotid artery stenosis (ICAS) is responsible for approximately 30% of ischemic strokes. Internal carotid artery stenosis of greater than 50% is present in about 4% to 8% of the population aged 50 to 79 years. Natural history studies and clinical trials have shown a small increase in stroke risk in patients with increasing degrees of ICAS, especially in those with greater than 80% reduction in carotid artery diameter. Randomized, prospective multicenter trials have revealed the superiority of carotid endarterectomy (CEA) over medical therapy in recently symptomatic patients with severe ICAS. However, the evidence from several randomized controlled trials of CEA in asymptomatic patients does not support the use of CEA in most of these patients; also, the role of noninvasive screening in this patient population remains uncertain and controversial. Furthermore, there is considerable uncertainty about whether the statistical benefit of avoiding a nondisabling stroke is worth the overall cost and risk of the procedure. Clinicians continue to struggle with treatment decisions for patients with asymptomatic ICAS. Carotid endarterectomy for asymptomatic ICAS should be considered only for medically stable patients with 80% or greater stenosis who are expected to live at least 5 years, and only in centers with surgeons who have a demonstrated low (<3%) perioperative complication rate. We outline the prevalence and natural history of ICAS, the evidence for CEA in patients with asymptomatic ICAS, the roles of screening and monitoring for ICAS, the methods of evaluating ICAS, and the implications for practicing clinicians.

Influence of smoking on predictors of vascular disease

Beyond the already well-established strong causative relationship with cancer, smoking increases the risk for vascular disease. Smoking may act directly or adversely influence risk factors contributing to the development of vascular disease. Smoking causes endothelial dysfunction, dyslipidemia (decreased high-density lipoprotein cholesterol levels, hypertriglyceridemia and increased oxidation of low-density lipoprotein cholesterol) and platelet activation leading to a prothrombotic state. Smoking increases emerging risk factors (eg, fibrinogen, homocysteine, and high-sensitivity C-reactive protein) and increases insulin resistance and the risk of developing type 2 diabetes mellitus. The beneficial effects of statins and antioxidants (eg, vitamins C and E, beta-carotene) are counteracted by smoking. Smoking-induced alterations in growth factors, adhesion molecules, and even in genes can accelerate the progression of atherosclerosis. The aim of this review is to consider the adverse consequences of smoking on the factors predisposing to vascular disease and to emphasize the beneficial effects of smoking cessation.

Multiple modifiable risk factors for first ischemic stroke: a population-based epidemiological study

The aims of this epidemiological population-based cohort study were to examine the prevalence of the multiple modifiable vascular risk factors, their distribution patterns and outcomes among a Bulgarian urban population. A total of 500 volunteers, 200 men and 300 women, without clinical signs and symptoms of cerebrovascular disease, aged 50-79 years, were enrolled in the study. A structured questionnaire, physical examination, electrocardiogram records, a battery of laboratory tests and carotid duplex scanning were employed. Three or more modifiable vascular risk factors were detected in 52% (260/500) of the subjects. Dyslipidemias, hypertension, obesity, cigarette smoking and cardiac diseases were found to be the most prevalent single risk factors. Asymptomatic carotid stenosis (ACS) of 50% or greater was detected in 8.8% (23/260) of the volunteers examined. After a 2-year follow-up, 2.7% (7/260) of the persons with modifiable vascular risk factors reached the end point transient ischemic attacks (TIAs), ischemic stroke and myocardial infarction. The following combinations of risk factors among the subjects enrolled in the study were significantly associated with these outcomes: hypertension and cardiac diseases (OR = 6.82; 95% CI, 1.21-38.41), cardiac diseases and obesity (OR = 6.13; 95% CI, 1.27-29.72), ACS and high low-density lipoprotein (LDL) cholesterol levels (OR = 11.11; 95% CI, 1.58-78.29). The identification of subjects with multiple vascular risk factors may be important for primary medical or surgical stroke prevention.