Do the facts and figures warrant a 10-fold increase in the performance of carotid endarterectomy on asymptomatic patients?

Surgery of acute occlusion of the extracranial internal carotid artery - a meta-analysis

Acute occlusion of the extracranial internal carotid artery (eICA) is associated with poor prognosis. Surgical desobliteration has not received adequate attention in recent years. We therefore conducted a literature review and meta-analysis of surgical studies published after 2000 that treated eICA occlusion surgically in an emergency setting. The search identified 10 relevant articles that included a total of 175 patients. The outcomes analysed included rates of recanalization (93 %), early neurological improvement (66 %), modified Rankin Scale 0-2 (62 %), mortality (5 %), early reocclusion (4 %), in-hospital stroke (4 %) and symptomatic intracerebral haemorrhage (4 %). In conclusion, acute surgical desobliteration of eICA occlusion leads to high rates of recanalization and a majority of patients experience early neurological improvement and achieve favourable outcome. Rates of mortality, early reocclusion, in-hospital stroke and sICH are acceptable in the view of unfavourable natural history.

Three-Dimensional Echographic Evaluation of Carotid Artery Disease

The introduction of three-dimensional echography (3D echo) in vascular field is not recent, but it still remains a seldom-used technique because of the costs of ultrasound probe and the need of dedicated laboratories. Therefore, despite significant prognostic implications, the high diagnostic accuracy in plaque definition, and the relative ease of use, 3D echo in vascular field is a niche technique. The purpose of this review is mainly clinical and intends to demonstrate the potential strength of a 3D approach, including technical aspects, in order to present to clinicians and imagers the appealing aspects of a noninvasive and radiation-free methodology with relevant diagnostic and prognostic correlates in the assessment of carotid atherosclerosis. A comprehensive literature search (since 1990s to date) using the PubMed, MEDLINE, and Cochrane libraries databases has been conducted. Articles written in English have been assessed, including reviews, clinical trials, meta-analyses, and interventional/observational studies. Manual cross-referencing was also performed, and relevant references from selected articles were reviewed. The search was limited to studies conducted in humans. Search terms, retrieved also with PubMed Advanced search and AND/OR Boolean operators (mainly in title and abstract), included three-dimensional, echo, stroke/transient ischemic attack, predictors, carotid, imaging, and biomarkers.

Association between Asymptomatic Unilateral Internal Carotid Artery Stenosis and Electrophysiological Function of the Retina and Optic Nerve

Purpose. This study was designed to assess retinal and optic nerve bioelectrical function in patients with unilateral asymptomatic but hemodynamically significant internal carotid artery stenosis (ICAS). Methods. Forty-two subjects with a diagnosis of unilateral ICAS and 34 controls were analyzed. Full-field electroretinogram (ERG), pattern electroretinogram (PERG), and pattern visual-evoked potentials, as well as optical coherence tomography and ophthalmological examination, were performed. Data analysis included eyes ipsilateral to ICAS (EIS) and eyes contralateral to ICAS (ECS). Results. Intraocular pressure was significantly decreased in EIS and ECS compared to that in the controls. In the macula, both the cube average thickness and cube volume values were significantly reduced both in EIS and ECS compared to those in the controls. Similarly, PERG P50 and N95 wave amplitudes were significantly smaller in EIS and ECS compared to those in the controls. The ERG rod b-wave and rod-cone a-wave amplitudes were decreased, and implicit times were significantly prolonged, whereas the OP wave index was reduced in EIS compared to that in the controls. No differences in IOP, OCT, or ERG and PERG parameters were identified between EIS and ECS. Conclusions. Our study demonstrated that retinal bioelectrical function is negatively affected by ICAS despite the absence of objective clinical signs and symptoms of ocular ischemia.

What Should We Do with Asymptomatic Carotid Stenosis?

The benefit of prophylactic carotid endarterectomy (CEA) for patients with asymptomatic severe carotid stenosis in the major randomised surgical studies was small, expensive and may now be absorbed by improvements in best practice medical intervention. Strategies to identify patients with high stroke risk are needed. If surgical intervention is to be considered the complication rates of individual surgeons should be available. Clinicians will differ in their interpretation of the same published data. Maintaining professional relationships with clinicians from different disciplines often involves compromise. As such, the management of a patient will, in part, depend on what kind of specialist the patient is referred to. The clinician's discussion with patients about this complex issue must be flexible to accommodate differing patient expectations. Ideally, patients prepared to undergo surgical procedures should be monitored in a trial setting or as part of an audited review process to increase our understanding of current practice outcomes.

Physician specialty and variation in carotid revascularization technique selected for Medicare patients

OBJECTIVE

Carotid artery stenting (CAS) has become an alternative to carotid endarterectomy (CEA) for select patients with carotid atherosclerosis. We hypothesized that the choice of CAS vs CEA varies as a function of treating physician specialty, which would result in regional variation in the relative use of these treatment types.

METHODS

We used Medicare claims (2002-2010) to calculate annual rates of CAS and CEA and examined changes by procedure type over time. To assess regional preferences surrounding CAS, we calculated the proportion of revascularizations by CAS, across hospital referral regions, defined according to the Dartmouth Atlas of Healthcare. We then examined relationships between patient factors, physician specialty, and regional use of CAS.

RESULTS

The annual number of all carotid revascularization procedures decreased by 30% from 2002 to 2010 (3.2 to 2.3 per 1000; P = .005). Whereas rates of CEA declined by 35% during these 8 years (3.0 to 1.9 per 1000; P < .001), CAS utilization increased by 5% during the same interval (0.30 to 0.32 per 1000; P = .014). Variation in utilization of carotid revascularization varied across the Unites States, with some regions performing as few as 0.7 carotid procedure per 1000 beneficiaries (Honolulu, Hawaii) and others performing nearly 8 times as many (5.3 per 1000 in Houma, La). Variation in procedure type (CEA vs CAS) was evident as well, as the proportion of carotid revascularization procedures that were constituted by CAS varied from 0% (Casper, Wyo, and Meridian, Miss) to 53% (Bend, Ore). The majority of CAS procedures were performed by cardiologists (49% of all CAS cases), who doubled their rates of CAS during the study period from 0.07 per 1000 in 2002 to 0.15 per 1000 in 2010.

CONCLUSIONS

Variation in rates of carotid revascularization exists. Whereas rates of carotid revascularization have declined by more than 30% in recent years, utilization of CAS has increased. The proportion of all carotid revascularization procedures performed as CAS varies markedly by geographic region, and regions with the highest proportion of cardiologists perform the most CAS procedures. Evidence-based guidelines for carotid revascularization will require a multidisciplinary approach to ensure uniform adoption across specialties that care for patients with carotid artery disease.

Carotid endarterectomy and carotid artery stenting: changing paradigm during 10 years in a high-volume centre

BACKGROUND

We analysed the results of internal carotid artery (ICA) stenosis treatment at our institution over the last 10 years according to treatment modalities (carotid endarterectomy [CEA] vs carotid artery stenting [CAS]). Furthermore, we compared our results of treatment prior to the EVA-3S study being implemented into our practice (2003-2007) and after that (2008-2012).

METHOD

During the years 2003-2012, a total of 1,471 procedures were performed for ICA stenosis. CEA was done in 815 cases and CAS in 656 cases. The primary outcome was disabling stroke (mRS > 2) or myocardial infarction (MI) within 30 days after treatment. Secondary outcomes were frequency of transient ischaemic attacks (TIAs), minor strokes (stroke without impaired activities of daily living [ADL]) and any other significant complication. Comparisons of the results before and after 2008 were performed.

RESULTS

Major mortality and morbidity were divided according to treatment groups; reached 1.0 % in the CEA group and 3.0 % in the CAS group, p = 0.004. Minor stroke was recorded at 1.8 % and 2.7 % in the CEA and CAS, p = 0.245. TIAs in 1.0 % (CEA) and 4.7 % (CAS), p < 0.001. Any complication in 11.9 % (CEA) and 13.3 % (CAS), p = 0.401. In the overall results (i.e. CEA and CAS together), we found in 2008-2012 a decrease of incidence of TIAs (from 30/840 to 9/631, p = 0.011) and any complications (from 120/840 to 64/631, p = 0.017).

CONCLUSIONS

CEA performed in a high-volume centre is a safe procedure in properly indicated patients. In all subgroup analyses, CEA fared better than or at least of equal benefit as CAS. Since 2008, the frequency of TIAs and other complications decreased significantly. This study supports an idea of CEA being the first choice of treatment and CAS being reserved for strictly selected cases, such as re-stenosis after a previous carotid procedure, carotid dissection, ICA stenosis after radiotherapy, previous major neck surgery, contralateral cranial nerve palsy or tandem stenosis.

Acute extracranial occlusion of the internal carotid artery: emergent surgery remains a viable option

BACKGROUND

Acute symptomatic occlusion of extracranial internal carotid artery (eICA) can lead to a critical and potentially devastating stroke associated with high morbidity and mortality. Optimal treatment remains unclear. We analyzed our institutional experience with emergent surgical recanalization of acutely occluded eICA.

METHODS

Retrospective analysis of hospital records, surgical reports, imaging studies and outpatient records. Final outcome was assessed according to modified Rankin Scale (mRS).

RESULTS

Between January 2010 and September 2013, 22 patients underwent emergent surgical recanalization. There were 17 men and five women, mean age 65.4 years (range 37-85). Mean admission National Institute of Health Stroke Scale (NIHSS) was 12 (range 6-21). All patients had evidence of salvageable penumbra on perfusion computed tomography. Tandem intracranial lesion was present in nine patients. Surgical recanalization was successful in 16 patients (72.7 %). Twenty-four hours after surgery, 17 patients (77.2 %) improved by a minimum of 1 point on NIHSS, 14 patients (63.6 %) improved by three and more points; two patients deteriorated by two and five points, the latter treated initially with systemic thrombolysis due to intracranial hemorrhage. No other intracranial hematoma was observed. During 30 days following surgery, two patients died (9 % mortality rate) due to severity of initial stroke. On discharge, four patients were classified as mRS 0, five patients as mRS 1, five patients as mRS 2 and six patients as mRS 4. Favorable recovery (mRS 0-2) was achieved in 14 patients (63.6 %). No change in mRS was observed at three months.

CONCLUSIONS

Our results suggest that emergent surgical desobliteration of occluded eICA can lead to favorable recovery in a majority of patients. Patient selection based on penumbra imaging is crucial. Given the popularity and simplicity of carotid endarterectomy, the procedure should by no means be abandoned in the treatment of acute eICA occlusion.

Effect of carotid artery stenting on ophthalmic artery flow patterns

OBJECTIVES

The purpose of this study was to assess the effect of carotid artery stenting on ophthalmic artery blood flow using transorbital color and spectral Doppler sonography and review the changes in relation to cerebral hemodynamics.

METHODS

Twenty-eight consecutive patients with severe internal carotid artery stenosis (≥ 70%) who were scheduled for carotid stenting were included. Ophthalmic artery Doppler sonography was performed bilaterally before and after stenting. The flow direction, peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistive index in the ophthalmic artery were recorded.

RESULTS

Twenty male and 8 female patients with 10 right-sided and 18 left-sided stenoses were studied. The mean overall carotid stenosis ratio ± SD was 87.3% ± 9.9%. After stenting in the ophthalmic artery ipsilateral to the stenosis, significant increases in the PSV (-3.87 ± 48.81 to 46.70 ± 25.33 cm/s; P < .001), and EDV (-3.02 ± 16.31 to 11.24 ± 7.37 cm/s; P < .001) were detected, and the increase in the PI approached significance (1.40 ± 0.59 to 1.62 ± 0.52; P = .055). A change in the flow direction from retrograde to antegrade was noted in 11 patients (39%) after stenting, and in 1 patient with no detectable flow, reconstitution of flow was observed. Increases in the PSV and EDV (P= .03 for ΔEDV) were more pronounced in symptomatic patients than asymptomatic patients after stenting.

CONCLUSIONS

Substantially decreased ophthalmic artery velocity and retrograde flow are suggestive of high-grade carotid artery stenosis (≳90%). Stenting improves ophthalmic artery perfusion and positively changes cerebral hemodynamics in high-grade carotid artery stenosis, especially in symptomatic patients, which can be monitored with ophthalmic artery Doppler sonography.

Population-based estimates of neuroendovascular procedures: results of a state-wide study

BACKGROUND

The Brain Attack Coalition identified the availability of neuroendovascular procedures as an essential component of a comprehensive stroke center.

OBJECTIVE

To provide population-based estimates of neuroendovascular procedures.

METHODS

State-wide estimates of cervicocerebral angiograms, endovascular ischemic stroke treatments, carotid angioplasty and stent placements, intracranial angioplasty and stent placements, endovascular treatment of intracranial aneurysms, and endovascular treatment of intracranial arteriovenous malformations (AVMs) were obtained. We calculated the annual incidence rates of various neuroendovascular and neurosurgical procedures (per 100,000 persons). For the denominator, total persons in each year were categorized in 10-year age intervals.

RESULTS

The incidence of carotid endarterectomy (387.6 per 100,000 persons) and carotid stent placement (34.7 per 100,000 persons) peaked at 75-84 years. The incidence of aneurysm embolization also peaked in that population bracket (67.9 per 100,000 persons), yet there was a dramatic reduction in the incidence of surgical aneurysm treatment (3.6 per 100,000 persons) in those aged 75-84 years. There was a prominent reduction in the incidence of all procedures in the population aged ≥85 years, except for intravenous/intra-arterial thrombolytic use in ischemic stroke. The incidence of ischemic stroke increased almost by 50% in the population aged ≥85 years compared to those aged 75-84 years. However, the incidence of endovascular procedures for acute ischemic stroke decreased from 22.8 per 100,000 persons in the population aged 75-84 years to 13.2 per 100,000 persons in the population aged ≥85 years.

CONCLUSIONS

A marked disproportion of neuroendovascular procedures performed and disease prevalence was noted in persons aged ≥85 years, an increasing segment of the population according to recent Census.

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.

Near/far matching: a study design approach to instrumental variables

Classic instrumental variable techniques involve the use of structural equation modeling or other forms of parameterized modeling. In this paper we use a nonparametric, matching-based instrumental variable methodology that is based on a study design approach. Similar to propensity score matching, though unlike classic instrumental variable approaches, near/far matching is capable of estimating causal effects when the outcome is not continuous. Unlike propensity score matching, though similar to instrumental variable techniques, near/far matching is also capable of estimating causal effects even when unmeasured covariates produce selection bias. We illustrate near/far matching by using Medicare data to compare the effectiveness of carotid arterial stents with cerebral protection versus carotid endarterectomy for the treatment of carotid stenosis.

Growth of carotid artery duplex ultrasound among Medicare beneficiaries (2000-2007)

OBJECTIVE

Although intervention in asymptomatic carotid artery stenosis remains controversial, most carotid interventions are performed in asymptomatic individuals. Carotid duplex ultrasound is the diagnostic test that precedes more than 90% of carotid interventions. In terms of economic incentives, providers who perform carotid artery revascularization may experience synergy if they also provide carotid duplex ultrasound, because the diagnostic service is reimbursed and also can lead to referrals for revascularization procedures. To test the hypothesis that providers of revascularization services are incentivized to increase utilization of carotid duplex ultrasound, we compared the utilization of carotid duplex ultrasound among Medicare beneficiaries by three specialties that perform revascularization for carotid stenosis (interventional radiology, vascular surgery, and cardiology) with one that usually does not (diagnostic radiology).

MATERIALS AND METHODS

We analyzed 100% of procedure-specific claims submitted to Medicare by the four specialties during 2000, 2002, 2004, 2005, 2006, and 2007. Only professional and global components of services approved by Medicare were included. Compounded annual growth rates were used to compare utilization by different specialties.

RESULTS

Utilization by diagnostic radiology increased at a compound annual growth rate of 1% during 2000-2007. Interventional radiology and vascular surgery experienced higher compound annual growth rates of 3% and 6%, respectively. Utilization by cardiology increased at a rate 11 times that of diagnostic radiology, translating into an additional 960 procedures per 100,000 Medicare beneficiaries by cardiology in 2007 than in 2000.

CONCLUSION

Medicare beneficiaries are increasingly being tested for carotid artery stenosis, especially by specialties that perform revascularization for carotid stenosis. The health benefits of this practice are uncertain.

Asymptomatic carotid artery stenosis--medical therapy alone versus medical therapy plus carotid endarterectomy or stenting

Vascular surgery has matured to the point that there exists robust bodies of literature exploring many of our therapies. However, this evidence is but one of the factors that dictate medical practice. Others include local patient demographics, the practical implications of healthcare delivery, and an individual surgeon's interpretation of this evidence, which can be somewhat subjective. As a result, there are numerous examples of vascular specialists' practice patterns differing depending on their geographic location. Recognizing this, the Editors of the Journal of Vascular Surgery and the European Journal of Vascular and Endovascular Surgery have developed a series of Trans-Atlantic Debates to explore these instances. The inaugural debate explores the controversial question of how best to manage asymptomatic carotid artery stenoses. Our debators, Peter Schneider and Ross Naylor, offer reasoned and passionate arguments to defend their differing approaches. We trust that this addition to our journals will prove enlightening and, perhaps, entertaining.

Optimisation of a high-resolution whole-body MR angiography protocol with parallel imaging and biphasic administration of a single bolus of Gd-BOPTA: preliminary experience in the systemic evaluation of atherosclerotic burden in patients referred for endovascular procedures

PURPOSE

This study was performed to validate a high-resolution whole-body magnetic resonance angiography (MRA) protocol with parallel imaging and biphasic administration of a single bolus of contrast agent in the preliminary assessment of systemic atherosclerotic burden in patients referred for endovascular procedures.

MATERIALS AND METHODS

Forty patients referred for endovascular treatment of atherosclerotic disease of the carotid arteries (n=23), peripheral vessels (n=14) or aorta (n=3) on the basis of previous clinical and diagnostic examinations underwent high-resolution whole-body MRA at 1.5 T with 3D spoiled gradient recalled echo (GRE) sequences, featuring parallel imaging acquisition technique with x2 acceleration factor. Sixty-eight surface coil elements and a four-station imaging protocol were employed. Biphasic intravenous administration of a paramagnetic contrast agent [gadolinium benzyloxyproprionic-tetraacetic acid (Gd-BOPTA)] was performed with the following protocol: 10 ml at a speed of 1 ml/s followed by further 10 ml at a speed of 0.5 ml/s. For image analysis, the arterial system was divided into 42 segments for evaluation. The presence or absence of atherosclerotic lesions was evaluated by two observers in consensus; segments were classified as having clinically significant disease (>or=50% stenosis or an aneurysmal dilatation) or no significant disease (<50% stenosis). The presence of stenoocclusive disease, determined at all segments, was compared with findings on digital subtraction angiography (DSA), which were interpreted by a third independent reader. Sensitivity, specificity and concordance of whole-body MRA findings with DSA were calculated, and receiver operating characteristic (ROC) analysis was performed for all vascular territories.

RESULTS

A total of 1,680 arterial segments was evaluated; 138 (8.3%) were affected by atherosclerotic alterations. Carotid lesions were confirmed in 23 patients (34 segments), involvement of peripheral vessels in 14 (57 segments) and abdominal aneurysms in three. Sensitivity and specificity of whole-body MRA were, respectively, 95%-97% for head and neck vessels, 100%-100% for thoracoabdominal vessels, 98%-97% for thigh vessels and 84%-88% for calf vessels; concordance with the DSA findings was significant (p<0.05). Subclinical atherosclerotic lesions were evidenced in 25 patients, involving carotid arteries (12 segments), peripheral vessels (21 segments) and abdominal aorta (one segment). All these lesions were confirmed by a second modality, and ten of these patients required further care.

CONCLUSIONS

High-resolution whole-body MRA with Gd-BOPTA may be considered a reliable modality for imaging systemic atherosclerosis in candidates for endovascular procedures. The subclinical detection of the total atherosclerotic burden has potential implications for secondary care in this population.

Validation of two different grading schemes to identify patients with asymptomatic carotid artery stenosis in general population

BACKGROUND

Identification of significant asymptomatic carotid artery stenosis (ACAS) is important because of potential stroke-risk reduction offered by carotid endarterectomy. We present an external validation of two previously developed scoring schemes designed to identify patients with ACAS.

METHODS

We used the data from the Cardiovascular Health Study (CHS)-a cohort study of cardiovascular risk factors, for external validation. Carotid Doppler ultrasound was performed in study participants. Two grading schemes, which used age more than 65 years, current smoking, and history of coronary artery disease and hyperlipidemia as predictors for ACAS, were validated using this dataset.

RESULTS

A total of 5,449 persons (mean age 72 +/- 5 years; 42% men; and 84% white) were screened. The overall prevalence of ACAS of > or =50% was 4.2%. The prevalence of ACAS in the highest risk category was 19% in both stratification schemes. The stratification remained effective in the white sub-population (P < .001), but was not significant in the African American population (P > .05).

CONCLUSION

Both schemes were effective in identifying persons with ACAS among general population aged 65 years or greater. A subset with a prevalence of ACAS of greater than 20% can be identified using these schemes making screening cost-effective among white population.

Extracranial stenosis: endovascular treatment

Stroke is the third-leading cause of death in the United States. It occurs in almost 700,000 people per year and cost an estimated US dollars 57.9 billion in 2006. Atherosclerotic disease is the cause of one third of these strokes, with more than one half of these stenoses being extracranial in location. Carotid stenoses are usually unifocal and 90% occur within 2 cm of the carotid bulb. Currently, carotid endarterectomy accounts for 117,000 surgical revascularizations per year, whereas carotid angioplasty and stenting are performed less than 10,000 times annually. Stenoses amenable to revascularization are the topic of this article.

Guidelines for Screening of Extracranial Carotid Artery Disease: A Statement for Healthcare Professionals from the Multidisciplinary Practice Guidelines Committee of the American Society of Neuroimaging; Cosponsored by the Society of Vascular and Interventional Neurology

The aim of this new statement is to provide comprehensive and timely evidence-based recommendations on the screening for asymptomatic carotid artery stenosis in the general population and selected subsets of patients. Recommendations are included for high-risk persons in the general population; patients undergoing open heart surgery including coronary artery bypass surgery; patients with peripheral vascular diseases, abdominal aortic aneurysms, and renal artery stenosis; patients after radiotherapy for head and neck malignancies; patients following carotid endarterectomy, or carotid artery stent placement; patients with retinal ischemic syndromes; patients with syncope, dizziness, vertigo or tinnitus; and patients with a family history of vascular diseases and hyperhomocysteinemia. The recommendations are based on prevalence of disease, anticipated benefit, and concurrent guidelines from other professional organizations in selected populations.

Contrast-Enhanced 3-D MRA in Decision Making for Carotid Endarterectomy: A 6-Year Experience

BACKGROUND

Systematic need for angiography in diagnosis of carotid artery stenosis and indication of surgical therapy is still debated. Noninvasive imaging techniques such as MR angiography (MRA) or CT angiography (CTA) offer an alternative to digital subtraction angiography (DSA) and are increasingly used in clinical practice. In this study, we present the radiological characteristics and clinical results of a series of patients operated on the basis of combined ultrasonography (US)/MRA.

METHODS

This observational study included all the patients consecutively operated for a carotid stenosis in our Department from October 1998 to December 2004. The applied MRA protocol had previously been established in a large correlation study with DSA. DSA was used only in case of discordance between US and MRA. The preoperative radiological information furnished by MRA was compared with intraoperative findings. The outcome of the operation was assessed according to ECST criteria.

RESULTS

Among 327 patients, preoperative MRA was performed in 278 (85%), DSA in 44 (13.5%) and CT angiography in 5 (1.5%). Most of DSA studies were performed as emergency for preparation of endovascular therapy or for reasons other than carotid stenosis. Eleven additional DSA (3.3%) complemented US/MRA, mostly because diverging diagnosis of subocclusion of ICA. No direct morbidity or intraoperative difficulty was related to preoperative MRA. Combined mortality/major morbidity rate was 0.9% (3 patients) and minor morbidity rate 5.5% (18 patients).

CONCLUSIONS

This observational study describes a well-established practice of carotid surgery and supports the exclusive use of non invasive diagnostic imaging for indicating and deciding the operation.

Carotid endarterectomy for asymptomatic carotid stenosis

BACKGROUND

Carotid endarterectomy (CEA) is of proven benefit in recently-symptomatic patients with severe carotid stenosis. Its role in asymptomatic stenosis is still debated. The Asymptomatic Carotid Surgery Trial (ACST) more than doubled the number of patients randomised to CEA trials. This revised review incorporates the recently published ACST results.

OBJECTIVES

Our objective was to determine the effects of CEA for patients with asymptomatic carotid stenosis.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (searched May 2004), MEDLINE (1966 to May 2004), EMBASE (1980 to June 2004), Current Contents (1995 to January 1997), and reference lists of relevant articles. We contacted researchers in the field to identify additional published and unpublished studies.

SELECTION CRITERIA

All completed randomised trials comparing CEA to medical treatment in patients with asymptomatic carotid stenosis.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data and assessed trial quality. Attempts were made to contact investigators to obtain missing information.

MAIN RESULTS

Three trials with a total of 5223 patients were included. In these trials, the overall net excess of operation-related perioperative stroke or death was 2.9%. For the primary outcome of perioperative stroke or death or any subsequent stroke, patients undergoing CEA fared better than those treated medically (relative risk (RR) 0.69, 95% confidence interval (CI) 0.57 to 0.83). Similarly, for the outcome of perioperative stroke or death or subsequent ipsilateral stroke, there was benefit for the surgical group (RR 0.71, 95% CI 0.55 to 0.90). For the outcome of any stroke or death, there was a non-significant trend towards fewer events in the surgical group (RR 0.92, 95% CI 0.83 to 1.02). Subgroup analyses were performed for the outcome of perioperative stroke or death or subsequent carotid stroke. CEA appeared more beneficial in men than in women and more beneficial in younger patients than in older patients although the data for age effect were inconclusive. There was no statistically significant difference between the treatment effect estimates in patients with different grades of stenosis but the data were insufficient.

AUTHORS' CONCLUSIONS

Despite about a 3% perioperative stroke or death rate, CEA for asymptomatic carotid stenosis reduces the risk of ipsilateral stroke, and any stroke, by approximately 30% over three years. However, the absolute risk reduction is small (approximately 1% per annum over the first few years of follow up in the two largest and most recent trials) but it could be higher with longer follow up.

Total-body 3D magnetic resonance angiography influences the management of patients with peripheral arterial occlusive disease

High-resolution total-body 3D MR angiography (MRA) has recently become available, revealing additional clinically relevant disease in patients with peripheral arterial occlusive disease (PAOD). However, the actual impact of total-body MRA on patient management in patients with PAOD has not been investigated so far. Two hundred forty-nine consecutive patients with angiographically proven PAOD were prospectively examined by means of contrast-enhanced total-body 3D MRA on a 1.5-T MR scanner. All correlative imaging studies performed within 60 days of total-body MRA were included in the efficacy analysis. Additional clinically relevant disease (luminal narrowing >50%, aneurysmal changes or dissections) was found in 73 segments (52 patients), including the renal arteries (36 segments), carotid arteries (28 segments), subclavian arteries (four segments) and abdominal aortic aneurysms (AAA) (five segments). Of the 73 segments, 36 were deemed necessary for further investigation by means of focused MRA examinations; the diagnosis was confirmed in all cases. Within the 60-day follow-up period, interventional or surgical therapy outside the peripheral arterial tree was performed in nine patients (11 segments), including carotid endatherectomy and renal artery angioplasty. The outlined total-body 3D MRA approach permits a comprehensive evaluation of the arterial system in patients with atherosclerosis and does indeed have an impact on patient management in patients with PAOD.

Comparison of ultrasonography, CT angiography, and digital subtraction angiography in severe carotid stenoses

Digital subtraction angiography (DSA) is considered to be the 'gold standard' for confirmation of severe (70-99%) stenoses of internal carotid arteries (ICAs). However, it is associated with a risk of complications. The aim of this study was to assess the accuracy of ultrasonography (US), computed tomographic angiography (CTA), and their combined use for the detection and quantification of severe carotid stenoses, when compared with DSA. Severe ICA stenoses were diagnosed by US in a set of 29 patients. All patients also underwent CTA and DSA. Sensitivity, specificity, positive (PPV), negative predictive values (NPV), and Pearson's correlation coefficient were used in the evaluation of the percentage of stenosis results. Homogeneity chi2 test was applied when assessing statistical significance. Severe stenosis was diagnosed in 34 ICAs. Two ICAs with uninterpretable CTA finding were excluded. The number of ICAs with stenoses 70-99%/<70%- US 32/0; CTA 29/3; US + CTA 29/3; DSA 24/8. Pearson's correlation coefficient - US 0.601; CTA 0.725; US + CTA 0.773. Sensitivity/specificity/PPV/NPV - US 1.0/0.75/0.75/xxx; CTA 1.0/0.844/0.828/1.0; US + CTA 1.0/0.844/0.828/1.0. Homogeneity chi2 test results - US, P = 0.002; CTA, P = 0.098; US + CTAG, P = 0.098. US in combination with CTA can be used for relatively secure diagnostics of severe ICA stenoses. Thus, invasive DSA can be avoided in a substantial number of patients.

Carotid artery surgery vs. stent: A cardiovascular perspective

Stroke is a major health catastrophe that is responsible for the third most common cause of death and the leading cause of disability. Carotid artery stenosis is an important cause of brain infarctions and the risk of stroke is directly related to the severity of carotid artery stenosis and to the presence of symptoms. Familiarity with different methods of measuring degrees of carotid artery stenosis is a key in understanding the role of revascularization of this disorder. Carotid endarterectomy (CEA), surgical removal of the carotid atherosclerotic plaque, is intended to prevent stroke in patients with carotid artery stenosis and currently the most commonly performed vascular procedure in the United States. Several randomized clinical trials had demonstrated the benefits of CEA in selected groups of patients with symptomatic and asymptomatic carotid artery stenosis. However, CEA can cause stroke, the very thing it intended to prevent, and is associated with significant perioperative complications such as those related to general anesthesia, cardiac or nerve injury. Moreover, several anatomical and medical conditions may limit candidates for CEA. Carotid artery stenting (CS) is an evolving and less invasive technique for carotid artery revascularization. Recent studies demonstrated that CS with embolic protection devices has become an alternative to CEA for high-surgical-risk patients and the procedure of choice for stenoses inaccessible by surgery. The role of CS in low risk patients awaits the completion of several ongoing studies.

Evaluation of Quality Improvement Interventions for Reducing Adverse Outcomes of Carotid Endarterectomy

BACKGROUND

Clinical and health services interventions should be evaluated for their effectiveness.

OBJECTIVES

The objectives of this study were to evaluate the effectiveness of quality improvement interventions for reducing the adverse outcome of the carotid endarterectomy (CEA) procedure, and to study the relationship between pre- and postintervention 30-day mortality and stroke rates. These interventions were implemented in 1997-1998 by the Peer Review Organizations (PRO) for 7 states.

RESEARCH DESIGN

In a quasiexperimental study, a control state was matched with each of the 7 intervention states. Pretest-posttest analyses compared the preintervention outcome rates in each intervention and control state with the corresponding postintervention rates. In a time (1991-2001) series analysis, the trends in the preintervention 30-day, 7-state mortality in intervention and control states were compared with the trends in the corresponding postintervention rates.

STUDY POPULATION

We studied Medicare beneficiaries aged 65 years and older who had a CEA procedure in 14 states during 1991-2001.

RESULTS

There was no correlation between the state-specific, preintervention 30-day mortality and the corresponding postintervention mortality. After interventions, there was no significant decline in 30-day mortality in any intervention or control state, or in all 7 intervention states combined or all control states combined. Similarly, the 30-day stroke rate did not decrease after interventions in any state. The trend in the 7-state, 30-day mortality also did not show further decline after interventions.

CONCLUSION

After PRO interventions, the post-CEA 30-day mortality and stroke rates did not decrease in any individual intervention state or in all states combined.

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.

The Asymptomatic Carotid Surgery Trial: bigger study, better evidence

Surgery works for asymptomatic disease

Variation and changes in state-specific carotid endarterectomy and 30-day mortality rates, United States, 1991-2000

OBJECTIVES

The objectives of this study were to investigate variations between states and changes in state-specific carotid endarterectomy (CEA) and 30-day mortality rates. Cross-sectional variations and changes over time in such measures may be indicative of improvement in the quality of care.

METHODS

We performed retrospective analyses of pre-existing administrative data on Medicare beneficiaries aged 65 years and older in the United States. Age-adjusted, state-specific CEA rates and 30-day postoperative mortality rates in 1991, 1995 and 2000 were examined, as well as changes in these rates from 1991 to 1995 and from 1995 to 2000. Stroke mortality in the general population of each state was used as a crude measure of the need for CEA procedure in the state. The Spearman rank correlation analysis was used to study correlations between rates. Oldham's method was used to avoid the effect of regression to the mean.

RESULTS

There were wide variations in the state-specific CEA rates, 30-day mortality, and in changes in these rates over time. The states with relatively low procedure rates in 1991 also had low rates in 1995 and 2000, and relatively higher increases in the rates. The states with relatively high 30-day mortality in 1991 or 1995 had lower increases or greater decreases in the rate. CEA rates were not correlated with any measure of surgical mortality, but they were correlated with stroke mortality in the general population.

CONCLUSIONS

The inter-state variation in CEA rates has not changed much since 1991, but variation in 30-day mortality decreased through 2000. The states with low procedure rates in 1991 did not have sufficient increase to catch up with the high-rate states by 1995, but they were prone to experience a higher increase in the subsequent 5 years. The validity of stroke mortality in a state as a measure of the need for CEA is questionable. Further research using clinical data is needed to better explain variations between states.

Detection of atherosclerosis: systemic imaging for systemic disease with whole-body three-dimensional MR angiography--initial experience

In 100 consecutive patients with peripheral vascular disease whole-body three-dimensional magnetic resonance (MR) angiography was performed by using the rolling table platform system with a 1.5-T MR unit and five three-dimensional MR angiographic data sets during 72 seconds (0.2 mol per kilogram of body weight of gadobenate dimeglumine). Apart from the proved peripheral vascular disease, additional clinically relevant disease was found in 33 segments in 25 patients as follows: renal arterial narrowing (n = 15), carotid arterial stenosis (n = 12), subclavian arterial stenosis (n = 2), and abdominal aortic aneurysms (n = 4). Confirmatory studies performed in 11 patients in this study revealed no false-positive or false-negative findings at examination.

Patient selection for carotid endarterectomy: how far is risk modeling applicable to the individual?

BACKGROUND AND PURPOSE

Risk-factor modeling has been proposed to identify patients with carotid stenosis who will most benefit from surgery. Validation by independent institutions performing carotid endarterectomy is necessary to determine the applicability of such models to the individual patient.

METHODS

A series of patients with a recently symptomatic high-grade carotid stenosis were selected for surgery according to current guidelines and were consecutively operated on in a single institution. In addition, a prognostic model was applied to the patients to analyze the concordance of both selection methods.

RESULTS

The study included 134 patients operated on between 1999 and 2001. The risk model predicted that 49% of the patients should have been excluded from surgery because the operation was found to be possibly harmful in 1 patient (1%) and not significantly beneficial in 65 patients (48%). This resulted from the predominant negative weight of the surgical risk factors in the model. However, this predominance was negated in our series by the fact that only 1 major complication (0.75%) occurred during follow-up.

CONCLUSIONS

Exclusion of single patients on the basis of risk modeling may be problematic when the rate of perioperative complications is very low.

Carotid endarterectomy and race: do clinical indications and patient preferences account for differences?

BACKGROUND AND PURPOSE

Carotid endarterectomy (CE) has been proved to reduce the risk of stroke for certain patients, but black patients are less likely than whites to receive CE. The purpose of this work was to determine the importance of clinical indications and patient preferences in predicting the use of carotid angiography and CE in a racially stratified sample of patients.

METHODS

Between 1997 and 1999, 708 patients with at least 1 carotid artery containing a >/=50% stenosis were enrolled (617 whites, 91 blacks) from 5 Veteran Affairs Medical Centers. Patient interviews were conducted at the time of the index carotid ultrasound, and each patient was followed up for 6 months to determine clinical events and receipt of carotid angiography or CE.

RESULTS

Black and white patients were similar in terms of age, sex, education level, and social support. More black than white patients received ultrasound for a completed stroke (36% versus 13%), and fewer black patients were classified as asymptomatic (56% versus 70%) or as having had a TIA (8% versus 17%; P<0.001). Health-related quality of life scores, trust in physician, and medical comorbidity scores were similar for black and white patients. Black patients expressed higher aversion to CE than white patients (31% versus 15% in the highest aversion quartile for blacks and whites, respectively; P=0.01). During follow-up, 20% of white patients and 14% of black patients received CE (P=0.19). In adjusted analyses, only patient clinical status as it relates to the indication for CE and site were associated with receipt of CE.

CONCLUSIONS

Contrary to prior research, patient's race was not associated with receipt of invasive carotid imaging or CE for older male veterans. These findings persist after controlling for patient preferences, comorbid illness, and quality of life. For patients enrolled in an equal-access health care system, clinical status was the primary determinant of the receipt of CE.

Auditing carotid endarterectomy: a regional experience

BACKGROUND

Proof from randomized controlled trials that carotid endarterectomy (CEA) is efficacious in stroke prevention has resulted in a large resurgence of its use in recent years. We wished to determine if patients in our region were being selected and treated with complication rates consistent with the randomized trials.

METHODS

We have completed four audits of CEAs performed in our region since 1994, each followed by feed-back of results to the participating surgeons. Operations for > 70% symptomatic stenosis were considered appropriate, those for 50%-69% symptomatic and > 60% asymptomatic stenosis were considered uncertain and all others, including those in medically or neurologically unstable patients, were designated inappropriate. In part 4, the referral source and nature of the patients was also determined.

RESULTS

Part 1 (April 1994-September 1995) found that of 291 CEAs performed 33% were appropriate, 48% were uncertain and 18% were inappropriate, and 40% of patients who underwent CEA were asymptomatic. In part 2 (September 1996-September 1997) appropriate indications significantly improved to 49% of 184 CEAs (P=0.005), uncertain indications remained nearly the same at 47%, inappropriate indications fell to 4% (P=.00002), and asymptomatic patients remained at 40%. The results of part 3 (October 1997-October 1998) remained nearly the same as part 2 (249 CEAs, 47% appropriate, 51% uncertain, 2% inappropriate, 45% asymptomatic). Part 4 (October 1999-October 2000) results were significantly better than part 3, appropriate indications increasing from 47% to 58% of 222 CEAs (P=0.02), and an elimination of inappropriate operations (P=0.03). Stroke and death complications declined over the study period from an overall rate of 5.2% in part 1 to 2.3% in part 4. In part 4 the majority of patients (69%) were referred to surgeons directly from general practitioners, including 58 (73%) of the 80 asymptomatic patients who underwent CEA.

INTERPRETATION

Regular auditing and feedback of results and information to surgeons has resulted in significant and continued improvements in the surgical performance of CEA in our region. Since the majority of patients are referred directly to surgeons by general practitioners, it is important that this group of physicians be familiar with current CEA guidelines.

Provincial carotid endarterectomy outcomes

BACKGROUND

Outcomes must be measured as a first step toward improving performance. We sought to measure the national and provincial outcomes from carotid endarterectomy (CE) and explain provincial differences.

METHODS

We analyzed a large Canada-wide administrative hospital discharge database of all patients, except those in Quebec, receiving CE in 1994-1997 and used logistic regression for risk adjustment to measure adverse outcomes nationally and by province. Our main outcome measures were in-hospital stroke and/or death.

RESULTS

A total of 14,268 patients underwent CE in the years 1994-1997. The overall death rate was 1.3% and the combined stroke and/or death rate was 4.1%. There was a trend towards improvement over the four years. The provinces of Saskatchewan and Newfoundland had significantly higher adverse event rates for the risk-adjusted combined outcome measure.

CONCLUSIONS

The outcome of CE in Canada is good and showed improvement over four years. However, significant differences in provincial outcomes were found. This suggests that regionalization across provincial boundaries may be needed to promote higher surgeon and hospital case volumes and thus improve outcomes.

Ophthalmic artery flow direction on color flow duplex imaging is highly specific for severe carotid stenosis

BACKGROUND/PURPOSE

Collateral flow patterns are important risk factors for brain ischemia in the presence of internal carotid artery (ICA) stenosis or occlusion. Ophthalmic artery (OA) flow reversal, routinely studied by transcranial Doppler sonography, is an important marker for high-grade ICA stenosis or occlusion. The authors sought to define the value of assessing OA flow direction with color flow duplex ultrasonography (CDUS) in the setting of significant ICA disease.

METHODS

Of all patients having routine carotid ultrasound in the neurosonology laboratory between July 1995 and November 2000, 152 had both carotid and orbital (OA flow direction by reduced power orbital CDUS) examinations as well as angiographic confirmation of stenosis to which North American Symptomatic Carotid Endarterectomy Trial criteria could be applied. Degree of angiographic stenosis in these 152 patients (304 arteries) was correlated with OA flow direction.

RESULTS

Of 304 arteries, 101 had greater than 80% stenosis by angiogram. In 56 of these 101 arteries with high-grade stenosis or occlusion, the ipsilateral OA was reversed; however, OA flow direction was never reversed ipsilateral to arteries with less than 80% stenosis (sensitivity 55%, specificity 100%, negative predictive value 82%, and positive predictive value 100% for OA flow reversal as a marker of high-grade carotid lesions).

DISCUSSION/CONCLUSIONS

OA flow direction is easily studied with CDUS. Reversed OA flow direction is highly specific (100%) for severe ipsilateral ICA stenosis or occlusion, with excellent positive predictive value, moderate negative predictive value, and limited sensitivity. OA flow reversal is not only quite specific for severe ICA disease, which may be helpful if the carotid CDUS is difficult or inadequate, but may also provide additional hemodynamic insights (i.e., the inadequacy of other collateral channels such as the anterior communicating artery). OA evaluation can provide important hemodynamic information and should be included as part of carotid CDUS if there is any evidence of ICA stenosis or occlusion.