North American Symptomatic Carotid Endarterectomy Research Articles

Simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis

Objectives: To evaluate a simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis for screening purposes.Material and methods: A total of 9,493 carotid arteries in 4,748 persons underwent carotid ultrasound examination. Most subjects were 65-year-old men attending screening for abdominal aortic aneurysm. The presence of a stenosis on B-mode and/or a mosaic pattern in post-stenotic areas on colour Doppler and maximum peak systolic velocity (PSV) in the internal carotid artery (ICA) were recorded. A carotid stenosis was defined as The North American Symptomatic Carotid Endarterectomy Trial (NASCET) >20% and a significant stenosis as NASCET >50%. The kappa (κ) statistic was used to assess agreement between methods. Sensitivity, specificity, positive predictive (PPV), and negative predictive (NPV) values were calculated for the greyscale/mosaic method compared to conventional assessment by means of PSV measurement.Results: An ICA stenosis was found in 121 (1.3%) arteries; 82 (0.9%) were graded 20%–49%, 16 (0.2%) were 50%–69%, and 23 (0.2%) were 70%–99%. Eighteen (0.2%) arteries were occluded. Overall, the greyscale/mosaic protocol showed a moderate agreement with ICA PSV measurements for the detection of carotid artery stenosis, κ = 0.455. The sensitivity, specificity, PPV, and NPV for detection of >20% ICA stenosis were 91% (95% CI 0.84–0.95), 97% (0.97–0.98), 31% (0.26–0.36), and 97% (0.97–0.97), respectively. The corresponding figures for >50% stenosis were 90% (0.83–0.95), 97% (0.97–0.98), 11% (0.08–0.15), and 100% (0.99–1.00).Conclusion: Compared with PSV measurements, the simplified greyscale/mosaic protocol had a high negative predictive value for detection of >50% carotid stenosis, suggesting that it may be suitable as a screening method to exclude significant disease.

Extracranial Vertebral Artery Atherosclerotic Disease in Patients with Symptomatic Stenosis of the Internal Carotid Artery. The North American Symptomatic Carotid Endarterectomy Trial (P6.065)

Extracranial Vertebral Artery Atherosclerotic Disease in Patients with Symptomatic Stenosis of the Internal Carotid Artery. The North American Symptomatic Carotid Endarterectomy Trial (P6.065)

Circle of Willis Collateral During Temporary Internal Carotid Artery Occlusion II: Observations From Computed Tomography Angiography.

The Circle of Willis (CoW) is the most effective collateral circulation to the brain during internal carotid artery (ICA) occlusion. Carotid stump pressure (CSP) is an established surrogate measure of the cerebral collateral circulation. This study aims to use hemodynamic and computed tomography angiography measurements to determine the strongest influences upon the dependent variable, CSP. These findings could help clinicians noninvasively assess the adequacy of the collateral circulation and facilitate surgical risk assessment in an outpatient setting. CSP and mean arterial pressure were measured during carotid endarterectomy or during carotid balloon test occlusion in 92 patients. Intracranial arterial diameters were measured on computed tomography angiography at 16 different locations. Univariate and multivariate analyses were used to determine the key factors associated with CSP. In a subgroup of individuals (n=27) with severe (>70% North American Symptomatic Carotid Endarterectomy Trial) contralateral stenosis or occlusion, the same analysis was performed. The contralateral anterior cerebral artery proximal to anterior communicating artery (A1) of the CoW had the strongest influence upon CSP, followed by the mean arterial pressure, the contralateral ICA diameter, and the anterior communicating artery diameter (R 2=0.364). In the subgroup with high-grade contralateral ICA stenosis, the ipsilateral posterior communicating artery exerted the strongest influence (R 2=0.620). During ICA occlusion, the anterior CoW dominates in preserving collateral flow, especially the contralateral A1 segment. In individuals with high-grade contralateral carotid stenosis, the posterior communicating artery calibre becomes a dominant influence. The most favourable anatomy consists of large contralateral A1 and anterior communicating arteries, and no contralateral carotid stenosis.

Doppler-Ultrasound and computed tomography correlation for quantification of carotid stenosis

Carotid disease is a major cause of cerebrovascular events. Risk is proportional to the extent and severity of atherosclerosis. Aim of this study was to assess the correlation between 64-multi-detector-row computed-tomography angiography (MDCTA) and Doppler ultrasound peak-systolic-velocity (DUS-PSV) in the quantification of stenosis. 116 consecutive patients were included; it was calculated the degree of carotid stenosis with the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method using MDCTA and DUS-PSV. MDCTA measurements of stenosis ranged from 35% to 95% (mean 67±16%). DUS-PSV ranged from 102 to 600 cm/s (mean 262±112 cm/s). A moderate correlation ( r 2 = 0.427) was found between MDCTA-NASCET stenosis and PSV values. At ROC curve analysis, PSV could significantly discriminate between stenoses ≥70% and 70% stenosis of MDCTA.

Optimal Peak Systolic Velocity Thresholds for Predicting Internal Carotid Artery Stenosis Greater than or Equal to 50%, 60%, 70%, and 80%

We aimed to determine the optimal peak systolic velocity (PSV) thresholds for predicting ≥50%, ≥60%, ≥70%, and ≥80% internal carotid artery (ICA) stenosis. Patients who underwent both carotid ultrasonography and cerebral angiography during hospitalization were consecutively and retrospectively enrolled. The degree of ICA stenosis was calculated using the North American Symptomatic Carotid Endarterectomy Trial method on cerebral angiography. The optimal PSV thresholds for predicting ≥50%, ≥60%, ≥70%, and ≥80% ICA stenosis were determined using receiver operating characteristic curves and the Youden index. A total of 127 ICAs were analyzed. The optimal PSV thresholds for predicting ≥50%, ≥60%, ≥70%, and ≥80% ICA stenosis were 130 cm/s (sensitivity, 95%; specificity, 85%; positive predictive value [PPV], 75%; negative predictive value [NPV], 97%; overall accuracy, 88%), 160 cm/s (sensitivity, 91%; specificity, 94%; PPV, 83%; NPV, 97%; overall accuracy, 93%), 200 cm/s (sensitivity, 96%; specificity, 95%; PPV, 83%; NPV, 99%; overall accuracy, 95%), and 270 cm/s (sensitivity, 89%; specificity, 94%; PPV, 74%; NPV, 98%; overall accuracy, 94%), respectively. The optimal PSV thresholds for predicting ≥50%, ≥60%, ≥70%, and ≥80% ICA stenosis were 130 cm/s, 160 cm/s, 200 cm/s, and 270 cm/s, respectively. All of them had high diagnostic accuracies.

Abstract 100: Extracranial Vertebral Artery Atherosclerotic Disease in Patients With Symptomatic Stenosis of the Internal Carotid Artery. The North American Symptomatic Carotid Endarterectomy Trial

Background and Purpose: The prevalence of atherosclerotic disease of extracranial vertebral artery and associated long-term outcomes in patients with stenosis of the internal carotid artery (ICA) are not well defined. Methods: We ascertained the rates of any stroke, vertebrobasilar stroke, and all-cause mortality over 5 years associated with various categories of extracranial vertebral artery disease based on angiographic severity (<30%, 30-69%, 70-99%, and occlusion) in patients with symptomatic ICA stenosis who participated in the North American Symptomatic Carotid Endarterectomy Trial (NASCET). We also studied the relative benefit of carotid endarterectomy in reduction of ipsilateral stroke in patients with various categories of extracranial vertebral artery disease after adjusting for age, gender, and severity of ICA stenosis. Results: Among the 798 patients who underwent angiographic catheterization of extracranial vertebral artery, the severity of stenosis was categorized as <30% (n=342), 30-69% (n=164), 70-99% (n=70), and occlusion (n=30). Compared with those with stenosis <30%, the relative risk of any stroke was similar between those with 30-69% (relative risk (RR) 1.1, 95% confidence interval [CI] 0.9-1.3 ), 70-99% (RR 0.9, 95% CI 0.7-1.3), and occlusion (RR 1.2, 95% CI 0.8-1.9) after adjustment for age, gender, severity of ICA stenosis, and allocated treatment (endarterectomy versus medical treatment). The relative risk of vertebrobasilar stroke was two folds higher in patients with extracranial vertebral artery stenosis 70-99% compared with those with <30% stenosis (RR 2.1, 95% CI 0.8-5.2) after adjusting for potential confounders. The relative benefit of carotid endarterectomy over medical treatment was similar according to categories of extracranial vertebral artery disease: <30% (RR 0.6, 95% CI 0.3-0.9), 30-69% (RR 0.3, 95% CI 0.2-0.9), 70-99% (RR 0.6, 95% CI 0.2-2.4), and occlusion (RR 0.4, 95% CI 0.07-2.9) Conclusions: The increased risk of vertebrobasilar stroke in patients with symptomatic ICA stenosis who have concurrent extracranial vertebral artery disease supports critical evaluation of additional endovascular treatment options in such patients.

Carotid Endarterectomy Is Safe, Effective, and Durable, but Can We Make It Better?

The first known carotid endarterectomy (CEA) was likely performed by Dr. Michael DeBakey in 1953. Since that time, the operation has gained widespread approval because it not only effectively reduces the rate of ischemic stroke but also has a relatively low rate of complications. Both the North American Symptomatic Carotid Endarterectomy Trial (NASCET) 1 and the Endarterectomy for Asymptomatic Carotid Artery Stenosis (ACAS) trial 2 demonstrated a significant benefit of endarterectomy over medical therapy alone. Both trials showed durable results with reduced rates of stroke at least 5 years after the operation. The article by Rong et al. recently published in WORLD NEUROSURGERY, “Risk Factors Associated with Ipsilateral Ischemic Events Following Carotid Endarterectomy for Carotid Artery Stenosis,” continues to add to the body of literature demonstrating the efficacy, safety, and durability of CEA. In their study cohort of more than 240 patients with a mean follow-up of more than 50 months, the 5-year risk of ischemic symptom recurrence was approximately 10%. When the authors identified risk factors associated with new ipsilateral ischemic events in these patients, they found that cigarette-smoking, family history of stroke, and atrial fibrillation were all associated with a greater risk of new ischemic events after CEA. Interestingly, symptomatic carotid stenosis was not significantly associated with new ischemic events, although there was a trend toward significance. Only one-third of the ischemic events happened within 30 days of the operation.

High-Intensity Signal in Carotid Plaque on Routine 3D-TOF-MRA Is a Risk Factor of Ischemic Stroke

Background: Carotid atherosclerotic disease is recognized as an important risk factor for brain ischemic events. However, high-grade stenosis does not always cause ischemic strokes, whereas moderate-grade stenosis may often cause ischemic strokes. It has been reported that there is an association between carotid intraplaque hemorrhage (IPH) and new cerebral ischemic events. The purpose of this study was to elucidate the relationship between high-intensity signals (HIS) on maximum intensity projection (MIP) images from routine 3-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) and prior ischemic strokes in the patients with moderate carotid stenosis. Materials and Methods: Sixty-one patients with moderate carotid artery stenosis (50-69% stenosis based on North American Symptomatic Carotid Endarterectomy Trial criteria) were included. Carotid IPH was defined as the presence of HIS in carotid plaques on MIP images detected by 3D-TOF-MRA using criteria we previously reported. We analyzed the relationship between the presence of HIS in plaques and prior ischemic strokes defined as ischemic lesions on diffusion-weighted brain images. Results: HIS in carotid plaques were present in 27 (44%) of 61 patients. Prior ipsilateral ischemic strokes occurred more frequently in the HIS-positive group than the HIS-negative group (67 vs. 9%, p < 0.001). Furthermore, there were more smokers in the group with ischemic stroke than without it (62 vs. 25%, p = 0.005). In multivariate logistic regression analysis, HIS in carotid plaque (OR 23.4, 95% CI 4.62-118.3, p < 0.001) and smoking (OR 5.44, 95% CI 1.20-24.6, p = 0.028) were independent determinants of prior ischemic strokes after adjustment for age. Conclusions: HIS in carotid plaques on 3D-TOF-MRA MIP images are independent determinants of prior ischemic strokes in patients with moderate carotid artery stenosis, and they can potentially provide a reliable risk stratification of patients with moderate carotid artery stenosis.

Abstract 13398: Impact of CREST on Carotid Artery Stenting and CEA Utilization in the Dallas/Fort Worth Area

Introduction: Carotid endarterectomy (CEA) is a safe and effective way to reduce the ischemic stroke risk in patients with both symptomatic and asymptomatic carotid stenosis. Following the North American Symptomatic Carotid Endarterectomy Trial and the Asymptomatic Carotid Atherosclerosis Study in the early 1990s, the number of CEAs performed annually surged. An alternative to this procedure is carotid angioplasty and stenting, which was introduced in 1994. In May 2010, the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) compared the overall effectiveness of carotid artery stenting (CAS) versus CEA. CREST is currently considered the definitive study demonstrating the therapeutic equivalence of CEA and CAS. The goal of our study is to compare the incidence of CEA before and after the CREST study in the Dallas-Fort Worth (DFW) area. We hypothesize that the number of CAS procedures has increased since the CREST study. This is the first report to determine the effect of CREST on CAS utilization. Methods: Consecutive cases of intervention for carotid artery stenosis were reviewed before and after CREST using data from the DFW Hospital Council from 7/1/07-7/1/13. The primary endpoint of the study was the number of CEA and CAS performed during Pre-CREST (7/1/07-6/30/10) and Post-CREST (7/1/10-7/1/13). Results: A total of 12021 interventions on patients with carotid stenosis were identified. Pre-CREST there were 4575 CEA and 1060 CAS performed. Post-CREST there were 5250 CEA and 1136 CAS performed. The adjusted p-value comparing the likelihood of undergoing CAS between the two study periods was 0.305. Conclusions: In contrast to previous carotid treatment trials the CREST study has not impacted the utilization CAS in the DFW area. Possible reasons for this include the higher rate of stroke with CAS compared with CEA in CREST, the CMS restrictions on re-imbursement for CAS compared with CEA, limitations in the physician workforce performing CAS, and non-malleable referral patterns that favor the status quo for these two procedures.

Acoustic shadowing impairs accurate characterization of stenosis in carotid ultrasound examinations

Duplex ultrasonography (DUS) has been the mainstay for diagnosing carotid artery stenosis and is often the sole diagnostic modality used prior to intervention. Highly calcified plaque, however, results in an acoustic shadow (AcS) that obscures the vessel lumen and inhibits the sonographer's ability to obtain Doppler velocity measurements. It is unknown whether DUS can accurately determine the degree of carotid stenosis in these settings. From July 2012 to December 2013, all patients with AcS on DUS measuring ≥5mm in the longitudinal axis were cross-referenced with multidetector computed tomographic angiography (MD-CTA) images of the neck to define the study population. After standardizing the MD-CTA windows, percent stenosis was determined by cross-sectional area reduction using two separate previously described methods based on North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) criteria. DUS waveform parameters in the internal carotid artery near the AcS were then compared with these MD-CTA measurements to determine the accuracy of DUS in characterizing the severity of carotid stenosis. During this period, 8517 DUS studies were performed at the Massachusetts General Hospital, 550 of which had AcS, for an incidence of 6.45%. There were 92 lesions with a concomitant MD-CTA; however, seven were excluded because of poor study quality, because ≥6months had elapsed between DUS and MD-CTA, or because the patient had undergone carotid reconstruction between studies. Of the 85 remaining lesions, DUS characterized 17 as severe (peak systolic velocity [PSV] >250cm/s), 31 as moderate (PSV= 151-250cm/s), and 37 as mild (PSV ≤150cm/s) stenoses using PSV criteria. PSV weakly correlated with CTA-NASCET (r= 0.361; P= .004) and CTA-ECST (r= 0.306; P= .004) percent stenosis. Using PSV >250cm/s as the predictor of >70% stenosis, and a ≥70% cutoff by both CTA-ECST and CTA-NASCET methods as the reference measure, DUS sensitivity ranged from 22.7% to 32.5%, specificity from 89.4% to 91.1%, positive predictive value from 88.2% to 76.4%, and negative predictive value from 25% to 60.2%. A subgroup analysis of lesions identified as non-severe by DUS revealed that waveforms with lower deceleration were associated with severe stenosis on CTA. In the presence of AcS, DUS alone is inadequate to accurately determine the degree of carotid stenosis with sensitivity, specificity, and negative predictive values far below that needed for clinical decision-making. MD-CTA may be necessary for improved characterization of plaque in these AcS lesions. Further studies are needed to determine DUS parameters that may identify patients who should undergo further evaluation with MD-CTA to characterize the true severity of the stenosis.

Clinical trials for carotid stenosis revascularization and relation to methods of stenosis quantification

Severe carotid stenosis patients in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) were shown to have a high risk of stroke and significant benefit from carotid endarterectomy. More than 20 years after the 1991 NASCET results for severe stenosis, there is a common claim to use the NASCET method to determine % carotid stenosis, but without following the details necessary to properly identify the group most benefitting from carotid endarterectomy. NASCET interpreted for loss of diameter of the cervical ICA, near occlusion, and didn’t calculate % stenosis if present as it is fallacious. NASCET measured the distal ICA for well beyond the tapering ICA bulb where the ICA walls are parallel. The pitfalls of stenosis quantification and differences between methods are problems of the ratio’s denominator, and may potentially be resolved by the use of absolute measurements for stenosis on CTA or MRA. Furthermore, trials evaluating vessel wall components including intraplaque hemorrhage such as CAIN may add to or replace degree of stenosis for the prediction of cerebrovascular outcomes.

Practicing Evidence-Based Medicine

Today, a plethora of resources for evidence-based medicine (EBM) are available via alert services, compendia, and more. In theory, a clinician researching a topic or looking for information regarding a clinical decision should easily find the literature or synopses needed. However, the real challenge lies in recognizing which resources (out of hundreds or possibly thousands) present the best and most reliable evidence. As well, evidence from research is only part of the decision calculus, and the clinician, not the evidence, makes the final decisions. Medical decision analysis attempts to formalize the process and reduce it to algebra, but it is difficult or impossible to represent all the components of a decision mathematically and validly let alone do so in “real time” for individual patients. This review discusses these challenges and more, including how to ask answerable questions, understand the hierarchy for evidence-based information resources, critically appraise evidence, and apply research results to patient care. Figures show the total number of new articles in Medline from 1965 to 2012, a “4S” hierarchy of preappraised medicine, percentage of physician and medical student respondents with a correct or incorrect answer to a question about calculating the positive predictive value of a hypothetical screening test, a nomogram for Bayes’s rule, an example of nomogram use for pulmonary embolism, and a model for evidence-informed clinical decisions. Tables list selected barriers to the implementation of EBM; Patient, Intervention, Comparison, and Outcome (PICO) framework for formulating clinical questions; guides for assessing medical texts for evidence-based features; clinically useful measures of disease frequency and statistical significance and precision; definitions of clinically useful measures of diagnostic test performance and interpretation; definitions of clinically useful measures of treatment effects from clinical trials; summary of results and derived calculations from the North American Symptomatic Carotid Endarterectomy Trial (NASCET); and selected number needed to treat values for common therapies. This review contains 6 highly rendered figures, 9 tables, and 28 references.

Practicing Evidence-Based Medicine

Today, a plethora of resources for evidence-based medicine (EBM) are available via alert services, compendia, and more. In theory, a clinician researching a topic or looking for information regarding a clinical decision should easily find the literature or synopses needed. However, the real challenge lies in recognizing which resources (out of hundreds or possibly thousands) present the best and most reliable evidence. As well, evidence from research is only part of the decision calculus, and the clinician, not the evidence, makes the final decisions. Medical decision analysis attempts to formalize the process and reduce it to algebra, but it is difficult or impossible to represent all the components of a decision mathematically and validly let alone do so in “real time” for individual patients. This review discusses these challenges and more, including how to ask answerable questions, understand the hierarchy for evidence-based information resources, critically appraise evidence, and apply research results to patient care. Figures show the total number of new articles in Medline from 1965 to 2012, a “4S” hierarchy of preappraised medicine, percentage of physician and medical student respondents with a correct or incorrect answer to a question about calculating the positive predictive value of a hypothetical screening test, a nomogram for Bayes’s rule, an example of nomogram use for pulmonary embolism, and a model for evidence-informed clinical decisions. Tables list selected barriers to the implementation of EBM; Patient, Intervention, Comparison, and Outcome (PICO) framework for formulating clinical questions; guides for assessing medical texts for evidence-based features; clinically useful measures of disease frequency and statistical significance and precision; definitions of clinically useful measures of diagnostic test performance and interpretation; definitions of clinically useful measures of treatment effects from clinical trials; summary of results and derived calculations from the North American Symptomatic Carotid Endarterectomy Trial (NASCET); and selected number needed to treat values for common therapies. This review contains 6 highly rendered figures, 9 tables, and 28 references.

Practicing Evidence-Based Medicine

Today, a plethora of resources for evidence-based medicine (EBM) are available via alert services, compendia, and more. In theory, a clinician researching a topic or looking for information regarding a clinical decision should easily find the literature or synopses needed. However, the real challenge lies in recognizing which resources (out of hundreds or possibly thousands) present the best and most reliable evidence. As well, evidence from research is only part of the decision calculus, and the clinician, not the evidence, makes the final decisions. Medical decision analysis attempts to formalize the process and reduce it to algebra, but it is difficult or impossible to represent all the components of a decision mathematically and validly let alone do so in “real time” for individual patients. This review discusses these challenges and more, including how to ask answerable questions, understand the hierarchy for evidence-based information resources, critically appraise evidence, and apply research results to patient care. Figures show the total number of new articles in Medline from 1965 to 2012, a “4S” hierarchy of preappraised medicine, percentage of physician and medical student respondents with a correct or incorrect answer to a question about calculating the positive predictive value of a hypothetical screening test, a nomogram for Bayes’s rule, an example of nomogram use for pulmonary embolism, and a model for evidence-informed clinical decisions. Tables list selected barriers to the implementation of EBM; Patient, Intervention, Comparison, and Outcome (PICO) framework for formulating clinical questions; guides for assessing medical texts for evidence-based features; clinically useful measures of disease frequency and statistical significance and precision; definitions of clinically useful measures of diagnostic test performance and interpretation; definitions of clinically useful measures of treatment effects from clinical trials; summary of results and derived calculations from the North American Symptomatic Carotid Endarterectomy Trial (NASCET); and selected number needed to treat values for common therapies. This review contains 6 highly rendered figures, 9 tables, and 28 references.

Practicing Evidence-Based Medicine (SAGHE)

Today, a plethora of resources for evidence-based medicine (EBM) are available via alert services, compendia, and more. In theory, a clinician researching a topic or looking for information regarding a clinical decision should easily find the literature or synopses needed. However, the real challenge lies in recognizing which resources (out of hundreds or possibly thousands) present the best and most reliable evidence. As well, evidence from research is only part of the decision calculus, and the clinician, not the evidence, makes the final decisions. Medical decision analysis attempts to formalize the process and reduce it to algebra, but it is difficult or impossible to represent all the components of a decision mathematically and validly let alone do so in “real time” for individual patients. This review discusses these challenges and more, including how to ask answerable questions, understand the hierarchy for evidence-based information resources, critically appraise evidence, and apply research results to patient care. Figures show the total number of new articles in Medline from 1965 to 2012, a “4S” hierarchy of preappraised medicine, percentage of physician and medical student respondents with a correct or incorrect answer to a question about calculating the positive predictive value of a hypothetical screening test, a nomogram for Bayes’s rule, an example of nomogram use for pulmonary embolism, and a model for evidence-informed clinical decisions. Tables list selected barriers to the implementation of EBM; Patient, Intervention, Comparison, and Outcome (PICO) framework for formulating clinical questions; guides for assessing medical texts for evidence-based features; clinically useful measures of disease frequency and statistical significance and precision; definitions of clinically useful measures of diagnostic test performance and interpretation; definitions of clinically useful measures of treatment effects from clinical trials; summary of results and derived calculations from the North American Symptomatic Carotid Endarterectomy Trial (NASCET); and selected number needed to treat values for common therapies. This review contains 6 highly rendered figures, 9 tables, and 28 references.

Practicing Evidence-Based Medicine

Today, a plethora of resources for evidence-based medicine (EBM) are available via alert services, compendia, and more. In theory, a clinician researching a topic or looking for information regarding a clinical decision should easily find the literature or synopses needed. However, the real challenge lies in recognizing which resources (out of hundreds or possibly thousands) present the best and most reliable evidence. As well, evidence from research is only part of the decision calculus, and the clinician, not the evidence, makes the final decisions. Medical decision analysis attempts to formalize the process and reduce it to algebra, but it is difficult or impossible to represent all the components of a decision mathematically and validly let alone do so in “real time” for individual patients. This review discusses these challenges and more, including how to ask answerable questions, understand the hierarchy for evidence-based information resources, critically appraise evidence, and apply research results to patient care. Figures show the total number of new articles in Medline from 1965 to 2012, a “4S” hierarchy of preappraised medicine, percentage of physician and medical student respondents with a correct or incorrect answer to a question about calculating the positive predictive value of a hypothetical screening test, a nomogram for Bayes’s rule, an example of nomogram use for pulmonary embolism, and a model for evidence-informed clinical decisions. Tables list selected barriers to the implementation of EBM; Patient, Intervention, Comparison, and Outcome (PICO) framework for formulating clinical questions; guides for assessing medical texts for evidence-based features; clinically useful measures of disease frequency and statistical significance and precision; definitions of clinically useful measures of diagnostic test performance and interpretation; definitions of clinically useful measures of treatment effects from clinical trials; summary of results and derived calculations from the North American Symptomatic Carotid Endarterectomy Trial (NASCET); and selected number needed to treat values for common therapies. This review contains 6 highly rendered figures, 9 tables, and 28 references.

Reproducibility of Middle Cerebral Artery Stenosis Measurements by DSA: Comparison of the NASCET and WASID Methods

PurposeTo evaluate the intra- and inter-observer variability of the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) criteria for the evaluation of middle cerebral artery (MCA) stenosis using digital subtraction angiography (DSA).Materials and MethodsDSA images of 114 cases with 131 stenotic MCAs were retrospectively analyzed. Two radiologists and a researcher measured the degree of MCA stenosis independently using both NASCET and WASID methods. To determine intra-observer agreement, all the observers reevaluated the degree of MCA stenosis 4 weeks later. The linear relation and coefficient of variation (CV) between the measurements made by the two methods were assessed by correlation coefficient and multi-factor analysis of variance (ANOVA), respectively. Intra- and inter-observer variability of the two methods was evaluated by intraclass correlation coefficient (ICC), Spearman’s R value, Pearson correlation coefficient and Bland-Altman plots.ResultsDespite the fact that the degree of MCA stenosis measured by NASCET was lower than measured using the WASID method, there was good linear correlation between the measurements made by the two methods (for the mean measurements of the 3 observers, NASCET% = 0.891 × WASID% - 1.89%; ICC, Spearman’s R value and Pearson correlation were 0.874, 0.855, and 0.874, respectively). The CVs of both intra- and inter-observer measurements of MCA stenosis using WASID were significantly lower than that using NASCET confirmed by the multi-factor ANOVA results, which showed only the measurement methods of MCA stenosis had significant effects on the CVs both in intra- and inter-observer measurements (both P values < 0.001). Intra-observer measurements showed good or excellent agreement with respect to WASID and NASCET evaluation (ICC, 0.656 to 0.817 and 0.635 to 0.761, respectively). Good agreement for the WASID evaluation (ICC, 0.592 to 0.628) and for the NASCET evaluation (ICC, 0.529 to 0.568) was observed for inter-observer measurements. Bland-Altman plots demonstrated that the WASID method had better reproducibility and intra-observer agreement than NASCET method for evaluating MCA stenosis.ConclusionBoth NASCET and WASID methods have an acceptable level of agreement; however, the WASID method had better reproducibility for the evaluation of MCA stenosis, and thus the WASID method may serve as a standard for measuring the degree of MCA stenosis.

Comparative Review of the Treatment Methodologies of Carotid Stenosis.

The treatment of carotid stenosis entails three methodologies, namely, medical management, carotid angioplasty and stenting (CAS), as well as carotid endarterectomy (CEA). The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trial (ECST) have shown that symptomatic carotid stenosis greater than 70% is best treated with CEA. In asymptomatic patients with carotid stenosis greater than 60%, CEA was more beneficial than treatment with aspirin alone according to the Asymptomatic Carotid Atherosclerosis (ACAS) and Asymptomatic Carotid Stenosis Trial (ACST) trials. When CAS is compared with CEA, the CREST resulted in similar rates of ipsilateral stroke and death rates regardless of symptoms. However, CAS not only increased adverse effects in women, it also amplified stroke rates and death in elderly patients compared with CEA. CAS can maximize its utility in treating focal restenosis after CEA and patients with overwhelming cardiac risk or prior neck irradiation. When performing CEA, using a patch was equated to a more durable result than primary closure, whereas eversion technique is a new methodology deserving a spotlight. Comparing the three major treatment strategies of carotid stenosis has intrinsic drawbacks, as most trials are outdated and they vary in their premises, definitions, and study designs. With the newly codified best medical management including antiplatelet therapies with aspirin and clopidogrel, statin, antihypertensive agents, strict diabetes control, smoking cessation, and life style change, the current trials may demonstrate that asymptomatic carotid stenosis is best treated with best medical therapy. The ongoing trials will illuminate and reshape the treatment paradigm for symptomatic and asymptomatic carotid stenosis.

Leptomeningeal collateral vessels are a major risk factor for intracranial hemorrhage after carotid stenting in patients with carotid atherosclerotic plaque

AimTo evaluate the relationship between leptomeningeal collaterals and intracranial hemorrhage (ICH) after carotid artery stenting (CAS).MethodsA retrospective study was undertaken of 228 patients (median age 75 years (range 44–90); 187...

Assessing internal carotid artery stenosis with a semiautomated computed tomography angiography tool and duplex ultrasound

Duplex ultrasound (DUS) and computed tomography angiography (CTA) are both used as first-line noninvasive methods to investigate patients for internal carotid artery (ICA) disease. Although manual assessment of CTA is well established, semiautomated vessel analysis programs have yet to prove their clinical benefit. We compared one such vessel analysis program (TeraRecon, Foster City, Calif) with DUS. A total of 85 arteries in 50 patients (35 men, 15 women; mean age, 73 ± 10 years) were eligible for comparison with the North American Symptomatic Carotid Endarterectomy Trial method. Duplex scanning comprised stenosis estimation based on (1) the intrastenotic and distal ICA diameter measurements on color-coded imaging (CCI), (2) the application of German Society for Ultrasound in Medicine (DEGUM) criteria (intrastenotic peak systolic velocity [PSV] ≥ 2 00 cm/s indicates 50% stenosis; intrastenotic PSV ≥ 300 cm/s together with a PSV of ≥ 50 cm/s in the distal ICA indicates 70% stenosis), and (3) the application of the University of Washington stenosis criteria (≥ 50% stenosis is indicated by PSV >125 cm/s and end-diastolic velocity <140 cm/s; ≥ 80% stenosis is indicated by PSV >125 cm/s and end-diastolic velocity ≥ 140 cm/s). The minimum and maximum diameters at the stenosis site and at the distal reference ICA were automatically measured with the CTA vessel analysis tool. In addition, automated tracking generated corresponding cross-sectional areas at these two sites. Angiographic stenosis was then calculated using the minimum diameter (CTAmin), the average of the minimum and maximum diameters (CTAavg), and the areas (CTAarea) at both sites. Compared with duplex CCI, the three CTA modalities exhibited only a moderate agreement in terms of regression analysis (R(2) = 0.41-0.54) and Bland-Altman analysis (the standard deviation of the stenosis differences was >20%). In terms of sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, DEGUM stenosis graduation was best balanced by duplex CCI (50% stenosis: 100%, 93%, 85%, 100%, 95%; 70% stenosis: 71%, 100%, 100%, 97%, 98%) followed by CTAarea (50% stenosis: 80%, 73%, 54%, 90%, 75%; 70% stenosis: 66%, 94%, 55%, 96%, 96%). University of Washington stenosis was best balanced by duplex CCI followed by CTAarea. CTA analysis with a semiautomated vessel analysis tool provides variable results. Large discrepancies between methods in the degree of reported stenosis must be taken into consideration when CTA and DUS are used for clinical purposes. The semiautomated software tools need further improvements.