Effect of image normalization on carotid plaque classification and the risk of ipsilateral hemispheric ischemic events: results from the asymptomatic carotid stenosis and risk of stroke study

The aim of this study was to determine the effect of image normalization on plaque classification and the risk of ipsilateral ischemic neurologic events in patients with asymptomatic carotid stenosis. The first 1,115 patients recruited to the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study with a follow-up of 6 to 84 months (mean 37.1 months) were included in this study. Duplex ultrasonography was used for grading the degree of internal carotid artery stenosis and for plaque characterization (types 1-5), which was performed before and after image normalization. One hundred sixteen ipsilateral ischemic hemispheric events occurred. Image normalization resulted in 60% of plaques being reclassified. Before image normalization, a high event rate was associated with all types of plaque. After image normalization, 109 (94%) of the events occurred in patients with plaque types 1 to 3. For patients with European Carotid Stenosis Trial (ECST) 70 to 99% diameter stenosis (equivalent to North American Symptomatic Carotid Endarterectomy Trial [NASCET] 50-99%) with plaque types 1 to 3, the cumulative stroke rate was 14% at 7 years (2% per year), and for patients with plaque types 4 and 5, the cumulative stroke rate was 0.9% at 7 years (0.14% per year). The results suggest that asymptomatic patients with plaque types 4 and 5 classified as such after image normalization are at low risk irrespective of the degree of stenosis.     

Patients at elevated risk of major adverse events following endarterectomy for asymptomatic carotid stenosis

Background

Carotid endarterectomy (CEA) as treatment in patients with asymptomatic carotid stenosis is the subject of much debate.

Methods

The National Surgical Quality Improvement Program database from 2005 to 2012 was queried. Patients undergoing CEA for asymptomatic carotid stenosis were identified. Preoperative risk factors and patient demographics were compared using chi-square analysis and logistic regression to determine their relation with stroke and death.

Results

During an 8-year period, 24,211 CEAs performed for asymptomatic carotid stenosis were identified. Patients with dependent functional status (12.5%), recent myocardial infarction (6.3%), chronic heart failure (5.0%), hypoalbuminemia (4.8%), angina (4.1%), dialysis dependence (3.4%), steroid dependence (3.4%), chronic obstructive pulmonary disease (3.3%), and American Society of Anesthesiologists > 3 (3.2%) had a clinically significant increase in risk of stroke and death. Patients with none of the above risk factors had a stroke and death rate of 1.08%, which was significantly less than the overall stroke and death rate (P < .001).

Conclusions

A high-risk subset of patients undergoing CEA for asymptomatic carotid stenosis can be identified. If patient selection is optimized and perioperative morbidity and mortality are minimized, CEA will continue to play an important role in stroke prevention for those with significant asymptomatic carotid stenosis.     

Immediate and long-term results of carotid endarterectomy for asymptomatic high-grade stenosis

We examined the operative risks and long-term results of carotid endarterectomy for asymptomatic patients in terms of stroke, death, and recurrent stenosis. The results of a nonrandomized study with a follow-up of 1 to 104 months (mean 46 months) is reported. A tertiary referral center served as the setting for this report. One hundred consecutive patients with severe but asymptomatic carotid artery stenosis out of a total of 514 patients undergoing carotid endarterectomy were entered into this study. The severity of carotid disease was determined by duplex scanning and confirmed arteriographically. No patients were lost to follow-up after surgery. Eighty-nine operations (77%) were done under cervical block anesthesia and all arteries were closed with saphenous vein patches. Life-table analysis showed that the stroke-free rate at 5 years was 96.3% with an ipsilateral stroke-free rate of 98.2%. The 5-year overall survival rate was 78.2% with a stroke-free survival rate of 75%. Carotid endarterectomy can be performed safely for asymptomatic patients believed to be at risk for stroke. The potential for early death due to myocardial disease, late stroke, and recurrent stenosis do not justify advising patients against undergoing prophylactic carotid endarterectomy for asymptomatic high-grade stenosis.     

Screening for asymptomatic carotid stenosis in patients with peripheral vascular disease: a prospective study and risk factor analysis.

Screening for asymptomatic carotid artery stenosis using color flow duplex scan was performed on 186 Chinese patients with peripheral vascular disease. They consist of 121 male and 65 females, with a mean age of 70.6 years. A carotid bruit was present in 43 (23.1%) of the patients. Internal carotid artery stenosis of 70% or greater was detected in 46 patients (24.7%) including six total occlusions. Another 79 patients (42.5%) had internal carotid artery stenosis in the 30-69% range. Significant internal carotid artery stenosis was associated with age, male sex, the quantity and duration of smoking and a carotid bruit, and inversely with cholesterol, triglyceride and VLDL. Age, the number of cigarettes consumed per day, and carotid bruit were independent significant predictors of > or =70% internal carotid artery stenosis on logistic regression analysis. The degree of internal carotid artery stenosis is more severe in patients with a carotid bruit, and correlated positively with age (P<0.01), the number of cigarettes smoked (P = 0.04), and the duration of smoking (P = 0.03). Multiple linear regression analysis showed that only the age of the patient bears a significant relationship with the degree of internal carotid artery stenosis (P<0.01). There was no relationship between the degree of lower limb ischemia with carotid stenosis. The prevalence of > or =70% internal carotid artery stenosis in a high risk population with peripheral vascular disease was 24.7%. Routine duplex screening is worthwhile in this group of patients, particularly in male, elderly smokers.     

The risk of stroke in patients with asymptomatic carotid stenosis undergoing cardiac surgery: a follow-up study

During a 7-year period, 4047 patients underwent a battery of noninvasive carotid tests before cardiac surgery. Two thirds of the patients with abnormal studies underwent carotid angiography. One hundred fifty-three patients (3.8%) had significant carotid disease, narrowing the luminal diameter by greater than 50%. The incidence of transient ischemic attack or cerebrovascular accident following cardiac surgery was 1.9% in those patients with no carotid disease and 9.2% in those patients with carotid lesions. The incidence of transient ischemic attack or cerebrovascular accident in 32 patients with inoperable (occluded) carotid vessels was 15.6% and in 121 patients with operable (stenotic) lesions was 7.4%. In the group of patients with stenosis, 57 patients underwent carotid operation with an 8.8% incidence of neurologic deficit. During the last 1 1/2 years, no patient with asymptomatic carotid stenosis underwent simultaneous carotid and coronary surgery. Four of 64 patients with combined lesions but no carotid surgery (6.3%) had a neurologic deficit, one of which was severe and permanent. The highest incidence of neurologic dysfunction occurred in patients with unilateral occlusions and contralateral stenosis. Four of 12 patients in this group had a deficit (three of seven patients underwent operation; one of five did not), one of which was permanent. The operative mortality rate after cardiac surgery was three times higher in patients with carotid disease than in those patients with normal carotid arteries. Combined carotid and coronary surgery is currently reserved for patients with neurologic symptoms and severe cardiac disease.     

Long-term results of surgical treatment of patients with asymptomatic carotid artery stenosis

Results of treatment of 148 patients with asymptomatic carotid stenosis were analyzed in terms from 5 to 180 months. 75 (51%) patients were operated, 73 (49%)--were not operated. Non-operated asymptomatic patients with more than 90% stenosis and patients with prolonged (more than 18 mm) stenosis have the highest risk of cerebral events (4% annually and more). In long-term period (from the 70th month of follow-up) patients with the 70-90% stenosis are the group of high risk of cerebro-vascular symptoms.     

Progression of asymptomatic carotid stenosis: A natural history study in 1004 patients

Purpose: The purpose of this study was to delineate the natural history of the progression of asymptomatic carotid stenosis. Methods: In a 10-year period, 1701 carotid arteries in 1004 patients who were asymptomatic were studied with serial duplex scans (mean follow-up period, 28 months; mean number of scans, 2.9/patient). At each visit, stenoses of the internal carotid artery (ICA) and the external carotid artery (ECA) were categorized as none (0 to 14%), mild (15% to 49%), moderate (50% to 79%), severe (80% to 99%), preocclusive, or occluded. Progression was defined as an increase in ICA stenosis to ≥50% for carotid arteries with a baseline of <50% or as an increase to a higher category of stenosis if the baseline stenosis was ≥50%. The Cox proportional hazards model was used for data analysis. Results: The risk of progression of ICA stenosis increased steadily with time (annualized risk of progression, 9.3%). With multivariate modeling, the four most important variables that affected the progression (P < .02) were baseline ipsilateral ICA stenosis ≥50% (relative risk [RR], 3.34), baseline ipsilateral ECA stenosis ≥50% (RR, 1.51), baseline contralateral ICA stenosis ≥50% (RR, 1.41), and systolic pressure more than 160 mm Hg (RR, 1.37). Ipsilateral neurologic ischemic events (stroke/transient ischemic attack) occurred in association with 14.0% of the carotid arteries that were studied. The progression of ICA stenosis correlated with these events (P < .001), but baseline ICA stenosis was not a significant predictor. Conclusion: In contrast to recently published studies, we found that the risk of progression of carotid stenosis is substantial and increases steadily with time. Baseline ICA stenosis was the most important predictor of the progression, but baseline ECA stenosis also was identified as an important independent predictor. Contralateral ICA stenosis and systolic hypertension were additional significant predictors. We found further that the progression of ICA stenosis correlated with ischemic neurologic events but not baseline stenosis. The data provide justification for the use of serial duplex scans to follow carotid stenosis and suggest that different follow-up intervals may be appropriate for different patient subgroups. (J Vasc Surg 1999;29:208-16.)     

Cerebral haemodynamic aspects of severe carotid stenosis: asymptomatic vs symptomatic.

OBJECTIVES: to compare cerebral haemodynamics in patients with asymptomatic and symptomatic severe (> or =70%) internal carotid artery (ICA) stenosis. METHODS: we assessed 195 consecutive patients, 116 with asymptomatic carotid stenosis (ACS) and 79 with symptomatic carotid stenosis (SCS). Using transcranial Doppler we assessed cerebral vasoreactivity (CVR) following acetazolamide test, the middle cerebral artery flow velocity ratio after/before carotid clamping (mv-MCA ratio), and the carotid back pressure (CBP) during crossclamping. RESULTS: no significant differences between the two groups were demonstrated regarding CVR (47 vs 39%), mv-MCA ratio (50 vs 52%), or CBP (36 vs 44 mmHg). However, in patients with contralateral ICA occlusion all three variables were significantly lower as compared to patients with patent contralateral ICA. Also patients who needed a shunt during surgery had significantly lower values of mv-MCA ratio and CBP. Patients who suffered peri-operative neurologic deficits (n=6; 3%) did not differ from patients who had an uneventful course. CONCLUSIONS: clinical state of ICA stenosis is independent of cerebral haemodynamics. Occluded contralateral ICA is more important for predicting cerebral ischaemia caused by carotid clamping. Finally, none of the haemodynamic parameters showed predictive value for peri-operative neurologic morbidity.     

Stenosis following carotid endarterectomy. Its implication in management of asymptomatic carotid stenosis

Carotid endarterectomy is established in the treatment of atherosclerosis of the carotid bifurcation, but the incidence of restenosis and the role of endarterectomy in the management of asymptomatic carotid stenosis are variable. During a four-year period, we performed 80 endarterectomies of the internal carotid artery in 73 patients. Patients were prospectively studied by means of Doppler ultrasonography in combination with real-time spectral analysis to determine the incidence of restenosis postoperatively. A concomitant study of 116 patients with 79 asymptomatic carotid stenoses was undertaken. We found a 12.5% incidence of stenosis following carotid endarterectomy and a 3% risk of transient neurologic deficit in the patients with asymptomatic carotid stenoses.     

Minor asymptomatic carotid stenosis contralateral to carotid endarterectomy (CEA): our experience.

The authors report their experience from 1985 to 1988 with 75 consecutive patients affected by bilateral carotid artery stenosis in whom only one side was surgically treated and the other had a minor (15-45%) asymptomatic carotid stenosis. These patients have been followed for a period ranging from 10 to 50 months (mean follow-up 21 months) by clinical examinations and non-invasive investigations (Doppler CW, Duplex scanner). The non-invasive evaluation included assessment of haemodynamic data and characterisation of plaque morphology (regular vs. irregular or ulcerated surface, homogeneous vs. heterogeneous plaque). During follow-up eight patients died: two (2.6%) from acute myocardial infarction, four from stroke (5.3%), and two (2.6%) from other causes. Twenty-five patients (33.3%) had neurological symptoms related to the unoperated side: and four suffered stroke (5.3%). Twenty-one patients had TIAs (28%) related to the observed side. During follow-up five out of 29 (17.2%) homogeneous and 20 out of 46 (43.4%) heterogeneous plaques progressed (p less than 0.01). With regard to the surface characteristics, nine out of 25 regular plaques progressed and only three patients (12%) had neurological events; 19 out of 34 (55.9%) irregular plaques showed a progression and 14 caused neurological symptoms. Fourteen ulcerated plaques (87.5%) progressed (p less than 0.01). Our experience suggests that the basic trend in the follow-up of patients with bilateral carotid artery disease, is that the contralateral unoperated lesion may evolve and become symptomatic. These symptoms are generally TIAs but five patients (4.3%) suffered from strokes related to the unoperated side, all without warning TIAs.     

Modifiable risk factors for occurrence of ipsilateral ischemic events after carotid endarterectomy beyond perioperative period

ObjectiveThe purpose of this study was to quantify the effects of several modifiable variables on the occurrence of stroke after the initial perioperative period for patients who had undergone carotid endarterectomy (CEA).MethodsThe primary outcome for the present study was the development of an ischemic stroke or transient ischemic attack (TIA) in the cerebral hemisphere ipsilateral to CEA after the initial hospitalization. All CEAs in the VQI between January 2003 and May 2022 were queried. We identified 171,816 CEAs in the database. The exclusion criteria for the study were the lack of follow-up data for >30 days, concomitant coronary artery bypass surgery, concomitant proximal or distal carotid intervention at CEA, other arterial interventions at CEA, and stroke or TIA during the initial hospital admission, leaving 126,290 patients for analysis. We used the χ² test for statistical analysis of the outcome of ipsilateral ischemic stroke or TIA after the initial CEA hospital admission to determine the relevant variables. Age was evaluated as an ordinal variable using the Student t test. Variables with P ≤ .05 on univariable analysis were included in the multivariable Cox regression time-to-event analysis for the primary outcome. Kaplan-Meier curves were constructed of the most significant variables on Cox regression as a visual aid.ResultsThe following variables achieved significance on Cox regression for an association with development of ipsilateral hemispheric ischemic events after the index CEA hospital admission: lack of patch placement at CEA site (hazard ratio [HR], 18.24; P < .0001), lack of antiplatelet therapy at long-term follow-up (LTFU; HR, 9.75; P < .0001), lack of statin therapy at LTFU (HR, 3.18; P < .001), lack of statin therapy at hospital discharge (HR, 1.25; P = .015), anticoagulation at LTFU (HR, 1.53; P < .001), development of >70% recurrent stenosis (HR, 2.15; P < .001), and shunt use at surgery (HR, 1.20; P = .007). Patients with patch placement at surgery and patients with confirmed antiplatelet therapy at LTFU had had 99.8% and 99.6% freedom from an ischemic event ipsilateral to the side of the CEA at LTFU, respectively. This finding is in contrast to the 5.7% and 4.7% positivity for ischemic events for those without patch placement at surgery and those not receiving antiplatelet therapy at LTFU, respectively (P < .0001 for both).ConclusionsPerformance of patch angioplasty arterial closure was remarkably protective against ipsilateral cerebral ischemic events at LTFU after CEA. Discharging and maintaining patients with antiplatelet and statin medication after CEA significantly reduces the incidence of future ipsilateral ischemic events. Thus, a significant opportunity exists for enhanced outcomes with improved implementation of these measures.     

Severe contralateral carotid stenosis or occlusion does not have an impact on risk of ipsilateral stroke after carotid endarterectomy

Objective

This study evaluates the impact of severe (>70%) contralateral carotid stenosis or occlusion (SCSO) on outcomes after carotid endarterectomy (CEA).

Markers of inflammation in patients with symptomatic and asymptomatic carotid artery stenosis: a case-control study

OBJECTIVES: There is evidence that inflammation plays a role in the pathogenesis of atherosclerosis. We compared levels of inflammatory markers between patients undergoing carotid endarterectomy (CEA) and controls, and between patients with symptomatic and asymptomatic internal carotid artery (ICA) stenosis. MATERIALS AND METHODS: A total of 180 patients with ICA stenosis were compared with 180 age-matched and sex-matched controls. The biomarkers evaluated were high-sensitivity C-reactive protein (hs-CRP), soluble intercellular adhesion molecule 1, soluble vascular cell adhesion molecule 1 (sVCAM-1), and interleukin-6 (IL-6). RESULTS: The levels of hs-CRP, sVCAM-1, and IL-6 in the CEA group were significantly higher than in the control group (1.87 mg/mL vs 1.44 mg/mL, P = .011; 1408 ng/dL vs 672 ng/dL, P < .001; 11.9 pg/mL vs 6.3 pg/mL, P < .001). Multivariate linear regression analysis, adjusted for all clinical and physiologic parameters, showed a significant association between ICA stenosis and hs-CRP, sVCAM-1, and IL-6 concentrations. Analysis of symptomatic (n = 101) and asymptomatic (n = 79) ICA stenosis did not detect a difference in levels of these markers. CONCLUSIONS: Our study suggests that inflammatory markers could serve as markers for ICA atherosclerosis but are not useful to identify carotid plaque at risk for symptomatic conversion.     

Recurrent carotid stenosis: operative strategy and late results

From 1957 to 1985, 116 consecutive operations for recurrent carotid stenosis were performed in 99 patients at the University of California, San Francisco. Ninety-four patients underwent 103 reoperations for primary recurrent stenosis (nine patients had bilateral repairs). Seventy-two operations (70%) were performed to relieve cerebrovascular symptoms whereas the indication for 31 operations (30%) was high-grade stenosis. The cause of primary recurrent stenosis was myointimal hyperplasia (MIH) in 47 cases, whereas 56 were caused by recurrent atherosclerosis (ASO). Secondary recurrent stenosis developed in six patients from our own series (5.8%) and an additional six patients were referred after reoperation elsewhere. The 12 lesions in this group were evenly divided between MIH (six) and recurrent ASO (six). MIH resulted in a single tertiary recurrent stenosis. Myointimectomy or repeat endarterectomy and vein patch angioplasty were the most commonly used techniques for repair of a primary recurrent stenosis. Secondary recurrent stenosis necessitated resection of the carotid bifurcation and graft interposition when caused by MIH. Secondary recurrent stenosis caused by ASO could be treated by repeat endarterectomy and vein patch angioplasty in five of six cases. Five strokes occurred in the entire series (4.3%), resulting in two deaths. There were 23 cranial nerve palsies, which rarely persisted beyond 3 months. The morbidity and mortality rates for primary and secondary carotid reoperation are comparable to the original procedure and should not deter the vascular surgeon from reoperative carotid reconstruction whenever indicated.     

Optimal contemporary management of symptomatic and asymptomatic carotid artery stenosis

This commentary addresses the issue of optimal contemporary management of symptomatic and asymptomatic carotid artery stenosis. Based on current data, carotid endarterectomy (CEA) should be performed in the majority of patients with symptomatic carotid artery stenosis. Carotid artery stenting (CAS) should be reserved for a minority of these symptomatic patients, in whom CEA is contraindicated. In asymptomatic patients, all should be placed on best medical treatment (BMT). With the use of one or more of the proposed stroke risk stratification models or some as yet undetermined method, the identification of those asymptomatic individuals may be possible in whom stroke risk is higher than usual with BMT. This asymptomatic subgroup, which may be small and is yet to be determined with certainty, could be offered an invasive carotid procedure (either CAS or CEA).     

Contralateral internal carotid artery stenosis or occlusion: pitfall of correct ipsilateral classification--a study performed with color-flow imaging

The records of 183 patients who had undergone color-flow imaging of the extracranial carotid arteries and subsequent bilateral cerebral arteriography were reviewed to determine whether contralateral carotid arterial disease adversely affects the accuracy of duplex scanning by increasing the velocity of flow in the ipsilateral artery. In 83 arteries the contralateral internal carotid artery had a diameter reduction greater than or equal to 80%; in the remaining 283, the contralateral artery was less severely diseased. Noninvasive findings correlated less well with arteriography in the group with contralateral disease (k = 0.69 +/- 0.06) than in the group with less severe contralateral stenosis (k = 0.78 +/- 0.03), and the incidence of false-positive errors was significantly (p = 0.02) higher (18% vs 7%). For all categories of ipsilateral stenosis, the mean peak systolic and end-diastolic velocities were elevated in the group with severe contralateral disease. This effect was most evident in the 50% to 79% diameter reduction category, especially in reference to the end-diastolic velocity (p = 0.2). However, the data correlating velocity with diameter reduction were widely scattered, indicating that the effect of contralateral disease is inconsistent. We conclude that severe disease of the contralateral carotid artery can lead to overreading ipsilateral disease and that velocity determinations should be interpreted cautiously under such circumstances.