Risk for transient ischemic attacks is mainly determined by intima-media thickness and carotid plaque echogenicity

Carotid stenting with proximal cerebral protection in symptomatic low-grade vulnerable recurrent carotid stenosis

Background

Although the management of carotid disease is well established for symptomatic lesions ⩾70%, carotid revascularization for symptomatic low-grade (⩽50%) stenosis is not actually supported by data from randomized clinical trials. Such patients may occasionally have recurrent neurological symptoms despite optimal medical treatment owing to vulnerable plaques. In such cases, carotid artery stenting (CAS) may represent an option for treatment but this has not been tested in clinical trials. This study analyzed early and long-term outcomes of CAS performed in patients with low-grade symptomatic recurrent carotid stenosis.

Methods

From a prospective registry of 322 carotid revascularization in symptomatic patients, 21 consecutive patients with low-grade symptomatic recurrent carotid stenosis who underwent CAS with proximal cerebral protection device Mo.Ma, after ruling out any other source of cerebral embolization, were involved in the study.All patients had suggestive evidence of unstable plaque or plaque ulceration.

Results

Procedural technical success rate was 100%. No 30-day stroke or death occurred, and no patients had recurrent neurological events related to the revascularized hemisphere during follow up. No 30-day local complications were reported. No late carotid occlusions were detected. There was one late death, and no stroke-related deaths. Survival rates were 100% at 1 year and 96% at 3 years.

Conclusions

This study shows that CAS is a well-tolerated, effective and durable treatment for patients with recurrent symptomatic low-grade carotid stenosis associated with a vulnerable plaque. Patients had excellent protection against further ischemic events and survived long enough.

Short-Term Results of Carotid Endarterectomy and Stenting After the Introduction of Carotid Magnetic Resonance Imaging: A Single-Institution Retrospective Study

OBJECTIVE

Although carotid artery stenting (CAS) has been gaining popularity as an alternative to carotid endarterectomy (CEA), perioperative stroke rate following contemporary CAS remains significantly higher than stroke rate after CEA. The purpose of this study was to assess perioperative (within 30 days) therapeutic results in patients with carotid stenosis (CS) after introduction of preoperative carotid magnetic resonance imaging plaque evaluation in a single center performing both CEA and CAS.

METHODS

Based on prospectively collected data for patients with CS who were scheduled for carotid revascularization, retrospective analysis was conducted of 295 consecutive patients with CS. An intervention was selected after consideration of periprocedural risks for both CEA and CAS. Concerning risk factors for CAS, results of magnetic resonance imaging plaque evaluation were emphasized with a view toward reducing embolic complications.

RESULTS

CAS was performed in 114 patients, and CEA was performed in 181 patients. Comparing baseline characteristics of the 295 patients, age, T1 signal intensity of plaque, symptomatic CS, urgent intervention, and diabetes mellitus differed significantly between CAS and CEA groups. Among patients who underwent CAS, new hyperintense lesions on diffusion-weighted imaging were confirmed in 47 patients. New hyperintense lesions on diffusion-weighted imaging were recognized in 21.4% of patients who underwent CEA (n = 39), significantly less frequent than in patients who underwent CAS.

CONCLUSIONS

The overall short-term outcome of CEA and CAS is acceptable. Preoperative carotid magnetic resonance imaging evaluation of plaque might contribute to low rates of ischemic complications in CAS.

Plasma levels of vasostatin-1, a chromogranin A fragment, are associated with carotid artery maximum stenosis: A pilot study

BACKGROUND

Chromogranin A (CgA), a circulating protein released by the neuroendocrine system, can regulate vascular physiology and angiogenesis. Full-length CgA (CgA_1-439) and its fragment CgA_1-76 (called vasostatin-1, VS-1) preserve the physiological integrity of the endothelial barrier function and are antiangiogenic, whereas CgA_1-373 is proangiogenic. We investigated whether these polypeptides are altered in patients with various degrees of carotid artery atherosclerosis.

METHODS

We studied 81 patients with carotid artery atherosclerosis, asymptomatic for cerebrovascular diseases. Carotid arteries were examined by Doppler ultrasound and plaque characteristics were recorded. Plasma levels of CgA_1-439, VS-1, CgA_1-373, and total-CgA (CgA_1-439 plus truncated fragments lacking part or the entire C-terminal region) were assessed by specific ELISAs.

RESULTS

Plasma levels of VS-1 and total-CgA correlated with carotid artery maximum stenosis (r=0.349, p=0.001 and r=0.256, p=0.021, respectively). Stepwise multiple regression analysis indicated that VS-1 was a significant predictor of maximum stenosis after adjustment for age, gender, and conventional risk factors for atherosclerosis (regression coefficient=12.42, SE=4.84, p=0.012). In addition, logistic regression analysis indicated that relatively high levels of full-length CgA, but not total-CgA, predict the presence of hypoechoic, lipid-rich plaques (OR=1.47; 95% CI: 1.19-1.81, p=0.0003).

CONCLUSION

VS-1 is independently associated with carotid artery maximum stenosis. Furthermore, full-length CgA is an independent indicator of hypoechoic plaques, likely reflecting initial stages of atherosclerosis. Given the known capability of CgA and VS-1 to regulate vascular function and angiogenesis these polypeptides might play a role in the regulation of atherosclerosis pathophysiology.

Serum Osteoprotegerin Is Associated With Calcified Carotid Plaque: A Strobe-Compliant Observational Study

Osteoprotegerin (OPG) is a kind of tumor necrosis factor, which is related to bone metabolism and vascular calcification. The increase of Osteoprotegerin concentration in serum is related to cardiovascular diseases in humans. The purpose of this study was to figure out the relevance between osteoprotegerin in serum and carotid calcification. Serum OPG concentrations were compared in 145 patients who underwent carotid sonography (average age: 68 ± 9 years old, male: female = 81:64). A calcified plaque (CP) (37 people [27%]), a noncalcified plaque (NCP) (54 people [37%]), and a nonplaque (NP) (54 people [37%]) were classified for this study. No significant differences among 3 groups were demonstrated in the distribution of age, diabetes, high blood pressure, and hyperlipidemia. Serum osteoprotegerin concentrations were significantly increased in CP group rather than NCP group or NP group; (median [interquartile range], 4016 [1410] vs 3210 [1802] pg/mL, P < 0.05 and 4016 [1410] vs 3204 [1754] pg/mL, P < 0.05). Serum osteoprotegerin concentrations did not indicate a significant difference between NCP Group or NP Group. This study had proved that patient group accompanied with carotid calcification in carotid artery disease had an increased serum OPG concentration, so it could consider that OPG plays an important function on calcification related to arteriosclerosis.

Comparison of carotid intima-media thickness in pediatric patients with metabolic syndrome, heterozygous familial hyperlipidemia and normals

Background. Our goal was to compare the carotid intimal-medial thickness (CIMT) of untreated pediatric patients with metabolic syndrome (MS), heterozygous familial hyperlipidemia (heFH), and MS+heFH against one another and against a control group consisting of healthy, normal body habitus children. Methods. Our population consisted of untreated pediatric patients (ages 5–20 yrs) who had CIMT measured in a standardized manner. Results. Our population included 57 with MS, 23 with heFH, and 10 with MS+heFH. The control group consisted of 84 children of the same age range. Mean CIMT for the MS group was 469.8 μm (SD = 67), 443.8 μm (SD = 61) for the heFH group, 478.3 μm (SD = 70) for the MS+heFH group, and 423.2 μm (SD = 45) for the normal control group. Significance differences between groups occurred for heFH versus MS (P = 0.022), heFH versus control (P = 0.038), MS versus control (P = 9.0E − 10), and MS+heFH versus control (P = 0.003). Analysis showed significant negative correlation between HDL and CIMT (r = −0.32, P = 0.03) but not for LDL, triglycerides, BP, waist circumference, or BMI. Conclusion. For pediatric patients, the thickest CIMT occurred for patients with MS alone or for those with MS+heFH. This indicates that MS, rather than just elevated LDL, accounts for more rapid thickening of CIMT in this population.

Liver enzymes and stroke risk in middle-aged German adults

OBJECTIVE

To investigate the association between the liver enzymes γ-glutamyltransferase (GGT) and (alanine aminotransferase) ALT and risk of stroke, its subtypes including TIA as well as fatal and non-fatal events.

METHODS

A case-cohort study within the European Prospective Investigation into Cancer and Nutrition-Potsdam Study comprising 27548 middle-aged subjects was designed. GGT and ALT were measured in plasma of 353 individuals who developed a stroke and in 2110 individuals who remained free of cardiovascular events during a mean follow-up of 8.2 ± 2.2 years. Cox proportional-hazard models were applied to evaluate the association between liver enzymes and stroke risk.

RESULTS

After adjustment for established clinical and lifestyle factors, a 1 unit change in naturally logged GGT was related to a 1.20 (95%CI: 1.03-1.40) increased stroke risk. Risk estimates did not significantly differ between fatal (Relative Risk (RR) = 1.35, 95%CI: 1.14-1.61) and non-fatal events (RR = 1.15; 95%CI: 0.97-1.36). ALT was not associated with overall stroke risk (RR = 0.95; 95%CI: 0.71-1.26). However, in subtype analyses we observed in multivariable adjusted models a significant increased risk of hemorrhagic stroke (RR = 2.00; 95% CI: 1.01-3.96), but decreased risk of ischemic stroke (RR = 0.66; 95%CI: 0.44-0.998).

CONCLUSIONS

Our data provide further evidence for a link between GGT, but not ALT and overall stroke suggesting that these biomarkers are involved in different pathways of disease development. Further studies are needed to clarify the putative relationships between ALT and subtypes of stroke.

Echolucency of carotid plaques and cerebrovascular events

OBJECTIVES

To assess the relationship between carotid plaque echogenicity and degree of stenosis with acute and chronic stroke.

METHODS

A retrospective study of cerebral MRI and carotid B-mode and Doppler ultrasonography in 60 patients with stroke. Plaque echogenicity was graded as echolucent (1), predominantly echolucent (2), predominantly echogenic (3), or echogenic (4). Sonographic findings were compared between patients with acute (group 1) and chronic (group 2) stroke.

RESULTS

In group 1 (n = 39 patients), the carotid plaques were grade 1 in 21, grade 2 in 22, grade 3 in 9, and grade 4 in 4 carotid arteries. In group 2 (n = 21), the carotid plaques were grade 1 in 2, grade 2 in 8, grade 3 in 4, and grade 4 in 11 carotid arteries. Plaque echogenicity was lower in group 1 than in group 2 (p < 0.05). Plaque echolucency was associated independently with acute stroke from the degree of stenosis.

CONCLUSIONS

Patients with acute infarcts have predominantly echolucent plaques, regardless of the degree of stenosis.

Advances in noninvasive imaging for evaluating clinical risk and guiding therapy in carotid atherosclerosis

Managing asymptomatic carotid atherosclerosis with a view to preventing ischemic stroke is a challenging task. As the annual risk of stroke in untreated asymptomatic patients on average is less than the risk of surgical intervention, the key question is how to identify those asymptomatic individuals whose risk of stroke is elevated and who would benefit from surgery, while sparing low-risk asymptomatic patients from the risks of surgical intervention. The advent of a multitude of noninvasive carotid imaging techniques offers an opportunity to improve risk stratification in patients and to monitor the response to medical therapies; assessing efficacy at individual and population levels. As part of this, plaque measurement techniques (using ultrasound, computed tomography or MRI) may be employed in monitoring plaque/component regression and progression. Novel imaging applications targeted to plaque characteristics, inflammation and neovascularization, including contrast-enhanced ultrasound and MRI, dynamic contrast-enhanced MRI, and fluorodeoxyglucose-PET, are also being explored. Ultimately, noninvasive imaging and other advances in risk stratification aim to improve and individualize the management of patients with carotid atherosclerosis.

Algorithms to measure carotid intima-media thickness in trials: a comparison of reproducibility, rate of progression and treatment effect

BACKGROUND

Current ultrasound protocols to measure carotid intima-media thickness (CIMT) in trials differ considerably. The best CIMT protocol would be one that combines high reproducibility, a large and precise estimate of the rate of CIMT progression and a large and precise estimate of the treatment effect. We performed a post-hoc analysis to determine the best algorithm for determining CIMT using data from the METEOR study, a randomized double-blind, placebo-controlled study of the effect of rosuvastatin on CIMT progression in 984 low coronary heart disease risk individuals with increased CIMT.

METHODS

CIMT information was collected from two walls (near and far wall), three segments (common carotid, bifurcation and internal carotid artery), five different angles (for the right carotid artery - 60, 90, 120, 150, and 180 degrees on the Meijer's carotid arc; for the left - 300, 270, 240, 210, and 180 degrees) of two sides (left and right carotid artery), resulting in possibly (2 × 3 × 5 × 2 =) 60 measurements. On the basis of combinations of these measurements, we built 66 different ultrasound protocols to estimate a CIMT for each individual (22 protocols for mean common CIMT, 44 protocols for mean maximum CIMT). For each protocol we assessed reproducibility [intraclass correlation (ICC), mean difference of duplicate scans], 2-year progression rate in the placebo group with its corresponding standard error and treatment effect (difference in CIMT progression between rosuvastatin and placebo) and its corresponding standard error.

RESULTS

Data of duplicate ultrasound examinations at baseline and end of study were available for 688 participants (70% of 984). The ICC based on duplicate baseline examinations ranged from 0.81 to 0.95. CIMT progression rates in the placebo group ranged from 0.0046 to 0.0177 mm/year, with SE ranging from 0.00134 to 0.00337. Treatment effects ranged from 0.0141 to 0.0388 mm/year. The protocols with highest reproducibility, highest CIMT progression/precision ratio and highest treatment effect/precision ratio were those measuring both near and far wall for at least two angles.

CONCLUSION

Ultrasound protocols that include CIMT measurements at multiple angles of both near and far wall give the best balance between reproducibility, rate of CIMT progression, treatment effect and their associated precision in this low-risk population with subclinical atherosclerosis.

Symptomatic Low-Grade Carotid Stenosis With Intraplaque Hemorrhage and Expansive Arterial Remodeling Is Associated With a High Relapse Rate Refractory to Medical Treatment

BACKGROUND:

Carotid plaque characteristics influence future risk of stroke considerably. However, the severity of stenosis does not accurately reflect plaque burden in patients with expansive arterial remodeling.

OBJECTIVE:

To determine the therapeutic outcome of symptomatic carotid low-grade stenosis with vulnerable plaque based on magnetic resonance imaging (MRI) characterization.

METHODS:

We studied 25 (male, n = 23; age, 74.2 ± 5.6 years) of 29 consecutive patients with symptomatic carotid low-grade stenosis (&lt;50%) and both high-signal plaque and expansive remodeling on T1-weighted MRIs. The remaining 4 were excluded because of impending stroke. A single antithrombotic and statin were administered, and recurrent ischemic stroke was treated with dual antithrombotics. We considered carotid endarterectomy when recurrence was refractory to aggressive medical treatment.

RESULTS:

During a 31.3 ± 16.4-month follow-up, 11 of the 25 patients developed a total of 30 recurrent ischemic events (46.0% per patient-year). The patients' characteristics did not differ significantly between the groups with and without recurrence (n = 11 and n = 14, respectively). Seven of 11 patients in the recurrence group treated with carotid endarterectomy remained free of ischemic events during a postoperative follow-up of 19.1 ± 14.6 months.

CONCLUSION:

Symptomatic low-grade carotid stenosis with vulnerable plaque confirmed by MRI was associated with a high rate of stroke recurrence that was refractory to aggressive medical treatment. However, carotid endarterectomy was safe and effective for such patients. Plaque characterization by MRI has the potential for more accurate stroke risk stratification in the management of carotid low-grade stenosis.

Endothelial function affects early carotid atherosclerosis progression in hypertensive postmenopausal women

OBJECTIVES

Endothelial dysfunction is known to be associated with atherosclerosis progression and cardiovascular events. Limited information exists regarding the importance of this topic in hypertensive postmenopausal women. In this particular population the influence of endothelial dysfunction on cardio-vascular end cerebro-vascular events is well demonstrated. Therefore, we investigated, in a prospective study, the influence of endothelial-dependent vasodilation on carotid intima-media thickness (IMT) progression in our population of hypertensive postmenopausal women.

METHODS

In addition to common risk factors and pharmacological therapy, we measured carotid IMT and flow-mediated dilation (FMD) of the brachial artery at baseline and after 1 year of follow-up.

RESULTS

Baseline and follow-up data were available for 618 hypertensive postmenopausal women with an age of 55 ± 8 years. The mean IMT at baseline was 754 ± 161 μm [interquartile range (IQR) from 600 to 838 μm]. The mean FMD at baseline was 5.8 ± 3.9% (IQR from 3.2 to 8.2%). There was a significant correlation between baseline FMD and carotid IMT (r = -0.16; P = 0.003). Mean IMT progression resulted in 103 μm (range from -250 to 567 μm; IQR from 0 to 200 μm) per year. Baseline FMD, FMD change and the amount of SBP reduction during follow-up remained the independent predictors of IMT progression in multivariable analysis.

CONCLUSIONS

In this prospective study we observed a significant interaction between baseline FMD, FMD change during follow-up and IMT progression in our population of hypertensive postmenopausal women. These results are in accordance with the suggestion that endothelial dysfunction is associated with enhanced atherosclerosis development. This hypothesis could provide a pathophysiological explanation for the increase in cardio-vascular and cerebro-vascular episodes recorded in hypertensive postmenopausal women with endothelial dysfunction.

Noninvasive carotid artery imaging with a focus on the vulnerable plaque

Currently carotid imaging has 2 main focuses: assessment of luminal stenosis and classification of atherosclerotic plaque characteristics. Measurement of the degree of stenosis is the main assessment used for current treatment decision making, but an evolving idea that is now driving imaging is the concept of vulnerable plaque, which is where plaque components are identified and used to define which plaques are at high risk of causing symptoms compared with those at low risk. This review article covers the methods used for noninvasive assessment of carotid luminal stenosis and the options available for plaque imaging.

Carotid plaque age is a feature of plaque stability inversely related to levels of plasma insulin

Background

The stability of atherosclerotic plaques determines the risk for rupture, which may lead to thrombus formation and potentially severe clinical complications such as myocardial infarction and stroke. Although the rate of plaque formation may be important for plaque stability, this process is not well understood. We took advantage of the atmospheric ¹⁴C-declination curve (a result of the atomic bomb tests in the 1950s and 1960s) to determine the average biological age of carotid plaques.

Methodology/Principal Finding

The cores of carotid plaques were dissected from 29 well-characterized, symptomatic patients with carotid stenosis and analyzed for ¹⁴C content by accelerator mass spectrometry. The average plaque age (i.e. formation time) was 9.6±3.3 years. All but two plaques had formed within 5–15 years before surgery. Plaque age was not associated with the chronological ages of the patients but was inversely related to plasma insulin levels (p = 0.0014). Most plaques were echo-lucent rather than echo-rich (2.24±0.97, range 1–5). However, plaques in the lowest tercile of plaque age (most recently formed) were characterized by further instability with a higher content of lipids and macrophages (67.8±12.4 vs. 50.4±6.2, p = 0.00005; 57.6±26.1 vs. 39.8±25.7, p<0.0005, respectively), less collagen (45.3±6.1 vs. 51.1±9.8, p<0.05), and fewer smooth muscle cells (130±31 vs. 141±21, p<0.05) than plaques in the highest tercile. Microarray analysis of plaques in the lowest tercile also showed increased activity of genes involved in immune responses and oxidative phosphorylation.

Conclusions/Significance

Our results show, for the first time, that plaque age, as judge by relative incorporation of ¹⁴C, can improve our understanding of carotid plaque stability and therefore risk for clinical complications. Our results also suggest that levels of plasma insulin might be involved in determining carotid plaque age.

Uptake of F-18 FDG and ultrasound analysis of carotid plaque

OBJECTIVES

To elucidate the relation between the echolucent plaque on carotid ultrasound and acute inflammation on F-18 FDG carotid PET/CT.

METHODS

Thirty nine patients (M:F ratio = 23:16, mean age = 63 ± 11 years) that underwent coronary angiography and carotid ultrasound were divided into three groups-echolucent plaque (n = 22), calcified (n = 10), and no plaque(n = 7). All the patients underwent F-18 FDG carotid PET/CT. The mean standardized uptake values (SUV), namely target to background ratio (TBR) on 180 minutes delayed F-18 FDG carotid PET/CT images were compared with levels of serum inflammatory markers and lipid profiles, and in terms of the presence of carotid plaque on carotid US.

RESULTS

180 minutes TBR of carotid arterial wall at echolucent plaque, calcified plaque, and no plaque were 1.40 ± 0.05, 1.23 ± 0.03, 1.17 ± 0.03 in both carotid artery. TBR of carotid arterial walls for echolucent plaque were significantly larger than TBR for calcified, and no plaque respectively at the both side of carotid artery (P < .05). Serum HDL levels were found to be inversely correlated with F-18 FDG uptake at both carotid arteries (r = -0.43, P = .005) on 180 minutes delayed phase images. Also serum hs-CRP levels were found to be correlated with F-18 FDG TBR values of right carotid arteries (r = 0.41, P = .04).

CONCLUSIONS

Our results show that F-18 FDG carotid PET/CT can depict metabolically active atherosclerotic plaques, and suggest that F-18 FDG carotid PET/CT can be used as a noninvasive imaging modality for functional evaluation of atherosclerosis.

Comparison of degree of stenosis and plaque volume for the assessment of carotid atherosclerosis using 2-D ultrasound

The degree of carotid stenosis (%ST) remains the most frequently used parameter for identifying patients with high risk of stroke but the relationship between %ST and the occurrence of stroke remains controversial. The objectives of this study were to check (1) the relationship between the %ST and the plaque volume index (PVI) as measured by echography and Doppler, (2) the relationship between the intima media thickness (IMT), a vessel wall remodeling index and the PVI an atheromatous growth index. For each of the 128 patients, (165 carotid stenosis), we measured the % ST (section or diameter), the max stenosis velocity (V(max)), the PVI and the common carotid IMT. The %ST (section) ranged from 10% to 93% (mean 66+/-18), V(max) from 0.3m/s to 3m/s (mean 1.2+/-0.8), PVI from 0.61cm(3) to 1.17cm(3) (mean 0.41+/-0.21) and the IMT from 0.08cm up to 0.31cm (mean 0.12+/-0.03). There was no significant correlation between either PVI and %ST (section or diameter), PVI and minimal stenosis section area (S1) or between PVI and V(max). There was no significant correlation between IMT and both %ST area and PVI. PVI was significantly correlated with the whole artery section area (S2) and the plaque length (L). The %ST (section or diameter) was significantly correlated with S1 but not with S2. The absence of correlation between the PVI and the %ST confirm that these two parameters describe two different processes of the atheromatous development.