Intraplaque hemorrhage: its significance in cerebrovascular disease

Roadmap Consensus on Carotid Artery Plaque Imaging and Impact on Therapy Strategies and Guidelines: An International, Multispecialty, Expert Review and Position Statement

Current guidelines for primary and secondary prevention of stroke in patients with carotid atherosclerosis are based on the quantification of the degree of stenosis and symptom status. Recent publications have demonstrated that plaque morphology and composition, independent of the degree of stenosis, are important in the risk stratification of carotid atherosclerotic disease. This finding raises the question as to whether current guidelines are adequate or if they should be updated with new evidence, including imaging for plaque phenotyping, risk stratification, and clinical decision-making in addition to the degree of stenosis. To further this discussion, this roadmap consensus article defines the limits of luminal imaging and highlights the current evidence supporting the role of plaque imaging. Furthermore, we identify gaps in current knowledge and suggest steps to generate high-quality evidence, to add relevant information to guidelines currently based on the quantification of stenosis.

Review of imaging biomarkers for the vulnerable carotid plaque

Identification of carotid artery atherosclerosis is conventionally based on measurements of luminal stenosis. However, histopathologic studies demonstrate considerable differences between plaques with identical degrees of stenosis and indicate that certain plaque features are associated with increased risk for ischemic events. As a result of the rapid technological evolution in medical imaging, several important steps have been taken in the field of carotid plaque imaging allowing us to visualize the carotid atherosclerotic plaque and its composition in great detail. For computed tomography, magnetic resonance imaging, positron emission tomography, and ultrasound scan, evidence has accumulated on novel imaging-based markers that confer information on carotid plaque vulnerability, such as intraplaque hemorrhage and lipid-rich necrotic cores. In terms of the imaging-based identification of individuals at high risk of stroke, routine assessments of such imaging markers are the way forward for improving current clinical practice. The current review highlights the main characteristics of the vulnerable plaque indicating their role in the etiology of ischemic stroke as identified by intensive plaque imaging.

The Influence of Carotid Plaque Morphology on the Development of Cerebral Symptoms

Background: Large randomized trials such as the European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET) have defined a role for carotid endarterectomy in symptomatic patients with severe carotid artery stenosis. Data from the same trials also shows that a subgroup of patients with less severe stenosis with a higher risk of stroke might benefit form carotid endarterectomy. In recent years, it has become apparent that besides the degree of stenosis, the morphology of the plaque itself plays a significant role in its potential for development of symptoms, and noninvasive methods of assessing plaque morphology are currently being developed. This paper reviews the literature regarding the relationship between carotid plaque morphology and the potential for development of clinical symptoms.

Methods: A Medline search and a meta-analysis of the literature was carried out. Intraplaque hemorrhage and plaque ulceration were both found to be associated with a higher risk of stroke development (p = 0.001 and 0.0001, respectively). Intraluminal thrombus was not found to be associated with an increased risk of symptom development in the data analyzed. A possible explanation for this incongruous finding is discussed. In addition, the paper also discusses the role of noninvasive plaque characterization as a method of identifying unstable plaques in the future.

Conclusion: Certain characteristics of plaque morphology correlate with a higher risk of development of symptoms and better noninvasive identification of plaque characterization will lead to better patient selection and may be especially useful identifying patients with lower degrees of stenosis but with potentially unstable plaques who might benefit from carotid endarterectomy but do not qualify for surgery using currently accepted criteria.

Total burden of intraplaque hemorrhage in coronary arteries relates to the use of coumarin-type anticoagulants but not platelet aggregation inhibitors

Intraplaque hemorrhage (IPH) is a crucial factor in progression and destabilization of an atherosclerotic plaque. Anti-thromboembolic drugs are widely used as prophylactic treatment against arterial and venous thrombotic diseases, but a major complication is bleeding. We investigated the association between exposure to anti-thromboembolic therapy and IPH in postmortem coronary arteries. Coronary arteries with postmortem angiographically confirmed extensive atherosclerosis were obtained at autopsy from patients who had received oral anticoagulants (n = 10), platelet aggregation inhibitors (n = 10), or no anti-thrombotic drugs (n = 10) before death. Coronary arteries were cut at 3-mm interval, and all plaque-containing segments were immunohistochemically screened for IPH and microvessels. These data were related to overall plaque composition and the use of anti-thromboembolic therapies. IPH was found in 483 out of 904 (53 %) coronary segments with advanced atherosclerotic plaques and more frequently in patients on oral anticoagulants (174/284, 61 %) than in patients on anti-platelets (198/376, 53 %) or without therapy (111/244, 46 %) (P = 0.02 and P = 0.001, respectively). Also, intraplaque microvascular leakage was more frequently observed in patients on anticoagulants than in non-treated patients (P = 0.03). Finally, the IPH appeared to be larger in plaques of patients on anticoagulant treatment (P < 0.001). Density of intraplaque microvessels was highest in plaques of patients on platelet inhibitors (P < 0.05), but this was not associated with increased hemorrhagic burden. Prophylactic therapy with oral coumarin-type anticoagulants appears to be associated with a higher hemorrhagic burden in atherosclerotic coronary arteries, which may lead to increase in plaque volume over time, in this selected subgroup of patients.

Plaque hemorrhage in carotid artery disease: pathogenesis, clinical and biomechanical considerations

Stroke remains the most prevalent disabling illness today, with internal carotid artery luminal stenosis due to atheroma formation responsible for the majority of ischemic cerebrovascular events. Severity of luminal stenosis continues to dictate both patient risk stratification and the likelihood of surgical intervention. But there is growing evidence to suggest that plaque morphology may help improve pre-existing risk stratification criteria. Plaque components such a fibrous tissue, lipid rich necrotic core and calcium have been well investigated but plaque hemorrhage (PH) has been somewhat overlooked. In this review we discuss the pathogenesis of PH, its role in dictating plaque vulnerability, PH imaging techniques, marterial properties of atherosclerotic tissues, in particular, those obtained based on in vivo measurements and effect of PH in modulating local biomechanics.

Reprinted article "Carotid artery plaque composition--relationship to clinical presentation and ultrasound B-mode imaging"

OBJECTIVE

To correlate B-mode ultrasound findings to carotid plaque histology.

DESIGN

European multicentre study (nine centres).

MATERIAL AND METHODS

Clinical presentation and risk factors were recorded and preoperative ultrasound Duplex scanning with special emphasis on B-mode imaging studies was performed in 270 patients undergoing carotid endarterectomy. Perioperatively, macroscopic plaque features were evaluated and the removed specimens were analysed histologically for fibrous tissue, calcification and 'soft tissue' (primarily haemorrhage and lipid).

RESULTS

Males had more soft tissue than females (p = 0.0006), hypertensive patients less soft tissue than normotensive (p = 0.01) and patients with recent symptoms more soft tissue than patients with earlier symptoms (p = 0.004). There was no correlation between surface description on ultrasound images compared to the surface judged intraoperatively by the surgeon. Echogenicity on B-mode images was inversely related to soft tissue (p = 0.005) and calcification was directly related to echogenicity (p < 0.0001). Heterogeneous plaques contained more calcification than homogeneous (p = 0.003), however, there was no difference in content of soft tissue.

CONCLUSION

Ultrasound B-mode characteristics are related to the histological composition of carotid artery plaques and to patient's history. These results may imply that patients with distant symptoms may be regarded and treated as asymptomatic patients whereas asymptomatic patients with echolucent plaques should be considered for carotid endarterectomy.

MRI of carotid atherosclerosis: clinical implications and future directions

Atherosclerosis is now widely recognized as a multifactorial disease with outcomes that arise from complex factors such as plaque components, blood flow, and inflammation. Despite recent advances in understanding of plaque biology, diagnosis, and treatment, atherosclerosis remains a leading cause of morbidity and mortality. Further research into the development and validation of reliable indicators of the high-risk individual is greatly needed. Carotid MRI is a histologically validated, noninvasive imaging method that can track disease progression and regression, and quantitatively evaluate a spectrum of parameters associated with in vivo plaque morphology and composition. Intraplaque hemorrhage and the lipid-rich necrotic core are the best indicators of lesion severity currently visualized by carotid MRI. However, MRI methods capable of imaging other important aspects of carotid atherosclerotic disease in vivo-including inflammation, neovascularization, and mechanical forces-are emerging and may aid in advancing our understanding of the pathophysiology of this multifactorial disease.

Atherosclerotic plaque rupture and intraplaque hemorrhage do not correlate with symptoms in carotid artery stenosis

OBJECTIVE

Previously we failed to demonstrate a correlation between plaque type and symptoms in 165 carotid endarterectomy specimens. The purpose of this study was to analyze the relation between the anatomy of the carotid plaques and the presence of symptoms in 281 carotid endarterectomy specimens.

METHODS

The patients were 213 men (mean age, 68 years) and 68 women (mean age, 68.7 years), with symptomatic disease (n = 133) or asymptomatic disease (n = 148). Specimens were processed for histologic analysis and immunohistochemistry.

RESULTS

Plaques were categorized as complicated or noncomplicated, and ruptured or nonruptured. Risk factors could not be correlated with any pathologic or immunohistochemical findings or between plaque type and clinical symptoms.

CONCLUSIONS

Almost 70% of plaque specimens demonstrated thrombus, intraplaque hemorrhage, or both. Thrombosis was observed in one fourth of specimens, and intraplaque hemorrhage in almost two thirds of specimens. Sixty four percent of plaques demonstrated neovascularization. It was not possible to demonstrate that complicated plaques (plaque rupture, thrombosis, intraplaque hemorrhage) are associated with symptoms, and it appears that such plaques may occur at any time, irrespective of symptoms.

Stroke: epidemiology, clinical picture, and risk factors--Part I of III

The aim of this review is to present the current knowledge regarding stroke. It will appear in three parts (in part II the pathogenesis, investigations, and prognosis will be presented, while part III will consist of the management and rehabilitation). In the current part (I) the definitions of the clinical picture are presented. These include: amaurosis fugax, vertebrobasilar transient ischemic attack, and stroke (with good recovery, in evolution and complete). The role of the following risk factors is discussed in detail: age, gender, ethnicity, heredity, hypertension, cigarette smoking, hyperlipidemia, diabetes mellitus, obesity, fibrinogen and clotting factors, oral contraceptives, erythrocytosis and hematocrit level, prior cerebrovascular and other diseases, physical inactivity, diet and alcohol consumption, illicit drug use, and genetic predisposition. In particular, regarding the carotid arteries, the following characteristics are analyzed: atheroma, carotid plaque echomorphology, carotid stenosis, presence of ulcer, local variations in surface deformability, pathological characteristics, and dissection. Finally the significance of the cerebral collateral circulation and the conditions predisposing to cardioembolism and to cerebral hemorrhage are presented.

The symptomatic carotid plaque

BACKGROUND

The natural histories of equally severe symptomatic and asymptomatic carotid stenoses are very different, which suggests dichotomy in plaque behavior. The vascular biology of the symptomatic carotid plaque is presented in this review.

SUMMARY OF REVIEW

Histology studies comparing asymptomatic and symptomatic plaques were identified from MEDLINE. Reports in which stenosis severity was not stated or not similar for symptomatic and asymptomatic patients were excluded. In vitro studies and reports from the coronary circulation were reviewed with regard to the vascular biology of the plaque. Histology studies comparing carotid plaques removed from symptomatic and asymptomatic patients reveal characteristic features of unstable plaques: surface ulceration and plaque rupture (48% of symptomatic compared with 31% of asymptomatic, P<0.001), thinning of the fibrous cap, and infiltration of the cap by greater numbers of macrophages and T cells. In vitro studies suggest that macrophages and T cells release cytokines and proteinase, which stimulate breakdown of cap collagen and smooth muscle cell apoptosis and thereby promote plaque rupture.

CONCLUSIONS

Infiltration of inflammatory cells to the surface of carotid plaques may be a critical step in promoting plaque rupture and resultant embolization or carotid occlusion. Further understanding of cell recruitment and behavior in carotid atherosclerosis may allow better detection of unstable plaques and therapeutic methods of plaque stabilization.

Cerebral ischemic disease and morphometric analyses of carotid plaques

Atherosclerotic carotid plaque morphology and especially, intraplaque hemorrhage are assumed to be related to neurological symptoms. Most researchers have only investigated the incidence of intraplaque hemorrhage in symptomatic and asymptomatic patients. In the present study, the amount of intraplaque hemorrhage is determined in carotid endarterectomy specimens from 33 symptomatic and 14 asymptomatic patients that caused >70% luminal stenosis. The plaque components (fibrosis, lipids, intraplaque hemorrhage, calcification, and intraluminal thrombosis) were quantified as a percentage of the total plaque volume. A high incidence of intraplaque hemorrhage was found in both the symptomatic (94%, 31/33) and asymptomatic (71%, 10/14) patients. The amount of intraplaque hemorrhage was very small within the plaques of the symptomatic (0.39% +/- 0.70%) and asymptomatic (0.37% +/- 1.12%) patients. The plaques of the symptomatic patients contained more fibrosis than lipids (45.62% +/- 14.99% and 20.45% +/- 21.45%, respectively), as did the plaques of the asymptomatic patients (42. 51% +/- 15.28% and 15.46% +/- 15.22%, respectively). Finally, intraluminal thrombosis and calcification were rare. We conclude that the amount of intraplaque hemorrhage was very small and therefore question its direct role in the development of neurological symptoms. In general, the "unstable" plaque contained more fibrosis than lipids.

Ultrasound and lipoproteins as predictors of lipid-rich, rupture-prone plaques in the carotid artery

The aim of this review is to summarize present knowledge of the ultrasonic detection and determinants of carotid atherosclerosis with lipid-rich cores and to review the evidence that these measures of plaque type may predict cerebral events. With the use of high-resolution ultrasound B-mode imaging, carotid plaques evaluated as only weakly reflecting the ultrasound beam (echolucent) have been associated with a higher risk of neurological events than are plaques reflecting the ultrasound signal strongly (echorich). Histologically, these echolucent plaques have a higher content of lipid and hemorrhage than do echorich plaques, which contain more calcification and fibrous tissue. Findings in the coronary arteries indicate that a lipid-rich plaque with a thin, fibrous cap is more vulnerable, is more prone to rupture, and cause symptoms compared with fibrous plaques. A search for determinants in the blood for these vulnerable plaques suggests that low density lipoprotein (LDL) cholesterol is the best lipid predictor for the extent of atherosclerosis, whereas triglyceride-rich lipoproteins in particular seem to predict an echolucent plaque. Lowering of LDL cholesterol and triglyceride-rich lipoproteins in plasma is associated with reduced progression of coronary atherosclerosis and coronary events. LDL cholesterol reduction is also associated with a reduced stroke rate. These improvements in the prognosis are thought to be the result of a reduction in the lipid content of the plaques, making them more stable and resistant to rupture rather than an actual reduction in plaque volume and degree of stenosis. In conclusion, it appears that ultrasound B-mode imaging as well as lipoproteins presumably may predict dangerous and rupture-prone, lipid-rich plaques in the carotid arteries, thereby being potential diagnostic tools in the prevention of neurological events.

Clinical significance of intraplaque hemorrhage in carotid artery disease

Previous research has indicated that intraplaque hemorrhage is a significant pathogenetic factor in carotid artery disease. The present study was undertaken to evaluate whether the clinical presentation of patients with carotid artery disease could be correlated to quantitative histologic analysis of surgically removed carotid specimens. Two-hundred-seventy patients undergoing carotid endarterectomy comprised the material. Symptomatology was assessed preoperatively. After removal, the carotid plaques were analyzed histologically for relative volume content of hemorrhage, fatty tissue, fibrous tissue, and calcification. There was no difference between asymptomatic and symptomatic patients. However, when the time interval between onset of symptoms and surgery was considered, plaques from patients with recent symptoms contained more hemorrhage compared with plaques from asymptomatic patients (p = 0.0045). The paper supports the theory of intraplaque hemorrhage being related to clinical events in carotid artery disease.

Acute pathologic features with angiographic correlates of the nearly or completely occluded lesions of the cervical internal carotid artery

BACKGROUND

The true pathologic process of nearly or completely occluded lesions of the cervical internal carotid artery (ICA) has not been studied sufficiently. This information is important in determining the critical indications for endarterectomy.

METHODS

Acute pathologic features of these advanced occlusive lesions of the ICA were studied in 40 patients who underwent emergency carotid endarterectomy. Gross morphologic and histopathologic features of these occlusive lesions were examined, and the relationship between the clinical information and the pathologic characteristics was investigated.

RESULTS

Thirty-seven lesions had histologic features of advanced atherosclerosis complicated by fresh intraplaque hemorrhages with or without transintimal extension. Thinwalled neovessels were thought to be an important etiologic factor in producing intraplaque hemorrhage. The remaining three lesions without these changes had strangulated embolic material at the occluded portion. A good correlation between these pathologic features and angiographic findings was found.

CONCLUSION

The presented results clearly indicate that intraplaque hemorrhage is the most important factor in producing and determining the acute pathologic features of symptomatic and advanced atheromatous occlusive ICA lesions.

Carotid artery plaque composition--relationship to clinical presentation and ultrasound B-mode imaging. European Carotid Plaque Study Group

OBJECTIVE

To correlate B-mode ultrasound findings to carotid plaque histology.

DESIGN

European multicentre study (nine centres).

MATERIAL AND METHODS

Clinical presentation and risk factors were recorded and preoperative ultrasound Duplex scanning with special emphasis on B-mode imaging studies was performed in 270 patients undergoing carotid endarterectomy. Perioperatively, macroscopic plaque features were evaluated and the removed specimens were analysed histologically for fibrous tissue, calcification and 'soft tissue' (primarily haemorrhage and lipid).

RESULTS

Males had more soft tissue than females (p = 0.0006), hypertensive patients less soft tissue than normotensive (p = 0.01) and patients with recent symptoms more soft tissue than patients with earlier symptoms (p = 0.004). There was no correlation between surface description on ultrasound images compared to the surface judged intraoperatively by the surgeon. Echogenicity on B-mode images was inversely related to soft tissue (p = 0.005) and calcification was directly related to echogenicity (p < 0.0001). Heterogeneous plaques contained more calcification than homogeneous (p = 0.003), however, there was no difference in content of soft tissue.

CONCLUSION

Ultrasound B-mode characteristics are related to the histological composition of carotid artery plaques and to patient's history. These results may imply that patients with distant symptoms may be regarded and treated as asymptomatic patients whereas asymptomatic patients with echolucent plaques should be considered for carotid endarterectomy.

Plaque ulceration and lumen thrombus are the main sources of cerebral microemboli in high-grade internal carotid artery stenosis

BACKGROUND AND PURPOSE

Previous work has shown that rates of cerebral microemboli downstream of high-grade internal carotid artery stenosis are higher in recently symptomatic compared with asymptomatic patients. In addition, microembolic rates decline after carotid endarterectomy. We conducted a prospective investigation of 40 consecutive asymptomatic or recently symptomatic patients undergoing carotid endarterectomy for 70% to 95% internal carotid artery stenosis to determine the relationship between microembolic rate and pathoanatomic features of the carotid plaque.

METHODS

Transcranial Doppler monitoring including automated emboli detection was performed preoperatively to assess the rate of cerebral microemboli of the ipsilateral middle cerebral artery. The corresponding endarterectomy specimens were evaluated histologically with respect to the occurrence of plaque fissuring, intraplaque hemorrhage, plaque ulceration, or intraluminal thrombosis.

RESULTS

There were strong associations between plaque ulceration, intraluminal thrombosis, and downstream cerebral microemboli (P < or = .005, respectively). There were no correlations of microembolism with plaque fissuring or intraplaque hemorrhage (P = .82 and P = .28, respectively).

CONCLUSIONS

We conclude that ulceration and luminal thrombosis of the atheromatous plaque are the main sources of downstream cerebral microemboli in patients with high-grade internal carotid artery stenosis. Our data support the view that these pathoanatomic features may also play a key role in symptom development.

Carotid endarterectomy plaques: correlations of clinical and anatomic findings

To establish possible relationships between the structure of carotid plaque and neurologic symptoms, 187 consecutive endarterectomy specimens were studied prospectively. Each specimen was examined for gross and histopathological features. Intraplaque hemorrhage, although found infrequently, was closely correlated with the presence of symptoms. Plaque ulcerations were encountered more often when lesions were symptomatic. Calcifications were more frequently associated with asymptomatic lesions. Consistency of plaque was related to its morphological features (stenosis or ulceration) and symptoms. Soft plaques with predominant atheromatous grumous material and hemorrhage were associated more often with tightly stenotic, ulcerated, and symptomatic lesions. Consistency of atherosclerotic carotid plaques should be assessed and considered as an important element in the therapeutic decision.

Rupture of atheromatous plaque as a cause of thrombotic occlusion of stenotic internal carotid artery

We analyzed the clinical profiles and autopsy findings of five patients who died shortly after developing cerebral infarction following thrombotic occlusion of the internal carotid artery. In all five cases, thrombotic occlusion was caused by rupture of the fibrous lining over the gruel of atheroma at the origin of the internal carotid artery showing tight stenosis of the lumen. The mean +/- SD shorter diameter of the lumen at the site of occlusion was 1.5 +/- 0.4 mm. Our results show that an internal carotid artery with tight stenosis of the lumen by atheroma containing gruel harbors a risk of thrombotic occlusion, which may give rise to cerebral infarction by artery-to-artery embolism or by reduced cerebral perfusion.

"Haemorrhagic" carotid plaque does not contain haemorrhage

The presence of haemorrhage in carotid bifurcation atheromatous plaques is widely believed to be associated with the production of ischaemic neurological events. This study set out to characterise plaque composition in symptomatic (SYM) and asymptomatic (ASYM) patients and to identify, if possible, the origin of intra-plaque haemorrhage. Fifty-nine plaques (50 SYM and 9 ASYM) were serially sectioned and examined for haemorrhage, haemosiderin, fibrin, cholesterol and collagen. Immunoperoxidase and electron microscopy studies were carried out on sections from five plaques in order to identify blood breakdown products. Intra-plaque haemorrhage was identified in 40 (68%) plaques and was similar in SYM and ASYM plaques. In only one did it constitute more than 15% of plaque content, and in the remainder it consisted of small collections of erythrocytes constituting greater than 1% of plaque content in only 21 (35%) plaques. The predominant non-fibrous component was a pink amorphous material mixed with cholesterol. Apart from traces of platelet breakdown products there was no evidence of haemorrhage in this pink material. Plaque roof rupture or ulceration was seen in 39 (66%) and in almost all cases overlay the amorphous/cholesterol material. Blood vessels were identified in 51 87%) plaques but were in close proximity to haemorrhage in only nine (15%).

Safe extracranial vascular evaluation and surgery without preoperative arteriography

Carotid surgery without preoperative arteriography was performed in 101 consecutive patients with an average age of 68.5 years and almost equal sex distribution. This prospective study analyzed risk factors, operative approach, bruits, indications for surgery, and outcome. All patients were studied by real-time B-mode ultrasound and spectral analysis and none were referred for arteriogram. The majority of patients had a standard carotid endarterectomy, and the findings at surgery correlated with noninvasive imaging. No mortality was recorded in this series of patients; a 1% rate of neurologic morbidity was noted. These results suggest that one can safely operate on the basis of a duplex scan. A preoperative arteriogram is not always necessary for carotid evaluation.

Pathogenesis of carotid thrombosis

We histologically examined specimens from 11 patients with recent occluding thrombi at the carotid bifurcation to study local factors in the vessel wall that precipitated the thrombi. The area of stenosis of the vessel lumen was determined morphometrically. Severe atherosclerotic stenosis was frequent but was not a prerequisite for thrombus formation since specimens from almost one half of the patients had only moderate narrowing of the lumen (less than 60% stenosis). Specimens from three patients showed ulcerations, those from one showed intraplaque hemorrhage, and those from one massive plaque rupture, all of which were thought to be important in thrombogenesis. All such types of plaque complications may thus precipitate thrombi but no single complication was particularly predominant, and specimens from one half of the patients showed no complications at all. Screening of the carotid arteries for stenosis can therefore detect only one half of the individuals who ultimately will develop thrombosis, and the risk caused by plaque complications seems to be moderate in unselected materials.

Atherosclerotic carotid disease in asymptomatic individuals: An histological study of 53 cases

The carotid bifurcation was studied histologically in 53 consecutive autopsies from persons over 65 years of age who were asymptomatic for carotid artery disease and showed no carotid related brain infarcts. The autopsy material is considered to be representative for the population in Oslo. The area stenosis was determined morphometrically in histological sections and the cases were examined for the occurrence of atherosclerotic plaques, calcifications, plaque hemorrhages, ulcerations, and mural thrombi. About one half of the cases had more than 50% stenosis. There was increasing frequency of plaque hemorrhages, ulcerations and mural thrombi with increasing stenosis. When the stenosis exceeded 60%, most cases had small recent and old plaque hemorrhages and one half had ulcerations and mural thrombi. In addition, numerous healed ulcerations and organized thrombi were seen. It is concluded that plaque complications are frequent in cases with stenosis and that most of them apparently heal without giving rise to symptoms. The presence of such lesions in asymptomatic cases must therefore be interpreted with caution.

Lack of association between carotid plaque hematoma and ischemic cerebral symptoms

To investigate the association between carotid plaque hematoma and symptoms of cerebral ischemia a retrospective review of 200 consecutive carotid endarterectomies at the Neurological Institute of New York was carried out. Data analyzed included cerebral ischemic symptoms, angiographic findings, preoperative use of antithrombotic agents, and microscopic pathology of endarterectomy specimens. No association was found between ischemic symptoms ipsilateral to the endarterectomy and presence, size, or age of plaque hematomas. Plaque hematomas were less common among patients who took antithrombotic agents preoperatively than among those who did not. The presence of plaque hematoma was associated with angiographic carotid cross-sectional area stenosis of greater than 75%. Patients with stenosis of less than 75% were more likely than those with stenosis of greater than 75% to have ischemic symptoms ipsilateral to the endarterectomy, suggesting that criteria for surgical treatment of carotid atherosclerosis differ for those who are symptomatic vs. those who are asymptomatic. These results demonstrate the limitation of using a surgical series to extend causal inferences about the relation between plaque hematoma and cerebral ischemic symptoms to the general population of people with carotid atherosclerosis.

The effect of antiplatelet therapy on the incidence of carotid plaque hemorrhage

Hemorrhage into the carotid atheroma has recently been gaining attention with respect to the pathophysiology of cerebrovascular disease. Many patients are currently receiving platelet agents for various vascular diseases. Some researchers have postulated that antiplatelet therapy may be detrimental by possibly inducing intraplaque hemorrhage or by increasing preexisting hemorrhage. This retrospective study was undertaken to determine if the use of antiplatelet therapy increases the incidence of carotid plaque hemorrhage. Ninety-five consecutive carotid endarterectomies were performed and the atheromas examined microscopically for intraplaque hemorrhage. The atheromas were divided into two groups; those from patients receiving preoperative antiplatelet therapy and those who were not. Forty-five atheromas were removed from patients receiving preoperative antiplatelet therapy; 39 (87%) of these demonstrated intraplaque hemorrhage. Of the 50 atheromas which were removed from patients not receiving preoperative therapy, 45 (90%) showed intraplaque hemorrhage. We conclude that antiplatelet therapy does not increase the incidence of carotid plaque hemorrhage.