Age and coumarin-type anticoagulation are associated with the occurrence of intraplaque hemorrhage, while statins are associated less with intraplaque hemorrhage: A large histopathological study in carotid and femoral plaques

Evaluation of the Correlation Between Distribution Location and Vulnerability of Carotid Plaque in Patients with Transient Ischemic Attack

Purpose

To analyze the relationship among distribution location, characteristics, and vulnerability of carotid plaque using CTA and provide more information on the risk factors of carotid atherosclerotic plaque.

Patients and Methods

We retrospectively analyzed the CTA images of the head and neck of 93 patients with carotid atherosclerosis. Atherosclerosis was developed in 148 carotid arteries. The plaques were divided into a high-risk plaque group and a low-risk plaque group according to whether the plaques had high-risk characteristics. The maximum cross-sectional area of carotid artery bifurcation plaque on the axial image was selected, and the cross-sectional lumen was equally divided into four 90-degree sectors, ventral side wall, dorsal side wall, inner side wall, and outer side wall. The differences in the characteristics and distribution locations of the plaques in the two groups were analyzed. The characteristic parameters of the cross-sectional plaques at the bifurcation of the carotid artery. The logistic regression analysis was used to further analyze the risk factors associated with plaque vulnerability.

Results

Among 148 carotid arteries,80 were classified as high-risk and 68 as low-risk groups. There were significant differences between the two groups concerning the thickness, length, maximum cross-sectional area, burden, and cross-sectional distribution of the plaques (P < 0.05). The plaque distribution on the dorsal side wall of the carotid bifurcation was higher in the high-risk group than that in the low-risk group (P < 0.05), dorsal side wall plaque-independent risk factors for the development of vulnerability of plaques in transient ischemic attack (TIA) patients (95% CI:1.522~6.991, P<0.05).

Conclusion

High-risk plaques tend to occur on the dorsal side wall of the carotid bifurcation, whereas low-risk plaques tend to occur on the outer side wall of the carotid bifurcation.

Carotid Plaques From Symptomatic Patients With Mild Stenosis Is Associated With Intraplaque Hemorrhage

Carotid plaque vulnerability features beyond the degree of stenosis may play a key role in the pathogenesis and recurrence of ischemic cerebrovascular events. This study sought to compare intraplaque hemorrhage (IPH) as a marker of plaque vulnerability in symptomatic patients with mild (<50%), moderate (50%-69%), and severe (≥70%) carotid artery stenosis. We included patients who experienced ischemic cerebrovascular events with no other identifiable sources and underwent carotid endarterectomy for mild (n=32), moderate (n=47), and severe (n=58) carotid artery stenosis. The degree of stenosis and imaging hallmarks were assessed by computed tomography angiography or magnetic resonance angiography. Plaque specimens were stained with hematoxylin and eosin and Movat pentachrome staining. Carotid plaques of patients with mild stenosis had a higher extent of IPH (%) on tissue analysis compared with patients with moderate (mild, 15.7% [interquartile range, 7.8%-26.7%]; moderate, 3.9% [0.0%-9.2%]; P<0.001) and severe carotid artery stenosis (mild, 15.7% [interquartile range, 7.8%-26.7%]; severe, 2.5% [interquartile range, 0.0%-11.2%]; P<0.001). When considering the degree of carotid artery stenosis as a continuous variable, a lower lumen narrowing was associated with higher extent of IPH (P<0.001; R, -0.329). Our major finding is the association of IPH with mild carotid artery stenosis based on histological analysis. The current study may suggest that IPH potentially plays a role in the mechanism of stroke in patients with nonobstructive carotid stenosis.

Pre-Operative Plasma Extracellular Vesicle Proteins are Associated with a High Risk of Long Term Secondary Major Cardiovascular Events in Patients Undergoing Carotid Endarterectomy

OBJECTIVE

Patients undergoing carotid endarterectomy (CEA) maintain a substantial residual risk of major cardiovascular events (MACE). Improved risk stratification is warranted to select high risk patients qualifying for secondary add on therapy. Plasma extracellular vesicles (EVs) are involved in atherothrombotic processes and their content has been related to the presence and recurrence of cardiovascular events. The association between pre-operative levels of five cardiovascular disease related proteins in plasma EVs and the post-operative risk of MACE was assessed.

METHODS

In 864 patients undergoing CEA from 2002 to 2016 included in the Athero-Express biobank, three plasma EV subfractions (low density lipoprotein [LDL], high density lipoprotein [HDL], and tiny extracellular vesicles [TEX]) were isolated from pre-operative blood samples. Using an electrochemiluminescence immunoassay, five proteins were quantified in each EV subfraction: cystatin C, serpin C1, serpin G1, serpin F2, and CD14. The association between EV protein levels and the three year post-operative risk of MACE (any stroke, myocardial infarction, or cardiovascular death) was evaluated using multivariable Cox proportional hazard regression analyses.

RESULTS

During a median follow up of three years (interquartile range 2.2 - 3.0), 137 (16%) patients developed MACE. In the HDL-EV subfraction, increased levels of CD14, cystatin C, serpin F2, and serpin C1 were associated with an increased risk of MACE (adjusted hazard ratios per one standard deviation increase of 1.30, 95% confidence interval [CI] 1.15-1.48; 1.22, 95% CI 1.06-1.42; 1.36, 95% CI 1.16-1.61; and 1.29, 95% CI 1.10-1.51; respectively), independently of cardiovascular risk factors. No significant associations were found for serpin G1. CD14 improved the predictive value of the clinical model encompassing cardiovascular risk factors (net re-classification index = 0.16, 95% CI 0.08-0.21).

CONCLUSION

EV derived pre-operative plasma levels of cystatin C, serpin C1, CD14, and serpin F2 were independently associated with an increased long term risk of MACE after CEA and are thus markers for residual cardiovascular risk. EV derived CD14 levels could improve the identification of high risk patients who may benefit from secondary preventive add on therapy in order to reduce future risk of MACE.

Carotid intraplaque haemorrhage: pathogenesis, histological classification, imaging methods and clinical value

Vulnerable carotid atherosclerotic plaques are characterised by several risk factors, such as inflammation, neovascularization and intraplaque haemorrhage (IPH). Vulnerable plaques can lead to ischemic events such as stroke. Many studies reported a relationship between IPH, plaque rupture, and ischemic stroke. Histology is the gold standard to evaluate IPH, but it required carotid endarterectomy (CEA) surgery to collect the tissue sample. In this context, several imaging methods can be used as a non-invasive way to evaluate plaque vulnerability and detect IPH. Most imaging studies showed that IPH is associated with plaque vulnerability and stroke, with magnetic resonance imaging (MRI) being the most sensitive and specific to detect IPH as a predictor of ischemic events. These conclusions are however still debated because of the limited number of patients included in these studies; further studies are required to better assess risks associated with different IPH stages. Moreover, IPH is implicated in plaque vulnerability with other risk factors which need to be considered to predict ischemic risk. In addition, MRI sequences standardization is required to compare results from different studies and agree on biomarkers that need to be considered to predict plaque rupture. In these circumstances, IPH detection by MRI could be an efficient clinical method to predict stroke. The goal of this review article is to first describe the pathophysiological process responsible for IPH, its histological detection in carotid plaques and its correlation with plaque rupture. The second part will discuss the benefits and limitations of imaging the carotid plaque, and finally the clinical interest of imaging IPH to predict plaque rupture, focusing on MRI-IPH.

Use of oral anticoagulant drugs is associated with carotid intraplaque hemorrhage in atherosclerosis patients: a meta-analysis

Patients with carotid atherosclerosis, especially the elderly population, take antithrombotic medicine regularly. However, no previous meta-analysis has focused on one of the possible side effects of such drugs, namely intraplaque hemorrhage (IPH). To determine whether antiplatelet drugs or anticoagulants are associated with an increased risk of carotid IPH. We searched Pubmed, Embase, Ovid MEDLINE, Cochrane Library for relevant studies that were published in English, from January 1st, 1989 to January 1st, 2019. We pooled the odds ratio (OR) with 95% confidence interval (CI) from individual studies and conducted quality assessment, heterogeneity, publication bias analysis and sensitivity analysis. A total of four cross-sectional studies, involving 2714 participants with carotid atherosclerotic plaques was included into this meta-analysis. We found a significant association between the use of anticoagulants and higher risk of carotid IPH (OR 1.95; 95% CI 1.16-3.30, P = 0.92; I² = 0). No significant association was found between the use of antiplatelet drugs and increased risk of carotid IPH (OR 1.34; 95% CI 0.68-2.61, P = 0.03; I² = 65%). Our meta-analysis reveals that it is the use of oral anticoagulants rather than antiplatelet drugs that may be associated with an increased risk of carotid IPH in atherosclerosis patients.

Association between physical activity and sedentary behaviour on carotid atherosclerotic plaques: an epidemiological and histological study in 90 asymptomatic patients

OBJECTIVE

Carotid atherosclerotic plaques are a source of emboli for stroke. 'Unstable' carotid atherosclerotic plaques may have intraplaque haemorrhages, neovessels, prevalent macrophages, excessive calcium deposits, a large lipid core and a thin fibrous cap. Regular physical activity (PA) may lower the risk of plaques becoming unstable. We evaluated the association of both PA and sedentary behaviour (SB) with carotid plaque histopathology.

METHODS

90 asymptomatic patients who were undergoing carotid endarterectomy for carotid artery narrowing identified on ultrasound reported their PA and SB by questionnaires. We calculated PA intensity in MET (metabolic equivalent of task)-min/week. For analysis, the population was divided into tertiles according to PA (T1PA: the less PA patients; T2PA: the intermediate PA patients; T3PA: the most physically active patients) (T1PA<T2PA<T3PA) and SB (T1SB: the less sedentary behaviour patients; T2SB: the intermediate sedentary behaviour patients; T3SB: the most sedentary behaviour patients) (T1SB<T2SB<T3SB). PA was categorised as one of four PA intensities (600, 900, 1600 and 3000 MET-min/week). We obtained the carotid artery plaque at surgery and performed histological analysis of intraplaque haemorrhages (present/absent), neovessels, macrophages, lipid core, calcium deposits and the fibrous cap.

RESULTS

Intraplaque haemorrhage was less frequent in the most physically active tertile (T3PA, 48%) versus T1PA (74%) and in the least sedentary tertile T1SB (50%) versus T3SB (71%). The intraplaque haemorrhage was less frequent in those who exercised more than 900 MET-min/week (59% vs 47% for >900 and <900 MET-min/week, respectively). All the other features that associate with plaque instability (eg, neovessels, macrophages, etc) did not differ by level of PA or SB.

CONCLUSION

In this cross-sectional study of asymptomatic patients who underwent endarterectomy (i) higher reported PA, (ii) intensity of PA and (iii) lower reported SB were associated with lower prevalence of intraplaque haemorrhage. This could be a mechanism whereby PA protects against cerebrovascular disease (stroke) and death.

Shape and Location of Carotid Atherosclerotic Plaque and Intraplaque Hemorrhage: A High-resolution Magnetic Resonance Imaging Study

Aim: The present study aimed to investigate the association between shape and location of atherosclerotic plaques and intraplaque hemorrhage (IPH) in carotid arteries using magnetic resonance (MR) imaging.

Methods: Overall, 114 symptomatic patients (mean age: 64.9±10.9 years; 81 males) who underwent MR imaging and had advanced carotid plaques were included in analysis. IPH presence and carotid plaque shape and location (below and above bifurcation) were evaluated. The plaque shape was defined as follows: type-I: the arc-length of plaque is greater in the upstream; type-II: the arc-length of plaque in downstream and upstream is equal; and type-III: the arc-length of plaque is greater in downstream. The plaque shape and location were compared between plaques with and without IPH and their associations with IPH were determined.

Results: Of 181detectedplaques, 57 (31.5%) had IPH. Compared with plaques without IPH, those with IPH had higher incidence of the plaque shape of type-I (66.7% vs. 32.2%, P<0.001), lower incidence of plaque shape of type-III (24.6% vs. 50.0%, P=0.001), and were more likely located above carotid bifurcation (71.9% vs. 48.4%, P=0.003). The plaque shape of type-I (OR, 4.01; 95%CI, 1.36–11.83; P=0.012) and location above bifurcation (OR, 3.21; 95%CI, 1.07–9.61; P=0.037) of carotid plaques were significantly associated with IPH after adjusting for confounder factors.

Conclusions: Carotid plaque shape and location are significantly associated with the occurrence of IPH. Our findings could provide new insights for the pathogenesis of IPH and vulnerably plaques.

The effects of pigment epithelium-derived factor on atherosclerosis: putative mechanisms of the process

Cardiovascular disease (CVD) is a leading cause of death worldwide. Atherosclerosis is believed to be the major cause of CVD, characterized by atherosclerotic lesion formation and plaque disruption. Although remarkable advances in understanding the mechanisms of atherosclerosis have been made, the application of these theories is still limited in the prevention and treatment of atherosclerosis. Therefore, novel and effective strategies to treat high-risk patients with atherosclerosis require further development. Pigment epithelium-derived factor (PEDF), a glycoprotein with anti-inflammatory, anti-oxidant, anti-angiogenic, anti-thrombotic and anti-tumorigenic properties, is of considerable interest in the prevention of atherosclerosis. Accumulating research has suggested that PEDF exerts beneficial effects on atherosclerotic lesions and CVD patients. Our group, along with colleagues, has demonstrated that PEDF may be associated with acute coronary syndrome (ACS), and that the polymorphisms of rs8075977 of PEDF are correlated with coronary artery disease (CAD). Moreover, we have explored the anti-atherosclerosis mechanisms of PEDF, showing that oxidized-low density lipoprotein (ox-LDL) reduced PEDF concentrations through the upregulation of reactive oxygen species (ROS), and that D-4F can protect endothelial cells against ox-LDL-induced injury by preventing the downregulation of PEDF. Additionally, PEDF might alleviate endothelial injury by inhibiting the Wnt/β-catenin pathway. These data suggest that PEDF may be a novel therapeutic target for the treatment of atherosclerosis. In this review, we will summarize the role of PEDF in the development of atherosclerosis, focusing on endothelial dysfunction, inflammation, oxidative stress, angiogenesis and cell proliferation. We will also discuss its promising therapeutic implications for atherosclerosis.

Antithrombotic treatment is associated with intraplaque haemorrhage in the atherosclerotic carotid artery: a cross-sectional analysis of The Rotterdam Study

Aims

Antithrombotic treatment plays a key role in stroke prevention, but their direct effects on the composition of carotid artery atherosclerotic plaques are unknown. To investigate the association of antithrombotic treatment with carotid artery plaque composition, with a specific focus on an intraplaque haemorrhage (IPH).

Methods and results

From the population-based Rotterdam Study, 1740 participants with carotid atherosclerosis on ultrasound (mean age 72.9 years, 46.0 women) underwent magnetic resonance imaging of the carotid arteries to assess plaque composition. Information on the use of oral anticoagulants [vitamin K antagonists (VKA)] and antiplatelet agents (salicylates), including duration of use and dosage, was obtained from pharmacy records for all participants. We used logistic regression models to assess the association between the use of anticoagulants and antiplatelet agents, and the different plaque components adjusting for confounders. Current and past use of VKA [adjusted odds ratio (OR): 1.88, 95% confidence interval (CI): 0.74-4.75 and OR 1.89, 95% CI: 0.91-3.93] and antiplatelet agents (OR: 1.22, 95% CI: 0.91-1.62), and (OR: 1.23, 95% CI: 0.86-1.75) showed positive trend with a higher presence of IPH. Also, a longer duration of use was associated with a higher frequency of IPH (OR: 3.15, 95% CI: 1.23-8.05) for the use of VKA, and longer duration of the use for antiplatelet agents showed a positive trend (OR: 1.21, 95% CI: 0.88-1.67). We also found that higher levels of international normalized ratio above 2.97 for VKA (OR: 1.48, 95% CI: 1.03-2.15) and higher daily defined dosage than 1.0 for antiplatelet agents (OR: 1.50, 95% CI: 1.21-1.87) were related to a higher frequency of IPH. We found no association with lipid core or calcification.

Conclusions

The use of antithrombotic treatment relates to a higher frequency of IPH in carotid atherosclerotic plaques.

MicroRNA-221/222 expression in atherosclerotic coronary artery plaque versus internal mammarian artery and in peripheral blood samples

BACKGROUND

Atherosclerosis is a disease of the arterial wall with predilection to some sites on others. MicroRNAs (miRNAs) are a class of the non-coding RNAs regulating the target gene expression at post-transcriptional level. Different miRNAs were found at distinct stages of plaque development and expression of miRNAs' might play an important role in the local behaviour of atherosclerotic plaques.

OBJECTIVE

We aimed to investigate and compare mirR-221/222 expression levels in tissues and in circulation in patients with and without overt atherosclerosis.

METHODS

RNA was isolated from 40 tissues as 20 tissue samples from coronary artery atherosclerotic plaques (CAAP) and internal mammary arteries (IMA), obtained from same individual) and 80 blood (44 patients with atherosclerosis and 36 healthy subjects) samples. MiR-221/222 expression levels were measured using real time PCR.

RESULTS

Expression levels of miR-221 was significantly increased in CAAP compared with completely atherosclerosis-free IMA tissues with a 8.94 times fold-change (p = 0.015). The miR-221 expression in tissue samples was significantly different in patients with hypercholesterolemia (p = 0.010), hypertension (p = 0.018) and family history of CAD (p = 0.033) versus not. Expression of miR-222 was not statistically significant between the two tissue samples overall.

CONCLUSIONS

MiR-221 may be a potential biomarker for local atherosclerotic behavior.

Superficial and multiple calcifications and ulceration associate with intraplaque hemorrhage in the carotid atherosclerotic plaque

Objective

Intraplaque hemorrhage (IPH) and ulceration of carotid atherosclerotic plaques have been associated with vulnerability while calcification has been conventionally thought protective. However, studies suggested calcification size and location may increase plaque vulnerability. This study explored the association between calcium configurations and ulceration with IPH.

Methods

One hundred thirty-seven consecutive symptomatic patients scheduled for carotid endarterectomy were recruited. CTA and CTP were performed prior to surgery. Plaque samples were collected for histology. According to the location, calcifications were categorized into superficial, deep and mixed types; according to the size and number, calcifications were classified as thick and thin, multiple and single.

Results

Seventy-one plaques had IPH (51.8%) and 83 had ulceration (60.6%). The appearance of IPH and ulceration was correlated (r = 0.49; p < 0.001). The incidence of multiple, superficial and thin calcifications was significantly higher in lesions with IPH and ulceration compared with those without. After adjusting factors including age, stenosis and ulceration, the presence of calcification [OR (95% CI), 3.0 (1.1-8.2), p = 0.035], multiple calcification [3.9 (1.4-10.9), p = 0.009] and superficial calcification [3.4 (1.1-10.8), p = 0.001] were all associated with IPH. ROC analysis showed that the AUC of superficial and multiple calcifications in detecting IPH was 0.63 and 0.66, respectively (p < 0.05). When the ulceration was combined, AUC increased significantly to 0.82 and 0.83, respectively. Results also showed that patients with lesions of both ulceration and IPH have significantly reduced brain perfusion in the area ipsilateral to the infarction.

Conclusions

Superficial and multiple calcifications and ulceration were associated with carotid IPH, and they may be a surrogate for higher risk lesions.

Key Points

• CTA-defined superficial and multiple calcifications in carotid atherosclerotic plaques are independently associated with the presence of intraplaque hemorrhage.

• The combination of superficial and multiple calcifications and ulceration is highly predictive of carotid intraplaque hemorrhage.

• Patients with lesions of both ulceration and intraplaque hemorrhage have significantly reduced brain perfusion in the area ipsilateral to the infarction.

The coagulation system in atherothrombosis: Implications for new therapeutic strategies

Clinical manifestations of atherosclerotic disease include coronary artery disease (CAD), peripheral artery disease (PAD), and stroke. Although the role of platelets is well established, evidence is now accumulating on the contribution of coagulation proteins to the processes of atherosclerosis and atherothrombosis. Coagulation proteins not only play a role in fibrin formation and platelet activation, but also mediate various biological and pathophysiologic processes through activation of protease-activated-receptors (PARs). Thus far, secondary prevention in patients with CAD/PAD has been the domain of antiplatelet therapy, however, residual atherothrombotic risks remain substantial. Therefore, combining antiplatelet and anticoagulant therapy has gained more attention. Recently, net clinical benefit of combining aspirin with low-dose rivaroxaban in patients with stable atherosclerotic disease has been demonstrated. In this review, based on the State of the Art lecture "Clotting factors and atherothrombosis" presented at the ISTH Congress 2017, we highlight the role of coagulation proteins in the pathophysiology of atherothrombosis, and specifically focus on therapeutic strategies to decrease atherothrombotic events by optimization of vascular protection.

Blood Pressure Is a Major Modifiable Risk Factor Implicated in Pathogenesis of Intraplaque Hemorrhage: An In Vivo Magnetic Resonance Imaging Study

OBJECTIVE

Effective prevention and management strategies of intraplaque hemorrhage (IPH) remain elusive because of our limited knowledge regarding its contributing factors. This hypothesis-generating study aimed to investigate associations between cardiovascular risk factors and IPH for improved understanding of the pathogenesis of IPH.

APPROACH AND RESULTS

Asymptomatic subjects with 16% to 79% stenosis on ultrasound underwent carotid magnetic resonance imaging using a large-coverage, 3-dimensional magnetic resonance imaging protocol. Individual plaques (maximum thickness >1.5 mm) in bilateral carotid arteries were identified, and presence of IPH was determined. From 80 subjects, 176 de novo plaques were measured, of which 38 (21.6%) contained IPH. Blood pressure (BP), primarily low diastolic BP, was associated with IPH in multivariate analysis adjusted for age, sex, and plaque size (odds ratio with 95% confidence interval per 10-mm Hg increase: 0.51 [0.30-0.88]), which was little changed after adjusting for antihypertensive use and systemic atherosclerosis. Antiplatelet use was associated with IPH in age and sex-adjusted models (P=0.018), for which a trend remained after considering plaque size and past medical history (odds ratio for aspirin alone versus none: 3.1 [0.66-14.8]; odds ratio for clopidogrel or dual therapy versus none: 5.3 [0.80-35.0]; P=0.083).

CONCLUSIONS

Low diastolic BP was independently associated with IPH, which was not attributed to treatment difference or BP changes from systemic atherosclerosis. Hemodynamic changes from lowering diastolic BP may be the pathophysiological link. Prospective serial studies are needed to assess whether BP and antiplatelet use are associated with the development of new or repeated IPH.

Effect of Intensive Statin Therapy on Coronary High-Intensity Plaques Detected by Noncontrast T1-Weighted Imaging: The AQUAMARINE Pilot Study

BACKGROUND

Coronary high-intensity plaques detected by noncontrast T1-weighted imaging may represent plaque instability. High-intensity plaques can be quantitatively assessed by a plaque-to-myocardium signal-intensity ratio (PMR).

OBJECTIVES

This pilot, hypothesis-generating study sought to investigate whether intensive statin therapy would lower PMR.

METHODS

Prospective serial noncontrast T1-weighted magnetic resonance imaging and computed tomography angiography were performed in 48 patients with coronary artery disease at baseline and after 12 months of intensive pitavastatin treatment with a target low-density lipoprotein cholesterol level <80 mg/dl. The control group consisted of coronary artery disease patients not treated with statins that were matched by propensity scoring (n = 48). The primary endpoint was the 12-month change in PMR. Changes in computed tomography angiography parameters and high-sensitivity C-reactive protein levels were analyzed.

RESULTS

In the statin group, 12 months of statin therapy significantly improved low-density lipoprotein cholesterol levels (125 to 70 mg/dl; p < 0.001), PMR (1.38 to 1.11, an 18.9% reduction; p < 0.001), low-attenuation plaque volume, and the percentage of total atheroma volume on computed tomography. In the control group, the PMR increased significantly (from 1.22 to 1.49, a 19.2% increase; p < 0.001). Changes in PMR were correlated with changes in low-density lipoprotein cholesterol (r = 0.533; p < 0.001), high-sensitivity C-reactive protein (r = 0.347; p < 0.001), percentage of atheroma volume (r = 0.477; p < 0.001), and percentage of low-attenuation plaque volume (r = 0.416; p < 0.001).

CONCLUSIONS

Statin treatment significantly reduced the PMR of high-intensity plaques. Noncontrast T1-weighted magnetic resonance imaging could become a useful technique for repeated quantitative assessment of plaque composition. (Attempts at Plaque Vulnerability Quantification with Magnetic Resonance Imaging Using Noncontrast T1-weighted Technique [AQUAMARINE]; UMIN000003567).

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.

High-risk plaque in the superficial femoral artery of people with peripheral artery disease: prevalence and associated clinical characteristics

OBJECTIVE

We used magnetic resonance imaging (MRI) to study the prevalence and associated clinical characteristics of high-risk plaque (defined as presence of lipid-rich necrotic core [LRNC] and intraplaque hemorrhage) in the superficial femoral arteries (SFA) among people with peripheral artery disease (PAD).

BACKGROUND

The prevalence and clinical characteristics associated with high-risk plaque in the SFA are unknown.

METHODS

Three-hundred-three participants with PAD underwent MRI of the proximal SFA using a 1.5 T S platform. Twelve contiguous 2.5 mm cross-sectional images were obtained.

RESULTS

LRNC was present in 68 (22.4%) participants. Only one had intra-plaque hemorrhage. After adjusting for age and sex, smoking prevalence was higher among adults with LRNC than among those without LRNC (35.9% vs. 21.4%, p = 0.02). Among participants with vs. without LRNC there were no differences in mean percent lumen area (31% vs. 33%, p = 0.42), normalized mean wall area (0.71 vs. 0.70, p = 0.67) or maximum wall area (0.96 vs. 0.92, p = 0.54) in the SFA. Among participants with LRNC, cross-sectional images containing LRNC had a smaller percent lumen area (33% ± 1% vs. 39% ± 1%, p < 0.001), greater normalized mean wall thickness (0.25 ± 0.01 vs. 0.22 ± 0.01, p < 0.001), and greater normalized maximum wall thickness (0.41 ± 0.01 vs. 0.31 ± 0.01, p < 0.001), compared to cross-sectional images without LRNC.

CONCLUSIONS

Fewer than 25% of adults with PAD had high-risk plaque in the proximal SFA using MRI. Smoking was the only clinical characteristic associated with presence of LRNC. Further study is needed to determine the prognostic significance of LRNC in the SFA.

CLINICAL TRIAL REGISTRATION-URL

http://www.clinicaltrials.gov. Unique identifier: NCT00520312.

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.

10-years experience with the Athero-Express study

From cross-sectional studies we have learned that composition of atherosclerotic plaques differs, and that thrombosis on top of an inflammatory lipid rich plaque is a frequently observed pathological substrate of a cerebral or coronary event. Atherosclerosis develops over decades which hampers human studies on the natural history of the diseases. Therefore, the predictive value of atherosclerotic plaque composition for development of an adverse cardiovascular event is not clear. The elucidation of markers for atherosclerotic disease progression is essential to identify patients at high risk for vascular events, to refine treatment allocation and to serve as surrogate endpoints in pharmaceutical studies. The Athero-Express study is a large scale vascular biobank that collects vascular specimens including a clinical follow-up. This study design allows the prospective study of the local atherosclerotic plaque in relation to future local and systemic vascular outcome. The readout of the study can be assessed in terms of histology as well as RNA or protein level. This paper aims to give an overview of the results of the Athero-Express biobank since its initiation in 2002. We will also discuss the clinical implications and future directions in biobanking research.

Haptoglobin 2 allele associates with unstable carotid plaque and major cardiovascular events

OBJECTIVE

Intraplaque hemorrhages (IPH) may predispose to unstable atherosclerotic disease and its atherothrombotic complications, ischemic stroke and coronary syndromes. However, the discriminative value of IPH has been limited in histological and imaging studies suggesting that confounding factors modulate the response to IPH. We studied whether common variants of haptoglobin (Hp), which facilitates the removal of free hemoglobin and protects tissues from heme-iron induced oxidative damage, would modify the inflammatory response to IPH and the risk of unstable carotid stenosis (CS) and major cardiovascular diseases.

METHODS

We genotyped Hp polymorphism in 91 patients with a high-grade CS from Helsinki Carotid Endarterectomy Study (HeCES) and in 1417 individuals from Health 2000, a Finnish epidemiological cross-sectional health survey, and determined heme oxygenase-1 (HO1) expression in relation to Hp genotypes in carotid plaques.

RESULTS

In the Health 2000 cohort, Hp genotype frequencies were 0.143 (hp1-1), 0.486 (hp1-2) and 0.371 (hp2-2) consistent with Hardy-Weinberg equilibrium and those reported from other Caucasian populations. Among patients with unstable CS, the frequency of hp2-2 genotype was higher than in the control population (0.516 vs. 0.371, P = 0.025). Hp genotypes correlated with HO1 expression in the plaque (r = 0.47, P = 0.027). In the Health 2000 cohort, hp2 allele was associated with an increased risk of major cardiovascular diseases (ischemic stroke, TIA, myocardial infarction, coronary heart disease) with an adjusted OR of 1.46 (95% CI 1.03-2.06).

CONCLUSION

Common haptoglobin variants modulate the inflammatory response to IPH and associate with the risk of unstable carotid stenosis and major ischemic cardiovascular events.

Lower prevalence of carotid plaque hemorrhage in women, and its mediator effect on sex differences in recurrent cerebrovascular events

Background and Purpose

Women are at lower risk of stroke, and appear to benefit less from carotid endarterectomy (CEA) than men. We hypothesised that this is due to more benign carotid disease in women mediating a lower risk of recurrent cerebrovascular events. To test this, we investigated sex differences in the prevalence of MRI detectable plaque hemorrhage (MRI PH) as an index of plaque instability, and secondly whether MRI PH mediates sex differences in the rate of cerebrovascular recurrence.

Methods

Prevalence of PH between sexes was analysed in a single centre pooled cohort of 176 patients with recently symptomatic, significant carotid stenosis (106 severe [≥70%], 70 moderate [50–69%]) who underwent prospective carotid MRI scanning for identification of MRI PH. Further, a meta-analysis of published evidence was undertaken. Recurrent events were noted during clinical follow up for survival analysis.

Results

Women with symptomatic carotid stenosis (50%≥) were less likely to have plaque hemorrhage (PH) than men (46% vs. 70%) with an adjusted OR of 0.23 [95% CI 0.10–0.50, P<0.0001] controlling for other known vascular risk factors. This negative association was only significant for the severe stenosis subgroup (adjusted OR 0.18, 95% CI 0.067–0.50) not the moderate degree stenosis. Female sex in this subgroup also predicted a longer time to recurrent cerebral ischemic events (HR 0.38 95% CI 0.15–0.98, P = 0.045). Further addition of MRI PH or smoking abolished the sex effects with only MRI PH exerting a direct effect.

Meta-analysis confirmed a protective effect of female sex on development of PH: unadjusted OR for presence of PH = 0.54 (95% CI 0.45–0.67, p<0.00001).

Conclusions

MRI PH is significantly less prevalent in women. Women with MRI PH and severe stenosis have a similar risk as men for recurrent cerebrovascular events. MRI PH thus allows overcoming the sex bias in selection for CEA.

Relationships Between Recent Intraplaque Hemorrhage and Stroke Risk Factors in Patients With Carotid Stenosis

Objective—

Intraplaque hemorrhage (IPH) is an emerging marker of plaque instability. However, little is known about the relationships between IPH and traditional risk factors and whether these relationships differ between symptomatic and asymptomatic disease.

Methods and Results—

Two hundred thirty-four patients with symptomatic (n=114) or asymptomatic (n=120) carotid stenosis underwent high-resolution plaque magnetic resonance imaging. Seventy-five patients had recent IPH (symptomatic, 33%; asymptomatic, 31%). In symptomatic stenosis, recent IPH was independently associated with degree of stenosis (odds ratio [OR]=4.21, 1.61–10.98 for North American Symptomatic Carotid Endarterectomy Trial >35%; OR=2.92, 1.18–7.24 for European Carotid Surgery Trial >60%), qualifying event (OR=4.13; 1.11–15.32 for stroke or hemispheric transient ischemic attack ≥1 hour versus transient ischemic attack <1 hour or ocular symptoms), time from ischemic event (OR=6.65, 1.56–28.35 for ≤2 weeks; OR=2.24, 0.87–5.81 for 2–12 weeks versus >12 weeks; P for trend=0.03). In asymptomatic stenosis, IPH was only associated with stenosis severity >70% by ECST (OR=6.65; 1.95–22.73) but not by the NASCET method.

Conclusion—

Our findings support the potential link between recent IPH and risk of ipsilateral stroke in symptomatic disease but also imply that prognostic studies should adjust for known stroke risk factors in multivariate analyses. In asymptomatic stenosis, the potential predictive value of recent IPH is less likely to be confounded by stroke risk factors.

Intraplaque haemorrhages as the trigger of plaque vulnerability

Atherothrombosis remains one of the main causes of morbidity and mortality in the western countries. Human atherothrombotic disease begins early in life in relation to circulating lipid retention in the inner vascular wall. Risk factors enhance the progression towards clinical expression: dyslipidaemia, diabetes, smoking, hypertension, ageing, etc. The evolution from the initial lipid retention in the arterial wall to clinical events is a continuum of increasingly complex biological processes. Current strategies to fight the consequences of atherothrombosis are orientated either towards the promotion of a healthy life style and preventive treatment of risk factors, or towards late interventional strategies. Despite this therapeutic arsenal, the incidence of clinical events remains dramatically high, dependent, at least in part, on the increasing frequency of type 2 diabetes and ageing. But some medical treatments, focusing only on prevention of the metabolic risk, have failed to reduce cardiovascular mortality, thus illustrating that our understanding of the pathophysiology of human atherothrombosis leading to clinical events remain incomplete. New paradigms are now emerging which may give rise to novel experimental strategies to improve therapeutic efficacy and prediction of disease progression. Recent studies strengthen the concept that the intraplaque neovascularization and bleeding (Figure 1, upper panel) are events that could play a major role in plaque progression and leucocyte infiltration, and may also serve as a measure of risk for the development of future events. The recent advances in our understanding of IntraPlaque Hemorrhage as a critical event in triggering acute clinical events have important implications for clinical research and possibly future clinical practice.