Biomechanics and inflammation in atherosclerotic plaque erosion and plaque rupture: implications for cardiovascular events in women

Sex differences in the genetic and molecular mechanisms of coronary artery disease

Sex differences in coronary artery disease (CAD) presentation, risk factors and prognosis have been widely studied. Similarly, studies on atherosclerosis have shown prominent sex differences in plaque biology. Our understanding of the underlying genetic and molecular mechanisms that drive these differences remains fragmented and largely understudied. Through reviewing genetic and epigenetic studies, we identified more than 40 sex-differential candidate genes (13 within known CAD loci) that may explain, at least in part, sex differences in vascular remodeling, lipid metabolism and endothelial dysfunction. Studies with transcriptomic and single-cell RNA sequencing data from atherosclerotic plaques highlight potential sex differences in smooth muscle cell and endothelial cell biology. Especially, phenotypic switching of smooth muscle cells seems to play a crucial role in female atherosclerosis. This matches the known sex differences in atherosclerotic phenotypes, with men being more prone to lipid-rich plaques, while women are more likely to develop fibrous plaques with endothelial dysfunction. To unravel the complex mechanisms that drive sex differences in CAD, increased statistical power and adjustments to study designs and analysis strategies are required. This entails increasing inclusion rates of women, performing well-defined sex-stratified analyses and the integration of multi-omics data.

Ex Vivo Study Using Diffusion Tensor Imaging to Identify Biomarkers of Atherosclerotic Disease in Human Cadaveric Carotid Arteries

BACKGROUND

This study aims to address the potential of ex vivo diffusion tensor imaging to provide insight into the microstructural composition and morphological arrangement of aged human atherosclerotic carotid arteries.

METHODS

In this study, whole human carotid arteries were investigated both anatomically and by comparing healthy and diseased regions. Nonrigid image registration was used with unsupervised segmentation to investigate the influence of elastin, collagen, cell density, glycosaminoglycans, and calcium on diffusion tensor imaging derived metrics (fractional anisotropy and mean diffusivity). Early stage atherosclerotic features were also investigated in terms of microstructural components and diffusion tensor imaging metrics.

RESULTS

All vessels displayed a dramatic decrease in fractional anisotropy compared with healthy animal arterial tissue, while the mean diffusivity was sensitive to regions of advanced disease. Elastin content strongly correlated with both fractional anisotropy (r>0.7, P<0.001) and mean diffusivity (r>-0.79, P<0.0002), and the thickened intima was also distinguishable from arterial media by these metrics.

CONCLUSIONS

These different investigations point to the potential of diffusion tensor imaging to identify characteristics of arterial disease progression, at early and late-stage lesion development.

Anti-atherosclerotic therapies: Milestones, challenges, and emerging innovations

Atherosclerosis is the main underlying pathology for many cardiovascular diseases (CVDs), which are the leading cause of death globally and represent a serious health crisis. Atherosclerosis is a chronic condition that can lead to myocardial infarction, ischemic cardiomyopathy, stroke, and peripheral arterial disease. Elevated plasma lipids, hypertension, and high glucose are the major risk factors for developing atherosclerotic plaques. To date, most pharmacological therapies aim to control these risk factors, but they do not target the plaque-causing cells themselves. In patients with acute coronary syndromes, surgical revascularization with percutaneous coronary intervention has greatly reduced mortality rates. However, stent thrombosis and neo-atherosclerosis have emerged as major safety concerns of drug eluting stents due to delayed re-endothelialization. This review summarizes the major milestones, strengths, and limitations of current anti-atherosclerotic therapies. It provides an overview of the recent discoveries and emerging game-changing technologies in the fields of nanomedicine, mRNA therapeutics, and gene editing that have the potential to revolutionize CVD clinical practice by steering it toward precision medicine.

Research Landscape on Atherosclerotic Cardiovascular Disease and Inflammation: A Bibliometric and Visualized Study

Background

The atherosclerotic cardiovascular disease (ASCVD) is a major killer and health care burden worldwide. Atherosclerosis, the common pathological foundation, has been associated with inflammation over the past few years. Some promising results also have emerged suggesting the role of targeting inflammation as a potential therapeutic option to reduce cardiovascular events. In light of the pathogenic role that inflammation plays in ASCVD, we propose to evaluate the worldwide research architecture for ASCVD and inflammation using bibliometric analysis.

Methods

A search of the Web of Science Core Collection of Clarivate Analytics was performed for articles in the field published between 2012 and 2022. The number of publications per year has been visualized using GraphPad Prism through time. CiteSpace and VOSviewer were used to generate knowledge maps about the collaboration of countries, institutions, and authors, and to represent the landscape on ASCVD and inflammation research as well as to reveal current foci.

Results

There were a total of 19,053 publications examined in this study. The most publications came from China (6232, 32.71%). Capital Med Univ was the most productive institution (410, 2.15%). Christian Weber published the greatest number of articles (75, 0.39%). PloS one was identified as the most prolific journal (706, 3.71%). Circulation was the most co-cited journal (13276, 2.81%). Keywords with the ongoing strong citation bursts were "nucleotide-binding oligomerization (NOD), Leucine-rich repeat (LRR)-containing protein (NLRP3) inflammasome", "intestinal microbiota", "exosome", "lncRNAs", etc.

Conclusions

It can be shown that ASCVD and inflammation research benefited from manuscripts that had a high impact on the scientific community. Asian, European and North American countries dominated in the field in terms of quantitative, qualitative and collaborative parameters. The NLRP3 inflammasome, gut microbiota and trimethylamine N-oxide, autophagy, lncRNAs, exosomes, and nuclear factor erythroid 2-related factor 2 were described to be hot themes in the field.

Plaque Structural Stress: Detection, Determinants and Role in Atherosclerotic Plaque Rupture and Progression

Atherosclerosis remains a major cause of death worldwide, with most myocardial infarctions being due to rupture or erosion of coronary plaques. Although several imaging modalities can identify features that confer risk, major adverse cardiovascular event (MACE) rates attributable to each plaque are low, such that additional biomarkers are required to improve risk stratification at plaque and patient level. Coronary arteries are exposed to continual mechanical forces, and plaque rupture occurs when plaque structural stress (PSS) exceeds its mechanical strength. Prospective studies have shown that peak PSS is correlated with acute coronary syndrome (ACS) presentation, plaque rupture, and MACE, and provides additional prognostic information to imaging. In addition, PSS incorporates multiple variables, including plaque architecture, plaque material properties, and haemodynamic data into a defined solution, providing a more detailed overview of higher-risk lesions. We review the methods for calculation and determinants of PSS, imaging modalities used for modeling PSS, and idealized models that explore structural and geometric components that affect PSS. We also discuss current experimental and clinical data linking PSS to the natural history of coronary artery disease, and explore potential for refining treatment options and predicting future events.

The changing landscape of the vulnerable plaque: a call for fine-tuning of preclinical models

For decades, the pathological definition of the vulnerable plaque led to invaluable insights into the mechanisms that underlie myocardial infarction and stroke. Beyond plaque rupture, other mechanisms, such as erosion, may elicit thrombotic events underlining the complexity and diversity of the atherosclerotic disease. Novel insights, based on single-cell transcriptomics and other "omics" methods, provide tremendous opportunities in the ongoing search for cell-specific determinants that will fine-tune the description of the thrombosis prone lesion. It coincides with an increasing awareness that knowledge on lesion characteristics, cell plasticity and clinical presentation of ischemic cardiovascular events have shifted over the past decades. This shift correlates with an observed changes of cell composition towards phenotypical stabilizing of human plaques. These stabilization features and mechanisms are directly mediated by the cells present in plaques and can be mimicked in vitro via primary plaque cells derived from human atherosclerotic tissues. In addition, the rapidly evolving of sequencing technologies identify many candidate genes and molecular mechanisms that may influence the risk of developing an atherosclerotic thrombotic event - which bring the next challenge in sharp focus: how to translate these cell-specific insights into tangible functional and translational discoveries?

Role of mechanical stress and neutrophils in the pathogenesis of plaque erosion

Mechanical stress is a well-recognized driver of plaque rupture. Likewise, investigating the role of mechanical forces in plaque erosion has recently begun to provide some important insights, yet the knowledge is by far less advanced. The most significant example is that of shear stress, which has early been proposed as a possible driver for focal endothelial death and denudation. Recent findings using optical coherence tomography, computational sciences and mechanical models show that plaque erosion occurs most likely around atheromatous plaque throats with specific stress pattern. In parallel, we have recently shown that neutrophil-dependent inflammation promotes plaque erosion, possibly through a noxious action on ECs. Most importantly, spontaneous thrombosis - associated or not with EC denudation - can be impacted by hemodynamics, and it is now established that neutrophils promote thrombosis and platelet activation, highlighting a potential relationship between, mechanical stress, inflammation, and EC loss in the setting of coronary plaque erosion. Here, we review our current knowledge regarding the implication of both mechanical stress and neutrophils, and we discuss their implication in the promotion of plaque erosion via EC loss and thrombosis.

Sex-Specific Effects of the Nlrp3 Inflammasome on Atherogenesis in LDL Receptor-Deficient Mice

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In this study we observed sex-specific effects of the NLRP3 inflammasome on atherogenesis in LDLR-deficient mice, with NLRP3 inflammasome playing a more prominent role in atherosclerosis in female mice than in males.

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Sex hormones may be involved in NLRP3 inflammasome–mediated atherogenesis and may underlie differential responses to anti-NLRP3 therapy between males and females.

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Testosterone may play an inhibitory role by blocking NLRP3 inflammasome and inflammation in atherogenesis, whereas female sex hormones may promote NLRP3 inflammasome–mediated atherosclerosis.

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The results of the present study may help design future clinical trials, with the objective to personalize cardiovascular care for men and women.

In the Ldlr^-/- mouse model of atherosclerosis, female Nlrp3^-/- bone marrow chimera and Nlrp3^-/- mice developed significantly smaller lesions in the aortic sinus and decreased lipid content in aorta en face, but a similar protection was not observed in males. Ovariectomized female mice lost protection from atherosclerosis in the setting of NLRP3 deficiency, whereas atherosclerosis showed a greater dependency on NLRP3 in castrated males. Thus, castration increased the dependency of atherosclerosis on the NLRP3 inflammasome, suggesting that testosterone may block inflammation in atherogenesis. Conversely, ovariectomy reduced the dependency on NLRP3 inflammasome components for atherogenesis, suggesting that estrogen may promote inflammasome-mediated atherosclerosis.

Inflammation in acute coronary syndrome: Expression of TLR2 mRNA is increased in platelets of patients with ACS

Background

Platelets are key components in atherogenesis and determine the course of its clinical sequelae acute coronary syndrome (ACS). Components of the innate immune system—the superfamily of TLR receptors–are present in platelets and represent a link between atherothrombosis and inflammation. We hypothesize that alteration in platelet TLR mRNA expression is a result of inflammation driving coronary atherosclerosis and may represent an alternative platelet activation pathway in ACS.

TLR2-, TLR4- and TLR9- mRNA-expression was determined in ACS patients and compared to patients with invasive exclusion of atherosclerotic lesions of coronary arteries.

Methods

A total of fifty-four patients were enrolled in this clinical retrospective cohort single centre study. Total RNA from sepharose-filtered highly purified platelets was isolated using acid guanidinium thiocyanate-phenol-chloroform extraction and transcribed to cDNA using a first strand cDNA synthesis kit. To determine absolute copy numbers of TLR2, TLR4 and TLR9 we used plasmid based quantitative PCR with normalisation to an internal control.

Results

We found that mRNA expression levels of TLR2 but not TLR 4 and 9 are up-regulated in platelets of patients with ACS when compared to patients without coronary atherosclerosis.

Conclusion

Our results suggest elevated TLR2 mRNA expression in platelets as a biomarker reflecting the underlying inflammation in ACS and possibly severity of coronary atherosclerosis. Platelet TLR2 may represent a link between inflammation and atherothrombosis in ACS.

Mean Platelet Volume Predicts Short-term Prognosis in Young Patients with St-segment Elevation Myocardial Infarction

Background: Acute ST-elevation myocardial infarction (STEMI) is an uncommon diagnosis in patients less than 40 years of age. Over the last two decades, there is an increase in the frequency of cardiovascular events among young adults. However, at present there is only limited clinical data on the clinical characteristics and outcomes of STEMI in young patients who were treated with primary percutaneous coronary intervention (pPCI). Plaque erosion is the underlying pathological mechanism leading to STEMI in the vast majority of young adults. Thrombi that complicate superficial erosion seem more platelet-rich than the fibrinous clots precipitated by plaque rupture. Mean platelet volume (MPV) is recognized as a marker of the platelet activation process and may be a better indicator of short-term prognosis than the inflammatory markers in young patients with STEMI. Therefore, we aimed to investigate clinical and angiographic characteristics, risk factors and the independent value of MPV on predicting short-term major adverse cardiovascular events (MACEs) in young adults with STEMI. Methods: A total of 349 patients aged 40 years or younger who underwent pPCI at our center between 2010–2015 with the diagnosis of STEMI were retrospectively analyzed. Results: The mean age of the patients was 36.4 ± 3.6 years and 90% of them were men. Smoking was by far the most frequent cardiovascular risk factor. MACEs were observed in 23 patients (6.6%), and according to the multivariate regression analysis, Killip IIIIV (OR 7.52, 95% CI 1.25–45.24, p = 0.03), lower admission SBP (OR 0.94, 95% CI 0.90–0.98, p <0.01) and increased MPV (OR 1.67, 95% CI 1.05–2.67, p = 0.03) were found to be independently correlated with MACE in the study population. Conclusion: Our results indicate that MPV is an independent predictor of MACEs at the short-term follow-up in young patients with STEMI undergoing pPCI. Accordingly, we suggested that MPV, a marker of platelet activation, could play a significant role in predicting clinical evolution in young patients with STEMI.

Recognition and treatment of ischemic heart diseases in women

Heart disease is the leading cause of death among women in the industrialized world. However, women after myocardial infarctions (MIs) are less likely to receive preventive medications or revascularization and as many as 47% experience heart failure, stroke or die within 5 years. Premenopausal women with MIs frequently have coronary plaque erosions or dissections. Women under 50 years with angina and nonobstructive epicardial coronary artery disease often have coronary microvascular dysfunction (CMD) with reductions in coronary flow reserve that may require nontraditional therapies. In women with coronary artery disease treated with stents, the 3-year incidence of recurrent MI or death is 9.2%. Coronary bypass surgery operative mortality averages 4.6% for women compared with 2.4% in men. Addition of internal mammary artery and radial artery coronary grafts in women does not increase operative survival but improves 5-year outcome to greater than 80%.

Can Inflammation-Resolution Provide Clues to Treat Patients According to Their Plaque Phenotype?

Inflammation-resolution is an active process that is governed in part by specialized pro-resolving mediators (SPMs) such as lipoxins, resolvins, protectins, and maresins. SPMs, which are endogenously biosynthesized, quell inflammation and repair tissue damage in a manner that does not compromise host defense. Importantly, failed inflammation-resolution is an important driving force in the progression of several prevalent diseases including atherosclerosis. Atherosclerosis is a leading cause of death worldwide and uncovering mechanisms that underpin defective inflammation-resolution and whether SPMs themselves can revert the progression of the disease are of utmost clinical interest. Because atherosclerosis is a disease in which low-grade persistent inflammation results in tissue injury, SPMs have garnered immense interest as a potential treatment strategy. This mini review will highlight recent work that describes mechanisms associated with defective inflammation-resolution in atherosclerosis, as well as the protective actions of SPMs and their potential use as a therapeutic.

How Does the Presence of Diabetes Affect the Course of Acute Coronary Syndrome in Elderly Patients in Actual Clinical Practice?

The number of elderly patients with diabetes mellitus (DM) is constantly growing in general population. Accordantly, we have the growth of such patients in the group of acute coronary syndrome (ACS).

Aim.To compare clinical characteristics of the elderly patient (>75 years old) with and without DM.

Material and methods. This retrospective study included 1133 ACS patients who were aged ≥75 years and admitted to the City Clinical Hospital №1 from 01.01.2015 to 31.12.2016. Median age was 80 years, 66% were women. We analyzed 4 patient subgroups: Group 1 – 105 patients with ST-segment elevation myocardial infarction (STEMI) and DM, Group 2 – 254 STEMI patients without DM, Group 3 – 222 non-STEMI patients with DM and Group 4 – 552 non-STEMI patients without DM. We used Student’s t-test and c2 tests to find significant difference between pairs of groups.

Results. Median age of patients in 4 groups was 80, 81, 81 and 80 years (p>0.05), age variance was 75-100 years. DM was found in 29% of all elderly patients with no difference between STEMI and non-STEMI groups. STEMI and non-STEMI patients with DM were more likely women. NonSTEMI patients with DM more often had hypertension, previous stroke, lower median Hb (121 vs 127 g/l; p<0.001). Angiography data demonstrated more often three-vessel disease (43% vs 29.7%) and less one-vessel disease (15% vs 25.6%; p<0.05) between groups 3 and 4. Glomerular filtration rate (GFR) <60 ml/min/1.73 m2 occurred in 74%, 73%, 77% and 74% in patients of 4 groups (p>0,05), but GFR<45 ml/min/1.73 m2 was more prevalent in patients with DM than without DM: 45%, 39%, 45%, 36% in 4 groups. Finally, mortality rates didn’t demonstrate significant difference between DM and non-DM patients with STEMI (10% vs 13%; p>0.05) and non-STEMI (7% vs 7%) groups.

Conclusion. DM is associated with ACS approximately in one third of the elderly patients and is not associated with its type (STEMI or non-STEMI). In STEMI and non-STEMI patients the female sex and GFR level <45 ml/min/1.73 m2 were associated with DM. In non-STEMI group multi-vessel disease and presence of hypertension and previous stroke were associated with DM. We didn’t find any difference between mortality in elderly patients with and without DM. 

Evaluation of coronary features of HIV patients presenting with ACS: The CUORE, a multicenter study

BACKGROUND AND AIMS

The risk of recurrence of myocardial infarction (MI) in HIV patients presenting with acute coronary syndrome (ACS) is well known, but there is limited evidence about potential differences in coronary plaques compared to non-HIV patients.

METHODS

In this multicenter case-control study, HIV patients presenting with ACS, with intravascular-ultrasound (IVUS) data, enrolled between February 2015 and June 2017, and undergoing highly active antiretroviral therapy (HAART), were retrospectively compared to non-HIV patients presenting with ACS, before and after propensity score with matching, randomly selected from included centers. Primary end-point was the prevalence of multivessel disease. Secondary end-points were the prevalence of abnormal features at IVUS, the incidence of major-acute-cardiovascular-events (MACE), a composite end point of cardiovascular death, MI, target lesion revascularization (TLR), stent thrombosis (ST), non-cardiac death and target vessel revascularization (TVR). For each end-point, a subgroup analysis was conducted in HIV patients with CD4 cell count <200/mm³.

RESULTS

Before propensity score, 66 HIV patients and 120 non-HIV patients were selected, resulting in 20 and 40 after propensity score. Patients with multivessel disease were 11 and 17, respectively (p = 0.56). IVUS showed a lower plaque burden (71% vs. 75%, p < 0.001) and a higher prevalence of hyperechoic non-calcified plaques (100% vs. 35%, p < 0.05) in HIV patients; a higher prevalence of hypoechoic plaques (7% vs. 0%, p < 0.05), a higher incidence of MACE (17.4% vs. 9.1% vs. l'8.0%, p < 0.05), MI recurrence (17.2% vs. 0.0% vs. 2.3%, p < 0.05), and ST (6.7% vs. 0.3% vs. 03%, p < 0.05) in HIV patients with CD4 < 200/mm³.

CONCLUSIONS

Our study may provide a part of the pathophysiological basis of the differences in coronary arteries between HIV-positive and HIV-negative patients, suggesting that the former present with peculiar morphological features at IVUS, even after adjustment for clinical variables. Furthermore, we confirmed that an advanced HIV infection is associated with a high risk of non-calcific plaques and with a worse prognosis, including cardiovascular events and ACS recurrence.

Roles of PAD4 and NETosis in Experimental Atherosclerosis and Arterial Injury: Implications for Superficial Erosion

RATIONALE

Neutrophils likely contribute to the thrombotic complications of human atheromata. In particular, neutrophil extracellular traps (NETs) could exacerbate local inflammation and amplify and propagate arterial intimal injury and thrombosis. PAD4 (peptidyl arginine deiminase 4) participates in NET formation, but an understanding of this enzyme's role in atherothrombosis remains scant.

OBJECTIVE

This study tested the hypothesis that PAD4 and NETs influence experimental atherogenesis and in processes implicated in superficial erosion, a form of plaque complication we previously associated with NETs.

METHODS AND RESULTS

Bone marrow chimeric Ldlr deficient mice reconstituted with either wild-type or PAD4-deficient cells underwent studies that assessed atheroma formation or procedures designed to probe mechanisms related to superficial erosion. PAD4 deficiency neither retarded fatty streak formation nor reduced plaque size or inflammation in bone marrow chimeric mice that consumed an atherogenic diet. In contrast, either a PAD4 deficiency in bone marrow-derived cells or administration of DNaseI to disrupt NETs decreased the extent of arterial intimal injury in mice with arterial lesions tailored to recapitulate characteristics of human atheroma complicated by erosion.

CONCLUSIONS

These results indicate that PAD4 from bone marrow-derived cells and NETs do not influence chronic experimental atherogenesis, but participate causally in acute thrombotic complications of intimal lesions that recapitulate features of superficial erosion.

Preeclampsia and coronary plaque erosion: Manifestations of endothelial dysfunction resulting in cardiovascular events in women

Atherosclerosis is the major underlying pathology of cardiovascular disease (CVD). The risk for CVD is increased in women with a history of preeclampsia. Multiple studies have indicated that accelerated atherosclerosis underlies this increased CVD risk. Furthermore, it has been suggested that endothelial dysfunction and inflammation play an important role in the increased CVD risk of women with preeclampsia. Rupture or erosion of atherosclerotic plaques can induce the formation of thrombi that underlie the onset of acute clinical CVD such as myocardial infarction and stroke. In relatively young women, cardiovascular events are mainly due to plaque erosions. Eroded plaques have a distinct morphology compared to ruptured plaques, but have been understudied as a substrate for CVD. The currently available evidence points towards lesions with features of stability such as high collagen content and smooth muscle cells and with distinct mechanisms that further promote the pro-thrombotic environment such as Toll Like Receptor (TLR) signaling and endothelial apoptosis. These suggested mechanisms, that point to endothelial dysfunction and intimal thickening, may also play a role in preeclampsia. Pregnancy is considered a stress test for the cardiovascular system with preeclampsia as an additional pathological substrate for earlier manifestation of vascular disease. This review provides a summary of the possible common mechanisms involved in preeclampsia and accelerated atherosclerosis in young females and highlights plaque erosion as a likely substrate for CVD events in women with a history of preeclampsia.

Inflammatory Differences in Plaque Erosion and Rupture in Patients With ST-Segment Elevation Myocardial Infarction

Background

Plaque erosion causes 30% of ST‐segment elevation myocardial infarctions, but the underlying cause is unknown. Inflammatory infiltrates are less abundant in erosion compared with rupture in autopsy studies. We hypothesized that erosion and rupture are associated with significant differences in intracoronary cytokines in vivo.

Methods and Results

Forty ST‐segment elevation myocardial infarction patients with <6 hours of chest pain were classified as ruptured fibrous cap (RFC) or intact fibrous cap (IFC) using optical coherence tomography. Plasma samples from the infarct‐related artery and a peripheral artery were analyzed for expression of 102 cytokines using arrays; results were confirmed with ELISA. Thrombectomy samples were analyzed for differential mRNA expression using quantitative real‐time polymerase chain reaction. Twenty‐three lesions were classified as RFC (58%), 15 as IFC (38%), and 2 were undefined (4%). In addition, 12% (12 of 102) of cytokines were differentially expressed in both coronary and peripheral plasma. I‐TAC was preferentially expressed in RFC (significance analysis of microarrays adjusted P<0.001; ELISA IFC 10.2 versus RFC 10.8 log₂ pg/mL; P=0.042). IFC was associated with preferential expression of epidermal growth factor (significance analysis of microarrays adjusted P<0.001; ELISA IFC 7.42 versus RFC 6.63 log₂ pg/mL, P=0.036) and thrombospondin 1 (significance analysis of microarrays adjusted P=0.03; ELISA IFC 10.4 versus RFC 8.65 log₂ ng/mL, P=0.0041). Thrombectomy mRNA showed elevated I‐TAC in RFC (P=0.0007) epidermal growth factor expression in IFC (P=0.0264) but no differences in expression of thrombospondin 1.

Conclusions

These results demonstrate differential intracoronary cytokine expression in RFC and IFC. Elevated thrombospondin 1 and epidermal growth factor may play an etiological role in erosion.

High wall shear stress and high-risk plaque: an emerging concept

In recent years, there has been a significant effort to identify high-risk plaques in vivo prior to acute events. While number of imaging modalities have been developed to identify morphologic characteristics of high-risk plaques, prospective natural-history observational studies suggest that vulnerability is not solely dependent on plaque morphology and likely involves additional contributing mechanisms. High wall shear stress (WSS) has recently been proposed as one possible causative factor, promoting the development of high-risk plaques. High WSS has been shown to induce specific changes in endothelial cell behavior, exacerbating inflammation and stimulating progression of the atherosclerotic lipid core. In line with experimental and autopsy studies, several human studies have shown associations between high WSS and known morphological features of high-risk plaques. However, despite increasing evidence, there is still no longitudinal data linking high WSS to clinical events. As the interplay between atherosclerotic plaque, artery, and WSS is highly dynamic, large natural history studies of atherosclerosis that include WSS measurements are now warranted. This review will summarize the available clinical evidence on high WSS as a possible etiological mechanism underlying high-risk plaque development.

Lipids and cardiovascular disease: where does dietary intervention sit alongside statin therapy?

The Seven Countries Study suggested an association between serum cholesterol and cardiovascular disease (CVD). However, the association was not consistent across the various cohorts of participants in different countries; while it was very clear in US and Northern European cohorts, it was weak in Southern European and Japanese cohorts. Nevertheless, the study triggered research into cholesterol-lowering drug strategies, ultimately leading to the development of statins amongst others. Clinical evidence in support of statins is strong and the vast majority of the medical community advocate these drugs as highly effective first-line therapeutics in primary and secondary prevention of CVD. However, growing evidence of side-effects associated with statins in a significant proportion of patients suggests that these drugs are not a universal solution to CVD. There is a need, therefore, to revisit the evidence and to re-appraise the relative importance of cholesterol amongst many other lipids as potential modulators of atherogenesis. In this review, we assess the relative merits of statin therapy in CVD versus dietary interventions that impact on lipids other than cholesterol, including omega-3 fatty acids and polar lipid fractions of various foods (e.g. fish and olive oil). We conclude that careful design around the lipid components of dietary interventions presents a credible alternative in patients who are intolerant to statins or averse to taking such drugs.