Coronary plaque erosion without rupture into a lipid core. A frequent cause of coronary thrombosis in sudden coronary death

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.

Management of no Reflow during Percutaneous Transcoronary Angioplasty with Catheter-Directed Intracoronary Thrombolysis: A Retrospective Observational Study

Background

Intracoronary thrombus is common in patients with ST-elevation myocardial infarction (STEMI). Percutaneous coronary intervention (PCI) is the treatment of choice for these patients. Intracoronary thrombus is still a challenge during PCI in STEMI, even with dual antiplatelets, glycoprotein IIb/IIIa inhibitor, and anticoagulation. Intracoronary thrombus can cause distal or nonculprit vessel embolization and no-reflow state. No reflow results in large infarct size, adverse left ventricular remodeling, arrhythmias, and death. Recently, catheter-directed intracoronary thrombolysis (ICT) is gaining acceptance in patients with no-reflow due to a large thrombus burden.

Aim

Evaluation of catheter-directed ICT in patients with acute STEMI who develop no reflow due to large thrombus burden during PCI.

Materials and Methods and Results

This was a retrospective observational study conducted after approval of the institutional ethics committee in a tertiary care hospital of north India from April 15, 2021 to April 14, 2022, included 1020 adult patients who had undergone coronary evaluation. 37.25% patients had PCI, among these 10% had PCI for acute STEMI. Thrombolysis in myocardial infarction (TIMI) Grade 5 in 79.17% and Grade 4 in 20.83%. ICT was done with low-dose tenecteplase (15 ± 5 mg). The TIMI flow III in 91.67% and II in 8.33% of patients was achieved after intracoronary thrombolysis. Major risk factor was tobacco smoking in 41.67%, and the major complication was left ventricular failure in 33.33%.

Conclusions

Catheter-directed ICT is safe and effective in reducing thrombus burden, thus improving myocardial reperfusion in STEMI. This condition has a grave prognosis and can lead to adverse cardiac outcomes. There are many drugs that have been tried to manage no reflow. The use of ICT to treat no-reflow state can be life saving with minimal systemic side effects.

Association of Collagen, Elastin, Glycosaminoglycans, and Macrophages With Tissue Ultimate Material Strength and Stretch in Human Thoracic Aortic Aneurysms: A Uniaxial Tension Study

Fiber structures and pathological features, e.g., inflammation and glycosaminoglycan (GAG) deposition, are the primary determinants of aortic mechanical properties which are associated with the development of an aneurysm. This study is designed to quantify the association of tissue ultimate strength and extensibility with the structural percentage of different components, in particular, GAG, and local fiber orientation. Thoracic aortic aneurysm (TAA) tissues from eight patients were collected. Ninety-six tissue strips of thickened intima, media, and adventitia were prepared for uni-extension tests and histopathological examination. Area ratios of collagen, elastin, macrophage and GAG, and collagen fiber dispersion were quantified. Collagen, elastin, and GAG were layer-dependent and the inflammatory burden in all layers was low. The local GAG ratio was negatively associated with the collagen ratio (r2 = 0.173, p < 0.05), but positively with elastin (r2 = 0.037, p < 0.05). Higher GAG deposition resulted in larger local collagen fiber dispersion in the media and adventitia, but not in the intima. The ultimate stretch in both axial and circumferential directions was exclusively associated with elastin ratio (axial: r2 = 0.186, p = 0.04; circumferential: r2 = 0.175, p = 0.04). Multivariate analysis showed that collagen and GAG contents were both associated with ultimate strength in the circumferential direction, but not with the axial direction (collagen: slope = 27.3, GAG: slope = -18.4, r2 = 0.438, p = 0.002). GAG may play important roles in TAA material strength. Their deposition was found to be associated positively with the local collagen fiber dispersion and negatively with ultimate strength in the circumferential direction.

Conductance Artery Wall Layers and Their Respective Roles in the Clearance Functions

Evolutionary organization of the arterial wall into layers occurred concomitantly with the emergence of a highly muscularized, pressurized arterial system that facilitates outward hydraulic conductance and mass transport of soluble substances across the arterial wall. Although colliding circulating cells disperse potential energy within the arterial wall, the different layers counteract this effect: (1) the endothelium ensures a partial barrier function; (2) the media comprises smooth muscle cells capable of endocytosis/phagocytosis; (3) the outer adventitia and perivascular adipocytic tissue are the final receptacles of convected substances. While the endothelium forms a physical and a biochemical barrier, the medial layer is avascular, relying on the specific permeability properties of the endothelium for metabolic support. Different components of the media interact with convected molecules: medial smooth muscle cells take up numerous molecules via scavenger receptors and are capable of phagocytosis of macro/micro particles. The outer layers-the highly microvascularized innervated adventitia and perivascular adipose tissue-are also involved in the clearance functions of the media: the adventitia is the seat of immune response development, inward angiogenesis, macromolecular lymphatic drainage, and neuronal stimulation. Consequently, the clearance functions of the arterial wall are physiologically essential, but also may favor the development of arterial wall pathologies. This review describes how the walls of large conductance arteries have acquired physiological clearance functions, how this is determined by the attributes of the endothelial barrier, governed by endocytic and phagocytic capacities of smooth muscle cells, impacting adventitial functions, and the role of these clearance functions in arterial wall diseases.

Risk Stratification in Acute Coronary Syndrome by Comprehensive Morphofunctional Assessment With Optical Coherence Tomography

Background

Artificial intelligence enables simultaneous evaluation of plaque morphology and computational physiology from optical coherence tomography (OCT).

Objectives

This study sought to appraise the predictive value of major adverse cardiovascular events (MACE) by combined plaque morphology and computational physiology.

Methods

A total of 604 patients with acute coronary syndrome who underwent OCT imaging in ≥1 nonculprit vessel during index coronary angiography were retrospectively enrolled. A novel morphologic index, named the lipid-to-cap ratio (LCR), and a functional parameter to evaluate the physiologic significance of coronary stenosis from OCT, namely, the optical flow ratio (OFR), were calculated from OCT, together with classical morphologic parameters, like thin-cap fibroatheroma (TCFA) and minimal lumen area.

Results

The 2-year cumulative incidence of a composite of nonculprit vessel–related cardiac death, cardiac arrest, acute myocardial infarction, and ischemia-driven revascularization (NCV-MACE) at 2 years was 4.3%. Both LCR (area under the curve [AUC]: 0.826; 95% CI: 0.793-0.855) and OFR (AUC: 0.838; 95% CI: 0.806-0.866) were superior to minimal lumen area (AUC: 0.618; 95% CI: 0.578-0.657) in predicting NCV-MACE at 2 years. Patients with both an LCR of >0.33 and an OFR of ≤0.84 had significantly higher risk of NCV-MACE at 2 years than patients in whom at least 1 of these 2 parameters was normal (HR: 42.73; 95% CI: 12.80-142.60; P < 0.001). The combination of thin-cap fibroatheroma and OFR also identified patients at higher risk of future events (HR: 6.58; 95% CI: 2.83-15.33; P < 0.001).

Conclusions

The combination of LCR with OFR permits the identification of a subgroup of patients with 43-fold higher risk of recurrent cardiovascular events in the nonculprit vessels after acute coronary syndrome.

In vivo detection of plaque erosion by intravascular optical coherence tomography using artificial intelligence

Plaque erosion is one of the most common underlying mechanisms for acute coronary syndrome (ACS). Optical coherence tomography (OCT) allows in vivo diagnosis of plaque erosion. However, challenge remains due to high inter- and intra-observer variability. We developed an artificial intelligence method based on deep learning for fully automated detection of plaque erosion in vivo, which achieved a recall of 0.800 ± 0.175, a precision of 0.734 ± 0.254, and an area under the precision-recall curve (AUC) of 0.707. Our proposed method is in good agreement with physicians, and can help improve the clinical diagnosis of plaque erosion and develop individualized treatment strategies for optimal management of ACS patients.

Role of Intracoronary Imaging in Acute Coronary Syndromes

Intravascular imaging with optical coherence tomography (OCT) and intravascular ultrasound provides superior visualization of the culprit plaques for acute coronary syndromes (ACS) compared with coronary angiography. Combined with angiography, intravascular imaging can be used to instigate 'precision therapy' for ACS. Post-mortem histopathology identified atherothrombosis at the exposed surface of a ruptured fibrous cap as the main cause of ACS. Further histopathological studies identified intact fibrous caps and calcified nodules as other culprit lesions for ACS. These plaque types were subsequently also identified on intravascular imaging, particularly with the high-resolution OCT. The less-common non-atherothrombotic causes of ACS are coronary artery spasm, coronary artery dissection, and coronary embolism. In this review, the authors provide an overview of clinical studies using intravascular imaging with OCT in the diagnosis and management of ACS.

Differences in Plaque Characteristics and Myocardial Mass

Background

The mechanism of the fractional flow reserve (FFR) difference according to sex has not been clearly understood.

Objectives

This study sought to evaluate sex differences in coronary stenosis, plaque characteristics, and left ventricular (LV) mass and their implications for physiological significance.

Methods

This was a post hoc analysis of a pooled population of multicenter, international prospective cohorts. Patients (166 women and 489 men) underwent coronary computed tomography angiography (CCTA) within 90 days before invasive FFR measurements were included. The minimal lumen area, percent of plaque burden, whole vessel plaque volume by composition, high-risk plaque characteristics, and LV mass were analyzed from CCTA images.

Results

Among 1,188 vessels analyzed, the FFR value was higher in women than that in men (0.85 ± 0.13 vs 0.82 ± 0.14; P = 0.001) despite a similar percentage of diameter stenosis between the sexes (45.9% ± 18.9% vs 46.1% ± 17.7%; P = 0.920). The composition of fibrofatty plaque + necrotic core (13.1% ± 16.9% vs 21.2% ± 19.9%; P < 0.001) and frequencies of low attenuation plaque (12.7% vs 24.5%; P < 0.001) and positive remodeling (33.8% vs 45.5%; P = 0.001) were lower in women than in men. Vessel, plaque, and lumen volumes were significantly smaller in women than that in men (all P < 0.001); however, no sex difference was observed in any of these parameters after adjustment for LV mass (all P > 0.10). Sex was not an independent predictor of the FFR value after adjustment for stenosis severity, plaque characteristics, and LV mass.

Conclusions

Higher FFR values for the same stenosis severity in women can be explained by fewer high-risk plaque characteristics and smaller myocardial mass in women than that in men. (CCTA-FFR Registry for Risk Prediction; NCT04037163)

ST-Segment Elevation Myocardial Infarction: Sex Differences in Incidence, Etiology, Treatment, and Outcomes

PURPOSE

Although there have been marked improvements in the standard of care for treatment of ST-elevation myocardial infarction, women, especially younger women, continue to have significantly worse outcomes than men.

RECENT FINDINGS

This review highlights the current sex differences in presentation, etiology, treatment, and outcomes among these patients in order to make providers aware of the heterogeneous entities that cause ST-elevation myocardial infarction particularly in women and of disparities in treatment that lead to poorer outcomes in women. Furthermore, it emphasizes evidence-based strategies including standardized protocols for early revascularization, mechanical circulatory support, and access methodology that can reduce sex-based disparities in treatments and outcomes.

The evolving role of coronary computed tomography in understanding sex differences in coronary atherosclerosis

Our understanding of sex differences in subclinical atherosclerosis and plaque composition and characteristics have greatly improved with the use of coronary computed tomography (CCTA) over the past years. CCTA has emerged as an important frontline diagnostic test for women, especially as we continue to understand the impact of non-obstructive atherosclerosis as well as diffuse, high risk plaque as precursors of acute cardiac events in women. Based on its ability to identify complex plaque morphology such as low attenuation plaque, high risk non calcified plaque, positive remodeling, fibrous cap, CCTA can be used to assess plaque characteristics. CCTA can avoid false positive of other imaging studies, if included earlier in assessment of ischemic symptoms. In the contemporary clinical setting, CCTA will prove useful in further understanding and managing cardiovascular disease in women and those without traditional obstructive coronary disease.

Coronary Arterial Function and Disease in Women With No Obstructive Coronary Arteries

Ischemic heart disease (IHD) is the leading cause of mortality in women. While traditional cardiovascular risk factors play an important role in the development of IHD in women, women may experience sex-specific IHD risk factors and pathophysiology, and thus female-specific risk stratification is needed for IHD prevention, diagnosis, and treatment. Emerging data from the past 2 decades have significantly improved the understanding of IHD in women, including mechanisms of ischemia with no obstructive coronary arteries and myocardial infarction with no obstructive coronary arteries. Despite this progress, sex differences in IHD outcomes persist, particularly in young women. This review highlights the contemporary understanding of coronary arterial function and disease in women with no obstructive coronary arteries, including coronary anatomy and physiology, mechanisms of ischemia with no obstructive coronary arteries and myocardial infarction with no obstructive coronary arteries, noninvasive and invasive diagnostic strategies, and management of IHD.

Sex Differences in Coronary Atherosclerosis

PURPOSE OF REVIEW

The importance of cardiovascular disease (CVD) in women has long been underestimated. Therefore, we need to understand the impact of sex differences on CVD.

RECENT FINDINGS

Traditional risk factors contribute to coronary artery disease (CAD) differently in women and men. There are female-specific risk factors and comorbid conditions that affect the risk of CAD. Plaque erosion is frequently seen in younger women who smoke, while plaque rupture is common in older women and men who have elevated blood cholesterol. Coronary artery calcification is also different in both sexes. Thus, coronary artery calcification score-based risk stratification in women is challenging. A deeper understanding of the sex differences in the risk factors and plaque morphology of coronary atherosclerosis may lead to improved outcomes of CVD in women.

Imaging Approaches to the Diagnosis of Vascular Diseases

PURPOSE OF REVIEW

Vascular imaging is a complex field including numerous modalities and imaging markers. This review is focused on important and recent findings in atherosclerotic carotid artery plaque imaging with an emphasis on developments in magnetic resonance imaging (MRI) and computed tomography (CT).

RECENT FINDINGS

Recent evidence shows that carotid plaque characteristics and not only established measures of carotid plaque burden and stenosis are associated independently with cardiovascular outcomes. On carotid MRI, the presence of a lipid-rich necrotic core (LRNC) has been associated with incident cardiovascular disease (CVD) events independent of wall thickness, a traditional measure of plaque burden. On carotid MRI, intraplaque hemorrhage (IPH) presence has been identified as an independent predictor of stroke. The presence of a fissured carotid fibrous cap has been associated with contrast enhancement on CT angiography imaging. Carotid artery plaque characteristics have been associated with incident CVD events, and advanced plaque imaging techniques may gain additional prominence in the clinical treatment decision process.

Vulnerable Plaque in Patients with Acute Coronary Syndrome: Identification, Importance, and Management

MI is a leading cause of morbidity and mortality worldwide. Coronary artery thrombosis is the final pathologic feature of the most cases of acute MI primarily caused by atherosclerotic coronary artery disease. The concept of vulnerable plaque has evolved over the years but originated from early pioneering work unveiling the crucial role of plaque rupture and subsequent coronary thrombosis as the dominant cause of MI. Along with systemic cardiovascular risk factors, developments of intravascular and non-invasive imaging modalities have allowed us to identify coronary plaques thought to be at high risk for rupture. However, morphological features alone may only be one of many factors which promote plaque progression. The current vulnerable-plaque-oriented approaches to accomplish personalized risk assessment and treatment have significant room for improvement. In this review, the authors discuss recent advances in the understanding of vulnerable plaque and its management strategy from pathology and clinical perspectives.

Immune Mechanisms of Plaque Instability

Inflammation crucially drives atherosclerosis from disease initiation to the emergence of clinical complications. Targeting pivotal inflammatory pathways without compromising the host defense could compliment therapy with lipid-lowering agents, anti-hypertensive treatment, and lifestyle interventions to address the substantial residual cardiovascular risk that remains beyond classical risk factor control. Detailed understanding of the intricate immune mechanisms that propel plaque instability and disruption is indispensable for the development of novel therapeutic concepts. In this review, we provide an overview on the role of key immune cells in plaque inception and progression, and discuss recently identified maladaptive immune phenomena that contribute to plaque destabilization, including epigenetically programmed trained immunity in myeloid cells, pathogenic conversion of autoreactive regulatory T-cells and expansion of altered leukocytes due to clonal hematopoiesis. From a more global perspective, the article discusses how systemic crises such as acute mental stress or infection abruptly raise plaque vulnerability and summarizes recent advances in understanding the increased cardiovascular risk associated with COVID-19 disease. Stepping outside the box, we highlight the role of gut dysbiosis in atherosclerosis progression and plaque vulnerability. The emerging differential role of the immune system in plaque rupture and plaque erosion as well as the limitations of animal models in studying plaque disruption are reviewed.

Morphological Characteristics of Eroded Plaques with Noncritical Coronary Stenosis: An Optical Coherence Tomography Study

AIMS

Recent studies suggested plaque erosion with noncritical stenosis could be treated distinctly from that with critical stenosis, but their morphological features remained largely unknown. The present study aimed to investigate morphological features of eroded plaques with different lumen stenosis using optical coherence tomography (OCT).

METHODS

A total of 348 ST-segment elevated myocardial infarction patients with culprit OCT-defined plaque erosion (OCT-erosion) were analyzed. Based on the severity of lumen area stenosis, all patients with OCT-erosions were divided into the following three groups: Group A (area stenosis ＜50%, n=50); Group B (50% ≤ area stenosis ＜75%, n=146); Group C (area stenosis ≥ 75%, n=152).

RESULTS

Compared with patients in Groups A and B, patients in Group C were older (p=0.008) and had higher prevalence of hypertension (p=0.029). Angiographic analysis showed that 72.0% of the eroded plaques in Group A were located in the left anterior descending artery, followed by 67.8% in Group B, and 53.9% in Group C (p=0.039). OCT analysis showed that Group A had the highest prevalence of fibrous plaques (p＜0.001) and nearby bifurcation (p=0.036), but the lowest prevalence of lipid-rich plaques (p＜0.001), macrophage accumulation (p＜0.001), microvessels (p=0.009), cholesterol crystals (p＜0.001), and calcification (p=0.023). Multivariable regression analysis showed fibrous plaque (odds ratio [OR]: 3.014, 95% confidence interval [CI]: 1.932-4.702, p＜0.001) and nearby bifurcation (OR: 1.750, 95% CI: 1.109-2.761, p=0.016) were independently associated with OCT-erosion with an area stenosis of ＜75%.

CONCLUSIONS

More than half of OCT-erosions presented with ＜75% area stenosis, having distinct morphological features from those of OCT-erosions with critical stenosis. Fibrous plaque and nearby bifurcation were independently associated with noncritically stenotic OCT-erosion, suggesting that eroded plaques might need individualized treatment.

Quantitative plaque assessment by coronary computed tomography angiography: An up-to-date review

Coronary computed tomography angiography has an emerging role in the diagnostic workup of coronary artery disease. Due to its high sensitivity and negative predictive value, coronary computed tomography angiography can rule out obstructive coronary artery diseases and substitute invasive coronary angiography in many cases. In addition, coronary computed tomography angiography provides a unique information beyond stenosis grading as it can visualize atherosclerosis and quantify its extent. Qualitative and quantitative plaque assessment provides an incremental value in the prediction of future major adverse cardiac events. Moreover, determining adverse plaque features has a potential to identify advanced atherosclerosis and patients at increased risk of acute coronary syndrome. Nevertheless, challenges may emerge with the process of quantifying coronary plaques due to limited reproducibility, lack of automated, standardized and validated techniques. Therefore, reliable quantified data are scarce due to the various computed tomography scanners and software platforms and investigations with small sample sizes. Radiomics and machine learning-based image processing methods are relatively new in the field of cardiovascular plaque imaging. These techniques hold the promise to improve diagnostic performance, reproducibility and prognostic value of computed tomography based plaque assessment.

Coexistence of calcified- and lipid-containing plaque components and their association with incidental rupture points in acute coronary syndrome-causing culprit lesions: results from the prospective OPTICO-ACS study

AIMS

Rupture of the fibrous cap (RFC) represents the main pathophysiological mechanism causing acute coronary syndromes (ACS). Destabilization due to plaque biomechanics is considered to be importantly involved, exact mechanisms triggering plaque ruptures are, however, unknown. This study aims at characterizing the relation between plaque components and rupture points at ACS-causing culprit lesions in a large cohort of ACS-patients assessed by high-resolution intracoronary imaging.

METHODS AND RESULTS

Within the prospective, multicentric OPTICO-ACS study program, the ACS-causing culprit plaques of 282 consecutive patients were investigated following a standardized optical coherence tomography (OCT) imaging protocol. Each pullback was assessed on a frame-by-frame basis for the presence of lipid components (LC), calcium components (CC), and coexistence of both LC and CC (LCC) by two independent OCT-core labs. Of the 282 ACS-patients, 204 patients (72.3%) presented with ACS caused by culprit lesions with rupture of the fibrous cap (RFC-ACS) and 27.7% patients had ACS caused by culprit lesions with intact fibrous cap (IFC-ACS). When comparing RFC-ACS to IFC-ACS, a preferential occurrence of all three plaque components (LC, CC, and LCC) in RFC-ACS became apparent (P < 0.001). Within ruptured culprit lesions, the zone straight at the rupture point [extended rupture zone (RZ)] was characterized by similar (24.7% vs. 24.0%; P = ns) calcium content when compared with the proximal and distal border of the culprit lesion [border zone (BZ)]. The RZ displayed a significantly higher amount of both, LC (100% vs. 69.8%; P < 0.001) and LCC (22.7% vs. 6.8%; P < 0.001), when compared with the BZ. The relative component increase towards the RZ was particularly evident for LCC (+233.8%), while LC showed only a modest increase (+43.3%).

CONCLUSIONS

Calcified- and lipid-containing components characterize ruptured fibrous cap ACS-causing culprit lesions. Their coexistence is accelerated directly at the ruptured point, suggesting a pathophysiological contribution in the development of RFC-ACS.

Diverse ultrastructural landscape of atherosclerotic endothelium

BACKGROUND AND AIMS

The endothelium plays a major role in atherosclerosis, yet the endothelial plaque surface is a largely uncharted territory. Here we hypothesize that atherosclerosis-driven remodeling of the endothelium is a dynamic process, involving both damaging and regenerative mechanisms.

METHODS

Using scanning electron microscopy (SEM) and immuno-SEM, we studied endothelial junction ultrastructure, endothelial openings and immune cell-endothelium interactions in eight apoe^-/- mice and two human carotid plaques.

RESULTS

The surface of early mouse plaques (n = 11) displayed a broad range of morphological alterations, including junctional disruptions and large transcellular endothelial pores with the average diameter between 0.6 and 3 μm. The shoulder region of advanced atherosclerotic lesions (n = 7) had a more aggravated morphology with 8 μm-size paracellular openings at two-fold higher density. In contrast, the central apical surface of advanced plaques, i.e., the plaque body (n = 7), displayed endothelial normalization, as shown by a significantly higher frequency of intact endothelial junctions and a lower incidence of paracellular pores. This normalized endothelial phenotype correlated with low immune cell density (only 5 cells/mm²). The human carotid plaque surface (n = 2) displayed both well-organized and disrupted endothelium with similar features as described above. In addition, they were accompanied by extensive thrombotic areas.

CONCLUSIONS

Our study unveils the spectrum of endothelial abnormalities associated with the development of atherosclerosis. These were highly abundant in early lesions and in the shoulder region of advanced plaques, while normalized at the advanced plaque's body. Similar endothelial features were observed in human atherosclerotic plaques, underlining the versatility of endothelial transformations in atherosclerosis.

Molecular Imaging of Vulnerable Coronary Plaque with Radiolabeled Somatostatin Receptors (SSTR)

Atherosclerosis is responsible for the majority of heart attacks and is characterized by several modifications of the arterial wall including an inflammatory reaction. The silent course of atherosclerosis has made it necessary to develop predictors of disease complications before symptomatic lesions occur. Vulnerable to rupture atherosclerotic plaques are the target for molecular imaging. To this aim, different radiopharmaceuticals for PET/CT have emerged for the identification of high-risk plaques, with high specificity for the identification of the cellular components and pathophysiological status of plaques. By targeting specific receptors on activated macrophages in high-risk plaques, radiolabelled somatostatin analogues such as ⁶⁸Ga-DOTA-TOC, TATE,0 or NOC have shown high relevance to detect vulnerable, atherosclerotic plaques. This PET radiopharmaceutical has been tested in several pre-clinical and clinical studies, as reviewed here, showing an important correlation with other risk factors.

Inflammation during the life cycle of the atherosclerotic plaque

Inflammation orchestrates each stage of the life cycle of atherosclerotic plaques. Indeed, inflammatory mediators likely link many traditional and emerging risk factors with atherogenesis. Atheroma initiation involves endothelial activation with recruitment of leucocytes to the arterial intima, where they interact with lipoproteins or their derivatives that have accumulated in this layer. The prolonged and usually clinically silent progression of atherosclerosis involves periods of smouldering inflammation, punctuated by episodes of acute activation that may arise from inflammatory mediators released from sites of extravascular injury or infection or from subclinical disruptions of the plaque. Smooth muscle cells and infiltrating leucocytes can proliferate but also undergo various forms of cell death that typically lead to formation of a lipid-rich 'necrotic' core within the evolving intimal lesion. Extracellular matrix synthesized by smooth muscle cells can form a fibrous cap that overlies the lesion's core. Thus, during progression of atheroma, cells not only procreate but perish. Inflammatory mediators participate in both processes. The ultimate clinical complication of atherosclerotic plaques involves disruption that provokes thrombosis, either by fracture of the plaque's fibrous cap or superficial erosion. The consequent clots can cause acute ischaemic syndromes if they embarrass perfusion. Incorporation of the thrombi can promote plaque healing and progressive intimal thickening that can aggravate stenosis and further limit downstream blood flow. Inflammatory mediators regulate many aspects of both plaque disruption and healing process. Thus, inflammatory processes contribute to all phases of the life cycle of atherosclerotic plaques, and represent ripe targets for mitigating the disease.

Gender-based in vivo comparison of culprit plaque characteristics and plaque microstructures using optical coherence tomography in acute coronary syndrome

Introduction: Women perform worse after acute coronary syndrome (ACS) than men. The reason for these differences is unclear. The aim was to ascertain gender differences in the culprit plaque characteristics in ACS.

Methods: Patients with ACS undergoing percutaneous coronary intervention for the culprit vessel underwent optical coherence tomography (OCT) imaging. Culprit plaque was identified as lipid rich,fibrous, and calcific plaque. Mechanisms underlying ACS are classified as plaque rupture, erosion,or calcified nodule. A lipid rich plaque along with thin-cap fibroatheroma (TCFA) was a vulnerable plaque. Plaque microstructures including cholesterol crystals, macrophages, and microvessels were noted.

Results: A total of 52 patients were enrolled (men=29 and women=23). Baseline demographic features were similar in both the groups except men largely were current smokers (P <0.001). Plaque morphology,men vs. women: lipid rich 88.0% vs. 90.5%; fibrous 4% vs 0%; calcific 8.0% vs. 9.5% (P = 0.64). Of the ACS mechanisms in males versus females; plaque rupture (76.9 % vs. 50 %), plaque erosion (15.4 % vs.40 %) and calcified nodule (7.7 % vs. 10 %) was noted (P = 0.139). Fibrous cap thickness was (50.19 ±11.17 vs. 49.00 ± 10.71 mm, P = 0.71) and thin-cap fibroatheroma (96.2% vs. 95.0%, P = 1.0) in men and women respectively. Likewise no significant difference in presence of macrophages (42.3 % vs. 30%, P = 0.76), microvessels (73.1% vs. 60 %, P = 0.52) and cholesterol crystals (92.3% vs. 80%, P = 0.38).

Conclusion: No significant gender-based in-vivo differences could be discerned in ACS patients’ culprit plaques morphology, characteristics, and underlying mechanisms.

Distinct pathological mechanisms distinguish acute coronary syndrome caused by plaque erosion from plaque rupture

PURPOSE OF REVIEW

The current systematic review aims to provide novel insights into the distinct pathological features of acute coronary syndrome (ACS) with intact fibrous cap, also known as 'plaque erosion'. A more detailed understanding of its underlying pathomechanisms provides the basis for future personalized therapeutic approaches to ACS.

RECENT FINDINGS

In the past years, a mounting proportion of evidence point towards the concept of plaque erosion being responsible for more than one-third of all cases of ACS and representing an autonomous ACS-causing entity driven by biomechanical forces, immunological alternations and systemic elevation of inflammatory mediators. First pilot studies proved a therapeutic paradigm shift from primary PCI at the ACS-causing culprit lesion to systemic therapies in patients with ACS caused by plaque erosion.

SUMMARY

This review provides the current status of the broad basic and clinical studies focused to the topic of plaque erosion: a new ACS-causing pathophysiology with different pathological aspects providing appropriate implications for personalized therapies in ACS.

Differences in Culprit Lesions Between Premenopausal and Postmenopausal Women With Acute Coronary Syndrome: An Optical Coherence Tomography Study

BACKGROUND

Differences in culprit lesion characteristics remain unclear between premenopausal and postmenopausal women with acute coronary syndrome (ACS). Optical coherence tomography (OCT) enables high-resolution in vivo identification of plaques. We investigated potential differences in culprit lesions between premenopausal and postmenopausal women with ACS by means of OCT.

METHODS

We included 191 ACS patients who had undergone preinterventional OCT and stratified them into 2 groups according to their menopausal status: premenopausal (n = 97) and postmenopausal (n = 94). The characteristics of culprit lesions were compared between the 2 groups.

RESULTS

Multivessel lesions were more commonly noted on angiography in the postmenopausal group than in the premenopausal group (40.21% vs 72.34%; P < 0.0001). On OCT, the most common type of culprit plaque was the fibrous plaque in the premenopausal group and the lipid plaque in the postmenopausal group. Compared with the premenopausal group, plaque rupture was more common in the postmenopausal group (39.18% vs 55.32%; P = 0.0254); culprit lesions had more vulnerable features, including macrophage accumulation (58.76% vs 87.23%; P < 0.0001), microchannel (38.14% vs 84.04%; P < 0.0001), cholesterol crystals (30.93% vs 62.77%; P < 0.0001), lipid-rich plaque (32.99% vs 58.51%; P < 0.0001), thin-cap fibroatheroma (3.09% vs 21.28%; P = 0.0001), and calcium (20.62% vs 44.68%; P = 0.0004); maximum lipid arc was larger (121.06 ± 110.99° vs 220.12 ± 115.47°, P < 0.0001); and lipid length was longer (5.78 ± 5.29 mm vs 12.90 ± 8.97 mm; P < 0.0001).

CONCLUSIONS

Compared with premenopausal women with ACS, postmenopausal women with ACS had more vulnerable culprit lesions. These finding suggest potential optimised lipid-lowering therapy for postmenopausal women with ACS.

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?

Plaque erosion and acute coronary syndromes: phenotype, molecular characteristics and future directions

Although acute coronary syndromes (ACS) remain one of the leading causes of death, the clinical presentation has changed over the past three decades with a decline in the incidence of ST-segment elevation myocardial infarction (STEMI) and an increase in non-STEMI. This epidemiological shift is at least partially explained by changes in plaque biology as a result of the widespread use of statins. Historically, atherosclerotic plaque rupture of the fibrous cap was thought to be the main culprit in ACS. However, plaque erosion with an intact fibrous cap is now responsible for about one third of ACS and up to two thirds of non-STEMI. Two major research approaches have enabled a better understanding of plaque erosion. First, advanced intravascular imaging has provided opportunities for an 'optical biopsy' and extensive phenotyping of coronary plaques in living patients. Second, basic science experiments have shed light on the unique molecular characteristics of plaque erosion. At present, patients with ACS are still uniformly treated with coronary stents irrespective of the underlying pathobiology. However, pilot studies indicate that patients with plaque erosion might be treated conservatively without coronary stenting. In this Review, we discuss the patient phenotype and the molecular characteristics in atherosclerotic plaque erosion and provide our vision for a potential major shift in the management of patients with plaque erosion.

Culprit lesion characteristics in very young patients with acute coronary syndrome: An optical coherence tomography study

OBJECTIVE

The concept of managing patients on the basis of culprit lesion characteristics is emerging. Atherosclerotic plaques are reported to be rare in young patients presenting with acute coronary syndrome (ACS). We aimed to assess culprit lesion characteristics in very young patients presenting with ACS by optical coherence tomography (OCT).

METHODS

This was a prospective, single-center, open-label, observational study. Patients aged 35 years or less with ACS who underwent invasive coronary angiography and OCT were studied.

RESULTS

Of the 43 patients, 22 (51.2%) had plaque rupture, 16 (37.2%) had plaque erosion, and five (11.6%) had no specific lesion character. Plaque was fibroatheromatous in 34 (79.1%) patients and fibrous in seven (16.3%). Plaque was not found in two (4.7%) patients; of these, one (2.3%) had left anterior descending coronary artery bridging, and one (2.3%) had intimal dissection without any plaque. Plaque rupture was more commonly associated with fibroatheromatous plaques, whereas plaque erosion was more commonly associated with fibrous plaque (p=0.010).

CONCLUSION

Although plaque rupture and plaque erosion occurred at the same rate as seen in patients of all ages, calcified nodule as a culprit lesion was not found in young patients. Majority of the patients had plaque rupture and plaque erosion with fibroatheromatous plaque, signifying the occurrence of established coronary artery disease in very young patients of Southeast Asia.

Predictors of Coronary Plaque Erosion in Current and Non-Current Smokers With ST-Segment Elevation Myocardial Infarction - An Optical Coherence Tomography Study

BACKGROUND

Smoking is an important risk factor of plaque erosion. This study aimed to investigate the predictors of plaque erosion in current and non-current smokers presenting with ST-segment elevation myocardial infarction (STEMI).

METHODS AND RESULTS

A total of 1,320 STEMI patients with culprit plaque rupture or plaque erosion detected by pre-intervention optical coherence tomography were divided into a current smoking group (n=715) and non-current smoking group (n=605). Plaque erosion accounted for 30.8% (220/715) of culprit lesions in the current smokers and 21.2% (128/605) in the non-current smokers. Multivariable analysis showed age <50 years, single-vessel disease and the absence of dyslipidemia were independently associated with plaque erosion rather than plaque rupture, regardless of smoking status. In current smokers, diabetes mellitus (odds ratio [OR]: 0.29; 95% confidence interval [CI]: 0.10-0.83; P=0.021) was negatively associated with plaque erosion as compared with plaque rupture. In non-current smokers, minimal lumen area (MLA, OR: 1.37; 95% CI: 1.16-1.62; P<0.001) and nearby bifurcation (OR: 3.20; 95% CI: 1.98-5.16; P<0.001) were positively related to plaque erosion, but not plaque rupture.

CONCLUSIONS

In patients with STEMI, the presence of diabetes mellitus significantly increased the risk of rupture-based STEMI but may not have reduced the risk of plaque erosion-based STEMI in current smokers. Nearby bifurcation and larger MLA were associated with plaque erosion in non-current smokers.

Optical Coherence Tomography of Plaque Erosion: JACC Focus Seminar Part 2/3

Plaque erosion, a distinct histopathological and clinical entity, accounts for over 30% of acute coronary syndromes (ACS). Optical coherence tomography allows in vivo diagnosis of plaque erosion. Local flow perturbation with activation of Toll-like receptor 2 and CD8⁺ T cells and subsequent desquamation of endothelium and neutrophil extracellular trap formation contribute to mechanisms of plaque erosion. Compared with ACS patients with plaque rupture, those with plaque erosion are younger, have fewer traditional cardiovascular risk factors, have lower plaque burden, and are more likely to present with non-ST-segment elevation ACS. Early evidence suggests that in patients with ACS caused by plaque erosion, antithrombotic therapy without stenting may be a safe and effective option. Future randomized trials are needed to validate these findings. Clinical studies to develop noninvasive point-of-care biomarkers that distinguish plaque rupture from erosion, and to test novel therapies that target molecular pathways involved in plaque erosion are needed.

Postmortem coronary artery calcium score in cases of myocardial infarction

Sudden cardiac death (SCD) related to atherosclerotic coronary artery disease (ACAD) resulting in myocardial infarction is the most prevalent cause of death in western countries. In clinical practice, coronary artery calcium score (CACS) is considered an independent predictor of coronary events, closely related to atherosclerotic burden and is quantified radiologically by the Agatston score being calculated through computed tomography. Postmortem computed tomography (PMCT) allows the visualization and quantification of coronary calcifications before the autopsy. However, it was reported that some patients who died from severe ACAD had a zero CACS in PMCT. In this study, a retrospective evaluation of CACS in adult's myocardial infarction cases related to ACAD, with available CACS and histological slides of coronary arteries, was performed in order to gain a deeper understanding of coronary calcifications and their role in myocardial infarction cases. The CACS was calculated by using the software Smartscore 4.0 after the radiological examination on a 64-row CT unit using a specific cardiac protocol. Thirty-six cases were identified out of 582 autopsies, recorded during a 2-year study period (29 men, 7 women; age 56.3 ± 11.7). CACS was 0-10 in 5 cases (5 men, 44.8 ± 13.7), 11-100 in 8 cases (6 men, 2 women, 53.1 ± 7.7), 101-400 in 13 cases (11 men, 2 women, 57.4 ± 9.6), and > 400 in 10 cases (9 men, 1 woman, 63.1 ± 11.9). Coronary thrombosis was found in 28 cases, histologically identified as plaque erosions in 6 cases and as plaque ruptures in 22 cases. Statistical analyses showed that CACS increases significantly with age (p-value < 0.05) and does not show significant correlation with gender, body weight, body mass index, and heart weight. CACS was significantly higher in plaque ruptures than in plaque erosions (p-value < 0.01). Zero or low CACS on unenhanced PMCT cannot exclude the presence of myocardial infarction related to ACAD. This paradoxical discrepancy between imaging and autopsy findings can be explained considering the histological aspect of fatal coronary plaques.

Imaging angiogenesis in atherosclerosis in large arteries with 68Ga-NODAGA-RGD PET/CT: relationship with clinical atherosclerotic cardiovascular disease

BACKGROUND

Integrin alpha-V-beta-3 (αvβ3) pathway is involved in intraplaque angiogenesis and inflammation and represents a promising target for molecular imaging in cardiovascular diseases such as atherosclerosis. The aim of this study was to assess the clinical correlates of arterial wall accumulation of ⁶⁸Ga-NODAGA-RGD, a specific α_vβ₃ integrin ligand for PET.

MATERIALS AND METHODS

The data of 44 patients who underwent ⁶⁸Ga-NODAGA-RGD PET/CT scans were retrospectively analyzed. Tracer accumulation in the vessel wall of major arteries was analyzed semi-quantitatively by blood-pool-corrected target-to-background ratios. Tracer uptake was compared with clinically documented atherosclerotic cardiovascular disease, cardiovascular risk factors and calcified plaque burden. Data were compared using the Mann-Whitney U test, Pearson correlation and Spearman correlation.

RESULTS

⁶⁸Ga-NODAGA-RGD arterial uptake was significantly higher in patients with previous clinically documented atherosclerotic cardiovascular disease (mean TBR 2.44 [2.03-2.55] vs. 1.81 [1.56-1.96], p = 0.001) and showed a significant correlation with prior cardiovascular or cerebrovascular event (r = 0.33, p = 0.027), BMI (ρ = 0.38, p = 0.01), plaque burden (ρ = 0.31, p = 0.04) and hypercholesterolemia (r = 0.31, p = 0.04).

CONCLUSIONS

⁶⁸Ga-NODAGA-RGD holds promise as a non-invasive marker of disease activity in atherosclerosis, providing information about intraplaque angiogenesis.

Deep learning with convolutional neural network for estimation of the characterisation of coronary plaques: Validation using IB-IVUS

INTRODUCTION

Deep learning approaches have shown high diagnostic performance in image classifications, such as differentiation of malignant tumors and calcified coronary plaque. However, it is unknown whether deep learning is useful for characterizing coronary plaques without the presence of calcification using coronary computed tomography angiography (CCTA). The purpose of this study was to compare the diagnostic performance of deep learning with a convolutional neural network (CNN) with that of radiologists in the estimation of coronary plaques.

METHODS

We retrospectively enrolled 178 patients (191 coronary plaques) who had undergone CCTA and integrated backscatter intravascular ultrasonography (IB-IVUS) studies. IB-IVUS diagnosed 81 fibrous and 110 fatty or fibro-fatty plaques. We manually captured vascular short-axis images of the coronary plaques as Portable Network Graphics (PNG) images (150 × 150 pixels). The display window level and width were 100 and 700 Hounsfield units (HU), respectively. The deep-learning system (CNN; GoogleNet Inception v3) was trained on 153 plaques; its performance was tested on 38 plaques. The area under the curve (AUC) obtained by receiver operating characteristic analysis of the deep learning system and by two board-certified radiologists was compared.

RESULTS

With the CNN, the AUC and the 95% confidence interval were 0.83 and 0.69-0.96, respectively; for radiologist 1 they were 0.61 and 0.42-0.80; for radiologist 2 they were 0.68 and 0.51-0.86, respectively. The AUC for CNN was significantly higher than for radiologists 1 (p = 0.04); for radiologist 2 it was not significantly different (p = 0.22).

CONCLUSION

DL-CNN performed comparably to radiologists for discrimination between fatty and fibro-fatty plaque on CCTA images.

IMPLICATIONS FOR PRACTICE

The diagnostic performance of the CNN and of two radiologists in the assessment of 191 ROIs on CT images of coronary plaques whose type corresponded with their IB-IVUS characterization was comparable.

High-risk coronary artery plaque in asymptomatic patients with type 2 diabetes: clinical risk factors and coronary artery calcium score

BACKGROUND

High-risk coronary artery plaque (HRP) is associated with increased risk of acute coronary syndrome. We aimed to investigate the prevalence of HRP in asymptomatic patients with type 2 diabetes (T2D), and its relation to patient characteristics including cardiovascular risk factors, diabetes profile, and coronary artery calcium score (CACS).

METHODS

Asymptomatic patients with T2D and no previous coronary artery disease (CAD) were studied using coronary computed tomography angiography (CCTA) in this descriptive study. Plaques with two or more high-risk features (HRP) defined by low attenuation, positive remodeling, spotty calcification, and napkin-ring sign were considered HRP. In addition, total atheroma volume (TAV), proportions of dense calcium, fibrous, fibrous-fatty and necrotic core volumes were assessed. The CACS was obtained from non-enhanced images by the Agatston method. Cardiovascular and diabetic profiles were assessed in all patients.

RESULTS

In 230 patients CCTA was diagnostic and 161 HRP were detected in 86 patients (37%). Male gender (OR 4.19, 95% CI 1.99-8.87; p < 0.01), tobacco exposure in pack years (OR 1.02, 95% CI 1.00-1.03; p = 0.03), and glycated hemoglobin (HbA1c) (OR 1.04, 95% CI 1.02-1.07; p < 0.01) were independent predictors of HRP. No relationship was found to other risk factors. HRP was not associated with increased CACS, and 13 (23%) patients with zero CACS had at least one HRP.

CONCLUSION

A high prevalence of HRP was detected in this population of asymptomatic T2D. The presence of HRP was associated with a particular patient profile, but was not ruled out by the absence of coronary artery calcium. CCTA provides important information on plaque morphology, which may be used to risk stratify this high-risk population. Trial registration This trial was retrospectively registered at clinical trials.gov January 11, 2017 trial identifier NCT03016910.

Glucocorticoids: Fuelling the Fire of Atherosclerosis or Therapeutic Extinguishers?

Glucocorticoids are steroid hormones with key roles in the regulation of many physiological systems including energy homeostasis and immunity. However, chronic glucocorticoid excess, highlighted in Cushing's syndrome, is established as being associated with increased cardiovascular disease (CVD) risk. Atherosclerosis is the major cause of CVD, leading to complications including coronary artery disease, myocardial infarction and heart failure. While the associations between glucocorticoid excess and increased prevalence of these complications are well established, the mechanisms underlying the role of glucocorticoids in development of atheroma are unclear. This review aims to better understand the importance of glucocorticoids in atherosclerosis and to dissect their cell-specific effects on key processes (e.g., contractility, remodelling and lesion development). Clinical and pre-clinical studies have shown both athero-protective and pro-atherogenic responses to glucocorticoids, effects dependent upon their multifactorial actions. Evidence indicates regulation of glucocorticoid bioavailability at the vasculature is complex, with local delivery, pre-receptor metabolism, and receptor expression contributing to responses linked to vascular remodelling and inflammation. Further investigations are required to clarify the mechanisms through which endogenous, local glucocorticoid action and systemic glucocorticoid treatment promote/inhibit atherosclerosis. This will provide greater insights into the potential benefit of glucocorticoid targeted approaches in the treatment of cardiovascular disease.

Healed Erosion: The Role of Pre-interventional Optical Coherence Tomography in a Patient Clinically Suspected of Having Unstable Angina with Coronary Spasm

A 46-year-old man complained of chest pain at rest for the past three months. His symptoms gradually exacerbated and were suspected of being due to unstable angina. A coronary angiogram revealed focal tight stenosis at the proximal left anterior descending coronary artery with gross spastic coronary findings. Optical coherence tomography (OCT) revealed layered low-intensity structures with microvessels and the accumulation of macrophages, which indicated progressive stenosis with multiple-layered organized thrombus caused by coronary erosion. We treated the stenosis using a drug-coated balloon instead of drug-eluting stents. There was no restenosis, and OCT revealed good plaque healing at follow-up. This case suggests that the pre-interventional OCT plaque morphology can have a positive impact on the revascularization strategy.

Sclerostin Downregulation Globally by Naturally Occurring Genetic Variants, or Locally in Atherosclerotic Plaques, Does Not Associate With Cardiovascular Events in Humans

Inhibition of sclerostin increases bone formation and decreases bone resorption, leading to increased bone mass, bone mineral density, and bone strength and reduced fracture risk. In a clinical study of the sclerostin antibody romosozumab versus alendronate in postmenopausal women (ARCH), an imbalance in adjudicated serious cardiovascular (CV) adverse events driven by an increase in myocardial infarction (MI) and stroke was observed. To explore whether there was a potential mechanistic plausibility that sclerostin expression, or its inhibition, in atherosclerotic (AS) plaques may have contributed to this imbalance, sclerostin was immunostained in human plaques to determine whether it was detected in regions relevant to plaque stability in 94 carotid and 50 femoral AS plaques surgically collected from older female patients (mean age 69.6 ± 10.4 years). Sclerostin staining was absent in most plaques (67%), and when detected, it was of reduced intensity compared with normal aorta and was located in deeper regions of the plaque/wall but was not observed in areas considered relevant to plaque stability (fibrous cap and endothelium). Additionally, genetic variants associated with lifelong reduced sclerostin expression were explored for associations with phenotypes including those related to bone physiology and CV risk factors/events in a population-based phenomewide association study (PheWAS). Natural genetic modulation of sclerostin by variants with a significant positive effect on bone physiology showed no association with lifetime risk of MI or stroke. These data do not support a causal association between the presence of sclerostin, or its inhibition, in the vasculature and increased risk of serious cardiovascular events. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Incidence, characteristics and outcomes in very young patients with ST segment elevation myocardial infarction

OBJECTIVE

ST-segment elevation acute myocardial infarction (STEMI) in very young adults is uncommon. Many studies have focused on the cutoff of 45-50 years old to define young patients with STEMI leaving limited data on the group of very young patients aged less than 35 years old. We investigated the incidence of STEMI in different subgroups of young patients and focused on the characteristics, possible pathogenesis and outcomes in very young patients aged less than 35 years old.

METHODS

We retrospectively studied 792 STEMI patients aged less than 55 years who underwent successful primary PCI. We categorized patients as very young if they were or less 35 years old and as young if they were between 36 and 55 years old. Baseline characteristics, angiographic findings, as well as short- and long-term outcomes were compared between the two groups.

RESULTS

There were 46 (6%) very young patients (age ≤ 35 years) and 748 (94%) young patients (36 < age ≤ 55 years). Very young patients had fewer atherosclerotic risk factors than young patients, but there was no difference in short- or long-term outcomes. Overt hypercoagulable state was evident serologically (antiphospholipid antibodies) in 2/7 (29%) of screened patients and clinically (left ventricular thrombus or acute coronary thrombosis without an atherosclerotic plaque) in 6/46 patients (13%).

CONCLUSION

Very young patients with STEMI constitute a distinct subset of young patients with fewer atherosclerotic risk factors yet comparable outcomes. More efforts should be made screening for serologic and clinical evidence of hypercoagulability in this group of patients.

Functional assessment of coronary plaques using CT based hemodynamic simulations: Current status, technical principles and clinical value

In recent years, coronary computed tomography angiography (CCTA) has emerged as an accurate and safe non-invasive imaging modality in terms of detecting and excluding coronary artery disease (CAD). In the latest European Society of Cardiology Guidelines CCTA received Class I recommendation for the evaluation of patients with stable chest pain with low to intermediate clinical likelihood of CAD. Despite its high negative predictive value, the diagnostic performance of CCTA is limited by the relatively low specificity, especially in patients with heavily calcified lesions. The discrepancy between the degree of stenosis and ischemia is well established based on both invasive and non-invasive tests. The rapid evolution of computational flow dynamics has allowed the simulation of CCTA derived fractional flow reserve (FFR-CT), which improves specificity by combining anatomic and functional information regarding coronary atherosclerosis. FFR-CT has been extensively validated against invasively measured FFR as the reference standard. Due to recent technological advancements FFR-CT values can also be calculated locally, without offsite processing. Wall shear stress (WSS) and axial plaque stress (APS) are additional key hemodynamic elements of atherosclerotic plaque characteristics, which can also be measured using CCTA images. Current evidence suggests that WSS and APS are important hemodynamic features of adverse coronary plaques. CCTA based hemodynamic calculations could therefore improve prognostication and the management of patients with stable CAD.

Cannabinoids and myocardial ischemia: Novel insights, updated mechanisms, and implications for myocardial infarction

Cannabis is the most widely trafficked and abused illicit drug due to its calming psychoactive properties. It has been increasingly recognized as having potential health benefits and relatively less adverse health effects as compared to other illicit drugs; however, growing evidence clearly indicates that cannabis is associated with considerable adverse cardiovascular events. Recent studies have linked cannabis use to myocardial infarction (MI); yet, very little is known about the underlying mechanisms. A MI is a cardiovascular disease characterized by a mismatch in the oxygen supply and demand of the heart, resulting in ischemia and subsequent necrosis of the myocardium. Since cannabis is increasingly being considered a risk factor for MI, there is a growing need for better appreciating its potential health benefits and consequences. Here, we discuss the cellular mechanisms of cannabis that lead to an increased risk of MI. We provide a thorough and critical analysis of cannabinoids' actions, which include modulation of adipocyte biology, regional fat distribution, and atherosclerosis, as well as precipitation of hemodynamic stressors relevant in the setting of a MI. By critically dissecting the modulation of signaling pathways in multiple cell types, this paper highlights the mechanisms through which cannabis may trigger life-threatening cardiovascular events. This then provides a framework for future pharmacological studies which can identify targets or develop drugs that modulate cannabis' effects on the cardiovascular system as well as other organ systems. Cannabis' impact on the autonomic outflow, vascular smooth muscle cells, myocardium, cortisol levels and other hemodynamic changes are also mechanistically reviewed.

Differential immunological signature at the culprit site distinguishes acute coronary syndrome with intact from acute coronary syndrome with ruptured fibrous cap: results from the prospective translational OPTICO-ACS study

AIMS

Acute coronary syndromes with intact fibrous cap (IFC-ACS), i.e. caused by coronary plaque erosion, account for approximately one-third of ACS. However, the underlying pathophysiological mechanisms as compared with ACS caused by plaque rupture (RFC-ACS) remain largely undefined. The prospective translational OPTICO-ACS study programme investigates for the first time the microenvironment of ACS-causing culprit lesions (CL) with intact fibrous cap by molecular high-resolution intracoronary imaging and simultaneous local immunological phenotyping.

METHODS AND RESULTS

The CL of 170 consecutive ACS patients were investigated by optical coherence tomography (OCT) and simultaneous immunophenotyping by flow cytometric analysis as well as by effector molecule concentration measurements across the culprit lesion gradient (ratio local/systemic levels). Within the study cohort, IFC caused 24.6% of ACS while RFC-ACS caused 75.4% as determined and validated by two independent OCT core laboratories. The IFC-CL were characterized by lower lipid content, less calcification, a thicker overlying fibrous cap, and largely localized near a coronary bifurcation as compared with RFC-CL. The microenvironment of IFC-ACS lesions demonstrated selective enrichment in both CD4+ and CD8+ T-lymphocytes (+8.1% and +11.2%, respectively, both P < 0.05) as compared with RFC-ACS lesions. T-cell-associated extracellular circulating microvesicles (MV) were more pronounced in IFC-ACS lesions and a significantly higher amount of CD8+ T-lymphocytes was detectable in thrombi aspirated from IFC-culprit sites. Furthermore, IFC-ACS lesions showed increased levels of the T-cell effector molecules granzyme A (+22.4%), perforin (+58.8%), and granulysin (+75.4%) as compared with RFC plaques (P < 0.005). Endothelial cells subjected to culture in disturbed laminar flow conditions, i.e. to simulate coronary flow near a bifurcation, demonstrated an enhanced adhesion of CD8+T cells. Finally, both CD8+T cells and their cytotoxic effector molecules caused endothelial cell death, a key potential pathophysiological mechanism in IFC-ACS.

CONCLUSIONS

The OPTICO-ACS study emphasizes a novel mechanism in the pathogenesis of IFC-ACS, favouring participation of the adaptive immune system, particularly CD4+ and CD8+ T-cells and their effector molecules. The different immune signatures identified in this study advance the understanding of coronary plaque progression and may provide a basis for future development of personalized therapeutic approaches to ACS with IFC.

TRIAL REGISTRATION

The study was registered at clinicalTrials.gov (NCT03129503).

Multifunctional pathology-mapping theranostic nanoplatforms for US/MR imaging and ultrasound therapy of atherosclerosis

Atherosclerotic thrombosis is the leading cause of most life-threatening cardiovascular diseases (CVDs), particularly as a result of rupture or erosion of vulnerable plaques. Rupture or erosion-prone plaques are quite different in cellular composition and immunopathology, requiring different treatment strategies. The current imaging technology cannot distinguish the types of vulnerable plaques, and thus empirical treatment is still applied to all without a tailored and precise treatment. Herein, we propose a novel strategy called "Multifunctional Pathology-mapping Theranostic Nanoplatform (MPmTN)" for the tailored treatment of plaques based on the pathological classification. MPmTNs are made up of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs), containing contrast imaging materials Fe3O4 and perfluoropentane (PFP), and coated with specific plaque-targeted peptides PP1 and cyclic RGD. The PFP encapsulated inside the MPmTN can undergo a phase change from nanodroplets to gas microbubbles under therapeutic ultrasound (TUS) exposure. The acoustic and biological effects induced by TUS and disruption of microbubbles may further promote therapeutic effects. Hypothetically, MPmTN NPs can target the rupture-prone plaque via the binding of PP1 to class A scavenger receptors (SR-A) on macrophages, induce the apoptosis due to TUS exposure and thus reduce the chronic soakage of inflammatory cells. The MPmTN NPs can also target the erosion-prone plaque through the binding of cRGD to glycoprotein (GP) IIb/IIIa on activated platelets and promote platelet disaggregation under TUS exposure. Therefore, MPmTNs may work as a multifunctional pathology-mapping therapeutic agent. Our in vitro results show that the MPmTN with PP1 and cRGD peptides had a high binding affinity both for activated macrophages and blood clots. Under TUS exposure, the MPmTN could effectively induce macrophage apoptosis, destroy thrombus and exhibit good imaging properties for ultrasound (US) and MRI. In apoE-/- mice, MPmTNs can selectively accumulate at the plaque site and reduce the T2-weighted signal. The apoptosis of macrophages and disaggregation of activated platelets on the plaques were also confirmed in vivo. In summary, this study provides a potential strategy for a tailored treatment of vulnerable plaques based on their pathological nature and a multimodal imaging tool for the risk stratification and assessment of therapeutic efficacy.

Relationship among clinical characteristics, morphological culprit plaque features, and long-term prognosis in patients with acute coronary syndrome

Culprit lesions of acute coronary syndrome (ACS) could be classified as plaque rupture (PR), erosion, or calcified nodule (CN). We aimed to determine the relationship among clinical characteristics, morphological plaque features, and long-term prognosis in ACS. Patients with ACS, who underwent pre-intervention optical coherence tomography between April 2013 and July 2018 were retrospectively enrolled, and classified into the three groups based on the culprit lesion morphology. In the 436 patients enrolled, incidences of PR, erosion, and CN in ACS culprit lesions were 46.1, 39.9, and 14.0%, respectively. Plaque erosion was more frequent in men aged < 60 years and CN was more frequent in older adults in both sexes (≥ 80 years) (P < 0.001). Patients with CN had a higher incidence of hemodialysis treatment (P < 0.001) and diabetes (P = 0.003). Multivariate analysis revealed that ST elevation myocardial infarction (STEMI) (P = 0.049) and presence of thin-cap fibroatheroma (TCFA) at the culprit lesion were independently associated with PR; in younger patients (< 60 year), preserved left ventricular ejection fraction and lower incidence of TCFA were correlated with plaque erosion; and older age, non-STEMI, or unstable angina pectoris, higher serum brain natriuretic peptide levels, and lower incidence of TCFA were independently associated with CN. Multivariable analysis revealed that CN (odds ratio [OR] 1.990, P = 0.005), male sex (OR 2.012, P = 0.004), and older age (OR 1.036, P < 0.001) were independently associated with future adverse events during a median follow-up of 757 days. Different patient characteristics and morphological features were associated with the type of culprit lesion in patients with ACS.

Diagnosis and Management of Stable Angina: A Review

IMPORTANCE

Nearly 10 million US adults experience stable angina, which occurs when myocardial oxygen supply does not meet demand, resulting in myocardial ischemia. Stable angina is associated with an average annual risk of 3% to 4% for myocardial infarction or death. Diagnostic tests and medical therapies for stable angina have evolved over the last decade with a better understanding of the optimal use of coronary revascularization.

OBSERVATIONS

Coronary computed tomographic angiography is a first-line diagnostic test in the evaluation of patients with stable angina due to higher sensitivity and comparable specificity compared with imaging-based stress testing. Moreover, coronary computed tomographic angiography allows detection of nonobstructive atherosclerosis that would not be identified with other noninvasive imaging modalities, improving risk assessment and potentially triggering more appropriate allocation of preventive therapies. Novel therapies treating lipids (proprotein convertase subtilisin/kexin type 9 inhibitors, ezetimibe, and icosapent ethyl) and type 2 diabetes (sodium-glucose cotransporter 2 inhibitors, glucagon-like peptide 1 receptor agonists) have improved cardiovascular outcomes in patients with stable ischemic heart disease when added to usual care. Randomized clinical trials showed no improvement in the rates of mortality or myocardial infarction with revascularization (largely by percutaneous coronary intervention) compared with optimal medical therapy alone, even in the setting of moderate to severe ischemia. In contrast, revascularization provides a meaningful benefit on angina and quality of life compared with antianginal therapies. Measures of the effect of angina on a patient's quality of life should be integrated into the clinic encounter to assist with the decision to proceed with revascularization.

CONCLUSIONS AND RELEVANCE

For patients with stable angina, emphasis should be placed on optimizing lifestyle factors and preventive medications such as lipid-lowering and antiplatelet agents to reduce the risk for cardiovascular events and death. Antianginal medications, such as β-blockers, nitrates, or calcium channel blockers, should be initiated to improve angina symptoms. Revascularization with percutaneous coronary intervention should be reserved for patients in whom angina symptoms negatively influence quality of life, generally after a trial of antianginal medical therapy. Shared decision-making with an informed patient is important for effective treatment of stable angina.

Can OCT change the therapeutic strategy in ACS due to plaque erosion?

The pathophysiology of acute coronary syndromes was thought to be coronary thrombosis over a plaque rupture. Autopsy studies revealed that not all cases were due to plaque rupture, even denuded endothelium or calcific nodule can beget a thrombus. Introduction of OCT made, in vivo recognition of lesion morphology clear. Plaque ruptures are most common and need primary angioplasty. Recent studies established plaque erosion is responsible for ACS in one third of the cases and majority of them present as Non ST elevation myocardial infarction and commonly found in young patients without major risk factors. Evidence from recent studies suggested that stenting can be deferred and they can be managed conservatively with good long term outcomes. More randomized trials are needed comparing plaque rupture and plaque erosion as regards conservative versus invasive management. If these studies substantiate the concept of conservative management, it will lead to a paradigm shift in their management.