The myth of the "vulnerable plaque": transitioning from a focus on individual lesions to atherosclerotic disease burden for coronary artery disease risk assessment

Cardiac microcalcification burden: Global assessment in high cardiovascular risk subjects with Na[18F]F PET-CT

BACKGROUND

Fluorine-18 sodium fluoride (Na[18F]F) atherosclerotic plaque uptake in positron emission tomography with computed tomography (PET-CT) identifies active microcalcification. We aim to evaluate global cardiac microcalcification activity with Na[18F]F, as a measure of unstable microcalcification burden, in high cardiovascular (CV) risk patients.

METHODS AND RESULTS

Thirty-four high CV risk individuals without previous CV events were scanned with Na[18F]F PET-CT. Cardiac Na[18F]F uptake was assessed through the global molecular calcium score (GMCS), which was calculated by summing the product of the mean standardized uptake value times the area of the cardiac regions of interest times the slice thickness for all cardiac transaxial slices, divided by the total number of slices. Mean age is 63.5 ± 7.8 years and 62% male. Median GMCS is 320.9 (240.8-402.8). Individuals with more than five CV risk factors (50%) have increased GMCS [356.7 (321.0-409.6) vs. 261.1 (225.6-342.1), P = 0.01], which is positively correlated with predicted fatal CV risk by SCORE (rs = 0.32, P = 0.04). There is a positive correlation between GMCS and weight (rs = 0.61), body mass index (rs = 0.66), abdominal perimeter (rs = 0.74), thoracic fat volume (rs = 0.47), and epicardial adipose tissue (rs = 0.41), all with P ≤ 0.01. There is no correlation between GMCS and coronary calcium score nor coronary artery wall Na[18F]F uptake.

CONCLUSIONS

In a high CV risk group, the global cardiac microcalcification burden is related to CV risk factors, metabolic syndrome variables and cardiac fat. Cardiac GMCS is a promising risk stratification tool, combining a straightforward and objective methodology with a comprehensive analysis of both coronary and valvular microcalcification.

Aortic wall segmentation in 18F-sodium fluoride PET/CT scans: Head-to-head comparison of artificial intelligence-based versus manual segmentation

BACKGROUND

We aimed to establish and test an automated AI-based method for rapid segmentation of the aortic wall in positron emission tomography/computed tomography (PET/CT) scans.

METHODS

For segmentation of the wall in three sections: the arch, thoracic, and abdominal aorta, we developed a tool based on a convolutional neural network (CNN), available on the Research Consortium for Medical Image Analysis (RECOMIA) platform, capable of segmenting 100 different labels in CT images. It was tested on 18F-sodium fluoride PET/CT scans of 49 subjects (29 healthy controls and 20 angina pectoris patients) and compared to data obtained by manual segmentation. The following derived parameters were compared using Bland-Altman Limits of Agreement: segmented volume, and maximal, mean, and total standardized uptake values (SUVmax, SUVmean, SUVtotal). The repeatability of the manual method was examined in 25 randomly selected scans.

RESULTS

CNN-derived values for volume, SUVmax, and SUVtotal were all slightly, i.e., 13-17%, lower than the corresponding manually obtained ones, whereas SUVmean values for the three aortic sections were virtually identical for the two methods. Manual segmentation lasted typically 1-2 hours per scan compared to about one minute with the CNN-based approach. The maximal deviation at repeat manual segmentation was 6%.

CONCLUSIONS

The automated CNN-based approach was much faster and provided parameters that were about 15% lower than the manually obtained values, except for SUVmean values, which were comparable. AI-based segmentation of the aorta already now appears as a trustworthy and fast alternative to slow and cumbersome manual segmentation.

Sphingosine 1-phosphate receptor 2 promotes erythrocyte clearance by vascular smooth muscle cells in intraplaque hemorrhage through MFG-E8 production

Intraplaque hemorrhage (IPH) accelerates atherosclerosis progression. To scavenge excessive red blood cells (RBCs), vascular smooth muscle cells (VSMCs) with great plasticity may function as phagocytes. Here, we investigated the erythrophagocytosis function of VSMCs and possible regulations involved. Based on transcriptional microarray analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that genes up-regulated in human carotid atheroma with IPH were enriched in functions of phagocytic activities, while those down-regulated were enriched in VSMCs contraction function. Transcriptional expression of Milk fat globule-epidermal growth factor 8 (MFG-E8) was also down-regulated in atheroma with IPH. In high-fat diet-fed apolipoprotein E-deficient mice, erythrocytes were present in cells expressing VSMC markers αSMA in the brachiocephalic artery, suggesting VSMCs play a role in erythrophagocytosis. Using immunofluorescence and flow cytometry, we also found that eryptotic RBCs were bound to and internalized by VSMCs in a phosphatidylserine/MFG-E8/integrin α_Vβ₃ dependent manner in vitro. Inhibiting S1PR2 signaling with specific inhibitor JTE-013 or siRNA decreased Mfge8 expression and impaired the erythrophagocytosis of VSMCs in vitro. Partial ligation was performed in the left common carotid artery (LCA) followed by intra-intimal injection of isolated erythrocytes to observe their clearance in vivo. Interfering S1PR2 expression in VSMCs with Adeno-associated virus 9 inhibited MFG-E8 expression inside LCA plaques receiving RBCs injection and attenuated erythrocytes clearance. Erythrophagocytosis by VSMCs increased vascular endothelial growth factor-a secretion and promoted angiogenesis. The present study revealed that VSMCs act as phagocytes for RBC clearance through S1PR2 activation induced MFG-E8 release.

Prognostic value of the PDW/HDL-C ratio in patients with chest pain symptoms and coronary artery calcification

Background

Platelet-related parameters and HDL-C have been regarded as reliable and alternative markers of coronary heart disease (CHD) and the independent predictors of cardiovascular outcomes. PDW is a simple platelet index, which increases during platelet activation. Whether the PDW/HDL-C ratio predicts major adverse cardiovascular and cerebrovascular events (MACCEs) in patients who complained of chest pain and confirmed coronary artery calcification remains to be investigated. This study aimed to investigate the prognostic value of the PDW/HDL-C ratio in patients with chest pain symptoms and coronary artery calcification.

Methods

A total of 5,647 patients with chest pain who underwent coronary computer tomography angiography (CTA) were enrolled in this study. Patients were divided into two groups according to their PDW/HDL-C ratio or whether the MACCE occurs. The primary outcomes were new-onset MACCEs, defined as the composite of all-cause death, non-fatal MI, non-fatal stroke, revascularization, malignant arrhythmia, and severe heart failure.

Results

All patients had varying degrees of coronary calcification, with a mean CACS of 97.60 (22.60, 942.75), and the level of CACS in the MACCEs group was significantly higher than that in non-MACCE (P<0.001). During the 89-month follow-up, 304 (5.38%) MACCEs were recorded. The incidence of MACCEs was significantly higher in patients with the PDW/HDL-C ratio > 13.33. The K–M survival curves showed that patients in the high PDW/HDL-C ratio group had significantly lower survival rates than patients in the low PDW/HDL-C ratio group (log-rank test: P < 0.001). Multivariate Cox hazard regression analysis reveals that the PDW/HDL ratio was an independent predictor of MACCEs (HR: 1.604, 95% CI: 1.263–2.035; P < 0.001). Cox regression analysis showed that participants with a lower PDW/HDL-C ratio had a higher risk of MACCEs than those in the higher ratio group. The incidence of MACCEs was also more common in the PDW/HDL-C ratio > 13.33 group among different severities of coronary artery calcification. Furthermore, adding the PDW/HDL-C ratio to the traditional prognostic model for MACCEs improved C-statistic (P < 0.001), the NRI value (11.3% improvement, 95% CI: 0.018–0.196, P = 0.01), and the IDI value (0.7% improvement, 95% CI: 0.003–0.010, P < 0.001).

Conclusion

The higher PDW/HDL-C ratio was independently associated with the increasing risk of MACCEs in patients with chest pain symptoms and coronary artery calcification. In patients with moderate calcification, mild coronary artery stenosis, and CAD verified by CTA, the incidence of MACCEs increased significantly in the PDW/HDL-C ratio > 13.33 group. Adding the PDW/HDL-C ratio to the traditional model provided had an incremental prognostic value for MACCEs.

The role of cardiac computed tomography in predicting adverse coronary events

Cardiac computed tomography (CCT) is now considered a first-line diagnostic test for suspected coronary artery disease (CAD) providing a non-invasive, qualitative, and quantitative assessment of the coronary arteries and pericoronary regions. CCT assesses vascular calcification and coronary lumen narrowing, measures total plaque burden, identifies plaque composition and high-risk plaque features and can even assist with hemodynamic evaluation of coronary lesions. Recent research focuses on computing coronary endothelial shear stress, a potent modulator in the development and progression of atherosclerosis, as well as differentiating an inflammatory from a non-inflammatory pericoronary artery environment using the simple measurement of pericoronary fat attenuation index. In the present review, we discuss the role of the above in the diagnosis of coronary atherosclerosis and the prediction of adverse cardiovascular events. Additionally, we review the current limitations of cardiac computed tomography as an imaging modality and highlight how rapid technological advancements can boost its capacity in predicting cardiovascular risk and guiding clinical decision-making.

Role of Inflammation in Cardiac Remodeling After Acute Myocardial Infarction

Atherosclerosis is defined as an inflammatory disease. Low-grade inflammation is present in all phases of the cardiovascular continuum, since the establishment of cardiovascular risk factors and ischemic heart disease until cardiovascular events, such as myocardial infarction, heart failure and death. Not all inflammatory pathways are linked to cardiovascular outcomes, and thus, not all anti-inflammatory approaches decrease cardiovascular events. The most common cause of ventricular remodeling and heart failure is ischemic heart disease. Biomarkers such as high-sensitivity C-reactive protein can identify individuals at risk of major cardiovascular complications, but this biomarker has no causal effect on cardiovascular disease. On the other hand, interleukin 6 appears to be causally associated with cardiovascular disease. CANTOS was the first proof of concept study showing that anti-inflammatory therapy reduces major cardiovascular outcomes. Based on many anti-inflammatory trials, only therapies acting on the NLRP3 inflammasome, or interleukin 1beta, showed benefits on cardiovascular disease. Ventricular remodeling, particularly after myocardial infarction seems also influenced by the intensity of inflammatory responses, suggesting that anti-inflammatory therapies may reduce the residual cardiovascular risk. Inflammasome (NLRP3) activation, subtypes of lymphocytes, interleukin 6, and some inflammatory biomarkers, are associated with larger infarct size and impaired ventricular function after myocardial infarction. Cardiovascular risk factors commonly present in patients with myocardial infarction, and advanced age are associated with higher inflammatory activity.

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.

Association Between Dietary Intakes and Plaque Vulnerability Measured by Optical Coherence Tomography in Patients With Coronary Heart Disease: A Mediation Analysis of Inflammatory Factors

Although studies have proven that diet has a critical role in preventing or delaying atherosclerosis and is far simpler to adjust and adhere to than other risk factors, the underlying mechanisms behind this effect remain not well comprehended. The purpose of this investigation was to determine the impact of inflammatory factors on the connection between dietary ingestion and coronary plaque fragility as measured via optical coherence tomography (OCT) in patients with coronary heart disease (CHD). This research eventually comprised 194 participants with CHD who met the inclusion and exclusion criteria. Semi-quantitative food frequency questionnaire (SQFFQ) was utilized to investigate dietary consumption status, serum levels of inflammatory biomarkers were analyzed using enzyme-linked immunosorbent assay, and OCT was employed to identify the plaque susceptibility of causative lesions in the body. Following correction for statistically meaningful possible confounders in univariate analysis, quartiles of soy and nuts, fruits and vitamin C were negatively associated with coronary plaque vulnerability. Conversely, the upper quartile group of sodium intake had 2.98 times the risk of developing vulnerable plaques compared with the most minimal quartile group. Meanwhile, we observed an inverse dose–response connection between vitamin C consumption and inflammatory biomarkers as well as plaque vulnerability. More importantly, tumor necrosis factor- α (TNF-α) and interleukin-6 (IL-6) were significant mediators of the connection between vitamin C and plaque vulnerability, suggesting that vitamin C may inhibit the atherosclerotic inflammatory process by decreasing the expression of IL-6 and TNF-α, thereby reducing the risk of vulnerable plaques. These new findings provide crucial clues to identify anti-inflammatory dietary components as effective therapeutic approaches in the management of CHD, while also providing some insights into their mechanisms of action.

Simultaneous assessment of microcalcifications and morphological criteria of vulnerability in carotid artery plaque using hybrid 18F-NaF PET/MRI

BACKGROUND

Previous studies have suggested the role of microcalcifications in plaque vulnerability. This exploratory study sought to assess the potential of hybrid positron-emission tomography (PET)/magnetic resonance imaging (MRI) using 18F-sodium fluoride (18F-NaF) to check simultaneously 18F-NaF uptake, a marker of microcalcifications, and morphological criteria of vulnerability.

METHODS AND RESULTS

We included 12 patients with either recently symptomatic or asymptomatic carotid stenosis. All patients underwent 18F-NaF PET/MRI. 18F-NaF target-to-background ratio (TBR) was measured in culprit and nonculprit (including contralateral plaques of symptomatic patients) plaques as well as in other arterial walls. Morphological criteria of vulnerability were assessed on MRI. Mineral metabolism markers were also collected. 18F-NaF uptake was higher in culprit compared to nonculprit plaques (median TBR 2.6 [2.2-2.8] vs 1.7 [1.3-2.2]; P = 0.03) but was not associated with morphological criteria of vulnerability on MRI. We found a positive correlation between 18F-NaF uptake and calcium plaque volume and ratio but not with circulating tissue-nonspecific alkaline phosphatase (TNAP) activity and inorganic pyrophosphate (PPi) levels. 18F-NaF uptake in the other arterial walls did not differ between symptomatic and asymptomatic patients.

CONCLUSIONS

18F-NaF PET/MRI may be a promising tool for providing additional insights into the plaque vulnerability.

The Core Role of Neutrophil–Lymphocyte Ratio to Predict All-Cause and Cardiovascular Mortality: A Research of the 2005–2014 National Health and Nutrition Examination Survey

Objective

To further supplement the previous research on the relationship between neutrophil–lymphocyte ratio (NLR) and all-cause and cardiovascular mortality, and construct clinical models to predict mortality.

Methods

A total number of 2,827 observers were included from the National Health and Nutrition Examination Survey (NHANES) database in our research. NLR was calculated from complete blood count. According to the quartile of baseline NLR, those observers were divided into four groups. A multivariate weighted Cox regression model was used to analyze the association of NLR with mortality. We constructed simple clinical prognosis models by nomograms. Kaplan–Meier survival curves were used to depict cause-specific mortality. Restricted cubic spline regression was used to make explicit relationships between NLR and mortality.

Results

This study recruited 2,827 subjects aged ≥ 18 years from 2005 to 2014. The average age of these observers was 51.55 ± 17.62, and 57.69% were male. NLR is still an independent predictor, adjusted for age, gender, race, drinking, smoking, dyslipidemia, and other laboratory covariates. The area under the receiver operating characteristic curves (AUCs) of NLR for predicting all-cause mortality and cardiovascular mortality were 0.632(95% CI [0599, 0.664]) and 0.653(95% CI [0.581, 0.725]), respectively, which were superior to C-reactive protein (AUCs: 0.609 and 0.533) and WBC (AUCs: 0.522 and 0.513). The calibration and discrimination of the nomograms were validated by calibration plots and concordance index (C-index), and the C-indexes (95% CIs) of nomograms for all-cause and cardiovascular mortality were 0.839[0.819,0.859] and 0.877[0.844,0.910], respectively. The restricted cubic spline showed a non-linear relationship between NLR and mortality. NLR > 2.053 might be a risk factor for mortality.

Conclusion

There is a non-linear relationship between NLR and mortality. NLR is an independent factor related to mortality, and NLR > 2.053 will be a risk factor for prognosis. NLR and nomogram should be promoted to medical use for practicality and convenience.

Radiomics-Based Precision Phenotyping Identifies Unstable Coronary Plaques From Computed Tomography Angiography

OBJECTIVES

The aim of this study was to precisely phenotype culprit and nonculprit lesions in myocardial infarction (MI) and lesions in stable coronary artery disease (CAD) using coronary computed tomography angiography (CTA)-based radiomic analysis.

BACKGROUND

It remains debated whether any single coronary atherosclerotic plaque within the vulnerable patient exhibits unique morphology conferring an increased risk of clinical events.

METHODS

A total of 60 patients with acute MI prospectively underwent coronary CTA before invasive angiography and were matched to 60 patients with stable CAD. For all coronary lesions, high-risk plaque (HRP) characteristics were qualitatively assessed, followed by semiautomated plaque quantification and extraction of 1,103 radiomic features. Machine learning models were built to examine the additive value of radiomic features for discriminating culprit lesions over and above HRP and plaque volumes.

RESULTS

Culprit lesions had higher mean volumes of noncalcified plaque (NCP) and low-density noncalcified plaque (LDNCP) compared with the highest-grade stenosis nonculprits and highest-grade stenosis stable CAD lesions (NCP: 138.1 mm3 vs 110.7 mm3 vs 102.7 mm3; LDNCP: 14.2 mm3 vs 9.8 mm3 vs 8.4 mm3; both Ptrend < 0.01). In multivariable linear regression adjusted for NCP and LDNCP volumes, 14.9% (164 of 1,103) of radiomic features were associated with culprits and 9.7% (107 of 1,103) were associated with the highest-grade stenosis nonculprits (critical P < 0.0007) when compared with highest-grade stenosis stable CAD lesions as reference. Hierarchical clustering of significant radiomic features identified 9 unique data clusters (latent phenotypes): 5 contained radiomic features specific to culprits, 1 contained features specific to highest-grade stenosis nonculprits, and 3 contained features associated with either lesion type. Radiomic features provided incremental value for discriminating culprit lesions when added to a machine learning model containing HRP and plaque volumes (area under the receiver-operating characteristic curve 0.86 vs 0.76; P = 0.004).

CONCLUSIONS

Culprit lesions and highest-grade stenosis nonculprit lesions in MI have distinct radiomic signatures compared with lesions in stable CAD. Within the vulnerable patient may exist individual vulnerable plaques identifiable by coronary CTA-based precision phenotyping.

Influence of air pollutants on circulating inflammatory cells and microRNA expression in acute myocardial infarction

Air pollutants increase the risk and mortality of myocardial infarction (MI). The aim of this study was to assess the inflammatory changes in circulating immune cells and microRNAs in MIs related to short-term exposure to air pollutants. We studied 192 patients with acute coronary syndromes and 57 controls with stable angina. For each patient, air pollution exposure in the 24-h before admission, was collected. All patients underwent systematic circulating inflammatory cell analyses. According to PM_2.5 exposure, 31 patients were selected for microRNA analyses. STEMI patients exposed to PM_2.5 showed a reduction of CD4⁺ regulatory T cells. Furthermore, in STEMI patients the exposure to PM_2.5 was associated with an increase of miR-146a-5p and miR-423-3p. In STEMI and NSTEMI patients PM_2.5 exposure was associated with an increase of miR-let-7f-5p. STEMI related to PM_2.5 short-term exposure is associated with changes involving regulatory T cells, miR-146a-5p and miR-423-3p.

Atherothrombotic factors and atherosclerotic cardiovascular events: the multi-ethnic study of atherosclerosis

AIMS

Traditional atherosclerotic cardiovascular disease (ASCVD) risk factors fail to address the full spectrum of the complex interplay of atherosclerotic and atherothrombotic factors integral to ASCVD events. This study sought to examine the association between atherothrombotic biomarkers and ASCVD events.

METHODS AND RESULTS

The association between atherothrombotic biomarkers and 877 ASCVD events with and without adjustment for traditional risk factors was evaluated via Cox proportional hazards models and factor analysis in 5789 Multi-Ethnic Study of Atherosclerosis participants over a median follow-up of 14.7 years. Factor analysis accounted for multidimensional relationship and shared variance among study biomarkers, which identified two new variables: a thrombotic factor (Factor 1), principally defined by shared variance in fibrinogen, plasmin-antiplasmin complex, factor VIII, D-dimer, and lipoprotein(a), and a fibrinolytic factor (Factor 2), principally defined by shared variance of plasminogen and oxidized phospholipids on plasminogen. In a model including both factors, the thrombotic factor was associated with the higher risk of ASCVD events [hazard ratio (HR) 1.57, 95% confidence interval (CI) 1.45, 1.70], while the fibrinolytic factor was associated with the lower risk of ASCVD events (HR 0.76, 95% CI 0.70, 0.82), with estimated ASCVD free survival highest for low atherothrombotic Factor 1 and high atherothrombotic Factor 2.

CONCLUSION

Two atherothrombotic factors, one representative of thrombotic propensity and the other representative of fibrinolytic propensity, were significantly and complementarily associated with incident ASCVD events, remained significantly associated with incident ASCVD after controlling for traditional risk factors, and have promise for identifying patients at high ASCVD event risk specifically due to their atherothrombotic profile.

Non-invasive Multimodality Imaging of Coronary Vulnerable Patient

Atherosclerotic plaque rupture or erosion remain the primary mechanism responsible for myocardial infarction and the major challenge of cardiovascular researchers is to develop non-invasive methods of accurate risk prediction to identify vulnerable plaques before the event occurs. Multimodal imaging, by CT-TEP or CT-SPECT, provides both morphological and activity information about the plaque and cumulates the advantages of anatomic and molecular imaging to identify vulnerability features among coronary plaques. However, the rate of acute coronary syndromes remains low and the mechanisms leading to adverse events are clearly more complex than initially assumed. Indeed, recent studies suggest that the detection of a state of vulnerability in a patient is more important than the detection of individual sites of vulnerability as a target of focal treatment. Despite this evolution of concepts, multimodal imaging offers a strong potential to assess patient's vulnerability. Here we review the current state of multimodal imaging to identify vulnerable patients, and then focus on emerging imaging techniques and precision medicine.

Molecular imaging in atherosclerosis

Purpose

As atherosclerosis is a  prominent cause of morbidity and mortality, early detection of atherosclerotic plaques is vital to prevent complications. Imaging plays a significant role in this goal. Molecular imaging and structural imaging detect different phases of atherosclerotic progression. In this review, we explain the relation between these types of imaging with the physiopathology of plaques, along with their advantages and disadvantages. We also discuss in detail the most commonly used positron emission tomography (PET) radiotracers for atherosclerosis imaging.

Method

A comprehensive search was conducted to extract articles related to imaging of atherosclerosis in PubMed, Google Scholar, and Web of Science. The obtained papers were reviewed regarding precise relation with our topic. Among the search keywords utilized were "atherosclerosis imaging", "atherosclerosis structural imaging", "atherosclerosis CT scan" "positron emission tomography", "PET imaging", "18F-NaF", "18F-FDG", and "atherosclerosis calcification."

Result

Although structural imaging such as computed tomography (CT) offers essential information regarding plaque structure and morphologic features, these modalities can only detect macroscopic alterations that occur later in the disease’s progression, when the changes are frequently irreversible. Molecular imaging modalities like PET, on the other hand, have the advantage of detecting microscopic changes and allow us to treat these plaques before irreversible changes occur. The two most commonly used tracers in PET imaging of atherosclerosis are 18F-sodium fluoride (18F-NaF) and 18F-fluorodeoxyglucose (18F-FDG). While there are limitations in the use of 18F-FDG for the detection of atherosclerosis in coronary arteries due to physiological uptake in myocardium and high luminal blood pool activity of 18F-FDG, 18F-NaF PET is less affected and can be utilized to analyze the coronary arteries in addition to the peripheral vasculature.

Conclusion

Molecular imaging with PET/CT has become a useful tool in the early detection of atherosclerosis. 18F-NaF PET/CT shows promise in the early global assessment of atherosclerosis, but further prospective studies are needed to confirm its role in this area.

Observer repeatability and interscan reproducibility of 18F-sodium fluoride coronary microcalcification activity

BACKGROUND

We aimed to establish the observer repeatability and interscan reproducibility of coronary 18F-sodium-fluoride positron emission tomography (PET) uptake using a novel semi-automated approach, coronary microcalcification activity (CMA).

METHODS

Patients with multivessel coronary artery disease underwent repeated hybrid PET and computed tomography angiography (CTA) imaging (PET/CTA). CMA was defined as the integrated standardized uptake values (SUV) in the entire coronary tree exceeding 2 standard deviations above the background SUV. Coefficients of repeatability between the same observer (intraobserver repeatability), between 2 observers (interobserver repeatability) and coefficient of reproducibility between 2 scans (interscan reproducibility), were determined at vessel and patient level.

RESULTS

In 19 patients, CMA was assessed twice in 43 coronary vessels on two PET/CT scans performed 12 ± 5 days apart. There was excellent intraclass correlation for intraobserver and interobserver repeatability as well as interscan reproducibility (all ≥ 0.991). There was 100% intraobserver, interobserver and interscan agreement for the presence (CMA > 0) or absence (CMA = 0) of coronary18F-NaF uptake. Mean CMA was 3.12 ± 0.62 with coefficients of repeatability of ≤ 10% for all measures: intraobserver 0.24 and 0.22, interobserver 0.30 and 0.29 and interscan 0.33 and 0.32 at a per-vessel and per-patient level, respectively.

CONCLUSIONS

CMA is a repeatable and reproducible global measure of coronary atherosclerotic activity.

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.

Potential and Most Relevant Applications of Total Body PET/CT Imaging

ABSTRACT

The introduction of total body (TB) PET/CT instruments over the past 2 years has initiated a new and exciting era in medical imaging. These instruments have substantially higher sensitivity (up to 68 times) than conventional modalities and therefore allow imaging the entire body over a short period. However, we need to further refine the imaging protocols of this instrument for different indications. Total body PET will allow accurate assessment of the extent of disease, particularly, including the entire axial and appendicular skeleton. Furthermore, delayed imaging with this instrument may enhance the sensitivity of PET for some types of cancer. Also, this modality may improve the detection of venous thrombosis, a common complication of cancer and chemotherapy, in the extremities and help prevent pulmonary embolism. Total body PET allows assessment of atherosclerotic plaques throughout the body as a systematic disease. Similarly, patients with widespread musculoskeletal disorders including both oncologic and nononcologic entities, such as degenerative joint disease, rheumatoid arthritis, and osteoporosis, may benefit from the use of TB-PET. Finally, quantitative global disease assessment provided by this approach will be superior to conventional measurements, which do not reflect overall disease activity. In conclusion, TB-PET imaging may have a revolutionary impact on day-to-day practice of medicine and may become the leading imaging modality in the future.

In vivo evidence of atherosclerotic plaque erosion and healing in patients with acute coronary syndrome using serial optical coherence tomography imaging

BACKGROUND

The EROSION study (Effective Anti-Thrombotic Therapy Without Stenting: Intravascular Optical Coherence Tomography-Based Management in Plaque Erosion) allowed us to observe the healing process of coronary plaque erosion in vivo. The present study aimed to investigate the incidence of newly formed healed plaque and different baseline characteristics of acute coronary syndrome (ACS) patients caused by plaque erosion with or without newly formed healed plaque using optical coherence tomography (OCT).

METHODS

A total of 137 ACS patients with culprit plaque erosion who underwent pre-intervention OCT imaging and received no stent implantation were enrolled. Patients were stratified according to the presence or absence of newly formed healed phenotype at 1-month (137 patients) or 1-year OCT follow-up (52 patients). Patient's baseline clinical, angiographic, OCT characteristics and outcomes were compared.

RESULTS

There were 55.5% (76/137) of patients developed healed plaque at 1 month, and 69.2% (36/52) of patients developed healed plaque at 1 year. Patients with newly formed healed plaque had larger thrombus burden, and lower degree of area stenosis (AS%) at baseline than those without, and thrombus burden and AS% were predictors of plaque healing. The healing process was accompanied by the significant increase of AS% and incidence of microchannels, and greater inflammatory response. The outcomes appeared to be similar between the two groups.

CONCLUSIONS

Newly formed healed plaque was found in more than half of ACS patients with plaque erosion without stenting. Patients with newly formed healed plaque had lower luminal stenosis and larger thrombus burden. During healing process, luminal stenosis increased gradually.

Role of coronary computed tomography angiography (CTA) post the ISCHEMIA trial: Precision prevention based on coronary CTA-derived coronary atherosclerosis

The International Study of Comparative Health Effectiveness With Medical and Invasive Approaches (ISCHEMIA) trial has been recently published and suggested the importance of the selection of patients at high risk for future cardiovascular disease events and the enhancing optimal medical therapy. In the ISCHEMIA trial, coronary computed tomography angiography (CTA) was performed in most of the patients to exclude high-risk patients and those without obstructive coronary artery disease (CAD) who should not be randomized. Coronary CTA has been widely used as a non-invasive diagnostic modality to assess patients with suspected CAD. Currently, the international guidelines allow use of coronary CTA as a class I recommendation for patients with chest pain. Besides, in the numerous multicenter trials, the emerging role of coronary CTA has proven that it could soon become the standard for monitoring CAD and identifying patients at high risk of future cardiovascular events. In this review article, we summarize the current evidence on coronary CTA and the potential role of coronary CTA after the ISCHEMIA trial for patients with CAD. Risk assessment using detailed CAD data obtained non-invasively and prevention of future cardiovascular events through improved medical care will become increasingly essential for the precision treatment and prevention of CAD in patients.

Instantaneous wave-free ratio for guiding treatment of nonculprit lesions in patients with acute coronary syndrome: A retrospective study

BACKGROUND

The aim of this study was to analyze the feasibility of a physiological coronary evaluation with the instantaneous wave-free ratio (iFR) of nonculprit lesions in patients with acute coronary syndrome (ACS) successfully revascularized.

METHODS

A multicenter registry including patients of four high-volume PCI centers with ACS and underwent successful revascularization of the culprit vessel and had other nonculprit lesions that were physiologically evaluated with the iFR between January 2017 and December 2019. The primary endpoint was a composite of cardiac death, nonfatal myocardial infarction, probable or definitive stent thrombosis and new revascularization (MACEs).

RESULTS

A total of 356 patients with 472 nonculprit lesions were included. The mean age was 66 ± 11 years. The clinical presentation was ACS without persistent ST-segment elevation (NSTE-ACS) in 235 patients (66%) and ST-segment elevation myocardial infarction (STEMI) in 121 patients (34%). After a median follow-up period of 21 (14-30) months, the primary endpoint occurred in 32 patients (9%). There were no differences in outcomes regarding clinical presentation (NSTEMI vs. NSTE-ACS, 9.1 vs. 8.9%, p_adj  = 0.570) or iFR induced treatment strategy (patients with all lesions revascularized vs. patients with at least one lesion with an iFR > 0.89 deferred for revascularization, 10.5 vs. 8.4%, p_adj  = 0.476).

CONCLUSIONS

The use of the iFR to guide percutaneous coronary intervention decision making in nonculprit lesions seems to be feasible, with an acceptable percentage of MACEs at the mid-term follow-up. Patients with deferred revascularization of lesions without physiological significance and patients undergoing complete revascularization had a similar risk of MACEs.

PET-Based Imaging with 18F-FDG and 18F-NaF to Assess Inflammation and Microcalcification in Atherosclerosis and Other Vascular and Thrombotic Disorders

Positron emission tomography (PET) imaging with ¹⁸F-fluorodeoxyglucose (FDG) represents a method of detecting and characterizing arterial wall inflammation, with potential applications in the early assessment of vascular disorders such as atherosclerosis. By portraying early-stage molecular changes, FDG-PET findings have previously been shown to correlate with atherosclerosis progression. In addition, recent studies have suggested that microcalcification revealed by ¹⁸F-sodium fluoride (NaF) may be more sensitive at detecting atherogenic changes compared to FDG-PET. In this review, we summarize the roles of FDG and NaF in the assessment of atherosclerosis and discuss the role of global assessment in quantification of the vascular disease burden. Furthermore, we will review the emerging applications of FDG-PET in various vascular disorders, including pulmonary embolism, as well as inflammatory and infectious vascular diseases.

Artificial Intelligence in Vascular-PET:: Translational and Clinical Applications

Positron emission tomography (PET) offers an incredible wealth of diverse research applications in vascular disease, providing a depth of molecular, functional, structural, and spatial information. Despite this, vascular PET imaging has not yet assumed the same clinical use as vascular ultrasound, CT, and MR imaging which provides information about late-onset, structural tissue changes. The current clinical utility of PET relies heavily on visual inspection and suboptimal parameters such as SUVmax; emerging applications have begun to harness the tool of whole-body PET to better understand the disease. Even still, without automation, this is a time-consuming and variable process. This review summarizes PET applications in vascular disorders, highlights emerging AI methods, and discusses the unlocked potential of AI in the clinical space.

Coronary Computed Tomography Angiography Assessment of High-Risk Plaques in Predicting Acute Coronary Syndrome

Coronary computed tomography angiography (CCTA) is a comprehensive, non-invasive and cost-effective imaging assessment approach, which can provide the ability to identify the characteristics and morphology of high-risk atherosclerotic plaques associated with acute coronary syndrome (ACS). The development of CCTA and latest advances in emerging technologies, such as computational fluid dynamics (CFD), have made it possible not only to identify the morphological characteristics of high-risk plaques non-invasively, but also to assess the hemodynamic parameters, the environment surrounding coronaries and so on, which may help to predict the risk of ACS. In this review, we present how CCTA was used to characterize the composition and morphology of high-risk plaques prone to ACS and the current role of CCTA, including emerging CCTA technologies, advanced analysis, and characterization techniques in prognosticating the occurrence of ACS.

Clinical Molecular Imaging for Atherosclerotic Plaque

Atherosclerosis is a well-known disease leading to cardiovascular events, including myocardial infarction and ischemic stroke. These conditions lead to a high mortality rate, which explains the interest in their prevention, early detection, and treatment. Molecular imaging is able to shed light on the basic pathophysiological processes, such as inflammation, that cause the progression and instability of plaque. The most common radiotracers used in clinical practice can detect increased energy metabolism (FDG), macrophage number (somatostatin receptor imaging), the intensity of cell proliferation in the area (labeled choline), and microcalcifications (fluoride imaging). These radiopharmaceuticals, especially FDG and labeled sodium fluoride, can predict cardiovascular events. The limitations of molecular imaging in atherosclerosis include low uptake of highly specific tracers, possible overlap with other diseases of the vessel wall, and specific features of certain tracers’ physiological distribution. A common protocol for patient preparation, data acquisition, and quantification is needed in the area of atherosclerosis imaging research.

The Neutrophil-to-Lymphocyte Ratio Is an Important Indicator Predicting In-Hospital Death in AMI Patients

Objective: To explore the role of neutrophil-to-lymphocyte ratio (NLR) in predicting the short-term prognosis of NSTEMI and STEMI. Methods: This study was a single-center, retrospective and observational study. 2618 patients including 1289 NSTMI and 1329 STEMI patients were enrolled from June 2013 to February 2018 in Zhongda Hospital, Southeast University. The demographic information, clinical characteristics, medical history, laboratory examination, treatment, and outcome of individuals at admission and during hospitalization were extracted from the electronic medical record system. Outcome was defined as the all-cause death during hospitalization. Results: (1) In the NSTEMI group, the ability of NLR in predicting in-hospital death (AUC = 0.746) was higher than the neutrophil-monocyte ratio (NMR) (AUC = 0.654), the platelet-lymphocyte ratio (PLR) (AUC = 0.603) and the lymphocyte-monocyte ratio (LMR) (AUC = 0.685), and also higher than AST (AUC = 0.621), CK (AUC = 0.595), LDH (AUC = 0.653) and TnI (AUC = 0.594). The AUC of NLR in the STEMI group was only 0.621. (2) The optimal cut-off value of NLR in NSTEMI group was 5.509 (Youden index = 0.447, sensitivity = 77.01%, specificity = 67.72%). After adjusting variables including age, sex, diabetes history, smoking history, LDL-C and Cr, the logistic regression showed that the patients with NLR>5.509 had higher hazard risk of death (HR4.356; 95%CI 2.552-7.435; P < 0.001) than the patients with NLR ≤ 5.509. (3) Stratification analysis showed that the in-hospital mortality of patients with NLR > 5.509 was 14.611-fold higher than those with NLR ≤ 5.509 in patients aged <76, much higher than the ratio in patients aged ≥ 76. For patients with creatinine levels ≤ 71, the in-hospital death risk in high NLR group was 10.065-fold higher than in low NLR group (95%CI 1.761-57.514, P = 0.009), while the HR was only 4.117 in patients with creatinine levels > 71. The HR in patients with or without diabetes were 6.586 and 3.375, respectively. The HR in smoking or no smoking patients were 6.646 and 4.145, respectively. The HR in patients with LDL-C ≥ 2.06 or <2.06 were 5.526 and 2.967 respectively. Conclusion: Compared to NMR, PLR, and LMR, NLR had the best ability in predicting in-hospital death after NSTEMI. Age, creatinine, LDL-C, diabetes and smoking history were all important factors affecting the predictive efficiency in NSTEMI. NLR had the limited predictive ability in STEMI.

Optical Coherence Tomography of Plaque Vulnerability and Rupture: JACC Focus Seminar Part 1/3

Plaque rupture is the most common cause of acute coronary syndromes and sudden cardiac death. Characteristics and pathobiology of vulnerable plaques prone to plaque rupture have been studied extensively over 2 decades in humans using optical coherence tomography (OCT), an intravascular imaging technique with micron scale resolution. OCT studies have identified key features of plaque vulnerability and described the in vivo characteristics and spatial distribution of thin cap fibroatheromas as major precursors to plaque rupture. In addition, OCT data supports the evolving understanding of coronary heart disease as a panvascular process associated with inflammation. In the setting of high atherosclerotic burden, plaque ruptures often occur at multiple sites in the coronary arteries, and plaque progression and healing are dynamic processes modulated by systemic risk factors. This review details major investigations with intravascular OCT into the biology and clinical implications of plaque vulnerability and plaque rupture.

Using Optical Coherence Tomography and Intravascular Ultrasound Imaging to Quantify Coronary Plaque Cap Stress/Strain and Progression: A Follow-Up Study Using 3D Thin-Layer Models

Accurate plaque cap thickness quantification and cap stress/strain calculations are of fundamental importance for vulnerable plaque research. To overcome uncertainties due to intravascular ultrasound (IVUS) resolution limitation, IVUS and optical coherence tomography (OCT) coronary plaque image data were combined together to obtain accurate and reliable cap thickness data, stress/strain calculations, and reliable plaque progression predictions. IVUS, OCT, and angiography baseline and follow-up data were collected from nine patients (mean age: 69; m: 5) at Cardiovascular Research Foundation with informed consent obtained. IVUS and OCT slices were coregistered and merged to form IVUS + OCT (IO) slices. A total of 114 matched slices (IVUS and OCT, baseline and follow-up) were obtained, and 3D thin-layer models were constructed to obtain stress and strain values. A generalized linear mixed model (GLMM) and least squares support vector machine (LSSVM) method were used to predict cap thickness change using nine morphological and mechanical risk factors. Prediction accuracies by all combinations (511) of those predictors with both IVUS and IO data were compared to identify optimal predictor(s) with their best accuracies. For the nine patients, the average of minimum cap thickness from IVUS was 0.17 mm, which was 26.08% lower than that from IO data (average = 0.23 mm). Patient variations of the individual errors ranged from ‒58.11 to 20.37%. For maximum cap stress between IO and IVUS, patient variations of the individual errors ranged from ‒30.40 to 46.17%. Patient variations of the individual errors of maximum cap strain values ranged from ‒19.90 to 17.65%. For the GLMM method, the optimal combination predictor using IO data had AUC (area under the ROC curve) = 0.926 and highest accuracy = 90.8%, vs. AUC = 0.783 and accuracy = 74.6% using IVUS data. For the LSSVM method, the best combination predictor using IO data had AUC = 0.838 and accuracy = 75.7%, vs. AUC = 0.780 and accuracy = 69.6% using IVUS data. This preliminary study demonstrated improved plaque cap progression prediction accuracy using accurate cap thickness data from IO slices and the differences in cap thickness, stress/strain values, and prediction results between IVUS and IO data. Large-scale studies are needed to verify our findings.

Predictors for layered coronary plaques: an optical coherence tomography study

Healed coronary plaques, morphologically characterized by a layered pattern, are signatures of previous plaque disruption and healing. Recent optical coherence tomography (OCT) studies showed that layered plaque is associated with vascular vulnerability. However, factors associated with layered plaques have not been studied. The aim of this study was to investigate predictors for layered plaque at the culprit plaques and at non-culprit plaques. Patients with coronary artery disease who underwent pre-intervention OCT imaging of the culprit lesion were included. Layered plaques were defined as plaques with one or more layers of different optical density and a clear demarcation from underlying components. Among 313 patients, layered plaque at the culprit lesion was observed in 18.8% of ST-segment elevation myocardial infarction patients, 36.3% of non-ST-segment elevation acute coronary syndrome patients, and 53.4% of stable angina pectoris (SAP) patients (p < 0.001). In the multivariable model, SAP, multivessel disease, type B2/C lesion, and diameter stenosis > 70% were independent predictors for layered plaque at the culprit lesion. In addition, 394 non-culprit plaques in 190 patients were assessed to explore predictors for layered plaques at non-culprit lesions. SAP, and thin-cap fibroatheroma and layered plaque at the culprit lesion were independent predictors for layered plaques at non-culprit lesions. In conclusion, clinical presentation of SAP was a strong predictor for layered plaque at both culprit plaques and non-culprit plaques. Development and biologic significance of layered plaques may be related to a balance between pan-vascular vulnerability and endogenous anti-thrombotic protective mechanism.

Clinical significance of healed plaque detected by optical coherence tomography: a 2-year follow-up study

Recent studies have shown that healed plaque at the culprit lesion detected by optical coherence tomography (OCT) is a sign of pan-vascular vulnerability and advanced atherosclerosis. However, the clinical significance of healed plaque is unknown. A total of 265 patients who had OCT imaging of a culprit vessel and 2-year clinical follow-up data were included. Patients were stratified based on the presence or absence of a layered plaque phenotype, defined as layers of different optical density by OCT at either culprit or non-culprit lesions. The association between layered plaque and major adverse cardiac events (MACE), defined as cardiac death, acute coronary syndromes (ACS), or revascularization, was studied. Among 265 patients, 96 (36.2%) had the layered plaque phenotype. Layered plaque was more frequently observed in stable angina pectoris patients than in ACS patients (57.8%vs. 25.1%, p < 0.001). The average clinical follow-up period was 672 ± 172 days. Cumulative MACE was significantly higher in patients with layered plaque (p = 0.041), which was primarily driven by the high revascularization rate at 2 years (p = 0.002). Multivariate regression analysis showed that presence of layered plaque and low-density lipoprotein cholesterol levels were independently associated with an increased risk of revascularization (p = 0.026, p = 0.008, respectively). Patients with healed plaque in the culprit vessel had a higher incidence of revascularization, as compared to those without healed plaque, at 2 years.

Association of Stage 1 Hypertension Defined by the ACC/AHA 2017 Guideline With Asymptomatic Coronary Atherosclerosis

BACKGROUND

This study sought to assess the relationship between stage 1 hypertension and subclinical coronary atherosclerosis.

METHODS

A total of 4,666 individuals with available coronary computed tomography angiography (CCTA) results from a health checkup were enrolled. The classification of hypertension was adapted from the American College of Cardiology/American Heart Association (ACC/AHA) 2017 guideline. The presence of coronary plaques and its characteristics, and other CCTA findings were assessed.

RESULTS

There was a linear relationship between blood pressure (BP), both systolic BP (SBP) and diastolic BP (DBP), and the presence of coronary plaque. Patients were classified into 4 groups according to the BP category: normal BP (SBP <120 mm Hg and DBP <80 mm Hg; n = 2,395; 51.3%), elevated BP (SBP 120-129 mm Hg and DBP <80 mm Hg; n = 467; 10.0%), stage 1 hypertension (SBP 130-139 mm Hg or DBP 80-89 mm Hg; n = 1,139; 24.4%), and stage 2 hypertension (SBP ≥140 mm Hg or DBP ≥90 mm Hg; n = 665; 14.2%). Compared with the normal BP group after multivariate adjustment, the stage 1 hypertension group was significantly associated with the presence of atherosclerotic plaque (adjusted odds ratio [95% confidential interval], 1.37 [1.17-1.62]; P < 0.001), especially in noncalcified and mixed plaques. The relationship between stage 1 hypertension and stenosis >50% was not statistically significant. Isolated diastolic and isolated systolic stage 1 hypertensions were significantly related to the presence of coronary plaque. The elevated BP group was not associated with any positive CCTA findings.

CONCLUSIONS

Stage 1 hypertension was independently associated with subclinical coronary atherosclerosis.

Alavi-Carlsen Calcification Score (ACCS): A Simple Measure of Global Cardiac Atherosclerosis Burden

Multislice cardiac CT characterizes late stage macrocalcification in epicardial arteries as opposed to PET/CT, which mirrors early phase arterial wall changes in epicardial and transmural coronary arteries. With regard to tracer, there has been a shift from using mainly ¹⁸F-fluorodeoxyglucose (FDG), indicating inflammation, to applying predominantly ¹⁸F-sodium fluoride (NaF) due to its high affinity for arterial wall microcalcification and more consistent association with cardiovascular risk factors. To make NaF-PET/CT an indispensable adjunct to clinical assessment of cardiac atherosclerosis, the Alavi–Carlsen Calcification Score (ACCS) has been proposed. It constitutes a global assessment of cardiac atherosclerosis burden in the individual patient, supported by an artificial intelligence (AI)-based approach for fast observer-independent segmentation. Common measures for characterizing epicardial coronary atherosclerosis by NaF-PET/CT as the maximum standardized uptake value (SUV) or target-to-background ratio are more versatile, error prone, and less reproducible than the ACCS, which equals the average cardiac SUV. The AI-based approach ensures a quick and easy delineation of the entire heart in 3D to obtain the ACCS expressing ongoing global cardiac atherosclerosis, even before it gives rise to CT-detectable coronary calcification. The quantification of global cardiac atherosclerotic burden by the ACCS is suited for management triage and monitoring of disease progression with and without intervention.

Prospective Assessment of Biomarkers of Hypercoagulability for the Identification of Patients With Severe Coronary Artery Disease. The ROADMAP-CAD Study

In patients with stable coronary artery disease (CAD) blood hypercoagulability figures among factors leading to thrombosis. Tissue factor (TF) exposure at ruptured plaque initiates blood coagulation and hypercoagulability is responsible for thrombus formation. Early identification of patients eligible for angiography is a challenging issue for effective prevention of ACS. This pilot study aimed to identify biomarkers of hypercoagulability that can be prospectively used in risk assessment tools for the evaluation of CAD severity. Biomarkers of hypercoagulability could be a used for the evaluation of CAD severity. Platelet-poor plasma from 66 patients who were referred to coronary angiography was assessed for thrombin generation, phospholipid-dependent clotting time (Procoag-PPL^®) and D-Dimers, and evaluated against atherosclerotic burden. Patients with CAD, as compared to controls, showed attenuated thrombin generation lag time: 4.7 (3.8-5.4) min versus 2.5 (2.1-2.9) min; p < 0.0001, shorter Procoag-PPL^® clotting time 55.0(32-66) s versus 62.8 (42-85) s; p = 0.001), and higher D-Dimer levels 0.509 (0.27-2.58) μg/ml versus 0.309 (0.23-0.39) μg/ml; p = 0.038. Multivariate logistic regression model showed excellent discriminatory value in predicting CAD severity. The ROADMAP-CAD study showed that the Procoag-PPL^® clotting time and thrombin Peak are informative for the the burden of the coronary atherosclerotic disease. The clinical relevance of this observation in the development of a new clinic-biological risk assessment model for early diagnosis of severe CAD has to be examined in a prospective study.

Optical Coherence Tomography in Acute Coronary Syndromes

Advances in intravascular imaging have enabled assessment of the underlying plaque morphology in acute coronary syndromes, which allows for the initiation of individualized therapy. The atherothrombotic substrates for acute coronary syndromes consist of plaque rupture, erosion, and calcified nodule, whereas spontaneous coronary artery dissection, coronary artery spasm, and coronary embolism constitute rarer nonatherothrombotic etiologies. This review provides a brief overview of the data from clinical studies that have used intravascular optical coherence tomography to assess the culprit plaque morphology. We discuss the usefulness of intravascular imaging for effective treatment of patients presenting with acute coronary syndromes by percutaneous coronary intervention.

Predictors of 18F-sodium fluoride uptake in patients with stable coronary artery disease and adverse plaque features on computed tomography angiography

AIMS

In patients with stable coronary artery disease (CAD) and high-risk plaques (HRPs) on coronary computed tomography angiography (CTA), we sought to define qualitative and quantitative CTA predictors of abnormal coronary 18F-sodium fluoride uptake (18F-NaF) by positron emission tomography (PET).

METHODS AND RESULTS

Patients undergoing coronary CTA were screened for HRP. Those who presented with ≥3 CTA adverse plaque features (APFs) including positive remodelling; low attenuation plaque (LAP, <30 HU), spotty calcification; obstructive coronary stenosis ≥50%; plaque volume >100 mm3 were recruited for 18F-NaF PET. In lesions with stenosis ≥25%, quantitative plaque analysis and maximum 18F-NaF target to background ratios (TBRs) were measured. Of 55 patients, 35 (64%) manifested coronary 18F-NaF uptake. Of 68 high-risk lesions 49 (70%) had increased PET tracer activity. Of the APFs, LAP had the highest sensitivity (39.4%) and specificity (98.3%) for predicting 18F-NaF uptake. TBR values were higher in lesions with LAP compared to those without [1.6 (1.3-1.8) vs. 1.1 (1.0-1.3), P = 0.01]. On adjusted multivariable regression analysis, LAP (both qualitative and quantitative) was independently associated with plaque TBR [LAP qualitative: β = 0.47, 95% confidence interval (CI) 0.30-0.65; P < 0.001] and (LAP volume: β = 0.20 per 10 mm3, 95% CI 0.13-0.27; P < 0.001).

CONCLUSION

In stable CAD patients with HRP, LAP is predictive of 18F-NaF coronary uptake, but 18F-NaF is often seen in the absence of LAP. If 18F-NaF uptake is shown to be associated with adverse outcomes and becomes clinically used, the presence of LAP may define patients who would not benefit from the added testing.

Coronary Plaque Characterization From Optical Coherence Tomography Imaging With a Two-Pathway Cascade Convolutional Neural Network Architecture

Background: The morphological structure and tissue composition of a coronary atherosclerotic plaque determine its stability, which can be assessed by intravascular optical coherence tomography (OCT) imaging. However, plaque characterization relies on the interpretation of large datasets by well-trained observers. This study aims to develop a convolutional neural network (CNN) method to automatically extract tissue features from OCT images to characterize the main components of a coronary atherosclerotic plaque (fibrous, lipid, and calcification). The method is based on a novel CNN architecture called TwopathCNN, which is utilized in a cascaded structure. According to the evaluation, this proposed method is effective and robust in the characterization of coronary plaque composition from in vivo OCT imaging. On average, the method achieves 0.86 in F1-score and 0.88 in accuracy. The TwopathCNN architecture and cascaded structure show significant improvement in performance (p < 0.05). CNN with cascaded structure can greatly improve the performance of characterization compared to the conventional CNN methods and machine learning methods. This method has a higher efficiency, which may be proven to be a promising diagnostic tool in the detection of coronary plaques.

Impact of Arterial Remodeling of Intermediate Coronary Lesions on Long-Term Clinical Outcomes in Patients with Stable Coronary Artery Disease: An Intravascular Ultrasound Study

Background

Treatment of coronary intermediate lesions remains a controversy, and the role of arterial remodeling patterns determined by intravascular ultrasound in intermediate lesion is still not well known. The aim of this study was to investigate the impact of arterial remodeling of intermediate coronary lesions on long-term clinical outcomes.

Methods

Arterial remodeling patterns were assessed in 212 deferred intermediate lesions from 162 patients after IVUS examination. Negative, intermediate, and positive remodeling was defined as a remodeling index of <0.88, 0.88∼1.0, and >1.0, respectively. The primary endpoint was the composite vessel-oriented clinical events, defined as the composition of target vessel-related cardiac death, target vessel-related myocardial infarction, and target vessel revascularization. Quantitative flow ratio was assessed for evaluating the functional significance of intermediate lesions.

Results

72 intermediate remodeling lesions were present in 66 patients, whereas 77 negative remodeling lesions were present in 71 patients, and 63 positive remodeling lesions were present in 55 patients. Negative remodeling lesions had the smallest minimum lumen area (4.16 ± 1.03 mm² vs. 5.05 ± 1.39 mm² vs. 4.85 ± 1.76 mm²; P < 0.01), smallest plaque burden (63.45 ± 6.13% vs. 66.12 ± 6.82% vs. 71.17 ± 6.45%; P < 0.01), and highest area stenosis rate (59.32% ± 10.15% vs. 54.61% ± 9.09% vs. 51.67% ± 12.96%; P < 0.01). No significant difference was found in terms of quantitative flow ratio among three groups. At 5 years follow-up, negative remodeling lesions had a higher rate of composite vessel-oriented clinical event (14.3%), compared to intermediate (1.4%, P=0.004) or positive remodeling lesions (4.8%, P=0.06). After adjusting for multiple covariates, negative remodeling remained an independent determinant for vessel-oriented clinical event (HR: 4.849, 95% CI 1.542-15.251, P=0.007).

Conclusion

IVUS-derived negative remodeling is associated with adverse long-term clinical outcome in stable patients with intermediate coronary artery stenosis.

Prognosis of Coronary Atherosclerotic Burden in Non-Ischemic Dilated Cardiomyopathies

Background: Atherosclerosis is associated with a worse prognosis in many diseases such as ischemic cardiomyopathy, but its impact in non-ischemic dilated cardiomyopathy (dCMP) is lesser known. Our aim was to study the prognostic impact of coronary atherosclerotic burden (CAB) in patients with dCMP. Methods: Consecutive patients with dCMP and left ventricular (LV) dysfunction diagnosed by concomitant analysis of invasive coronary angiography (ICA) and CMR imaging were identified from registry-database. CAB was measured by Gensini score. The primary composite endpoint was the occurrence of major adverse cardiovascular events (MACE) defined as cardiovascular (CV) mortality, non-fatal MI and unplanned myocardial revascularization. The results of 139 patients constituting the prospective study population (mean age 59.4 ± 14.7 years old, 74% male), average LV ejection fraction was 31.1 ± 11.02%, median Gensini score was 0 (0–3), and mid-wall late gadolinium enhancement (LGE) was the most frequent LGE pattern (42%). Over a median follow-up of 2.8 years, 9% of patients presented MACE. Patients with MACE had significantly higher CAB compared to those who were free of events (0 (0–3) vs. 3.75 (2–15), p < 0.0001). CAB remained the significant predictor of MACE on multivariate logistic analysis (OR: 1.12, CI: 1.01–1.23, p = 0.02). Conclusion: High CAB may be a new prognostic factor in dCMP patients.

A Nano-Emulsion Platform Functionalized with a Fully Human scFv-Fc Antibody for Atheroma Targeting: Towards a Theranostic Approach to Atherosclerosis

Atherosclerosis is at the onset of the cardiovascular diseases that are among the leading causes of death worldwide. Currently, high-risk plaques, also called vulnerable atheromatous plaques, remain often undiagnosed until the occurrence of severe complications, such as stroke or myocardial infarction. Molecular imaging agents that target high-risk atheromatous lesions could greatly improve the diagnosis of atherosclerosis by identifying sites of high disease activity. Moreover, a "theranostic approach" that combines molecular imaging agents (for diagnosis) and therapeutic molecules would be of great value for the local management of atheromatous plaques. The aim of this study was to develop and characterize an innovative theranostic tool for atherosclerosis. We engineered oil-in-water nano-emulsions (NEs) loaded with superparamagnetic iron oxide (SPIO) nanoparticles for magnetic resonance imaging (MRI) purposes. Dynamic MRI showed that NE-SPIO nanoparticles decorated with a polyethylene glycol (PEG) layer reduced their liver uptake and extended their half-life. Next, the NE-SPIO-PEG formulation was functionalized with a fully human scFv-Fc antibody (P3) recognizing galectin 3, an atherosclerosis biomarker. The P3-functionalized formulation targeted atheromatous plaques, as demonstrated in an immunohistochemistry analyses of mouse aorta and human artery sections and in an Apoe^-/- mouse model of atherosclerosis. Moreover, the formulation was loaded with SPIO nanoparticles and/or alpha-tocopherol to be used as a theranostic tool for atherosclerosis imaging (SPIO) and for delivery of drugs that reduce oxidation (here, alpha-tocopherol) in atheromatous plaques. This study paves the way to non-invasive targeted imaging of atherosclerosis and synergistic therapeutic applications.

Protective Functions of Liver X Receptor α in Established Vulnerable Plaques: Involvement of Regulating Endoplasmic Reticulum-Mediated Macrophage Apoptosis and Efferocytosis

Background

Liver X receptor (LXR) belongs to the metabolic nuclear receptor superfamily, which plays a critical regulatory role in vascular physiology/pathology. However, effects of systemic LXR activation on established vulnerable plaques and the potential isotype‐specific role involved remain unclear.

Methods and Results

The 8‐week‐old male apolipoprotein E^−/− mice went through carotid branch ligation and renal artery constriction, combined with a high‐fat diet. Plaques in the left carotid artery acquired vulnerable features 4 weeks later, confirmed by magnetic resonance imaging scans and histological analysis. From that time on, mice were injected intraperitoneally daily with PBS or GW3965 (10 mg/kg per day) for an additional 4 weeks. Treatment with LXR agonists reduced the lesion volume by 52.61%, compared with the vehicle group. More important, a profile of less intraplaque hemorrhage detection and necrotic core formation was found. These actions collectively attenuated the incidence of plaque rupture. Mechanistically, reduced lesional apoptosis, enhanced efferocytosis, and alleviated endoplasmic reticulum stress are involved in the process. Furthermore, genetic ablation of LXRα, but not LXRβ, blunted the protective effects of LXR on the endoplasmic reticulum stress–elicited C/EBP‐homologous protein pathway in peritoneal macrophages. In concert with the LXRα‐predominant role in vitro, activated LXR failed to stabilize vulnerable plaques and correct the acquired cellular anomalies in LXRα^−/− apolipoprotein E^−/− mice.

Conclusions

Our results revealed that LXRα mediates the capacity of LXR activation to stabilize vulnerable plaques and prevent plaque rupture via amelioration of macrophage endoplasmic reticulum stress, lesional apoptosis, and defective efferocytosis. These findings might expand the application scenarios of LXR therapeutics for atherosclerosis.

Different Approaches in Therapy Aiming to Stabilize an Unstable Atherosclerotic Plaque

Atherosclerotic plaque vulnerability is a vital clinical problem as vulnerable plaques tend to rupture, which results in atherosclerosis complications—myocardial infarctions and subsequent cardiovascular deaths. Therefore, methods aiming to stabilize such plaques are in great demand. In this brief review, the idea of atherosclerotic plaque stabilization and five main approaches—towards the regulation of metabolism, macrophages and cellular death, inflammation, reactive oxygen species, and extracellular matrix remodeling have been presented. Moreover, apart from classical approaches (targeted at the general mechanisms of plaque destabilization), there are also alternative approaches targeted either at certain plaques which have just become vulnerable or targeted at the minimization of the consequences of atherosclerotic plaque erosion or rupture. These alternative approaches have also been briefly mentioned in this review.

The changing landscape of atherosclerosis

Emerging evidence has spurred a considerable evolution of concepts relating to atherosclerosis, and has called into question many previous notions. Here I review this evidence, and discuss its implications for understanding of atherosclerosis. The risk of developing atherosclerosis is no longer concentrated in Western countries, and it is instead involved in the majority of deaths worldwide. Atherosclerosis now affects younger people, and more women and individuals from a diverse range of ethnic backgrounds, than was formerly the case. The risk factor profile has shifted as levels of low-density lipoprotein (LDL) cholesterol, blood pressure and smoking have decreased. Recent research has challenged the protective effects of high-density lipoprotein, and now focuses on triglyceride-rich lipoproteins in addition to low-density lipoprotein as causal in atherosclerosis. Non-traditional drivers of atherosclerosis-such as disturbed sleep, physical inactivity, the microbiome, air pollution and environmental stress-have also gained attention. Inflammatory pathways and leukocytes link traditional and emerging risk factors alike to the altered behaviour of arterial wall cells. Probing the pathogenesis of atherosclerosis has highlighted the role of the bone marrow: somatic mutations in stem cells can cause clonal haematopoiesis, which represents a previously unrecognized but common and potent age-related contributor to the risk of developing cardiovascular disease. Characterizations of the mechanisms that underpin thrombotic complications of atherosclerosis have evolved beyond the 'vulnerable plaque' concept. These advances in our understanding of the biology of atherosclerosis have opened avenues to therapeutic interventions that promise to improve the prevention and treatment of now-ubiquitous atherosclerotic diseases.

Cardiovascular Imaging Techniques for Detection of Vulnerable Plaques

Various cardiovascular imaging techniques were developed for the detection of vulnerable atherosclerotic plaques, hoping to be able to predict a cardiovascular event. Plaque vulnerability results from compound pathophysiological mechanisms that lead to structural and morphological changes in lesions. The aim of this review is to present the most recent techniques for the assessment of vulnerable coronary plaques such as cardiac computed tomography angiography (CCTA), optical coherence tomography, or virtual histology intravascular ultra-sound, based on literature data from the last 3 years. CCTA permits direct visualization of the intravascular lumen, together with characterization of the arterial wall. Recent studies maintain that low-attenuation plaques, spotty calcifications, positive vessel remodeling, and the napkin-ring sign are considered main markers of plaque vulnerability and instability. Emerging analytical techniques, such as machine learning or radiomics, will probably demonstrate useful as an auxiliary diagnostic tool for vulnerable plaque detection. The data from the two imaging techniques together provide useful information, especially in patients undergoing a PCI procedure for an acute coronary syndrome. Invasive and noninvasive imaging techniques are able to deliver a large amount of scientific data to assess vulnerable coronary atheromatous plaques. Recent studies demonstrated that information defined by the two techniques is complementary, and using both methods is essential for adequate diagnosis, therapeutic strategy, and prognostic assessment.