Fibrous Cap Atheroma Research Articles

High-resolution silicon photonics focused ultrasound transducer with a sub-millimeter aperture.

We present an all-optical focused ultrasound transducer with a sub-millimeter aperture and demonstrate its capability for high-resolution imaging of tissue ex vivo. The transducer is composed of a wideband silicon photonics ultrasound detector and a miniature acoustic lens coated with a thin optically absorbing metallic layer used to produce laser-generated ultrasound. The demonstrated device achieves axial resolution and lateral resolutions of 12 μm and 60 μm, respectively, well below typical values achieved by conventional piezoelectric intravascular ultrasound. The size and resolution of the developed transducer may enable its use for intravascular imaging of thin fibrous cap atheroma.

SPECT/CT imaging of inflammation and calcification in human carotid atherosclerosis to identify the plaque at risk of rupture

BackgroundCalcification and inflammation are atherosclerotic plaque compositional biomarkers that have both been linked to stroke risk. The aim of this study was to evaluate their co-existing prevalence in human carotid plaques with respect to plaque phenotype to determine the value of hybrid imaging for the detection of these biomarkers. MethodsHuman carotid plaque segments, obtained from endarterectomy, were incubated in [111In]In-DOTA-butylamino-NorBIRT ([111In]In-Danbirt), targeting Leukocyte Function-associated Antigen-1 (LFA-1) on leukocytes. By performing SPECT/CT, both inflammation from DANBIRT uptake and calcification from CT imaging were assessed. Plaque phenotype was classified using histology. ResultsOn a total plaque level, comparable levels of calcification volume existed with different degrees of inflammation and vice versa. On a segment level, an inverse relationship between calcification volume and inflammation was evident in highly calcified segments, which classify as fibrocalcific, stable plaque segments. In contrast, segments with little or no calcification presented with a moderate to high degree of inflammation, often coinciding with the more dangerous fibrous cap atheroma phenotype. ConclusionCalcification imaging alone can only accurately identify highly calcified, stable, fibrocalcific plaques. To identify high-risk plaques, with little or no calcification, hybrid imaging of calcification and inflammation could provide diagnostic benefit.

Anti-Galectin-2 Antibody Treatment Reduces Atherosclerotic Plaque Size and Alters Macrophage Polarity.

Background Galectins have numerous cellular functions in immunity and inflammation. Short-term galectin-2 (Gal-2) blockade in ischemia-induced arteriogenesis shifts macrophages to an anti-inflammatory phenotype and improves perfusion. Gal-2 may also affect other macrophage-related cardiovascular diseases. Objectives This study aims to elucidate the effects of Gal-2 inhibition in atherosclerosis. Methods ApoE −/− mice were given a high-cholesterol diet (HCD) for 12 weeks. After 6 weeks of HCD, intermediate atherosclerotic plaques were present. To study the effects of anti-Gal-2 nanobody treatment on the progression of existing atherosclerosis, treatment with two llama-derived anti-Gal-2 nanobodies (clones 2H8 and 2C10), or vehicle was given for the remaining 6 weeks. Results Gal-2 inhibition reduced the progression of existing atherosclerosis. Atherosclerotic plaque area in the aortic root was decreased, especially so in mice treated with 2C10 nanobodies. This clone showed reduced atherosclerosis severity as reflected by a decrease in fibrous cap atheromas in addition to decreases in plaque size. The number of plaque resident macrophages was unchanged; however, there was a significant increase in the fraction of CD206 + macrophages. 2C10 treatment also increased plaque α-smooth muscle content, and Gal-2 may have a role in modulating the inflammatory status of smooth muscle cells. Remarkably, both treatments reduced serum cholesterol concentrations including reductions in very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein while triglyceride concentrations were unchanged. Conclusion Prolonged and frequent treatment with anti-Gal-2 nanobodies reduced plaque size, slowed plaque progression, and modified the phenotype of plaque macrophages toward an anti-inflammatory profile. These results hold promise for future macrophage modulating therapeutic interventions that promote arteriogenesis and reduce atherosclerosis.

Automated classification of coronary atherosclerotic plaque in optical frequency domain imaging based on deep learning

Background and aimsWe developed a deep learning (DL) model for automated atherosclerotic plaque categorization using optical frequency domain imaging (OFDI) and performed quantitative and visual evaluations. MethodsA total of 1103 histological cross-sections from 45 autopsy hearts were examined to compare the ex vivo OFDI scans. The images were segmented and annotated considering four histological categories: pathological intimal thickening (PIT), fibrous cap atheroma (FA), fibrocalcific plaque (FC), and healed erosion/rupture (HER). The DL model was developed based on pyramid scene parsing network (PSPNet). Given an input image, a convolutional neural network (ResNet50) was used as an encoder to generate feature maps of the last convolutional layer. ResultsFor the quantitative evaluation, the mean F-score and IoU values, which are used to evaluate how close the predicted results are to the ground truth, were used. The validation and test dataset had F-score and IoU values of 0.63, 0.49, and 0.66, 0.52, respectively. For the section-level diagnostic accuracy, the areas under the receiver-operating characteristic curve produced by the DL model for FC, PIT, FA, and HER were 0.91, 0.85, 0.86, and 0.86, respectively, and were comparable to those of an expert observer. ConclusionsDL semantic segmentation of coronary plaques in OFDI images was used as a tool to automatically categorize atherosclerotic plaques using histological findings as the gold standard. The proposed method can support interventional cardiologists in understanding histological properties of plaques.

Identification of securinine as vascular protective agent targeting atherosclerosis in vascular endothelial cells, smooth muscle cells, and apolipoprotein E deficient mice

BackgroundAtherosclerosis is a chronic vascular disease and characterized by accumulation within the intima of inflammatory cells, smooth muscle cells, lipid, and connective tissue. PurposeThe purpose of the present study was to identify natural agents that commonly reverse advanced atherosclerotic plaque to early atherosclerotic plaque. MethodsDifferentially expressed genes (DEGs) were analyzed in silico. The differentially expressed genes from 9 intimal thickening and 8 fibrous cap atheroma tissue which were collected from GEO data were assessed by the connectivity map. Natural candidate securinine, a main compound from Securinega suffruticosa, was selected and administrated 1, 5 mg/kg/day in apolipoprotein-E-deficient (ApoE KO) mice for 18 weeks. ResultsSecurinine significantly showed lowered blood pressure and improvement of metabolic parameters with hyperlipidemia. The impairment in vasorelaxation was remarkably decreased by treatment with securinine. H&E staining revealed that treatment with securinine reduced atherosclerotic lesions. Securinine suppressed the expression of adhesion molecules and matrix metalloproteinase-2/-9 in both ApoE KO and vascular endothelial cells (HUVEC). In HUVEC pretreatment with securinine significantly inhibited ROS generation and NF-κB activation. Growth curve assays using the real-time cell analyzer showed that securinine significantly decreased TNF-α-induced aortic smooth muscle cell proliferation and migration in a dose-dependent manner. ConclusionSecurinine may be a potential natural candidate for the treatment of atherosclerosis because it attenuates vascular inflammation and dysfunction as well as vascular lesion.

Interobserver variability in assessments of atherosclerotic lesion type via optical frequency domain imaging

BackgroundTo date, there have been no data available regarding the diagnostic performance of optical frequency domain imaging (OFDI) for in vivo histological classification of atherosclerotic lesions. This study investigated whether OFDI can be used to diagnose and classify histological atherosclerotic lesions in the coronary artery by ex vivo histological examinations. MethodsThree-hundred-fifteen histological cross-sections from 21 autopsy hearts were matched with the OFDI images. Histological cross-sections were classified into six categories: adaptive intimal thickening (AIT), pathological intimal thickening (PIT), fibrous cap atheroma (FA), fibrocalcific plaque (FC), calcified nodule, and healed erosion/rupture. The five observers with different years of experience in the interpretation of OFDI provided a single diagnosis for the OFDI scans of each cross-section according to the aforementioned six histological categories. The diagnostic accuracy and interobserver variability of lesion types for each OFDI observer were determined using histology as the gold standard. ResultsThe overall agreement rates between OFDI and histopathologic diagnosis for OFDI observers 1–5 were 81%, 70%, 68%, 61%, and 50% (κ values of 0.75, 0.61, 0.58, 0.49, and 0.36), respectively. Although the diagnostic accuracy of OFDI for detecting AIT and FC was excellent for all five observers, the sensitivity, and positive predictive values of OFDI for detecting PIT and FA were low in proportion to years of experience. ConclusionThe diagnostic accuracy of atherosclerotic tissue properties from OFDI scans correlated with the observers' years of experience, especially when lesions contained lipid components.

Inhibition of PFKFB3 Hampers the Progression of Atherosclerosis and Promotes Plaque Stability.

Aims6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB)3-mediated glycolysis is pivotal in driving macrophage- and endothelial cell activation and thereby inflammation. Once activated, these cells play a crucial role in the progression of atherosclerosis. Here, we analyzed the expression of PFKFB3 in human atherosclerotic lesions and investigated the therapeutic potential of pharmacological inhibition of PFKFB3 in experimental atherosclerosis by using the glycolytic inhibitor PFK158.Methods and ResultsPFKFB3 expression was higher in vulnerable human atheromatous carotid plaques when compared to stable fibrous plaques and predominantly expressed in plaque macrophages and endothelial cells. Analysis of advanced plaques of human coronary arteries revealed a positive correlation of PFKFB3 expression with necrotic core area. To further investigate the role of PFKFB3 in atherosclerotic disease progression, we treated 6–8 weeks old male Ldlr–/– mice. These mice were fed a high cholesterol diet for 13 weeks, of which they were treated for 5 weeks with the glycolytic inhibitor PFK158 to block PFKFB3 activity. The incidence of fibrous cap atheroma (advanced plaques) was reduced in PFK158-treated mice. Plaque phenotype altered markedly as both necrotic core area and intraplaque apoptosis decreased. This coincided with thickening of the fibrous cap and increased plaque stability after PFK158 treatment. Concomitantly, we observed a decrease in glycolysis in peripheral blood mononuclear cells compared to the untreated group, which alludes that changes in the intracellular metabolism of monocyte and macrophages is advantageous for plaque stabilization.ConclusionHigh PFKFB3 expression is associated with vulnerable atheromatous human carotid and coronary plaques. In mice, high PFKFB3 expression is also associated with a vulnerable plaque phenotype, whereas inhibition of PFKFB3 activity leads to plaque stabilization. This data implies that inhibition of inducible glycolysis may reduce inflammation, which has the ability to subsequently attenuate atherogenesis.

The accuracy and interobserver variability in the assessment of coronary atherosclerotic plaques by optical frequency domain imaging: involving five observers with different levels of coronary imaging

Abstract Background Whether optical frequency domain imaging (OFDI) images can realize pathological diagnosis of coronary atherosclerotic plaques, and whether its diagnostic accuracy of lesion types varies depending on the personal experience of the clinician caring for coronary intervention have not been elucidated. Purpose This study investigated the interobserver variability in characterizing atherosclerotic plaque types by OFDI for multiple OFDI observers with levels of different experience. Methods Three-hundred-thirty-three histological cross-sections from 21 autopsy hearts were co-registered with the corresponding OFDI images. Histological cross-sections were classified into the following 7 lesion types according to the modified AHA atherosclerosis classification by a single experienced pathologist blinded for OCT findings: adaptive intimal thickening (AIT), intimal xanthoma (IX), pathological intimal thickening (PIT), fibrous cap atheroma (FA), fibrocalcific plaque (FC), calcified nodule (CN), and healed erosion/rupture (HER). The five OFDI observers, unaware of the histological diagnosis, provided a single diagnosis for each corresponding OFDI image. The OFDI observer 1 was an expert interventional cardiologist with sufficient experience in OFDI imaging, followed by the OFDI observer 2, 3, and 4 as middle career interventional cardiologists who had completed training ten, seven, and four years. The OFDI observer 5 was a young career interventional cardiologist. The diagnostic accuracy of lesion types for each OFDI observer was determined taking histology as a gold standard. Results On histological analysis, 13% of histological cross-sections were diagnosed as AIT, 5% as IX, 23% as PIT, 25% as FA, 27% as FC, 2% as CN, and 5% as HER. The overall agreement between OFDI diagnosis and histopathologic diagnosis for OFDI observer 1 to 5 was 77%, 62%, 61%, 56%, and 46% (k values of 0.71, 0.54, 0.54, 0.45, and 0.33), respectively. Although the performance for characterizing AIT and FC was excellent and comparable among all OFDI observers, the sensitivity and positive predictive value for characterizing IX, PIT and FA varied depending on the OFDI observers' years of experience (Table). The main causes of false-positive or -negative diagnosis of FA were IX and PIT for all OFDI observers. Conclusion The diagnostic accuracy of atherosclerotic tissue properties from OFDI images correlated with the observers' years of experience, subspecialty training in coronary imaging, which suggests that the interpretation of OFDI images requires expertise and can be challenging to a less experienced reader. Table 1 Funding Acknowledgement Type of funding source: None

Near infrared spectroscopy and optical coherence tomography derived plaque characteristics associated with increased plaque progression over 12-month follow up

Abstract Background Serial intravascular ultrasound (IVUS) studies demonstrated patterns of either plaque progression, regression or stabilization during pharmacotherapy including statin. At present little is known on specific plaque characteristics that are associated with excessive plaque growth. Purpose To evaluate the utility of near infrared spectroscopy (NIRS) and optical coherence tomography (OCT) to identify characteristics of non-culprit plaques associated with an increase in wall thickness (WT). Methods In this prospective, single-center study, patients with acute coronary syndrome (ACS) underwent, after successful treatment of the culprit lesions, both NIRS-IVUS and OCT assessment of a non-culprit artery at baseline and 12-month follow-up. For each vessel, 1.5-mm segments were identified, matched and divided into 45° sectors. A sector was considered as NIRS positive or labeled as OCT-detected fibrous cap atheroma (FCA), lipid rich or fibrous plaque when >75% of the sector area exhibited NIRS signal or specific OCT-detected feature. The relationship between change in IVUS-based WT, and the presence of NIRS positive signal or OCT-detected plaque components (FCA, lipid rich, fibrous) was evaluated using mixed ANCOVA, with NIRS status and OCT plaque components as fixed factors, and patient as random factor, adjusting for clustering effect of the data. All analyses of plaque WT change were adjusted for baseline WT. To examine the value of NIRS and OCT-detected plaque components in predicting plaque progression, a logistic mixed model was built with plaque progression defined as WT increase >0.2mm over the 12-month follow-up. Results A total of 38 patients (92% male, 21% diabetic) with 9167 matched sectors were analyzed at baseline and 12 months. Mean change in WT between baseline and 12 months was 0.014mm (95% confidence interval [CI] 0.011–0.018, p<0.001). Positive NIRS sectors showed more pronounced plaque progression than NIRS negative sectors (0.057mm, 95% CI 0.032–0.084 vs 0.014mm 95% CI 0.010–0.017, p=0.001) (Figure 1). FCA showed significant progression of WT over the 12-month follow-up (0.104mm, 95% CI 0.007–0.201), whereas a decrease in WT was observed in sectors with fibrous tissue (−0.031mm, 95% CI 0.048–0.014) (p=0.022). Baseline NIRS positive (OR 1.88, 95% CI 1.34–2.64) and OCT-detected lipid rich plaque (OR 1.47, 95% CI 1.20–1.81) were associated with 12-month plaque progression (>0.2mm) by logistic regression. Conclusions Positive NIRS signal and OCT-detected lipid plaque components imaged at baseline in non-culprit coronary arteries of patients presenting with ACS could identify vessel wall regions prone to plaque progression over a 12-month period. Figure 1. Plaque progression and NIRS Funding Acknowledgement Type of funding source: Other. Main funding source(s): M. Tomaniak acknowledges funding received as a Laureate of the European Society of Cardiology Research and Training Programme in the form of the ESC 2018 Grant.

Imaging of inflammatory cellular protagonists in human atherosclerosis: a dual-isotope SPECT approach

PurposeAtherosclerotic plaque development and progression signifies a complex inflammatory disease mediated by a multitude of proinflammatory leukocyte subsets. Using single photon emission computed tomography (SPECT) coupled with computed tomography (CT), this study tested a new dual-isotope acquisition protocol to assess each radiotracer’s capability to identify plaque phenotype and inflammation levels pertaining to leukocytes expressing leukocyte function-associated antigen-1 (LFA-1) and the leukocyte subset of proinflammatory macrophages expressing somatostatin receptor subtype-2 (SST2). Individual radiotracer uptake was quantified and the presence of corresponding immunohistological cell markers was assessed.MethodsHuman symptomatic carotid plaque segments were obtained from endarterectomy. Segments were incubated in dual-isotope radiotracers [111In]In-DOTA-butylamino-NorBIRT ([111In]In-Danbirt) and [99mTc]Tc-[N0–14,Asp0,Tyr3]-octreotate ([99mTc]Tc-Demotate 2) before scanning with SPECT/CT. Plaque phenotype was classified as pathological intimal thickening, fibrous cap atheroma or fibrocalcific using histology sections based on distinct morphological characteristics. Plaque segments were subsequently immuno-stained with LFA-1 and SST2 and quantified in terms of positive area fraction and compared against the corresponding SPECT images.ResultsFocal uptake of co-localising dual-radiotracers identified the heterogeneous distribution of inflamed regions in the plaques which co-localised with positive immuno-stained regions of LFA-1 and SST2. [111In]In-Danbirt and [99mTc]Tc-Demotate 2 uptake demonstrated a significant positive correlation (r = 0.651; p = 0.001). Fibrous cap atheroma plaque phenotype correlated with the highest [111In]In-Danbirt and [99mTc]Tc-Demotate 2 uptake compared with fibrocalcific plaques and pathological intimal thickening phenotypes, in line with the immunohistological analyses.ConclusionA dual-isotope acquisition protocol permits the imaging of multiple leukocyte subsets and the pro-inflammatory macrophages simultaneously in atherosclerotic plaque tissue. [111In]In-Danbirt may have added value for assessing the total inflammation levels in atherosclerotic plaques in addition to classifying plaque phenotype.

Securinine protects vascular dysfunction targeting atherosclerosis in vascular endothelial cells, smooth muscle cells, and apolipoprotein E deficient mice

Atherosclerosis is a chronic vascular disease and characterized by accumulation within the intima of inflammatory cells, smooth muscle cells, lipid, and connective tissue. Here, we suggest securinine as an anti‐atherosclerotic agent to attenuate vascular dysfunction and lesion. To identify natural agents that commonly reverse advanced atherosclerotic plaque to early atherosclerotic plaque, significantly regulated genes were analyzed in silico. The differentially expressed genes from 9 intimal thickening and 8 fibrous cap atheroma tissue which were collected from GEO data were assessed by the connectivity map. Natural candidate securinine, a main compound from Securinega suffruticosa, was selected and administrated 1, 5 mg/kg/day in apolipoprotein‐E‐deficient (ApoE KO) mice for 18 weeks. Securinine significantly showed lowered blood pressure and improvement of metabolic parameters with hyperlipidemia. The impairment in vasorelaxation was remarkably decreased by treatment with securinine. H&E staining revealed that treatment with securinine reduced atherosclerotic lesions. Securinine suppressed the expression of adhesion molecules and matrix metalloproteinase‐2/‐9 in both ApoE KO and vascular endothelial cells (HUVEC). In HUVEC pretreatment with securinine significantly inhibited ROS generation and NF‐κB activation. Growth curve assays using the real‐time cell analyzer showed that securinine significantly decreased TNF‐α‐induced aortic smooth muscle cell proliferation and migration in a dose‐dependent manner. Thus securinine may be a potential natural candidate for the treatment of atherosclerosis because it attenuates vascular inflammation and dysfunction as well as vascular lesion.Support or Funding InformationThis work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (2017R1A5A2015805)(2017R1D1A3B03029089) (2019R1A2C1085650).

P3109Coronary vulnerable plaque development is promoted by multidirectional wall shear stress

Abstract Aim Wall shear stress (WSS) has been widely associated with plaque development and destabilization. However, the multidirectionality of WSS, induced by the pulsatile nature of blood flow in combination with the arterial geometry, is rarely taken into account. The purpose of this study was to investigate the influence and predictive value of five (multidirectional) WSS parameters for coronary plaque progression and composition. Methods Familial hypercholesterolemic pigs (n=10, castrated male, 3 years old) were put on a high-fat diet and underwent imaging (near infrared spectroscopy-intravascular ultrasound (NIRS-IVUS), optical coherence tomography (OCT) and CT) of the three main coronary arteries at baseline and 10/12 months follow-up. IVUS-based lumen contours were combined with the centerline of artery as extracted from CT to obtain a 3D reconstruction of the coronary artery. Local flow velocity measurements were combined with the 3D-geometry of the coronary arterial lumen to calculate five multidirectional WSS parameters including: time average wall shear stress (TAWSS), oscilatory shear index (OSI), relative residence time (RRT), trans wall shear stress (TransWSS), cross flow index (CFI). For the analysis, arteries were divided into 3mm/45° sectors (n=3627). Per vessel each segment was classified as low, mid or high for each WSS metric based on the average value in the sector. Changes in wall thickness (WT) and plaque composition were assessed with NIRS-IVUS and OCT, and histology and related to the local (multidirectional) WSS. Results Half of the pigs developed lumen intruding, complex, lipid-rich plaques. In these pigs, coronary segments exposed to low baseline levels of TAWSS exhibited a significantly larger plaque growth per month compared to regions with either mid or high TAWSS (p<0.05, see figure). Furthermore, plaque growth correlated positively with the multidirectional WSS metrics OSI, RRT and CFI, with high multidirectionality resulting in the largest plaque growth (see figure). The positive predictive values (PPV) of the WSS metrics for plaque presence (WT>0.5mm) at follow up were 50% (low TAWSS), 48% (high OSI), 49% (high RRT), 47% (high CFI) and 43% (high transWSS). The PPVs for the presence of a fibroatheroma observed with histology were 61% (low TAWSS), 58% (high OSI), 61% (high RRT), 59% (high CFI) and 49% (high transWSS). Plaque growth vs. multidirectional WSS Conclusions This study shows that both low and multidirectional WSS promote the development of large and complex coronary atherosclerotic plaques with vulnerable characteristics. The high predictive values for fibrous cap atheroma development demonstrate the potential of multidirectional WSS metrics as a predictive clinical marker for vulnerable disease. Acknowledgement/Funding ERC- starter grant (grant agreement 310457)

P6413Aging increases the plaque vulnerability in non-ischemic non-culprit lesions of diabetic patients, data from COMBINE OCT-FFR study

Abstract Background Little is known about age-related differences in baseline atherosclerotic plaque morphology and composition in patients with diabetes mellites (DM). Purpose For this purpose, we studied DM patients from the Combine trial. Methods COMBINE (OCT-FFR, NCT02989740) is a multi-center, prospective study focusing on the natural history of non-ischemic, non-culprit coronary lesions and evaluate whether certain OCT-assessed variables could predict future adverse events originating from these lesions in a DM population. OCT analysis identifies plaque composition, estimates calcium arc (o), lipid arc (o), and measures thickness of the fibrous cap covering the lipid core. Moreover, OCT records the presence of typical plaque vulnerability traits like thin fibrous cap atheroma (TCFA), plaque erosion (PE), plaque rupture (PR), calcification nodule (CN), heterogeneous tissues (a probably healed plaque rupture), and macrophages accumulation (bright spots). A dedicated software estimated the interpolated percentage area stenosis (AS, %) measuring the minimal lumen area (MLA) and reference vessel area. The present analysis reports the baseline morphology of these lesions respectively in young (<70 years) vs. old (≥70 years) DM patients. Results OCT imaging was performed in 300 patients (361 lesions) from the COMBINE study, of which 203 lesions assessed in young and 158 lesions in old DM patients. There were no significant differences in MLA (mm2) 2.40 (1.85–315 vs. 2.30 (1.80–3.00), p=0.92), lesions length (mm 24.11 (15.10–33.10) vs. 24.20 (15.10–35.10), p=0.78), AS% (%) 63 (1.85–3.15) vs. 64 (56–73), p=0.41; lipid arc (o), 182 (140–250) vs. 175 (128–240), p=0.35), fibrous cap thickness covering the lipid arc (μm), 117 (65–193) vs. 110 (64–168), p=0.45, in the prevalence of TCFA 37 (18%) vs. 33 (21%), p=0.53, PR 17 (18%) vs. 15 (10%), p=0.71, heterogenous tissue 39 (19%) vs. 31 (20%), p=0.92, and bright spots 98 (48%) vs. 69 (44%), p=0.38. The patients ≥70 years had a higher prevalence of calcified plaques 171 (84%) vs. 143 (90%), p=0.08 and wider calcium arc. These lesions included more PE 7 (3%) vs. 13 (8%), p=0.05, CN 73 (36%) vs. 75 (47%), p=0.03, and CN associated with overlying thrombus 11 (5%) vs. 20 (13%), p=0.02. Conclusion Non-ischemic, non-culprit lesions in elderly DM patients present the same prevalence of soft, vulnerable plaques as it is a younger cohort, however, they have a higher prevalence of calcified plaque including complex calcified plaques as eroded plaques and calcification nodules with overlying thrombus. Whether these complex calcified plaques are associated with a higher risk of adverse events remains questionable and could be further elucidated from longer follow-up data of the COMBINE trial.

5222A distinct LDL profile to predict the risk of cardiovascular disease in familial hypercholesterolemia subjects: initial pre-clinical results

Abstract Aim Cardiovascular disease development is highly variable between patients with familial hypercholesterolemia (FH). Since current risk prediction methods fail to estimate the risk of individual patients, all patients are treated with high-intensity lipid-lowering medication like statins and PCSK9-inhibitors. To prevent overtreatment (with its associated costs and side effects) of patients with a low risk, reliable biomarkers are urgently needed. While studying atherosclerosis development in an FH porcine model, we discovered a specific LDL profile that was directly associated with the severity of atherosclerosis development. Methods 10 adult pigs with an LDLR mutation received a high-fat diet for 12 months. Atherosclerosis development in the three main coronary arteries was monitored with intravascular ultrasound (IVUS) and optical coherence tomography at three time points. After sacrifice, tissue was harvested for detailed histological analysis of the coronary plaque composition. Size-exclusion chromatography (SEC, n=10) and LC-MSMS (n=4) were used to assess the plasma lipoprotein profile, and the sphingolipid content of LDL, relative to cholesterol. Results Imaging and histology revealed a marked difference in pigs that developed large, lumen intruding plaques (IVUS-based plaque burden 13–77%) within 9 months (n=5) and pigs (n=5) that only developed early lesions (IVUS-based plaque burden 8–34%), even after 12 months of follow-up. The plaques seen in the fast responding pigs possessed distinct characteristics of advanced disease (i.e. heavy macrophage infiltration, large lipid-rich necrotic cores, neovascularisation, micro- and macrocalcifications and intraplaque haemorrhage, see figure). In these fast responders, fibrous cap atheroma occupied 34% of the total artery. SEC revealed two distinct LDL subclasses: regular and “larger” LDL particles. Fast responding pigs with advanced atherosclerosis displayed a significantly higher ratio in cholesterol concentration of regular/'larger' LDL than slow responding pigs (1.7 (1.3–1.9) vs. 0.8 (0.6–1.2); (p=0.004), see figure). Compared to regular LDL, “larger” LDL contained relatively more sphingolipids in the fast responding than in the slow responding animals (regular LDL/'larger' LDL: S1P 0.5 (0.5–0.5) vs. 1.0 (0.8–1.2); Cer16:0 0.70 (0.67–0.73) vs. 1.04 (0.95–1.13); Cer18:0 0.60 (0.58–0.61) vs. 1.15 (1.13–1.16); Cer20:0 0.73 (0.73–0.74) vs. 0.94 (0.94–0.94)). “Larger” LDL particles and comparable sphingolipid ratios were also observed in FH patients. Cardiovascular data from our FH patient cohort, coupled to the LDL subclass distribution, will provide more insight into the potential of this novel biomarker. Conclusion A distinct difference in LDL subclasses, including a new “larger” LDL particle, was found in fast versus slow responding FH animals. This finding can potentially be used to identify FH patients at the highest risk of CVD to avoid overtreatement of low risk patients. Acknowledgement/Funding ERC- starter grant (grant agreement 310457)

Morphological spectrum of atherosclerotic lesions in a tertiary care Institute in Punjab

Background: The incidence of coronary artery disease (CAD) has risen considerably in developing world due to industrialization, urbanisation and lifestyle changes, especially among Indians and South Asians. The onset of CAD has been seen to occur at an early age and the severity of the disease and mortality associated with CAD has also increased. The pathology of atherosclerosis needs to be re-evaluated to develop targeted therapy which can contain the disease process at the earliest stage.
 Aims and Objectives: Most of the morphological studies on atherosclerosis have been done on autopsy cases. In this study, we have analysed the morphological spectrum of atherosclerotic lesions in live patients.
 Materials and Methods: We retrospectively analysed the histopathology slides of 85 cases whose endarterectomy plaques were received in the Department of Pathology over a period of three and half years (January 2014 to June 2017) and classified the lesions according to Modified American Heart Association classification of atherosclerosis.
 Results: The average age of patients was 60 years and male to female ratio of 4.3:1. Left anterior descending artery was the commonest vessel involved (52.4%). Majority of the cases had fibrocalcific plaques,followed by fibrous cap atheroma and calcified nodules.
 Conclusion: Coronary artery plaques were found even in patients less than 40 years old. Aggressive lipid defense therapy needs to be the cornerstone of management of CAD.

Plaque burden influences accurate classification of fibrous cap atheroma by in vivo optical coherence tomography in a porcine model of advanced coronary atherosclerosis.

In vivo validation of coronary optical coherence tomography (OCT) against histology and the effects of plaque burden (PB) on plaque classification remain unreported. We aimed to investigate this in a porcine model with human-like coronary atherosclerosis. Five female Yucatan D374Y-PCSK9 transgenic hypercholesterolaemic minipigs were implanted with a coronary shear-modifying stent to induce advanced atherosclerosis. OCT frames (n=201) were obtained 34 weeks after implantation. Coronary arteries were perfusion-fixed, serially sectioned and co-registered with OCT using a validated algorithm. Lesions were adjudicated using the Virmani classification and PB assessed from histology. OCT had a high sensitivity, but modest specificity (92.9% and 74.6%), for identifying fibrous cap atheroma (FCA). The reduced specificity for OCT was due to misclassification of plaques with histologically defined pathological intimal thickening (PIT) as FCA (46.1% of the frames with histological PIT were misclassified). PIT lesions misclassified as FCA by OCT had a statistically higher PB than in other OCT frames (median 32.0% versus 13.4%; p<0.0001). Misclassification of PIT lesions by OCT occurred when PB exceeded approximately 20%. Compared with histology, in vivo OCT classification of FCA had high sensitivity but reduced specificity due to misclassification of PITs with high PB.

TCT-54 The distribution of high-risk plaques with respect to artery stenosis in non-culprit non-ischemic native coronary lesions of diabetic patients – data from COMBINE OCT-FFR study

Thin fibrous cap atheroma (TCFA), plaque rupture (PR), plaque erosion (PE) triggers the acute coronary syndrome. However, the prevalence of these plaques in non-ischemic lesions in diabetes mellitus (DM) patients was barely reported. This report presents the distribution of high-risk plaques in non-

Endothelial erosion of plaques as a substrate for coronary thrombosis.

Myocardial infarction is a prevalent, life-threatening consequence of athero-thrombosis. Post-mortem histology and intravascular imaging in live patients have shown that approximately one third of myocardial infarctions are caused by a thrombus overlying an intact, non-ruptured atherosclerotic plaque. Histology identifies erosion of luminal endothelial cells from smooth muscle and proteoglycan-rich, thick fibrous cap atheromas as the underlying pathology. Unlike plaque ruptures, endothelial erosions tend to occur on thick-capped atherosclerotic plaques and may or may not be associated with inflammation. Smoking and female gender are strong risk factors for erosion. Multiple mechanisms may contribute to endothelial erosion, including endothelial dysfunction, TLR signalling, leukocyte activation and modification of sub-endothelial matrix by endothelial or smooth muscle cells, which may trigger loss of adhesion to the extracellular matrix or endothelial apoptosis. Diagnosis of endothelial erosion by intravascular imaging, especially high resolution optical coherence tomography, may influence treatment strategies, offering prognostic value and utility as an endpoint in trials of agents designed to preserve an intact coronary endothelium.

Imaging and analysis of microcalcifications and lipid/necrotic core calcification in fibrous cap atheroma.

The presence of microcalcifications (µCalcs) >5 µm within the cap of human fibroatheroma has been shown to produce a 200-700% increase in peak circumferential stress, which can transform a stable plaque into a vulnerable one, whereas µCalcs < 5 µm do not appear to increase risk. We quantitatively examine the possibility to distinguish caps with µCalcs > 5 µm based on the gross morphological features of fibroatheromas, and the correlation between the size and distribution of µCalcs in the cap and the calcification in the lipid/necrotic core beneath it. Atherosclerotic lesions (N = 72) were imaged using HR-μCT at 2.1-μm resolution for detailed analysis of atheroma morphology and composition, and validated using non-decalcified histology. At 2.1-μm resolution one observes four different patterns of calcification within the lipid/necrotic core, and is able to elucidate the 3D spatial progression of the calcification process using these four patterns. Of the gross morphological features identified, only minimum cap thickness positively correlated with the existence of µCalcs > 5 µm in the cap. We also show that µCalcs in the cap accumulate in the vicinity of the lipid/necrotic core boundary with few on the lumen side of the cap. HR-μCT enables three-dimensional assessment of soft tissue composition, lipid content, calcification patterns within lipid/necrotic cores and analysis of the axial progression of calcification within individual atheroma. The distribution of µCalcs within the cap is highly non-uniform and decreases sharply as one proceeds from the lipid pool/necrotic core boundary to the lumen.

The basics of intravascular optical coherence tomography.

Optical coherence tomography (OCT) has opened new horizons for intravascular coronary imaging. It utilizes near-infrared light to provide a microscopic insight into the pathology of coronary arteries in vivo. Optical coherence tomography is also capable of identifying the chemical composition of atherosclerotic plaques and detecting traits of their vulnerability. At present it is the only tool to measure the thickness of the fibrous cap covering the lipid core of the atheroma, and thus it is an exceptional modality to detect plaques that are prone to rupture (thin fibrous cap atheromas). Moreover, it facilitates distinguishing between plaque rupture and plaque erosion as a cause of acute intracoronary thrombosis. Optical coherence tomography is applied to guide angioplasties of coronary lesions and to assess outcomes of percutaneous coronary interventions broadly. It identifies stent malapposition, dissections, and thrombosis with unprecedented precision. Furthermore, OCT helps to monitor vessel healing after stenting. It evaluates the coverage of stent struts by the neointima and detects in-stent neoatherosclerosis. With so much potential, new studies are warranted to determine OCT's clinical impact. The following review presents the technical background, basics of OCT image interpretation, and practical tips for adequate OCT imaging, and outlines its established and potential clinical application.