Detection by near-infrared spectroscopy of large lipid core plaques at culprit sites in patients with acute ST-segment elevation myocardial infarction. JACC Cardiovasc Interv. 2013;6:838-846. [PMID: 23871513 DOI: 10.1016/j.jcin.2013.04.012]

Intravascular imaging in the diagnosis and management of patients with suspected intracoronary pathologies: A CJC White Paper

Intravascular imaging has become an integral part of the diagnostic and management strategies for intracoronary pathologies. This White Paper summarizes current evidence and its implications on the use of intravascular imaging in interventional cardiology practice. The areas addressed are planning and optimization of percutaneous coronary intervention, management of stent failure, and evaluation of ambiguous coronary lesions and myocardial infarction with non-obstructive coronary disease (MINOCA). Findings are presented following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system in an expert consensus process involving a diverse Writing group and vetted by a Review group. Expert consensus was achieved around nine statements. Use of intravascular imaging in guiding percutaneous revascularization is supported by high quality evidence, particularly for lesions with increased risk of recurrent events or stent failure. Specific considerations for intravascular imaging guidance of intervention in left main lesions, chronic occlusion lesions as well as patients at high risk of contrast nephropathy are explored. Use of intravascular imaging to identify pathologies associated with stent failure and guide repeat intervention, resolve ambiguities in lesion assessment and establish diagnoses in patients presenting with MINOCA is supported by moderate to low quality evidence. Each topic is accompanied by clinical pointers to aid the practicing interventional cardiologist in implementation of the White paper findings. The findings of this White Paper will help to guide the utilization of intravascular imaging towards those situations in which the balance of efficacy, safety and cost are most optimal.

Intracoronary Near-Infrared Spectroscopy to Predict No-Reflow Phenomenon During Percutaneous Coronary Intervention in Acute Coronary Syndrome

Near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) can identify the lipid-rich lesions, described as high lipid-core burden index (LCBI). The aim of this study was to investigate the relation between lipid-core plaque (LCP) in the infarct-related lesion detected using NIRS-IVUS and no-reflow phenomenon during percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS). We investigated 371 patients with ACS who underwent NIRS-IVUS in the infarct-related lesions before PCI. The extent of LCP in the infarct-related lesion was calculated as the maximum LCBI for each of the 4-mm longitudinal segments (maxLCBI4mm) measured by NIRS-IVUS. The patients were divided into 2 groups using a maxLCBI4mm cut-off value of 400. The overall incidence of no-reflow phenomenon was 53 of 371 (14.3%). No-reflow phenomenon more frequently occurred in patients with maxLCBI4mm ≥400 compared with those with maxLCBI4mm<400 (17.5% vs 2.5%, p <0.001). After propensity score matching, multivariable logistic regression analysis demonstrated that maxLCBI4mm (odds ratio: 1.008; 95% confidence interval: 1.005 to 1.012, p <0.001) was independently associated with the no-reflow phenomenon. The maxLCBI4mm of 719 in the infarct-related lesion had the highest combined sensitivity (69.8%) and specificity (72.1%) for the identification of no-reflow phenomenon. In conclusion, in patients with ACS, maxLCBI4mm in the infarct-related lesion assessed by NIRS-IVUS was independently associated with the no-reflow phenomenon during PCI.

Colchicine and plaque: A focus on atherosclerosis imaging

Colchicine is an anti-inflammatory medication, classically used to treat a wide spectrum of autoimmune diseases. More recently, colchicine has proven itself a key pharmacotherapy in cardiovascular disease (CVD) management, atherosclerotic plaque modification, and coronary artery disease (CAD) treatment. Colchicine acts on many anti-inflammatory pathways, which translates to cardiovascular event reduction, plaque transformation, and plaque reduction. With the FDA's 2023 approval of colchicine for reducing cardiovascular events, a novel clinical pathway opens. This advancement paves the route for CVD management that synergistically merges lipid lowering approaches with inflammation inhibition modalities. This pioneering moment spurs the need for this manuscript's comprehensive review. Hence, this paper synthesizes and surveys colchicine's new role as an atherosclerotic plaque modifier, to provide a framework for physicians in the clinical setting. We aim to improve understanding (and thereby application) of colchicine alongside existing mechanisms for CVD event reduction. This paper examines colchicine's anti-inflammatory mechanism, and reviews large cohort studies that evidence colchicine's blossoming role within CAD management. This paper also outlines imaging modalities for atherosclerotic analysis, reviews colchicine's mechanistic effect upon plaque transformation itself, and synthesizes trials which assess colchicine's nuanced effect upon atherosclerotic transformation.

Automatic assessment of atherosclerotic plaque features by intracoronary imaging: a scoping review

Background

The diagnostic performance and clinical validity of automatic intracoronary imaging (ICI) tools for atherosclerotic plaque assessment have not been systematically investigated so far.

Methods

We performed a scoping review including studies on automatic tools for automatic plaque components assessment by means of optical coherence tomography (OCT) or intravascular imaging (IVUS). We summarized study characteristics and reported the specifics and diagnostic performance of developed tools.

Results

Overall, 42 OCT and 26 IVUS studies fulfilling the eligibility criteria were found, with the majority published in the last 5 years (86% of the OCT and 73% of the IVUS studies). A convolutional neural network deep-learning method was applied in 71% of OCT- and 34% of IVUS-studies. Calcium was the most frequent plaque feature analyzed (26/42 of OCT and 12/26 of IVUS studies), and both modalities showed high discriminatory performance in testing sets [range of area under the curve (AUC): 0.91-0.99 for OCT and 0.89-0.98 for IVUS]. Lipid component was investigated only in OCT studies (n = 26, AUC: 0.82-0.86). Fibrous cap thickness or thin-cap fibroatheroma were mainly investigated in OCT studies (n = 8, AUC: 0.82-0.94). Plaque burden was mainly assessed in IVUS studies (n = 15, testing set AUC reported in one study: 0.70).

Conclusion

A limited number of automatic machine learning-derived tools for ICI analysis is currently available. The majority have been developed for calcium detection for either OCT or IVUS images. The reporting of the development and validation process of automated intracoronary imaging analyses is heterogeneous and lacks critical information.

Systematic Review Registration

Open Science Framework (OSF), https://osf.io/nps2b/.Graphical AbstractCentral Illustration.

The accuracy of detailed analysis of optical coherence tomography in detection of plaque lipid content: dual-imaging study with optical coherence tomography and near-infrared spectroscopy

BACKGROUND

Lipid-rich plaque covered by a thin fibrous cap (FC) has been identified as a frequent morphological substrate for the development of acute coronary syndrome. Optical coherence tomography (OCT) permits the identification and measurement of the FC. Near-infrared spectroscopy (NIRS) has been approved for detection of coronary lipids.

AIMS

We aimed to assess the ability of detailed OCT analysis to identify coronary lipids, using NIRS as the reference method.

METHODS

In total, 40 patients with acute coronary syndrome underwent imaging of a non-culprit lesion by both NIRS and OCT. For each segment, the NIRS-derived 4 mm segment with maximal lipid core burden index (maxLCBI4mm) was assessed. OCT analysis was performed using a semi-automated method including measurement of the fibrous cap thickness (FCT) of all detected fibroatheromas. Subsequent quantitative volumetric evaluation furnished FCT, FC surface area (FC SA), lipid arc, and FC (fibrous cap) volume data. OCT features of lipid plaques were compared with maxLCBI4mm. Predictors of maxLCBI4mm >400 was assessed by using univariable and multivariable analysis.

RESULTS

OCT features (mean FCT, total FC SA, FC volume, maximal, mean, and total lipid arcs) strongly correlated with the maxLCBI4mm (p = 0.012 for the mean FCT, respectively p < 0.001 for all other aforementioned features). The strongest predictors of maxLCBI4mm >400 were the maximal (p = 0.002) and mean (p = 0.002) lipid arc, and total FC SA (p = 0.012).

CONCLUSIONS

We found a strong correlation between the OCT-derived features and NIRS findings. Detailed OCT analysis may be reliably used for detection of the presence of coronary lipids.

Determination of lipid-rich plaques by artificial intelligence-enabled quantitative computed tomography using near-infrared spectroscopy as reference

BACKGROUND AND AIMS

Artificial intelligence quantitative CT (AI-QCT) determines coronary plaque morphology with high efficiency and accuracy. Yet, its performance to quantify lipid-rich plaque remains unclear. This study investigated the performance of AI-QCT for the detection of low-density noncalcified plaque (LD-NCP) using near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS).

METHODS

The INVICTUS Registry is a multi-center registry enrolling patients undergoing clinically indicated coronary CT angiography and IVUS, NIRS-IVUS, or optical coherence tomography. We assessed the performance of various Hounsfield unit (HU) and volume thresholds of LD-NCP using maxLCBI4mm ≥ 400 as the reference standard and the correlation of the vessel area, lumen area, plaque burden, and lesion length between AI-QCT and IVUS.

RESULTS

This study included 133 atherosclerotic plaques from 47 patients who underwent coronary CT angiography and NIRS-IVUS The area under the curve of LD-NCP<30HU was 0.97 (95% confidence interval [CI]: 0.93-1.00] with an optimal volume threshold of 2.30 mm3. Accuracy, sensitivity, and specificity were 94% (95% CI: 88-96%], 93% (95% CI: 76-98%), and 94% (95% CI: 88-98%), respectively, using <30 HU and 2.3 mm3, versus 42%, 100%, and 27% using <30 HU and >0 mm3 volume of LD-NCP (p < 0.001 for accuracy and specificity). AI-QCT strongly correlated with IVUS measurements; vessel area (r2 = 0.87), lumen area (r2 = 0.87), plaque burden (r2 = 0.78) and lesion length (r2 = 0.88), respectively.

CONCLUSIONS

AI-QCT demonstrated excellent diagnostic performance in detecting significant LD-NCP using maxLCBI4mm ≥ 400 as the reference standard. Additionally, vessel area, lumen area, plaque burden, and lesion length derived from AI-QCT strongly correlated with respective IVUS measurements.

Characterization of plaque phenotypes exhibiting an elevated pericoronary adipose tissue attenuation: insights from the REASSURE-NIRS registry

Inflammation has been considered to promote atheroma instability. Coronary computed tomography angiography (CCTA) visualizes pericoronary adipose tissue (PCAT) attenuation, which reflects coronary artery inflammation. While PCAT attenuation has been reported to predict future coronary events, plaque phenotypes exhibiting high PCAT attenuation remains to be fully elucidated. The current study aims to characterize coronary atheroma with a greater vascular inflammation. We retrospectively analyzed culprit lesions in 69 CAD patients receiving PCI from the REASSURE-NIRS registry (NCT04864171). Culprit lesions were evaluated by both CCTA and near-infrared spectroscopy/intravascular ultrasound (NIRS/IVUS) imaging prior to PCI. PCAT attenuation at proximal RCA (PCATRCA) and NIRS/IVUS-derived plaque measures were compared in patients with PCATRCA attenuation ≥ and < -78.3 HU (median). Lesions with PCATRCA attenuation ≥ -78.3 HU exhibited a greater frequency of maxLCBI4mm ≥ 400 (66% vs. 26%, p < 0.01), plaque burden ≥ 70% (94% vs. 74%, p = 0.02) and spotty calcification (49% vs. 6%, p < 0.01). Whereas positive remodeling (63% vs. 41%, p = 0.07) did not differ between two groups. On multivariable analysis, maxLCBI4mm ≥ 400 (OR = 4.07; 95%CI 1.12-14.74, p = 0.03), plaque burden ≥ 70% (OR = 7.87; 95%CI 1.01-61.26, p = 0.04), and spotty calcification (OR = 14.33; 95%CI 2.37-86.73, p < 0.01) independently predicted high PCATRCA attenuation. Of note, while the presence of only one plaque feature did not necessarily elevate PCATRCA attenuation (p = 0.22), lesions harboring two or more features were significantly associated with higher PCATRCA attenuation. More vulnerable plaque phenotypes were observed in patients with high PCATRCA attenuation. Our findings suggest PCATRCA attenuation as the presence of profound disease substrate, which potentially benefits from anti-inflammatory agents.

First-in-Human Drug-Eluting Balloon Treatment of Vulnerable Lipid-Rich Plaques: Rationale and Design of the DEBuT-LRP Study

Patients with non-obstructive lipid-rich plaques (LRPs) on combined intravascular ultrasound (IVUS) and near-infrared spectroscopy (NIRS) are at high risk for future events. Local pre-emptive percutaneous treatment of LRPs with a paclitaxel-eluting drug-coated balloon (PE-DCB) may be a novel therapeutic strategy to prevent future adverse coronary events without leaving behind permanent coronary implants. In this pilot study, we aim to investigate the safety and feasibility of pre-emptive treatment with a PE-DCB of non-culprit non-obstructive LRPs by evaluating the change in maximum lipid core burden in a 4 mm segment (maxLCBImm4) after 9 months of follow up. Therefore, patients with non-ST-segment elevation acute coronary syndrome underwent 3-vessel IVUS-NIRS after treatment of the culprit lesion to identify additional non-obstructive non-culprit LRPs, which were subsequently treated with PE-DCB sized 1:1 to the lumen. We enrolled 45 patients of whom 20 patients (44%) with a non-culprit LRP were treated with PE-DCB. After 9 months, repeat coronary angiography with IVUS-NIRS will be performed. The primary endpoint at 9 months is the change in maxLCBImm4 in PE-DCB-treated LRPs. Secondary endpoints include clinical adverse events and IVUS-derived parameters such as plaque burden and luminal area. Clinical follow-up will continue until 1 year after enrollment. In conclusion, this first-in-human study will investigate the safety and feasibility of targeted pre-emptive PE-DCB treatment of LRPs to promote stabilization of vulnerable coronary plaque at risk for developing future adverse events.

Regression and stabilization of atherogenic plaques

Atherosclerotic plaque assessment has become a crucial element in the examination of cardiovascular diseases. Plaque may exhibit progression and could become unstable if not treated, making plaque regression and stabilization among the most important goals of any cardiovascular intervention in cardiovascular medicine. In this review, we explore the current understanding of plaque regression and stabilization, discuss imaging and measurement techniques, and examine the evidence for pharmacological interventions and other interventions aimed at addressing this condition.

Clinical outcomes of acute myocardial infarction arising from non-lipid-rich plaque determined by NIRS-IVUS

Acute myocardial infarction (AMI) can rarely arise from non-lipid-rich coronary plaques. This study sought to compare the clinical outcomes after percutaneous coronary intervention (PCI) between AMI showing maximum lipid-core burden index in 4 mm (maxLCBI_4mm) < 400 and ≥ 400 in the infarct-related lesions assessed by near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS). We investigated 426 AMI patients who underwent NIRS-IVUS in the infarct-related lesions before PCI. Major adverse cardiovascular events (MACE) were defined as the composite of cardiac death, non-fatal MI, clinically driven target lesion revascularization (TLR), clinically driven non-TLR, and congestive heart failure requiring hospitalization. 107 (25%) patients had infarct-related lesions of maxLCBI_4mm < 400, and 319 (75%) patients had those of maxLCBI_4mm ≥ 400. The maxLCBI_4mm < 400 group had a younger median age at onset (68 years [IQR: 57-78 years] vs. 73 years [IQR: 64-80 years], P = 0.007), less frequent multivessel disease (39% vs. 51%, P = 0.029), less frequent TIMI flow grade 0 or 1 before PCI (62% vs. 75%, P = 0.007), and less frequent no-reflow immediately after PCI (5% vs. 11%, P = 0.039). During a median follow-up period of 31 months [IQR: 19-48 months], the frequency of MACE was significantly lower in the maxLCBI_4mm < 400 group compared with the maxLCBI_4mm ≥ 400 group (4.7% vs. 17.2%, P = 0.001). MaxLCBI_4mm < 400 was an independent predictor of MACE-free survival at multivariable analysis (hazard ratio: 0.36 [confidence interval: 0.13-0.98], P = 0.046). MaxLCBI_4mm < 400 measured by NIRS in the infract-related lesions before PCI was associated with better long-term clinical outcomes in AMI patients.

Utility of optical coherence tomography in acute coronary syndromes

Studies utilizing intravascular imaging have replicated the findings of histopathological studies, identifying the most common substrates for acute coronary syndromes (ACS) as plaque rupture, erosion, and calcified nodule, with spontaneous coronary artery dissection, coronary artery spasm, and coronary embolism constituting the less common etiologies. The purpose of this review is to summarize the data from clinical studies that have used high-resolution intravascular optical coherence tomography (OCT) to assess culprit plaque morphology in ACS. In addition, we discuss the utility of intravascular OCT for effective treatment of patients presenting with ACS, including the possibility of culprit lesion-based treatment by percutaneous coronary intervention.

Intravascular Ultrasound in Vulnerable Plaque and Acute Coronary Syndrome

Vulnerable plaque plays a pivotal role in the pathogenesis of acute coronary syndrome (ACS), being responsible for most ACS. The concept of vulnerable plaque has evolved with advancements in basic and clinical investigations along with developments and rapid expansion of coronary imaging modalities. Intravascular ultrasound (IVUS) is the first widely applied clinical technology with sufficient tissue penetration and enables us to identify vulnerable plaque and comprehensively understand the pathophysiology of ACS. In this review, we summarize current clinical evidence established by IVUS and the recent advancements in our understanding of vulnerable plaque and its role in ACS management.

Invasive Intracoronary Imaging of Cardiac Allograft Vasculopathy: Established Modalities and Emerging Technologies

Despite advances in the care of heart transplant recipients during the past 5 decades, cardiac allograft vasculopathy (CAV) continues to be a major barrier to long-term survival. The early diagnosis and treatment of CAV is crucial for improving long-term outcomes. Coronary angiography, the current gold standard for CAV screening, has low sensitivity for detecting early CAV. Increasingly, invasive intracoronary imaging modalities that provide a more detailed analysis of vessel anatomy and allow for plaque characterization are being used to detect CAV earlier after transplant and uncover mechanistic insights. Studies validating these emerging imaging platforms are needed before their widespread adoption.

Advances in Intravascular Ultrasound

Since its inception, intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have played a significant role in evaluating the pathophysiology of coronary artery disease (CAD) guiding the interventional and medical management of CAD improving outcomes in patients. Although the benefits of each of these modalities have been proven, due to some limitations, no single intravascular imaging technique has been proven to provide a detailed and complete evaluation of all CAD lesions. The use of different intravascular imaging modalities sequentially may lead to complications, which are cumbersome, consume time, and add financial burden to the patient. Recently, hybrid imaging catheters that combine OCT and IVUS benefits have been developed to limit these problems. Intravascular imaging techniques we are using currently have some drawbacks that hinder accurate assessment of plaque morphology and pathobiology as demonstrated in many histological studies, causing difficulty in identifying high-risk plaques. To overcome these limitations, great efforts have been put into developing hybrid, dual-probe catheters by combining imaging modalities to get an accurate analysis of plaque characteristics, and high-risk lesions. At present, many dual-probe catheters are available including combined IVUS-OCT, near-infrared spectroscopy-IVUS that is available commercially, the OCT-near infrared fluorescence (NIRF) molecular imaging, IVUS-NIRF, and combined fluorescence lifetime-IVUS imaging. Application of this combined multimodal imaging in clinical practice overcomes the limitations of standalone imaging and helps in providing a comprehensive and accurate visualization of plaque characteristics, composition, and plaque biology. The present article summarizes the advances in hybrid intravascular imaging, analyses the technical hindrances that should be known to have a use in the different clinical circumstances, and the till date shreds of evidence available from their first clinical application aiming to bring these modalities into the limelight and their potential role in the study of CAD.

Relationship between coronary high-intensity plaques on T1-weighted imaging by cardiovascular magnetic resonance and vulnerable plaque features by near-infrared spectroscopy and intravascular ultrasound: a prospective cohort study

BACKGROUND

This study aimed to compare the coronary plaque characterization by cardiovascular magnetic resonance (CMR) and near-infrared spectroscopy (NIRS)-intravascular ultrasound (IVUS) (NIRS-IVUS), and to determine whether pre-percutaneous coronary intervention (PCI) evaluation using CMR identifies high-intensity plaques (HIPs) at risk of peri-procedural myocardial infarction (pMI). Although there is little evidence in comparison with NIRS-IVUS findings, which have recently been shown to identify vulnerable plaques, we inferred that CMR-derived HIPs would be associated with vulnerable plaque features identified on NIRS-IVUS.

METHODS

52 patients with stable coronary artery disease who underwent CMR with non-contrast T1-weighted imaging and PCI using NIRS-IVUS were studied. HIP was defined as a signal intensity of the coronary plaque-to-myocardial signal intensity ratio (PMR) ≥ 1.4, which was measured from the data of CMR images. We evaluated whether HIPs were associated with the NIRS-derived maximum 4-mm lipid-core burden index (maxLCBI4mm) and plaque morphology on IVUS, and assessed the incidence and predictor of pMI defined by the current Universal Definition using high-sensitive cardiac troponin-T.

RESULTS

Of 62 lesions, HIPs were observed in 30 lesions (48%). The HIP group had a significantly higher remodeling index, plaque burden, and proportion of echo-lucent plaque and maxLCBI4mm ≥ 400 (known as large lipid-rich plaque [LRP]) than the non-HIP group. The correlation between the maxLCBI4mm and PMR was significantly positive (r = 0.51). In multivariable logistic regression analysis for prediction of HIP, NIRS-derived large LRP (odds ratio [OR] = 5.41; 95% confidence intervals [CIs] 1.65-17.8, p = 0.005) and IVUS-derived echo-lucent plaque (OR = 5.12; 95% CIs 1.11-23.6, p = 0.036) were strong independent predictors. Furthermore, pMI occurred in 14 of 30 lesions (47%) with HIP, compared to only 5 of 32 lesions (16%) without HIP (p = 0.005). In multivariable logistic regression analysis for prediction of incidence of pMI, CMR-derived HIP (OR = 5.68; 95% CIs 1.53-21.1, p = 0.009) was a strong independent predictor, but not NIRS-derived large LRP and IVUS-derived echo-lucent plaque.

CONCLUSIONS

There is an important relationship between CMR-derived HIP and NIRS-derived large LRP. We also confirmed that non-contrast T1-weighted CMR imaging is useful for characterization of vulnerable plaque features as well as for pre-PCI risk stratification. Trial registration The ethics committee of Juntendo Clinical Research and Trial Center approved this study on January 26, 2021 (Reference Number 20-313).

Risk Factors for Vulnerable Plaque Detected Using Near-Infrared Spectroscopy in Patients Receiving Statin Therapy with No History of Coronary Artery Disease

Residual risk of atherosclerosis remains high despite the use of lipid-lowering therapy with statins. Near-infrared spectroscopy intravascular ultrasound imaging (NIRS-IVUS) can identify vulnerable plaque via the detection of lipid-rich plaque. This study aimed to reveal the clinical characteristics of patients with vulnerable plaque despite statin therapy.NIRS-IVUS was used to determine the maximum 4 mm Lipid Core Burden Index (MaxLCBI_{4 mm}) values of 38 de novo culprit lesions from 32 patients with acute coronary syndrome (53%) (mean age: 73.1 ± 13.1 years) who underwent percutaneous coronary intervention after a minimum 6 months of statin therapy for primary prevention. A patient with vulnerable plaque was defined as an individual presenting at least 1 target lesion with a vulnerable plaque (MaxLCBI_{4 mm} > 400). Overall, the average low-density lipoprotein cholesterol (LDL-C) level was 95.5 ± 27.2 mg/dL. Patients in the vulnerable plaque group were younger and had higher LDL-C, triglycerides, and non-high-density lipoprotein cholesterol (HDL-C) levels than those in the non-vulnerable plaque group. The MaxLCBI_{4 mm} was positively correlated with LDL-C (P = 0.0002), triglycerides (P = 0.0003), and non-HDL-C (P = 0.0001). In multivariate analysis, all 3 treatable lipid components failed to show an independent relationship with the patients with vulnerable plaque. Using receiver-operating characteristics curve analysis, the cutoff points for LDL-C, triglycerides, and non-HDL-C were determined to be 78 mg/dL, 108 mg/dL, and 111 mg/dL, respectively, at MaxLCBI_{4 mm} > 400. In conclusion, this study supports a more comprehensive and aggressive lipid-lowering therapy for the primary prevention of coronary artery disease.

Relationship Between Optical Coherence Tomography-Derived In-Stent Neoatherosclerosis and the Extent of Lipid-Rich Neointima by Near-Infrared Spectroscopy and Intravascular Ultrasound: A Multimodal Imaging Study

Background In-stent restenosis, especially for neoatherosclerosis, is a major concern following percutaneous coronary intervention. This study aimed to elucidate the association of features of in-stent restenosis lesions revealed by optical coherence tomography (OCT)/optical frequency domain imaging (OFDI) and the extent of lipid-rich neointima (LRN) assessed by near-infrared spectroscopy (NIRS) and intravascular ultrasound, especially for neoatherosclerosis. Methods and Results We analyzed patients undergoing percutaneous coronary intervention for in-stent restenosis lesions using both OCT/OFDI and NIRS-intravascular ultrasound. OCT/OFDI-derived neoatherosclerosis was defined as lipid neointima. The existence of large LRN (defined as a long segment with 4-mm maximum lipid core burden index ≥400) was evaluated by NIRS. In 59 patients with 64 lesions, neoatherosclerosis and large LRN were observed in 17 (26.6%) and 21 lesions (32.8%), respectively. Naturally, large LRN showed higher 4-mm maximum lipid core burden index (median [interquartile range], 623 [518-805] versus 176 [0-524]; P<0.001). In OCT/OFDI findings, large LRN displayed lower minimal lumen area (0.9±0.4 versus 1.3±0.6 mm²; P=0.02) and greater max lipid arc (median [interquartile range], 272° [220°-360°] versus 193° [132°-247°]; P=0.004). In the receiver operating characteristic curve analysis, 4-mm maximum lipid core burden index was the best predictor for neoatherosclerosis, with a cutoff value of 405 (area under curve, 0.92 [95% CI, 0.83-1.00]). In multivariable logistic analysis, only low-density lipoprotein cholesterol (odds ratio, 1.52 [95% CI, 1.11-2.08]) was an independent predictor for large LRNs. Conclusions NIRS-derived large LRN was significantly associated with neoatherosclerosis by OCT/OFDI. The neointimal characterization by NIRS-intravascular ultrasound has potential as an alternative method of OCT/OFDI for in-stent restenosis lesions.

Epicardial Adipose Tissue Thickness Is Related to Plaque Composition in Coronary Artery Disease

(1) Background: Currently, limited data are available regarding the relationship between epicardial fat and plaque composition. The aim of this study was to assess the relationship between visceral fat surrounding the heart and the lipid core burden in patients with coronary artery diseases; (2) Methods: Overall, 331 patients undergoing coronary angiography with combined near-infrared spectroscopy and intravascular ultrasound imaging were evaluated for epicardial adipose tissue (EAT) thickness using transthoracic echocardiography. Patients were divided into thick EAT and thin EAT groups according to the median value; (3) Results: There was a positive correlation between EAT thickness and maxLCBI4mm, and maxLCBI4mm was significantly higher in the thick EAT group compared to the thin EAT group (437 vs. 293, p < 0.001). EAT thickness was an independent predictor of maxLCBI4mm ≥ 400 along with age, low-density lipoprotein-cholesterol level, acute coronary syndrome presentation, and plaque burden in a multiple linear regression model. Receiver operating characteristic curve analysis showed that EAT thickness was a predictor for maxLCBI4mm ≥ 400; (4) Conclusions: In the present study, EAT thickness is related to the lipid core burden assessed by NIRS-IVUS in patients with CAD which suggests that EAT may affect the stability of the plaques in coronary arteries.

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.

High-Risk Coronary Plaque Features: A Narrative Review

Advances in coronary plaque imaging over the last few decades have led to an increased interest in the identification of novel high-risk plaque features that are associated with cardiovascular events. Existing practices focus on risk stratification and lipid monitoring for primary and secondary prevention of cardiac events, which is limited by a lack of assessment and treatment of vulnerable plaque. In this review, we summarize the multitude of studies that have identified plaque, haemodynamic and patient factors associated with risk of acute coronary syndrome. Future progress in multi-modal imaging strategies and in our understanding of high-risk plaque features could expand treatment options for coronary disease and improve patient outcomes.

Influence of myocardial bridge on atherosclerotic plaque distribution and characteristics evaluated by near-infrared spectroscopy intravascular ultrasound

BACKGROUND

This study aims to clarify whether myocardial bridge (MB) could influence atherosclerotic plaque characteristics assessed using near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) imaging.

METHODS

One hundred and sixteen patients who underwent percutaneous coronary intervention (PCI) using NIRS-IVUS imaging were included. MB was defined as an echo-lucent band surrounding left anterior descending artery (LAD). In MB patients, LAD was divided into three segments: proximal, MB, and distal segments. In non-MB patients, corresponding three segments were defined based on the average length of the above segments. Segmental maximum plaque burden and lipid content derived from NIRS-IVUS imaging in the section of maximum plaque burden were evaluated in each segment. Lipid content of atherosclerotic plaque was evaluated as lipid core burden index (LCBI) and maxLCBI_4mm. LCBI is the fraction of pixels indicating lipid within a region multiplied by 1000, and the maximum LCBI in any 4-mm region was defined as maxLCBI_4mm.

RESULTS

MB was identified in 42 patients. MB was not associated with maximum plaque burden in proximal segment. LCBI and maxLCBI_4mm were significantly lower in patients with MB than those without in proximal segment. Multivariable analysis demonstrated both MB and maximum plaque burden in proximal segment to be independent predictors of LCBI in proximal segment.

CONCLUSIONS

Lipid content of atherosclerotic plaque assessed by NIRS-IVUS imaging was significantly smaller in patients with MB than those without. MB could be considered as a predictor of lipid content of atherosclerotic plaque when assessed by NIRS-IVUS imaging.

Near-infrared spectroscopy predicts events in men and women: Results from the Lipid Rich Plaque study

Background

The Lipid Rich Plaque (LRP) study demonstrated that near-infrared spectroscopy imaging of non-obstructive lesions identified patients and segments at higher risk for subsequent non-culprit major adverse cardiac events (NC-MACE). Whether this is true for both men and women is not known. In this post hoc analysis of the LRP study, we sought to investigate whether the maximum 4-mm Lipid Core Burden Index (maxLCBI_4mm) was of similar predictive value in men and women for NC-MACE.

Methods

Patients with an evaluable maxLCBI_4mm were stratified on the basis of sex at birth. A Cox proportional-hazards model was used to assess the predictive value of maxLCBI_4mm on future NC-MACE at the patient and plaque levels. The primary endpoint was cumulative incidence of NC-MACE at 24 months.

Results

Among 1271 patients, 388 (30.5%) were women. Women were older and had a higher cardiovascular risk profile. Cumulative incidence of NC-MACE at 24 months was 10.3% for women and 7.6% for men (log-rank p = 0.11). When comparing maxLCBI_4mm > 400 to maxLCBI_4mm ≤ 400, the hazard ratio (HR) for future NC-MACE was not significantly different between sexes: 2.10 (95% confidence interval [CI]: 1.28–3.44; p = 0.003) for men and 2.24 (95% CI: 1.18–4.28; p = 0.014) for women (p = 0.87). At the plaque level, the HR comparing maxLCBI_4mm > 400 to maxLCBI_4mm ≤ 400 was 3.49 (95% CI: 1.60–7.60, p = 0.002) for men and 4.79 (95% CI: 2.02–11.38, p < 0.001) for women, which was not significantly different (p = 0.57).

Conclusions

The maxLCBI_4mm was of similar predictive value for NC-MACE within 24 months in men and women.

Discrepancy between plaque vulnerability and functional severity of angiographically intermediate coronary artery lesions

This study sought to investigate the relationship between physiological severity and plaque vulnerability of intermediate coronary artery stenoses as assessed by fractional flow reserve (FFR) and near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS). We included vessels where both FFR and NIRS-IVUS were performed. A positive FFR was defined as FFR ≤ 0.80. Lipid core burden index of the entire target vessel (TV-LCBI), maximum LCBI in 4 mm (maxLCBI_4mm), and maximum plaque burden (PB) were evaluated using NIRS-IVUS. A vulnerable plaque was defined as a lipid-rich plaque (maxLCBI4_mm ≥ 400) with large PB (≥ 70%). A total of 59 vessels of 45 patients were included. Median FFR value was 0.75 [interquartile 0.72, 0.82]. An FFR value of ≤ 0.80 was observed in 42 vessels (71%). TV-LCBI (correlation coefficient [CC] = - 0.331, p = 0.011), lesion length (CC = - 0.350, p = 0.007), and PB (CC = - 0.230, p = 0.080) negatively correlated with FFR value, while maxLCBI_4mm did not (CC = - 0.156, p = 0.24). The prevalence of vulnerable plaques (26.2% vs. 29.4%, p > 0.99) and mean TV-LCBI, maxLCBI_4mm, and PB values were not significantly different between the vessels with FFR ≤ 0.80 and those with FFR > 0.80. In multivariable logistic models, diabetes mellitus (p = 0.003) and hemoglobin A1c (p = 0.012) were associated with the presence of a vulnerable plaque. In conclusion, the results of the present study suggested that FFR may reflect total lipid burden but not necessarily plaque vulnerability. In patients with coronary artery disease and a high likelihood of rapid atherosclerosis progression, such as diabetes mellitus patients, assessing plaque vulnerability in addition to the functional severity of coronary artery lesions may help stratify better the risk of future events.

Detection of Vulnerable Coronary Plaques Using Invasive and Non-Invasive Imaging Modalities

Acute coronary syndrome (ACS) mostly arises from so-called vulnerable coronary plaques, particularly prone for rupture. Vulnerable plaques comprise a specific type of plaque, called the thin-cap fibroatheroma (TFCA). A TCFA is characterized by a large lipid-rich necrotic core, a thin fibrous cap, inflammation, neovascularization, intraplaque hemorrhage, microcalcifications or spotty calcifications, and positive remodeling. Vulnerable plaques are often not visible during coronary angiography. However, different plaque features can be visualized with the use of intracoronary imaging techniques, such as intravascular ultrasound (IVUS), potentially with the addition of near-infrared spectroscopy (NIRS), or optical coherence tomography (OCT). Non-invasive imaging techniques, such as computed tomography coronary angiography (CTCA), cardiovascular magnetic resonance (CMR) imaging, and nuclear imaging, can be used as an alternative for these invasive imaging techniques. These invasive and non-invasive imaging modalities can be implemented for screening to guide primary or secondary prevention therapies, leading to a more patient-tailored diagnostic and treatment strategy. Systemic pharmaceutical treatment with lipid-lowering or anti-inflammatory medication leads to plaque stabilization and reduction of cardiovascular events. Additionally, ongoing studies are investigating whether modification of vulnerable plaque features with local invasive treatment options leads to plaque stabilization and subsequent cardiovascular risk reduction.

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.

Combined Use of Multiple Intravascular Imaging Techniques in Acute Coronary Syndrome

Recent advances in intravascular imaging techniques have made it possible to assess the culprit lesions of acute coronary syndrome (ACS) in the clinical setting. Intravascular ultrasound (IVUS) is the most commonly used intravascular imaging technique that provides cross-sectional images of coronary arteries. IVUS can assess plaque burden and vessel remodeling. Optical coherence tomography (OCT) is a high-resolution (10 μm) intravascular imaging technique that uses near-infrared light. OCT can identify key features of atheroma, such as lipid core and thin fibrous cap. Near-infrared spectroscopy (NIRS) can detect lipid composition by analyzing the near-infrared absorption properties of coronary plaques. NIRS provides a chemogram of the coronary artery wall, which allows for specific quantification of lipid accumulation. These intravascular imaging techniques can depict histological features of plaque rupture, plaque erosion, and calcified nodule in ACS culprit lesions. However, no single imaging technique is perfect and each has its respective strengths and limitations. In this review, we summarize the implications of combined use of multiple intravascular imaging techniques to assess the pathology of ACS and guide lesion-specific treatment.

CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) update 2022

Primary Percutaneous Coronary Intervention (PCI) has significantly contributed to reducing the mortality of patients with ST-segment elevation myocardial infarction (STEMI) even in cardiogenic shock and is now the standard of care in most of Japanese institutions. The Task Force on Primary PCI of the Japanese Association of Cardiovascular Interventional and Therapeutics (CVIT) society proposed an expert consensus document for the management of acute myocardial infarction (AMI) focusing on procedural aspects of primary PCI in 2018. Updated guidelines for the management of AMI were published by the European Society of Cardiology (ESC) in 2017 and 2020. Major changes in the guidelines for STEMI patients included: (1) radial access and drug-eluting stents (DES) over bare-metal stents (BMS) were recommended as a Class I indication, (2) complete revascularization before hospital discharge (either immediate or staged) is now considered as Class IIa recommendation. In 2020, updated guidelines for Non-ST-Elevation Myocardial Infarction (NSTEMI) patients, the followings were changed: (1) an early invasive strategy within 24 h is recommended in patients with NSTEMI as a Class I indication, (2) complete revascularization in NSTEMI patients without cardiogenic shock is considered as Class IIa recommendation, and (3) in patients with atrial fibrillation following a short period of triple antithrombotic therapy, dual antithrombotic therapy (e.g., DOAC and single oral antiplatelet agent preferably clopidogrel) is recommended, with discontinuation of the antiplatelet agent after 6 to 12 months. Furthermore, an aspirin-free strategy after PCI has been investigated in several trials those have started to show the safety and efficacy. The Task Force on Primary PCI of the CVIT group has now proposed the updated expert consensus document for the management of AMI focusing on procedural aspects of primary PCI in 2022 version.

Novel Applications for Invasive and Non-invasive Tools in the Era of Contemporary Percutaneous Coronary Revascularisation

Percutaneous coronary intervention (PCI) is an expanding treatment option for patients with coronary artery disease (CAD). It is considered the default strategy for the unstable presentation of CAD. PCI techniques have evolved over the last 4 decades with significant improvements in stent design, an increase in functional assessment of coronary lesions, and the use of intra-vascular imaging. Nonetheless, the morbidity and mortality related to CAD remain significant. Advances in technology have allowed a better understanding of the nature and progression of CAD. New tools are now available that reflect the pathophysiological changes at the level of the myocardium and coronary atherosclerotic plaque. Certain changes within the plaque would render it more prone to rupture leading to acute vascular events. These changes are potentially detected using novel tools invasively, such as near infra-red spectroscopy, or non-invasively using T2 mapping cardiovascular magnetic resonance imaging (CMR) and ¹⁸F-Sodium Fluoride positron emission tomography/ computed tomography. Similarly, changes at the level of the injured myocardium are feasibly assessed invasively using index microcirculatory resistance or non-invasively using T1 mapping CMR. Importantly, these changes could be detected immediately with the opportunity to tailor treatment to those considered at high risk. Concurrently, novel therapeutic options have demonstrated promising results in reducing future cardiovascular risks in patients with CAD. This Review article will discuss the role of these novel tools and their applicability in employing a mechanical and pharmacological treatment to mitigate cardiovascular risk in patients with CAD.

Near-infrared spectroscopy to predict microvascular obstruction after primary percutaneous coronary intervention

BACKGROUND

Successful restoration of epicardial coronary artery patency by primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction (STEMI) does not always lead to adequate reperfusion at the microvascular level.

AIMS

This study sought to investigate the association between lipid-rich coronary plaque identified by near-infrared spectroscopy combined with intravascular ultrasound (NIRS-IVUS) and microvascular obstruction (MVO) detected by cardiac magnetic resonance imaging (MRI) after PPCI for STEMI.

METHODS

We investigated 120 patients with STEMI undergoing PPCI. NIRS-IVUS was used to measure the maximum lipid core burden index in 4 mm (maxLCBI4 mm) in the infarct-related lesions before PPCI. Delayed contrast-enhanced cardiac MRI was performed to evaluate MVO one week after PPCI.

RESULTS

MVO was identified in 40 (33%) patients. MaxLCBI4 mm in the infarct-related lesion was significantly larger in the MVO group compared with the no-MVO group (median [interquartile range]: 745 [522-853] vs 515 [349-698], p<0.001). A multivariable logistic regression model showed that maxLCBI4 mm was an independent predictor of MVO (odds ratio: 24.7 [95% confidence interval: 2.5-248.0], p=0.006). Receiver operating characteristic curve analysis demonstrated that maxLCBI4 mm >600 was the optimal cut-off value to predict MVO (Youden index=0.44 and area under the curve=0.71) with a sensitivity of 75% and a specificity of 69%.

CONCLUSIONS

Lipid content measured by NIRS in the infarct-related lesions was associated with the occurrence of MVO after PPCI in STEMI.

Extent of lipid core plaque in patients with Achilles tendon xanthoma undergoing percutaneous coronary intervention for coronary artery disease

BACKGROUND

It has been reported that Achilles tendon xanthoma (ATX), being one of the important diagnostic criteria for familial hypercholesterolemia, is independently associated with the severity of coronary artery disease (CAD). The aim of this study was to investigate plaque vulnerability in CAD patients with ATX.

METHODS

Patients with CAD who underwent percutaneous coronary intervention (PCI) with near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) guidance were enrolled. Soft X-ray radiography of the Achilles tendon was performed, and a maximum thickness of 9 mm or more was regarded as ATX. Using NIRS-IVUS, the degree of lipid core plaque (LCP) was evaluated by calculating the maximum value of lipid core burden index (LCBI) for any of the 4-mm segments (maxLCBI_4mm) in the target lesion and non-target vessel.

RESULTS

In a total of 156 patients, 14 patients (9.0%) had ATX. MaxLCBI_4mm in the ATX group was significantly greater in the target lesion (p<0.001) and in the non-target vessel (p=0.032) compared to the non-ATX group. When patients were divided into tertiles according to Achilles tendon thickness, maxLCBI_4mm was progressively increased in favor of thickness, although there was only a tendency in the target lesion (p=0.062), and no statistical significance in the non-target vessel (p=0.189). Multiple linear regression analysis determined ATX as an independent predictor for maxLCBI_4mm in the target lesion and non-target vessel.

CONCLUSIONS

ATX was associated with the degree of LCP in CAD patients requiring PCI. High-risk patients with lipid-rich vulnerable plaque can possibly be detected by evaluating Achilles tendon thickness.

Long-term changes after carotid stenting assessed by intravascular ultrasound and near-infrared spectroscopy

BACKGROUND

Long-term effect of carotid stenting (CAS) on the stabilization of the plaque is almost unrecognized. Vascular healing and remodeling might seal the atherosclerotic plaque with neointimal hyperplasia decreasing the vulnerability. We aimed to assess long-term change in the lipid signal, stent and luminal dimensions and restenosis after CAS with the intravascular ultrasound (IVUS) and near-infrared spectroscopy (NIRS) imaging.

METHODS

We performed follow-up angiography and NIRS-IVUS imaging of 58 carotid stents in 52 patients. Median time from CAS to the follow-up examination was 31 months (range, 5-56). The lipid signal of the stented segment was calculated from a NIRS-derived chemogram (a spectroscopic map) as the lipid core burden index (LCBI, a dimensionless number from 0 to 1,000). Planimetric and volumetric measurements from IVUS were performed to assess change in minimal stent area (MSA), minimal luminal area (MLA), stent and luminal volume, late stent expansion and percentage in-stent restenosis (ISR) volume.

RESULTS

During the follow-up period, the mean (±SD) LCBI significantly decreased from 32±56 to 17±27 (P=0.002). The mean stent volume significantly increased from 717±302 to 1,019±429 mm3 (P<0.001) with mean stent expansion 43%±24%. The mean luminal volume increased from 717±302 to 760±359 mm3 (P=0.025) due to ISR encroaching 26%±15% of the stent volume.

CONCLUSIONS

Lipid signal decreased during the follow-up period suggesting stabilization of the plaque. Late stent expansion was balanced with neointimal hyperplasia.

TRIAL REGISTRATION

The trial is registered under clinicaltrials.gov NCT03141580.

Plaque Rupture, Compared With Plaque Erosion, Is Associated With a Higher Level of Pancoronary Inflammation

OBJECTIVES

The aim of this study was to compare the level of coronary inflammation between plaque rupture and plaque erosion using pericoronary adipose tissue (PCAT) attenuation.

BACKGROUND

Vascular inflammation plays a key role in plaque rupture, while the role of inflammation in plaque erosion remains less well defined. PCAT attenuation determined using computed tomography has emerged as a marker specific for coronary artery inflammation.

METHODS

Patients with non-ST-segment elevation acute coronary syndromes who underwent preintervention coronary computed tomographic angiography and optical coherence tomographic culprit lesion imaging were enrolled. PCAT attenuation was measured around the culprit lesion and in the proximal 40 mm of all coronary arteries.

RESULTS

Among 198 patients, plaque rupture was the underlying mechanism in 107 (54.0%) and plaque erosion in 91 (46.0%). Plaque rupture had higher PCAT attenuation than plaque erosion both at the culprit plaque level (-65.8 ± 7.5 HU vs -69.5 ± 11.4 HU; P = 0.010) and at the culprit vessel level (-67.1 ± 7.1 HU vs -69.6 ± 8.2 HU; P = 0.024). The mean PCAT attenuation of all 3 coronary arteries was also significantly higher in patients with plaque rupture than in plaque erosion, indicating a higher level of inflammation (-67.9 ± 5.7 HU vs -69.9 ± 6.8 HU; P = 0.030). In multivariable analysis, plaque rupture was significantly associated with high PCAT attenuation.

CONCLUSIONS

PCAT attenuation in culprit plaque, culprit vessel, and all 3 coronary arteries was higher in plaque rupture than in plaque erosion. The results suggest that pancoronary inflammation plays a more significant role in plaque rupture than in plaque erosion. (Massachusetts General Hospital and Tsuchiura Kyodo General Hospital Coronary Imaging Collaboration; NCT04523194).

Lipid-rich plaques detected by near-infrared spectroscopy predict coronary events irrespective of age: A Lipid Rich Plaque sub-study

BACKGROUND AND AIMS

In this Lipid Rich Plaque (LRP) sub-study, 1551 patients undergoing coronary angiography for acute coronary syndromes or stable angina were examined with near-infrared spectroscopy (NIRS) and intravascular ultrasound (IVUS). We aimed to assess the correlation of patient age with the presence of high-risk plaques, defined as maximum 4-mm Lipid Core Burden Index (maxLCBI_4mm) >400 and plaque burden >70%, and 2-year incidence of non-culprit major adverse cardiovascular events (NC-MACE).

METHODS

The study population was divided into four groups according to age: <50 years (122), 50-64 years (700), 65-74 years (502), and ≥75 years (227). The primary outcome was NC-MACE from index procedure to event or the end of the study. Cox regression and mixed-effects Cox regression models were used to assess the effect of age on the association between LCBI and NC-MACE at the patient and plaque levels.

RESULTS

Average maxLCBI_4mm and percentage of patients with at least one segment with maxLCBI_4mm > 400 were similar across the four age groups at both the patient and coronary segment levels. Having at least one segment with maxLCBI_4mm > 400 was strongly associated with NC-MACE, and that association did not differ significantly across age subgroups. Although less common (prevalence of 0.8%-1.3%), a similar trend toward greater NC-MACE rates was seen in patients with plaque burden >70% at the maximum LCBI site across age subgroups.

CONCLUSIONS

Lipid-rich plaques were as frequent in older as in younger patients and predicted a higher incidence of NC-MACE over 2-year follow-up irrespective of age.

In vivo relationship between near-infrared spectroscopy-detected lipid-rich plaques and morphological plaque characteristics by optical coherence tomography and intravascular ultrasound: a multimodality intravascular imaging study

AIMS

We assessed morphological features of near-infrared spectroscopy (NIRS)-detected lipid-rich plaques (LRPs) by using optical coherence tomography (OCT) and intravascular ultrasound (IVUS).

METHODS AND RESULTS

IVUS-NIRS and OCT were performed in the two non-infarct-related arteries (non-IRAs) in patients undergoing percutaneous coronary intervention for treatment of an acute coronary syndrome. A lesion was defined as the 4 mm segment with the maximum amount of lipid core burden index (maxLCBI4mm) of each LRP detected by NIRS. We divided the lesions into three groups based on the maxLCBI4mm value: <250, 250-399, and ≥400. OCT analysis and IVUS analysis were performed blinded for NIRS. We measured fibrous cap thickness (FCT) by using a semi-automated method. A total of 104 patients underwent multimodality imaging of 209 non-IRAs. NIRS detected 299 LRPs. Of those, 41% showed a maxLCBI4mm <250, 39% a maxLCBI4mm 251-399, and 19% a maxLCBI4mm ≥400. LRPs with a maxLCBI4mm ≥400, as compared with LRPs with a maxLCBI4mm 250-399 and <250, were more frequently thin-cap fibroatheroma (TCFA) (42.1% vs. 5.1% and 0.8%; P < 0.001) with a smaller minimum FCT (80 μm vs. 110 μm and 120 μm; P < 0.001); a higher IVUS-derived percent atheroma volume (53% vs. 53% and 44%; P < 0.001) and a higher remodelling index (1.08 vs. 1.02 and 1.01; P < 0.001). MaxLCBI4mm correlated with OCT-derived FCT (r = 0.404; P < 0.001) and was the best predictor for TCFA with an optimal cut-off value of 401 (area under the curve = 0.882; P < 0.001).

CONCLUSION

LRPs with increasing maxLCBI4mm exhibit OCT and IVUS features of presumed plaque vulnerability including TCFA morphology, increased plaque burden, and positive remodelling.

Effects of the PCSK9 antibody alirocumab on coronary atherosclerosis in patients with acute myocardial infarction: a serial, multivessel, intravascular ultrasound, near-infrared spectroscopy and optical coherence tomography imaging study-Rationale and design of the PACMAN-AMI trial

BACKGROUND

The risk for cardiovascular adverse events after acute myocardial infarction (AMI) remains high despite potent medical treatment including low-density lipoprotein cholesterol (LDL-C) lowering with statins. Proprotein convertase subtilisin/kexin type 9 (PCSK9) antibodies substantially reduce LDL-C when added to statin. Alirocumab, a monoclonal antibody to PCSK9, reduces major adverse cardiovascular events after AMI. The effects of alirocumab on coronary atherosclerosis including plaque burden, plaque composition and fibrous cap thickness in patients presenting with AMI remains unknown.

AIMS

To determine the effect of LDL-C lowering with alirocumab on top of high-intensity statin therapy on intravascular ultrasound (IVUS)-derived percent atheroma volume (PAV), near-infrared spectroscopy (NIRS)-derived maximum lipid core burden index within 4 mm (maxLCBI_{4 mm}) and optical coherence tomography (OCT)-derived fibrous cap thickness (FCT) in patients with AMI.

METHODS

In this multicenter, double-blind, placebo-controlled trial, 300 patients with AMI (ST-elevation or non-ST-elevation myocardial infarction) were randomly assigned to receive either biweekly subcutaneous alirocumab (150 mg) or placebo beginning <24 hours after the acute event as add-on therapy to rosuvastatin 20 mg. Patients undergo serial IVUS, NIRS and OCT in the two non-infarct related arteries at baseline (at the time of treatment of the culprit lesion) and at 52 weeks. The primary endpoint, change in IVUS-derived PAV, and the powered secondary endpoints, change in NIRS-derived maxLCBI_{4 mm}, and OCT-derived minimal FCT, will be assessed 52 weeks post randomization.

SUMMARY

The PACMAN-AMI trial will determine the effect of alirocumab on top of high-intensity statin therapy on high-risk coronary plaque characteristics as assessed by serial, multimodality intracoronary imaging in patients presenting with AMI.

CLINICAL TRIAL REGISTRATION

NCT03067844.

Adoption of a new automated optical coherence tomography software to obtain a lipid plaque spread-out plot

PURPOSE

Near infrared spectroscopy-Intravascular ultrasound (NIRS-IVUS) provide a fully automated Lipid Core Burden Index (LCBI). Optical coherence tomography (OCT) is potentially capable of measuring lipid longitudinal extension in a dedicated two-dimensional LCBI spread-out plot. The present study has been designed to validate an automated approach to assess OCT images, able of providing a dedicated LCBI spread-out plot.

METHODS

We compared results obtained with conventional (manual) OCT, with those obtained with a novel automated OCT algorithm and with NIRS-IVUS in consecutive 40 patients. Our goal was to calculate the lipid core longitudinal extension in a dedicated two-dimensional LCBI spread-out plot. Three groups were identified according to the studied lesions: (1) culprit lesions in ACS patients (n = 16), (2) non-culprit lesions in ACS patients (n = 12) and (3) lesions in stable patients (n = 12). OCT (either manual and automated) and NIRS-IVUS assessment showed for culprit ACS plaques a more complex anatomy.

RESULTS

A strong trend for increased LCBI was found in the culprit ACS group, regardless of the adopted imaging modality (either NIRS-IVUS or automated OCT). A fair correlation was obtained for the maximum 4 mm LCBI measured by NIRS-IVUS and automated OCT (r = 0.75). The sensitivity and specificity of automated OCT to detect significant LCBI (> 400) were 90.5 and 84.2 respectively.

CONCLUSION

We developed an OCT automated approach that can provide a dedicated lipid plaque spread-out plot to address plaque vulnerability. The automated OCT software can promote and improve OCT clinical applications for the identification of patients at risk of hard events.

Lipid Core Burden Index Assessed by Near-Infrared Spectroscopy of Symptomatic Carotid Plaques: Association with Magnetic Resonance T1-Weighted Imaging

INTRODUCTION

Vulnerable plaques are a strong predictor of cerebrovascular ischemic events, and high lipid core plaques (LCPs) are associated with an increased risk of embolic infarcts during carotid artery stenting (CAS). Recent developments in magnetic resonance (MR) plaque imaging have enabled noninvasive assessment of carotid plaque vulnerability, and the lipid component and intraplaque hemorrhage (IPH) are visible as high signal intensity areas on T1-weighted MR images. Recently, catheter-based near-infrared spectroscopy (NIRS) has been shown to accurately distinguish LCPs without IPH. This study aimed to determine whether the results of assessment of high LCPs by catheter-based NIRS correlate with the results of MR plaque imaging.

METHODS

We recruited 82 consecutive symptomatic carotid artery stenosis patients who were treated with CAS under NIRS and MR plaque assessment. Maximum lipid core burden index (max-LCBI) at minimal luminal areas (MLA), defined as max-LCBIMLA, and max-LCBI for any 4-mm segment in a target lesion, defined as max-LCBIAREA, were assessed by NIRS. Correlations were investigated between max-LCBI and MR T1-weighted plaque signal intensity ratio (T1W-SIR) and MR time-of-flight signal intensity ratio (TOF-SIR) in the same regions as assessed by NIRS.

RESULTS

Both T1W-SIRMLA and T1W-SIRAREA were significantly lower in the high LCP group (max-LCBI >504, p < 0.001 for both), while TOF-SIRMLA and TOF-SIRAREA were significantly higher in the high LCP group (p < 0.001 and p = 0.004, respectively). A significant linear correlation was present between max-LCBIMLA and both TIW-SIRMLA and TOF-SIRMLA (r = -0.610 and 0.452, respectively, p < 0.0001 for both). Furthermore, logistic regression analysis revealed that T1W-SIRMLA and TOF-SIRMLA were significantly associated with a high LCP assessed by NIRS (OR, 44.19 and 0.43; 95% CI: 6.55-298.19 and 0.19-0.96; p < 0.001 and = 0.039, respectively).

CONCLUSIONS

A high LCP assessed by NIRS correlates with the signal intensity ratio of MR imaging in symptomatic patients with unstable carotid plaques.

Target Lesion Lipid Content Detected by Near-Infrared Spectroscopy After Stenting and the Risk of Subsequent Target Lesion Failure

[Figure: see text].

Atherothrombosis in Acute Coronary Syndromes-From Mechanistic Insights to Targeted Therapies

The atherothrombotic substrates for acute coronary syndromes (ACS) consist of plaque ruptures, erosions and calcified nodules, while the non-atherothrombotic etiologies, such as spontaneous coronary artery dissection, coronary artery spasm and coronary embolism are the rarer causes of ACS. The purpose of this comprehensive review is to (1) summarize the histopathologic insights into the atherothrombotic plaque subtypes in acute ACS from postmortem studies; (2) provide a brief overview of atherogenesis, while mainly focusing on the events that lead to plaque destabilization and disruption; (3) summarize mechanistic data from clinical studies that have used intravascular imaging, including high-resolution optical coherence tomography, to assess culprit plaque morphology and its underlying pathobiology, especially the newly described role of innate and adaptive immunity in ACS secondary to plaque erosion; (4) discuss the utility of intravascular imaging for effective treatment of patients presenting with ACS by percutaneous coronary intervention; and (5) discuss the opportunities that these mechanistic and imaging insights may provide for more individualized treatment of patients with ACS.

Coronary lipid-rich plaque characteristics in Japanese patients with acute coronary syndrome and stable angina: A near infrared spectroscopy and intravascular ultrasound study

BACKGROUND

Asians have a much lower incidence of adverse coronary events than Caucasians. We sought to evaluate the characteristics of coronary lipid-rich plaques (LRP) in Asian patients with acute coronary syndrome (ACS) and stable angina (SA). We also aimed to identify surrogate markers for the extent of LRP.

METHODS

We evaluated 207 patients (ACS, n = 75; SA, n = 132) who underwent percutaneous coronary intervention under near infrared spectroscopy intravascular ultrasound (NIRS-IVUS). Plaque characteristics and the extent of LRP [defined as a long segment with a 4-mm maximum lipid-core burden index (maxLCBI4mm)] on NIRS in de-novo culprit and non-culprit segments were analyzed.

RESULTS

The ACS culprit lesions had a significantly higher maxLCBI4mm (median [interquartile range (IQR)]: 533 [385-745] vs. 361 [174-527], p < 0.001) than the SA culprit lesions. On multivariate logistic analysis, a large LRP (defined as maxLCBI4mm ≥ 400) was the strongest independent predictor of the ACS culprit segment (odds ratio, 3.87; 95% confidence interval, 1.95-8.02). In non-culprit segments, 19.8% of patients had at least one large LRP without a small lumen. No significant correlation was found between the extent of LRP and systematic biomarkers (hs-CRP, IL-6, TNF-α), whereas the extent of LRP was positively correlated with IVUS plaque burden (r = 0.24, p < 0.001).

CONCLUSIONS

We confirmed that NIRS-IVUS plaque assessment could be useful to differentiate ACS from SA culprit lesions, and that a threshold maxLCBI4mm ≥ 400 was clinically suitable in Japanese patients. No surrogate maker for a high-risk LRP was found; consequently, direct intravascular evaluation of plaque characteristics remains important.

The association between the extent of lipidic burden and delta-fractional flow reserve: analysis from coronary physiological and near-infrared spectroscopic measures

Background

Vulnerable plaque features including lipidic plaque have been shown to affect fractional flow reserve (FFR). Given that formation and propagation of lipid plaque is accompanied by endothelial dysfunction which impairs vascular tone, the degree of lipidic burden may affect vasoreactivity during hyperemia, potentially leading to reduced FFR. Our aim is to elucidate the relationship of the extent of lipidic plaque burden with coronary physiological vasoreactivity measure.

Methods

We analyzed 89 subjects requeuing PCI due to angiographically intermediate coronary stenosis with FFR ≤0.80. Near-infrared spectroscopy (NIRS) and intravascular ultrasound were used to evaluate lipid-core burden index (LCBI) and atheroma volume at both target lesion (maxLCBI_4mm; maximum value of LCBI within any 4 mm segments) and entire target vessel (LCBI_vessel: LCBI within entire vessel). In addition to FFR, delta-FFR was measured by difference of distal coronary artery pressure/aortic pressure (Pd/Pa) between baseline and hyperemic state.

Results

The averaged FFR and delta-FFR was 0.74 (0.69-0.77), and 0.17±0.05, respectively. On target lesion-based analysis, maxLCBI_4mm was negatively correlated to FFR (ρ=-0.213, P=0.040), and it was positively correlated to delta-FFR (ρ=0.313, P=0.002). Furthermore, target vessel-based analysis demonstrated similar relationship of LCBI_vessel with FFR (ρ=-0.302, P=0.003) and delta-FFR (ρ=0.369, P<0.001). Even after adjusting clinical characteristics and lesion/vessel features, delta-FFR (by 0.10 increase) was independently associated with maxLCBI_4mm (β=57.2, P=0.027) and LCBI_vessel (β=24.8, P=0.007) by mixed linear model analyses.

Conclusions

A greater amount of lipidic plaque burden at not only "target lesion" alone but "entire target vessel" was associated with a greater delta-FFR. The accumulation of lipidic plaque materials at both local site and entire vessel may impair hyperemia-induced vasoreactivity, which causes a reduced FFR.

The feasibility and limitation of coronary computed tomographic angiography imaging to identify coronary lipid-rich atheroma in vivo: Findings from near-infrared spectroscopy analysis

BACKGROUND

Coronary computed tomography angiography (CCTA) non-invasively visualizes lipid-rich plaque. However, this ability is not fully validated in vivo. The current study aimed to elucidate the association of CCTA features with near-infrared spectroscopy-derived lipidic plaque measure in patients with coronary artery disease.

METHODS

95 coronary lesions (culprit/non-culprit = 51/44) in 35 CAD subjects were evaluated by CCTA and NIRS imaging. CT density, positive remodeling, spotty calcification, napkin-ring sign and NIRS-derived maximum 4-mm lipid-core burden index (maxLCBI_4mm) were analyzed by two independent physicians. The association of CCTA-derived plaque features with maxLCBI_4mm ≥ 400 was evaluated.

RESULTS

The median CT density and maxLCBI_4mm were 57.7 Hounsfield units (HU) and 304, respectively. CT density (r = -0.75, p < 0.001) and remodeling index (RI) (r = 0.58, p < 0.001) were significantly associated with maxLCBI_4mm, respectively. Although napkin-ring sign (p < 0.001) showed higher prevalence of maxLCBI_4mm ≥ 400 than those without it, spotty calcification did not (p = 0.13). On multivariable analysis, CT density [odds ratio (OR) = 0.95, 95% confidence interval (CI) = 0.93-0.97; p < 0.001] and positive remodeling [OR = 7.71, 95%CI = 1.37-43.41, p = 0.02] independently predicted maxLCBI_4mm ≥ 400. Receiver operating characteristic curve analysis demonstrated CT density <32.9 HU (AUC = 0.92, sensitivity = 85.7%, specificity = 91.7%) and RI ≥ 1.08 (AUC = 0.83, sensitivity = 74.3%, specificity = 85.0%) as optimal cut-off values of maxLCBI_4mm ≥ 400. Of note, only 52.6% at lesions with one of these plaque features exhibited maxLCBI_4mm ≥ 400, whereas the frequency of maxLCBI_4mm ≥ 400 was highest at those with both features (88.5%, p < 0.001 for trend).

CONCLUSIONS

CT density <32.9 HU and RI ≥ 1.08 were associated with lipid-rich plaque on NIRS imaging. Our findings underscore the synergistic value of CT density and positive remodeling to detect lipid-rich plaque by CCTA.

Spatial relationships among hemodynamic, anatomic, and biochemical plaque characteristics in patients with coronary artery disease

BACKGROUND AND AIMS

We aimed to characterize the spatial proximity of plaque destabilizing features local endothelial shear stress (ESS), minimal luminal area (MLA), plaque burden (PB), and near-infrared spectroscopy (NIRS) lipid signal in high- vs. low-risk plaques.

METHODS

Coronary arteries imaged with angiography and NIRS-intravascular ultrasound (IVUS) underwent 3D reconstruction and computational fluid dynamics calculations of local ESS. ESS, PB, MLA, and lipid core burden index (LCBI), for each 3-mm arterial segment were obtained in arteries with large lipid-rich plaque (LRP) vs. arteries with smaller LRP. The locations of the MLA, minimum ESS (minESS), maximum ESS (maxESS), maximum PB (maxPB), and maximum LCBI in a 4-mm segment (maxLCBI_4mm) were determined along the length of each plaque.

RESULTS

The spatial distributions of minESS, maxESS, maxPB, and maxLCBI_4mm, in reference to the MLA, were significantly heterogeneous within and between each variable. The location of maxLCBI_4mm was spatially discordant from sites of the MLA (p<0.0001), minESS (p = 0.003), and maxESS (p = 0.003) in arteries with large LRP (maxLCBI_4mm ≥ 400) and non-large LRP. Large LRP arteries had higher maxESS (9.31 ± 4.78 vs. 6.32 ± 5.54 Pa; p = 0.023), lower minESS (0.41 ± 0.16 vs. 0.61 ± 0.26 Pa; p = 0.007), smaller MLA (3.54 ± 1.22 vs. 5.14 ± 2.65 mm²; p = 0.002), and larger maxPB (70.64 ± 9.95% vs. 56.70 ± 13.34%, p<0.001) compared with non-large LRP arteries.

CONCLUSIONS

There is significant spatial heterogeneity of destabilizing plaque features along the course of both large and non-large LRPs. Large LRPs exhibit significantly more abnormal destabilizing plaque features than non-large LRPs. Prospective, longitudinal studies are required to determine which patterns of heterogeneous destabilizing features act synergistically to cause plaque destabilization.

Effects of lipid composition on photothermal optical coherence tomography signals

SIGNIFICANCE

Photothermal optical coherence tomography (PT-OCT) has the promise to offer structural images coregistered with chemical composition information, which can offer a significant impact in early detection of diseases such as atherosclerosis.

AIM

We take the first step in understanding the relation between PT-OCT signals and the endogenous tissue composition by considering the interplay between the opto-thermo-physical properties of tissue as a function of its lipid composition and the ensuing effects on the PT-OCT signals.

APPROACH

Multiparameter theoretical estimates for PT-OCT signal as a function of composition in a two-component lipid-water model are derived and discussed. Experimental data from various concentrations of lipid in the form of droplets and injections under bovine cardiac muscle align with theoretical predictions.

RESULTS

Theoretical and experimental results suggest that the variations of heat capacity and mass density with tissue composition significantly contribute to the amount of optical path length difference measured by OCT phase.

CONCLUSION

PT-OCT has the potential to offer key insights into the chemical composition of the subsurface lipid pools in tissue; however, the interpretation of results needs to be carried out by keeping the nonlinear interplay between the tissue of opto-thermo-physical properties and PT-OCT signals in mind.

The role of intracoronary imaging in translational research

Atherosclerotic cardiovascular disease is a key public health concern worldwide and leading cause of morbidity, mortality and health economic costs. Understanding atherosclerotic plaque microstructure in relation to molecular mechanisms that underpin its initiation and progression is needed to provide the best chance of combating this disease. Evolving vessel wall-based, endovascular coronary imaging modalities, including intravascular ultrasound (IVUS), optical coherence tomography (OCT) and near-infrared spectroscopy (NIRS), used in isolation or as hybrid modalities, have been advanced to allow comprehensive visualization of the pathological substrate of coronary atherosclerosis and accurately measure temporal changes in both the vessel wall and plaque characteristics. This has helped further our appreciation of the natural history of coronary artery disease (CAD) and the risk for major adverse cardiovascular events (MACE), evaluate the responsiveness to conventional and experimental therapeutic interventions, and assist in guiding percutaneous coronary intervention (PCI). Here we review the use of different imaging modalities for these purposes and the lessons they have provided thus far.

NIRS-IVUS for Differentiating Coronary Plaque Rupture, Erosion, and Calcified Nodule in Acute Myocardial Infarction

OBJECTIVES

This study sought to investigate the ability of combined near-infrared spectroscopy and intravascular ultrasound (NIRS-IVUS) to differentiate plaque rupture (PR), plaque erosion (PE), or calcified nodule (CN) in acute myocardial infarction (AMI).

BACKGROUND

Most acute coronary syndromes occur from coronary thrombosis based on PR, PE, or CN. In vivo differentiation among PR, PE, and CN is a major challenge for intravascular imaging.

METHODS

The study enrolled 244 patients with AMI who had a de novo culprit lesion in a native coronary artery. The culprit lesions were assessed by both NIRS-IVUS and optical coherence tomography (OCT). Maximum lipid core burden index in 4 mm (maxLCBI_4mm) was measured by NIRS. Plaque cavity and convex calcium was detected by IVUS. The OCT diagnosis of PR (n = 175), PE (n = 44), and CN (n = 25) was used as a reference standard.

RESULTS

In the development cohort, IVUS-detected plaque cavity showed a high specificity (100%) and intermediate sensitivity (62%) for identifying OCT-PR. IVUS-detected convex calcium showed a high sensitivity (93%) and specificity (100%) for identifying OCT-CN. NIRS-measured maxLCBI_4mm was largest in OCT-PR (705 [interquartile range (IQR): 545 to 854]), followed by OCT-CN (355 [IQR: 303 to 478]) and OCT-PE (300 [IQR: 126 to 357]) (p < 0.001). The optimal cutoff value of maxLCBI_4mm was 426 for differentiating between OCT-PR and -PE; 328 for differentiating between OCT-PE and -CN; and 579 for differentiating between OCT-PR and -CN. In the validation cohort, the NIRS-IVUS classification algorithm using plaque cavity, convex calcium, and maxLCBI_4mm showed a sensitivity and specificity of 97% and 96% for identifying OCT-PR, 93% and 99% for OCT-PE, and 100% and 99% for OCT-CN, respectively.

CONCLUSIONS

By evaluating plaque cavity, convex calcium, and maxLCBI_4mm, NIRS-IVUS can accurately differentiate PR, PE, and CN.

Impact of clinical presentations on lipid core plaque assessed by near-infrared spectroscopy intravascular ultrasound

Near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) studies have demonstrated that lipid core plaque (LCP) is frequently observed in the culprit segment of myocardial infarction (MI). However, little is known about the impact of clinical presentations such as chronic coronary syndrome (CCS) and acute coronary syndrome (ACS) including unstable angina (UA), non ST-segment elevation MI (NSTEMI), and ST-segment elevation MI (STEMI) on LCP. The present prospective single-center registry included a total of 178 patients who underwent percutaneous coronary intervention under NIRS-IVUS guidance. Patients were divided into CCS and ACS groups, and ACS patients were further sub-divided into the 3 groups according to the clinical presentation. The primary endpoint was coronary LCP in the target lesion assessed by NIRS-IVUS with maximal lipid core burden index over any 4 mm segment (maxLCBI_4mm). The study population included 124 and 54 patients with CCS and ACS. MaxLCBI_4mm in the target lesion was significantly higher in the ACS group than in the CCS group (503 [284-672] vs. 406 [250-557], p = 0.046). Among ACS patients, MaxLCBI_4mm in the target lesion was also significantly different in those with UA (n = 18), NSTEMI (n = 21), and STEMI (n = 15) (288 [162-524] vs. 518 [358-745] vs. 646 [394-848], p = 0.021). In conclusion, LCP assessed by NIRS-IVUS, a surrogate of coronary plaque vulnerability, was significantly different according to the clinical presentations such as CCS, UA, NSTEMI, and STEMI.