Role of new imaging modalities in pursuit of the vulnerable plaque and the vulnerable patient

Current Toolset in Predicting Acute Coronary Thrombotic Events: The “Vulnerable Plaque” in a “Vulnerable Patient” Concept

Despite major advances in pharmacotherapy and interventional procedures, coronary artery disease (CAD) remains a principal cause of morbidity and mortality worldwide. Invasive coronary imaging along with the computation of hemodynamic forces, primarily endothelial shear stress and plaque structural stress, have enabled a comprehensive identification of atherosclerotic plaque components, providing a unique insight into the understanding of plaque vulnerability and progression, which may help guide patient treatment. However, the invasive-only approach to CAD has failed to show high predictive value. Meanwhile, it is becoming increasingly evident that along with the “vulnerable plaque”, the presence of a “vulnerable patient” state is also necessary to precipitate an acute coronary thrombotic event. Non-invasive imaging techniques have also evolved, providing new opportunities for the identification of high-risk plaques, the study of atherosclerosis in asymptomatic individuals, and general population screening. Additionally, risk stratification scores, circulating biomarkers, immunology, and genetics also complete the armamentarium of a broader “vulnerable plaque and patient” concept approach. In the current review article, the invasive and non-invasive modalities used for the detection of high-risk plaques in patients with CAD are summarized and critically appraised. The challenges of the vulnerable plaque concept are also discussed, highlighting the need to shift towards a more interdisciplinary approach that can identify the “vulnerable plaque” in a “vulnerable patient”.

Imaging diagnosis and research progress of carotid plaque vulnerability

Ischemic stroke (IS) exhibits a high disability rate, mortality, and recurrence rate, imposing a serious threat to human survival and health. Its occurrence is affected by various factors. Although the previous research has demonstrated that the occurrence of IS is mainly associated with lumen stenosis caused by carotid atherosclerotic plaque (AP), recent studies have revealed that many patients will still suffer from IS even with mild carotid artery lumen stenosis. Blood supply disturbance causes 10% of IS to the corresponding cerebral blood supply area caused by carotid vulnerable plaque. Thrombus blockage of distal branch vessels caused by rupture of vulnerable carotid plaque is the main cause of ischemic stroke. Therefore, how to accurately evaluate vulnerable plaque and intervene as soon as possible is a problem that needs to be solved in clinic. The vulnerability of plaque is determined by its internal components, including thin and incomplete fibrous cap, necrotic lipid core, intra-plaque hemorrhage, intra-plaque neovascularization, and ulcerative plaque formation. The development of imaging technology enables the routine detection of AP vulnerability. By analyzing the pathological changes, characteristics, and formation mechanism of carotid plaque vulnerability, this article aims to explore the modern imaging methods which can be used to identify plaque composition and plaque vulnerability to provide a reference basis for disease diagnosis and differential diagnosis.

Robotics, imaging, and artificial intelligence in the catheterisation laboratory

The catheterisation laboratory today combines diagnosis and therapeutics, through various imaging modalities and a prolific list of interventional tools, led by balloons and stents. In this review, we focus primarily on advances in image-based coronary interventions. The X-ray images that are the primary modality for diagnosis and interventions are combined with novel tools for visualisation and display, including multi-imaging co-registration modalities with three- and four-dimensional presentations. Interpretation of the physiologic significance of coronary stenosis based on prior angiographic images is being explored and implemented. Major efforts to reduce X-ray exposure to the staff and the patients, using computer-based algorithms for image processing, and novel methods to limit the radiation spread are being explored. The use of artificial intelligence (AI) and machine learning for better patient care requires attention to universal methods for sharing and combining large data sets and for allowing interpretation and analysis of large cohorts of patients. Barriers to data sharing using integrated and universal protocols should be overcome to allow these methods to become widely applicable. Robotic catheterisation takes the physician away from the ionising radiation spot, enables coronary angioplasty and stenting without compromising safety, and may allow increased precision. Remote coronary procedures over the internet, that have been explored in virtual and animal studies and already applied to patients in a small pilot study, open possibilities for sharing experience across the world without travelling. Application of those technologies to neurovascular, and particularly stroke interventions, may be very timely in view of the need for expert neuro-interventionalists located mostly in central areas.

Cardiovascular Imaging Techniques for Detection of Vulnerable Plaques

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

Susceptible gene polymorphism in patients with three-vessel coronary artery disease

Background

Data of susceptible gene polymorphisms related to progression of coronary atherosclerosis in patients with three-vessel disease (TVD) is limited in China. This case-control study aimed to analyze the differences of variant carrier frequencies between cases and controls, and to explain the possible genetic effects on the progression of TVD.

Methods

A total of 8943 TVD patients were consecutively enrolled. Major adverse cardiac and cerebrovascular events (MACCE) included all-cause death, acute myocardial infarction, repeat revascularization, readmission and stroke. Patients with 1-year MACCE in this cohort were selected as MACCE group. Blood samples from MACCE group and non-CAD control groups were collected, and a deoxyribonucleic acid library was created. A total of 34 tag or hot single nucleotide polymorphisms (SNPs) in six genes including CDKN2B-AS1, ADAMTS7, ABO, ADAMTS13, IL-18, and PECAM1 were analyzed by a SNPscan™ multi-genotyping kit. Carrier frequencies of each SNP were compared between the two groups using dominant, recessive and codominant allele model, respectively. Multivariate logistic regression model was established.

Results

Variant allele frequencies of rs10757274, rs1333042, rs1333049, rs4977574, rs9632884, rs1063192 and rs3217986 on CDKN2B-AS1 gene showed significant differences between the two groups in at least one allele model. Variant allele frequency of rs3217986 was not statistically significant after adjusting for the false discovery rate using Benjamini-Hochberg procedure (Q > 0.05). Variant allele frequencies of rs1333049, rs10757274, rs4977574 on CDKN2B-AS1 gene were significantly higher in MACCE group in all dominant, recessive and codominant models. Rs1055432 on ADAMTS13 and rs8176694 on ABO gene showed threshold significance between the two groups. After multivariable adjustment, G mutant homozygous rs9632884 (GG vs. GC + CC) (OR: 0.24; 95% CI: 0.09–0.65; P = 0.005) on CDKN2B-AS1 gene were independent protective factor of MACCE in recessive model.

Conclusions

In patients with TVD in China, variant alleles on CDKN2B-AS1 gene may form part of the genetic basis of coronary atherosclerosis progression, promoting or suppressing ischemic events.

Vulnerable plaque imaging using 18F-sodium fluoride positron emission tomography

Positron emission tomography (PET) with ¹⁸F-sodium fluoride (¹⁸F-NaF) has emerged as a promising non-invasive imaging modality to identify high-risk and ruptured atherosclerotic plaques. By visualizing microcalcification, ¹⁸F-NaF PET holds clinical promise in refining how we evaluate coronary artery disease, shifting our focus from assessing disease burden to atherosclerosis activity. In this review, we provide an overview of studies that have utilized ¹⁸F-NaF PET for imaging atherosclerosis. We discuss the associations between traditional coronary artery disease measures (risk factors) and ¹⁸F-NaF plaque activity. We also present the data on the histological validation as well as show how ¹⁸F-NaF uptake is associated with plaque morphology on intravascular and CT imaging. Finally, we discuss the technical challenges associated with ¹⁸F-NaF coronary PET highlighting recent advances in this area.

Feasibility of Coronary 18F-Sodium Fluoride Positron-Emission Tomography Assessment With the Utilization of Previously Acquired Computed Tomography Angiography

BACKGROUND

We assessed the feasibility of utilizing previously acquired computed tomography angiography (CTA) with subsequent positron-emission tomography (PET)-only scan for the quantitative evaluation of ¹⁸F-NaF PET coronary uptake.

METHODS AND RESULTS

Forty-five patients (age 67.1±6.9 years; 76% males) underwent CTA (CTA1) and combined ¹⁸F-NaF PET/CTA (CTA2) imaging within 14 [10, 21] days. We fused CTA1 from visit 1 with ¹⁸F-NaF PET (PET) from visit 2 and compared visual pattern of activity, maximal standard uptake (SUVmax) values, and target to background ratio (TBR) measurements on (PET/CTA1) fused versus hybrid (PET/CTA2). On PET/CTA2, 226 coronary plaques were identified. Fifty-eight coronary segments from 28 (62%) patients had high ¹⁸F-NaF uptake (TBR >1.25), whereas 168 segments had lesions with ¹⁸F-NaF TBR ≤1.25. Uptake in all lesions was categorized identically on coregistered PET/CTA1. There was no significant difference in ¹⁸F-NaF uptake values between PET/CTA1 and PET/CTA2 (SUVmax, 1.16±0.40 versus 1.15±0.39; P=0.53; TBR, 1.10±0.45 versus 1.09±0.46; P=0.55). The intraclass correlation coefficient for SUVmax and TBR was 0.987 (95% CI, 0.983-0.991) and 0.986 (95% CI, 0.981-0.992). There was no fixed or proportional bias between PET/CTA1 and PET/CTA2 for SUVmax and TBR. Cardiac motion correction of PET scans improved reproducibility with tighter 95% limits of agreement (±0.14 for SUVmax and ±0.15 for TBR versus ±0.20 and ±0.20 on diastolic imaging; P<0.001).

CONCLUSIONS

Coronary CTA/PET protocol with CTA first followed by PET-only allows for reliable and reproducible quantification of ¹⁸F-NaF coronary uptake. This approach may facilitate selection of high-risk patients for PET-only imaging based on results from prior CTA, providing a practical workflow for clinical application.

Prognostic Value and Therapeutic Perspectives of Coronary CT Angiography: A Literature Review

Coronary stenosis severity is both a powerful and a still debated predictor of prognosis in coronary artery disease. Coronary computed tomographic angiography (CCTA) has emerged as a noninvasive technique that enables anatomic visualization of coronary artery disease (CAD). CCTA with newer applications, plaque characterization and physiologic/functional evaluation, allows a comprehensive diagnostic and prognostic assessment of otherwise low-intermediate subjects for primary prevention. CCTA measures the overall plaque burden, differentiates plaque subtypes, and identifies high-risk plaque with good reproducibility. Research in this field may also advance towards an era of personalized risk prediction and individualized medical therapy. It has been demonstrated that statins may delay plaque progression and change some plaque features. The potential effects on plaque modifications induced by other medical therapies have also been investigated. Although it is not currently possible to recommend routinely serial scans to monitor the therapeutic efficacy of medical interventions, the plaque modulation, as a part of risk modification, appears a feasible strategy. In this review we summarize the current evidence regarding vulnerable plaque and effects of lipid lowering therapy on morphological features of CAD. We also discuss the potential ability of CCTA to characterize coronary atherosclerosis, stratify prognosis of asymptomatic subjects, and guide medical therapy.