Artificial intelligence and optical coherence tomography for the automatic characterisation of human atherosclerotic plaques

Revolutionising Acute Cardiac Care With Artificial Intelligence: Opportunities and Challenges

This article reviews the application of artificial intelligence (AI) in acute cardiac care, highlighting its potential to transform patient outcomes in the face of the global burden of cardiovascular diseases. It explores how AI algorithms can rapidly and accurately process data for the prediction and diagnosis of acute cardiac conditions. The review examines AI's impact on patient health across various diagnostic tools such as echocardiography, electrocardiography, coronary angiography, cardiac computed tomography, and magnetic resonance imaging, discusses the regulatory landscape for AI in health care, and categorises AI algorithms by their risk levels. Furthermore, it addresses the challenges of data quality, generalisability, bias, transparency, and regulatory considerations, underscoring the necessity for inclusive data and robust validation processes. The review concludes with future perspectives on integrating AI into clinical workflows and the ongoing need for research, regulation, and innovation to harness AI's full potential in improving acute cardiac care.

Vulnerable plaque features and adverse events in patients with diabetes mellitus: a post hoc analysis of the COMBINE OCT-FFR trial

BACKGROUND

Thin-cap fibroatheroma (TCFA) lesions are associated with a high risk of future major adverse cardiovascular events. However, the impact of other optical coherence tomography-detected vulnerability features (OCT-VFs) and their interplay with TCFA in predicting adverse events remains unknown.

AIMS

We aimed to evaluate the individual as well as the combined prognostic impact of OCT-VFs in predicting the incidence of the lesion-oriented composite endpoint (LOCE) in non-ischaemic lesions in patients with diabetes mellitus (DM).

METHODS

COMBINE OCT-FFR (ClinicalTrials.gov: NCT02989740) was a prospective, double-blind, international, natural history study that included DM patients with ≥1 non-culprit lesions with a fractional flow reserve>0.80 undergoing systematic OCT assessment. OCT-VFs included the following: TCFA, reduced minimal lumen area (r-MLA), healed plaque (HP), and complicated plaque (CP). The primary endpoint, LOCE - a composite of cardiac mortality, target vessel myocardial infarction, or clinically driven target lesion revascularisation up to 5 years - was analysed according to the presence of these OCT-VFs, both individually and in combination.

RESULTS

TCFA, r-MLA, HP and CP were identified in 98 (25.3%), 190 (49.0%), 87 (22.4%), and 116 (29.9%) patients, respectively. The primary endpoint rate increased progressively from 6.3% to 55.6% (hazard ratio 15.2, 95% confidence interval: 4.53-51.0; p<0.001) in patients without OCT-VFs as compared to patients with concomitant HP, r-MLA, CP, and TCFA. The coexistence of TCFA with other OCT-VFs resulted in an increased risk of the LOCE at 5 years.

CONCLUSIONS

In DM patients with non-ischaemic lesions, TCFA was the strongest predictor of future LOCE events. However, lesions that present additional OCT-VFs are associated with a higher risk of adverse events than OCT-detected TCFA alone. Further randomised studies are warranted to confirm these findings and their potential clinical implications.

Dynamic natural components and morphological changes in nonculprit subclinical atherosclerosis in patients with acute coronary syndrome and mild chronic kidney disease at the 1-year follow-up and clinical significance at the 5-year follow-up

INTRODUCTION

The natural outcome of coronary plaque in acute coronary syndrome (ACS) patients with chronic kidney disease (CKD) is unique, which can be analyzed quantitatively by optical flow ratio (OFR) software.

METHODS

A total of 184 ACS patients with at least one nonculprit subclinical atherosclerosis (NSA) detected by optical coherence tomography (OCT) at baseline and 1-year follow-up were divided into non-CKD group (n = 106, estimated glomerular filtration rate (eGFR)> 90 mL/(min×1.73 m2)) and mild CKD group (n = 78, 60≤eGFR<90 mL/(min×1.73 m2)). Changes of normalized total atheroma volume (TAVn) of NSA was the primary endpoint at the 1-year follow-up.

RESULTS

Patients with mild CKD showed more TAVn progression of NSA than non-CKD (p = 0.019) from baseline to the 1-year follow-up, which was mainly due to an increase in calcium TAVn (p<0.001). The morphological change in the maximal calcification thickness (p = 0.026) was higher and the change in the distance from the calcified surface to the contralateral coronary media membrane (ΔC-to-M) at the maximal cross-sectional calcium area was lower (p<0.001) in mild CKD group than in non-CKD group. Mild CKD had more NSA related MACEs at the 5-year follow-up than non-CKD (30.8% vs. 5.8%, p = 0.045).

CONCLUSIONS

Mild CKD patients had more plaque progression of NSA which showed the increase of calcium component with more protrusion into the lumen morphologically at the 1-year follow-up and a higher corresponding incidence of NSA-related MACEs at the 5-year follow-up.

TRIAL REGISTRATION

Clinical Trial registration ClinicalTrials.gov. NCT02140801. https://classic.clinicaltrials.gov/ct2/show/NCT02140801.

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.

Temporal changes in coronary plaque as assessed by an artificial intelligence-based optical coherence tomography: from the first-in-human trial on DREAMS 3G scaffold

AIMS

The aim of the study is to assess the impact of the baseline plaque composition on the DREAMS 3G luminal late loss and to compare the serial plaque changes between baseline and 6 and 12 months (M) follow-up.

METHODS AND RESULTS

A total of 116 patients were enrolled in the BIOMAG-I trial. Patients were imaged with optical coherence tomography (OCT) pre- and post-DREAMS 3G implantation and at 6 and 12 M. OCTPlus software uses artificial intelligence to assess composition (i.e. lipid, calcium, and fibrous tissue) of the plaque. The differences between the OCT-derived minimum lumen area (MLA) post-percutaneous coronary intervention and 12 M were grouped into three terciles. Patients with larger MLA differences at 12 M (P = 0.0003) had significantly larger content of fibrous tissue at baseline. There was a reduction of 24.8% and 20.9% in lipid area, both P < 0.001, between the pre-DREAMS 3G OCT and the 6 and 12 M follow-up. Conversely, the fibrous tissue increased by 48.4% and 36.0% at 6 and 12 M follow-up, both P < 0.001.

CONCLUSION

The larger the fibrous tissue in the lesion at baseline, the larger the luminal loss seen at 6 and 12 M. Following the implantation of DREAMS 3G, favourable healing of the vessel coronary wall occurs as shown by a decrease in the lipid area and an increase in fibrous tissue.

Artificial Intelligence for the Interventional Cardiologist: Powering and Enabling OCT Image Interpretation

Intravascular optical coherence tomography (IVOCT) is a form of intra-coronary imaging that uses near-infrared light to generate high-resolution, cross-sectional, and 3D volumetric images of the vessel. Given its high spatial resolution, IVOCT is well-placed to characterise coronary plaques and aid with decision-making during percutaneous coronary intervention. IVOCT requires significant interpretation skills, which themselves require extensive education and training for effective utilisation, and this would appear to be the biggest barrier to its widespread adoption. Various artificial intelligence-based tools have been utilised in the most contemporary clinical IVOCT systems to facilitate better human interaction, interpretation and decision-making. The purpose of this article is to review the existing and future technological developments in IVOCT and demonstrate how they could aid the operator.

Coronary calcifications, the Achilles heel in coronary interventions

Percutaneous coronary intervention in severely calcified coronaries has been associated with higher rates of procedural complications, including myocardial infarction and death in addition to increased frequency of coronary revascularization on an intermediate and long-term basis. The SYNTAX score, which is designed to assess the complexity of coronary artery disease and aids in choosing a revascularization method, allocates two points per lesion when there is heavy calcification present on fluoroscopy. With the advent of novel multimodality imaging technologies, the detection and evaluation of coronary calcifications improved significantly over the last decade. Several tools are now available for modifying calcified lesions including different types of dedicated balloons and atherectomy devices, which may create some degree of confusion regarding the suitable application of each instrument. The aim of this review is to cover this vital topic from different aspects. First, we tried to provide an overview on the pathophysiology and types of coronary calcification and its risk factors. Then, we outlined the available imaging modalities for the evaluation of calcified coronary lesions, highlighting the points of strength and weakness of each of them. A comprehensive discussion of calcium-modifying techniques was elaborated, summarizing their mechanism of action, pros and cons, and possible complications. Finally, an integrated algorithm was proposed for the best management of calcified coronary lesions.

Reproducibility of an artificial intelligence optical coherence tomography software for tissue characterization: Implications for the design of longitudinal studies

BACKGROUND

To assess the reproducibility of coronary tissue characterization by an Artificial Intelligence Optical Coherence Tomography software (OctPlus, Shanghai Pulse Medical Imaging Technology Inc.).

METHODS

74 patients presenting with multivessel ST-segment elevation myocardial infarction (STEMI) underwent optical coherence tomography (OCT) of the infarct-related artery at the end of primary percutaneous coronary intervention (PPCI) and during staged PCI (SPCI) within 7 days thereafter in the MATRIX (Minimizing Adverse Hemorrhagic Events by Transradial Access Site and angioX) Treatment-Duration study (ClinicalTrials.gov, NCT01433627). OCT films were run through the OctPlus software. The same region of interest between either side of the stent and the first branch was identified on OCT films for each patient at PPCI and SPCI, thus generating 94 pairs of segments. 42 pairs of segments were re-analyzed for intra-software difference. Five plaque characteristics including cholesterol crystal, fibrous tissue, calcium, lipid, and macrophage content were analyzed for various parameters (span angle, thickness, and area).

RESULTS

There was no statistically significant inter-catheter (between PPCI and SPCI) or intra-software difference in the mean values of all the parameters. Inter-catheter correlation for area was best seen for calcification [intraclass correlation coefficient (ICC) 0.86], followed by fibrous tissue (ICC 0.87), lipid (ICC 0.62), and macrophage (ICC 0.43). Some of the inter-catheter relative differences for area measurements were large: calcification 9.75 %; cholesterol crystal 74.10 %; fibrous tissue 5.90 %; lipid 4.66 %; and macrophage 1.23 %. By the intra-software measurements, there was an excellent correlation (ICC > 0.9) for all tissue types. The relative differences for area measurements were: calcification 0.64 %; cholesterol crystal 5.34 %; fibrous tissue 0.19 %; lipid 1.07 %; and macrophage 0.60 %. Features of vulnerable plaque, minimum fibrous cap thickness and lipid area showed acceptable reproducibility.

CONCLUSION

The present study demonstrates an overall good reproducibility of tissue characterization by the Artificial Intelligence Optical Coherence Tomography software. In future longitudinal studies, investigators may use discretion in selecting the imaging endpoints and sample size, accounting for the observed relative differences in this study.

Roadmap on the use of artificial intelligence for imaging of vulnerable atherosclerotic plaque in coronary arteries

Artificial intelligence (AI) is likely to revolutionize the way medical images are analysed and has the potential to improve the identification and analysis of vulnerable or high-risk atherosclerotic plaques in coronary arteries, leading to advances in the treatment of coronary artery disease. However, coronary plaque analysis is challenging owing to cardiac and respiratory motion, as well as the small size of cardiovascular structures. Moreover, the analysis of coronary imaging data is time-consuming, can be performed only by clinicians with dedicated cardiovascular imaging training, and is subject to considerable interreader and intrareader variability. AI has the potential to improve the assessment of images of vulnerable plaque in coronary arteries, but requires robust development, testing and validation. Combining human expertise with AI might facilitate the reliable and valid interpretation of images obtained using CT, MRI, PET, intravascular ultrasonography and optical coherence tomography. In this Roadmap, we review existing evidence on the application of AI to the imaging of vulnerable plaque in coronary arteries and provide consensus recommendations developed by an interdisciplinary group of experts on AI and non-invasive and invasive coronary imaging. We also outline future requirements of AI technology to address bias, uncertainty, explainability and generalizability, which are all essential for the acceptance of AI and its clinical utility in handling the anticipated growing volume of coronary imaging procedures.

Prognostic value of optical flow ratio for cardiovascular outcomes in patients after percutaneous coronary stent implantation

Background

The relationship between the optical flow ratio (OFR) and clinical outcomes in patients with coronary artery disease (CAD) after percutaneous coronary stent implantation (PCI) remains unknown.

Objective

To examine the correlation between post-PCI OFR and clinical outcomes in patients with CAD following PCI.

Methods

Patients who underwent optical coherence tomography (OCT) guided PCI at Guangdong Provincial People's Hospital were retrospectively and continuously enrolled. Clinical data, post-PCI OCT characteristics, and OFR measurements were collected and analyzed to identify predictors of target vessel failure (TVF) after PCI.

Results

Among 354 enrolled patients, 26 suffered TVF during a median follow-up of 484 (IQR: 400-774) days. Post-PCI OFR was significantly lower in the TVF group than in the non-TVF group (0.89 vs. 0.93; P = 0.001). In multivariable Cox regression analysis, post-PCI OFR (HR per 0.1 increase: 0.60; 95% CI: 0.41-0.89; P = 0.011), large stent edge dissection (HR: 3.85; 95% CI: 1.51-9.84; P = 0.005) and thin-cap fibroatheroma (TCFA) (HR: 2.95; 95% CI: 1.19-7.35; P = 0.020) in the non-stented segment were independently associated with TVF. In addition, the inclusion of post-PCI OFR to baseline characteristics and post-PCI OCT findings improved the predictive power of the model to distinguish subsequent TVF after PCI (0.838 vs. 0.796; P = 0.028).

Conclusion

The post-PCI OFR serves as an independent determinant of risk for TVF in individuals with CAD after PCI. The inclusion of post-PCI OFR assessments, alongside baseline characteristics and post-PCI OCT findings, substantially enhances the capacity to differentiate the subsequent manifestation of TVF in CAD patients following PCI.

Clinical quantitative coronary artery stenosis and coronary atherosclerosis imaging: a Consensus Statement from the Quantitative Cardiovascular Imaging Study Group

The detection and characterization of coronary artery stenosis and atherosclerosis using imaging tools are key for clinical decision-making in patients with known or suspected coronary artery disease. In this regard, imaging-based quantification can be improved by choosing the most appropriate imaging modality for diagnosis, treatment and procedural planning. In this Consensus Statement, we provide clinical consensus recommendations on the optimal use of different imaging techniques in various patient populations and describe the advances in imaging technology. Clinical consensus recommendations on the appropriateness of each imaging technique for direct coronary artery visualization were derived through a three-step, real-time Delphi process that took place before, during and after the Second International Quantitative Cardiovascular Imaging Meeting in September 2022. According to the Delphi survey answers, CT is the method of choice to rule out obstructive stenosis in patients with an intermediate pre-test probability of coronary artery disease and enables quantitative assessment of coronary plaque with respect to dimensions, composition, location and related risk of future cardiovascular events, whereas MRI facilitates the visualization of coronary plaque and can be used in experienced centres as a radiation-free, second-line option for non-invasive coronary angiography. PET has the greatest potential for quantifying inflammation in coronary plaque but SPECT currently has a limited role in clinical coronary artery stenosis and atherosclerosis imaging. Invasive coronary angiography is the reference standard for stenosis assessment but cannot characterize coronary plaques. Finally, intravascular ultrasonography and optical coherence tomography are the most important invasive imaging modalities for the identification of plaques at high risk of rupture. The recommendations made in this Consensus Statement will help clinicians to choose the most appropriate imaging modality on the basis of the specific clinical scenario, individual patient characteristics and the availability of each imaging modality.

Practical Application of Coronary Physiologic Assessment: Asia-Pacific Expert Consensus Document: Part 1

Coronary physiologic assessment is performed to measure coronary pressure, flow, and resistance or their surrogates to enable the selection of appropriate management strategy and its optimization for patients with coronary artery disease. The value of physiologic assessment is supported by a large body of evidence that has led to major recommendations in clinical practice guidelines. This expert consensus document aims to convey practical and balanced recommendations and future perspectives for coronary physiologic assessment for physicians and patients in the Asia-Pacific region based on updated information in the field that including both wire- and image-based physiologic assessment. This is Part 1 of the whole consensus document, which describes the general concept of coronary physiology, as well as practical information on the clinical application of physiologic indices and novel image-based physiologic assessment.

The Role of Intracoronary Imaging for the Management of Calcified Lesions

Interventional cardiologists in everyday practice are often confronted with calcified coronary lesions indicated for percutaneous transluminal coronary angioplasty (PTCA). PTCA of calcified lesions is associated with diverse technical challenges resulting in suboptimal coronary stenting and adverse long-term clinical outcomes. Angiography itself offers limited information regarding coronary calcification, and the adjuvant use of intracoronary imaging such as intravascular ultrasound (IVUS) and Optical Coherence Tomography (OCT) can guide the treatment of calcified coronary lesions, optimizing the different stages of the procedure. This review offers a description of why, when, and how to use intracoronary imaging for PTCA of calcified coronary lesions in order to obtain the most favorable results. We used the PubMed and Google Scholar databases to search for relevant articles. Keywords were calcified coronary lesions, intracoronary imaging, IVUS, OCT, coronary calcium modification techniques, PTCA, and artificial intelligence in intracoronary imaging. A total of 192 articles were identified. Ninety-one were excluded because of repetitive or non-important information.

Quantitative flow ratio modulated by intracoronary optical coherence tomography for predicting physiological efficacy of percutaneous coronary intervention

BACKGROUND

The combination of coronary imaging assessment and blood flow perturbation estimation has the potential to improve percutaneous coronary intervention (PCI) guidance.

OBJECTIVES

We aimed to evaluate a novel method for fast computation of Murray law-based quantitative flow ratio (μQFR) from coregistered optical coherence tomography (OCT) and angiography (OCT-modulated μQFR, OCT-μQFR) in predicting physiological efficacy of PCI.

METHODS

Patients treated by OCT-guided PCI in the OCT-arm of the Fractional Flow Reserve versus Optical Coherence Tomography to Guide RevasculariZAtion of Intermediate Coronary Stenoses trial (FORZA, NCT01824030) were included. Based on angiography and OCT before PCI, simulated residual OCT-μQFR was computed by assuming full stent expansion to the intended-to-treat segment. Plaque composition was automatically characterized using a validated artificial intelligence algorithm. Actual post-PCI OCT-μQFR pullback was computed based on coregistration of angiography and OCT acquired immediately after PCI. Suboptimal functional stenting result was defined as OCT-μQFR ≤ 0.90.

RESULTS

Paired simulated residual OCT-μQFR and actual post-PCI OCT-μQFR were obtained in 76 vessels from 74 patients. Simulated residual OCT-μQFR showed good correlation (r = 0.80, p < 0.001), agreement (mean difference = -0.02 ± 0.02, p < 0.001), and diagnostic concordance (79%, 95% confidence interval: 70%-88%) with actual post-PCI OCT-μQFR. Actual post-PCI in-stent OCT-μQFR had a median value of 0.02 and was associated with left anterior descending artery lesion location (β = 0.38, p < 0.001), higher baseline total plaque burden (β = 0.25, p = 0.031), and fibrous plaque volume (β = 0.24, p = 0.026).

CONCLUSIONS

This study based on patients enrolled in a prospective OCT-guidance PCI trial shows that simulated residual OCT-μQFR had good correlation, agreement, and diagnostic concordance with actual post-PCI OCT-μQFR. In OCT-guided procedures, OCT-μQFR in-stent pressure drop was low and was significantly predicted by pre-PCI vessel/plaque characteristics.

The role of invasive and non-invasive imaging technologies and calcium modification therapies in the evaluation and management of coronary artery calcifications

The treatment of coronary artery disease (CAD) has advanced significantly in recent years due to improvements in medical therapy and percutaneous or surgical revascularization. However, a persistent obstacle in the percutaneous management of CAD is coronary artery calcification (CAC), which portends to higher rates of procedural challenges, post-intervention complications, and overall poor prognosis. With the advent of novel multimodality imaging technologies spanning from intravascular ultrasound to optical coherence tomography to coronary computed tomography angiography combined with advances in calcium debulking and modification techniques, CACs are now targets for intervention with growing success. This review will summarize the most recent developments in the diagnosis and characterization of CAC, offer a comparison of the aforementioned imaging technologies including which ones are most suitable for specific clinical presentations, and review the CAC modifying therapies currently available.

Optical Coherence Tomography in Vulnerable Plaque and Acute Coronary Syndrome

Optical coherence tomography (OCT) is an intravascular imaging technique that uses near-infrared light. OCT provides high-resolution cross-sectional images of coronary arteries and enables tissue characterization of atherosclerotic plaques. OCT can identify plaque rupture, plaque erosion, and calcified nodule in culprit lesions of acute coronary syndrome. OCT can also detect important morphologic features of vulnerable plaques such as thin fibrous caps, large lipid cores, macrophages accumulation, intraplaque microvasculature, cholesterol crystals, healed plaques, and intraplaque hemorrhage.

Morphologies and composition changes in nonculprit subclinical atherosclerosis in diabetic versus nondiabetic patients with acute coronary syndrome who underwent long-term statin therapy

Although patients are undergoing similar lipid-lowering therapy (LLT) with statins, the outcomes of coronary plaque in diabetic mellitus (DM) and non-DM patients are different. Clinical data of 239 patients in this observational study with acute coronary syndrome was from our previous randomized trial were analyzed at 3 years, and 114 of them underwent OCT detection at baseline and the 1-year follow-up were re-anlayzed by a novel artificial intelligence imaging software for nonculprit subclinical atherosclerosis (nCSA). Normalized total atheroma volume changes (ΔTAVn) of nCSA were the primary endpoint. Plaque progression (PP) was defined as any increase in ΔTAVn. DM patients showed more PP in nCSA (ΔTAVn; 7.41 (- 2.82, 11.85) mm³ vs. - 1.12 (- 10.67, 9.15) mm³, p = 0.009) with similar reduction of low-density lipoprotein cholesterol (LDL-C) from baseline to 1-year. The main reason is that the lipid component in nCSA increases in DM patients and non-significantly decreases in non-DM patients, which leads to a significantly higher lipid TAVn (24.26 (15.05, 40.12) mm³ vs. 16.03 (6.98, 26.54) mm³, p = 0.004) in the DM group than in the non-DM group at the 1-year follow-up. DM was an independent predictor of PP in multivariate logistic regression analysis (OR = 2.731, 95% CI 1.160-6.428, p = 0.021). Major adverse cardiac events (MACEs) related to nCSA at 3 years were higher in the DM group than in the non-DM group (9.5% vs. 1.7%, p = 0.027). Despite a comparable reduction in LDL-C levels after LLT, more PP with an increase in the lipid component of nCSA and a higher incidence of MACEs at the 3-year follow-up was observed in DM patients.Trial registration: ClinicalTrials.gov. identifier: NCT02140801.

Clinical use of optical coherence tomography during percutaneous coronary intervention and coronary procedures in Southeast Asia: a survey-based expert consensus summary

Optical coherence tomography (OCT), an established intravascular imaging technique, enables rapid acquisition of high-resolution images during invasive coronary procedures to assist physician decision-making. OCT has utility in identifying plaque/lesion morphology (e.g., thrombus, degree of calcification, and presence of lipid) and vessel geometry (lesion length and vessel diameter) and in guiding stent optimisation through identification of malapposition and underexpansion. The use of OCT guidance during percutaneous coronary interventions (PCI) has demonstrated improved procedural and clinical outcomes in longitudinal registries, although randomised controlled trial data remain pending. Despite growing data and guideline endorsement to support OCT guidance during PCI, its use in different countries is not well established. This article is based on an advisory panel meeting that included experts from Southeast Asia (SEA) and is aimed at understanding the current clinical utility of intracoronary imaging and OCT, assessing the barriers and enablers of imaging and OCT adoption, and mapping a path for the future of intravascular imaging in SEA. This is the first Southeast Asian consensus that provides insights into the use of OCT from a clinician's point of view.

Safety and efficiency of percutaneous coronary intervention using a standardised optical coherence tomography workflow

BACKGROUND

While intravascular imaging guidance during percutaneous coronary intervention (PCI) improves outcomes, routine intravascular imaging usage remains low, in part due to perceived inefficiency and safety concerns.  Aims: The LightLab (LL) Initiative was designed to evaluate whether implementing a standardised optical coherence tomography (OCT) workflow impacts PCI safety metrics and procedural efficiency.

METHODS

In this multicentre, prospective, observational study, PCI procedural data were collected over 2 years from 45 physicians at 17 US centres. OCT-guided PCI incorporating the LL workflow (N=264), a structured algorithm using routine pre- and post-PCI OCT imaging, was compared with baseline angiography-only PCI (angio) (N=428). Propensity score analysis identified 207 matched procedures. Outcomes included procedure time, radiation exposure, contrast volume, device utilisation, and treatment strategy.

RESULTS

Compared with angiography alone, LL workflow OCT-guided PCI increased the median procedural time by 9 minutes but reduced vessel preparation time (2 min LL workflow vs 3 min angio; p<0.001) and resulted in less unplanned additional treatment (4% LL workflow vs 10% angio; p=0.01). With LL workflow OCT guidance, fewer cineangiography views were needed compared to angiography guidance, leading to decreased radiation exposure (1,133 mGy LL workflow vs 1,269 mGy angio; p=0.02), with no difference in contrast utilisation between groups (p=0.28). Furthermore, LL workflow OCT guidance resulted in fewer predilatation balloons and stents being used, more direct stent placement, and greater stent post-dilatation than angiography-guided PCI.

CONCLUSIONS

The incorporation of a standardised pre- and post-PCI OCT imaging workflow improves procedural efficiency and safety metrics, at a cost of a modestly longer procedure time.

Advances in Diagnosis, Therapy, and Prognosis of Coronary Artery Disease Powered by Deep Learning Algorithms

Percutaneous coronary intervention has been a standard treatment strategy for patients with coronary artery disease with continuous ebullient progress in technology and techniques. The application of artificial intelligence and deep learning in particular is currently boosting the development of interventional solutions, improving the efficiency and objectivity of diagnosis and treatment. The ever-growing amount of data and computing power together with cutting-edge algorithms pave the way for the integration of deep learning into clinical practice, which has revolutionized the interventional workflow in imaging processing, interpretation, and navigation. This review discusses the development of deep learning algorithms and their corresponding evaluation metrics together with their clinical applications. Advanced deep learning algorithms create new opportunities for precise diagnosis and tailored treatment with a high degree of automation, reduced radiation, and enhanced risk stratification. Generalization, interpretability, and regulatory issues are remaining challenges that need to be addressed through joint efforts from multidisciplinary community.

Optical coherence tomography and coronary revascularization: from indication to procedural optimization

Angiography alone is the most commonly used imaging modality for guidance of percutaneous coronary interventions. Angiography is limited, however, by several factors, including that it only portrays a low resolution, two-dimensional outline of the lumen and does not inform on plaque composition and functional stenosis severity. Optical coherence tomography (OCT) is an intracoronary imaging technique that has superior spatial resolution compared to all other imaging modalities. High-resolution imaging of the vascular wall enables precise measurement of vessel wall and luminal dimensions, more accurately informing about the anatomic severity of epicardial stenoses, and also provides input for computational models to assess functional severity. The very high-resolution images also permit plaque characterization that may be informative for prognostication. Moreover, periprocedural imaging provides valuable information to guide lesion preparation, stent implantation and to evaluate acute stent complications for which iterative treatment might reduce the occurrence of major adverse stent events. As such, OCT represent a potential future all-in-one tool that provides the data necessary to establish the indications, procedural planning and optimization, and final evaluation of percutaneous coronary revascularization.

In-Hospital Heart Failure in Patients With Takotsubo Cardiomyopathy Due to Coronary Artery Disease: An Artificial Intelligence and Optical Coherence Tomography Study

BACKGROUND

Takotsubo syndrome (TTS) is often associated with symptoms of heart failure (HF) during the acute phase of the disease. 3-dimensional optical coherence tomography (OCT) may be used to assess the extent of angiographically silent underlying coronary artery disease (CAD). This study aims to use an artificial intelligence algorithm to analyze OCT findings and to determine whether the presence of pre-existing CAD predisposes TTS patients to present HF at admission.

METHODS

This is an observational and retrospective study that enrolled TTS patients who underwent coronary angiography and OCT examination of left anterior descending (LAD) coronary artery. Plaque characterization was automatically analyzed via an artificial intelligence model from OCT images. An angiography-derived index of microcirculatory resistance (IMRangio) using the optic flow ratio (OFR) was calculated to assess its correlation with plaque volumes.

RESULTS

Thirty-seven patients were included (94.6 % women) with a median age of 82.0 years. Ten patients (27 %) showed some degree of HF at admission. Sixty-seven coronary non-obstructive plaques were analyzed. Tissue compositional analysis showed that patients with HF had an increased overall plaque volume (79.0 mm³ vs 28.6 mm³; p = 0.011) and longer plaque lesion length (12.8 mm vs 7.2 mm; p = 0.006). Patients with HF also showed an increased percentage of lipidic and calcified plaque tissue (26.4 % vs 13.4 %; p = 0.019 and 4.5 % vs 0.0 %; p = 0.001, respectively). A moderate positive correlation was found between global overall plaque volume and IMRangio.

CONCLUSION

Increased overall plaque volume was associated with the development of HF during the acute phase of TTS, suggesting that the presence of angiographically silent underlying CAD may play a prognostic role in these patients.

Artificial intelligence in atherosclerotic disease: Applications and trends

Atherosclerotic cardiovascular disease (ASCVD) is the most common cause of death globally. Increasing amounts of highly diverse ASCVD data are becoming available and artificial intelligence (AI) techniques now bear the promise of utilizing them to improve diagnosis, advance understanding of disease pathogenesis, enable outcome prediction, assist with clinical decision making and promote precision medicine approaches. Machine learning (ML) algorithms in particular, are already employed in cardiovascular imaging applications to facilitate automated disease detection and experts believe that ML will transform the field in the coming years. Current review first describes the key concepts of AI applications from a clinical standpoint. We then provide a focused overview of current AI applications in four main ASCVD domains: coronary artery disease (CAD), peripheral arterial disease (PAD), abdominal aortic aneurysm (AAA), and carotid artery disease. For each domain, applications are presented with refer to the primary imaging modality used [e.g., computed tomography (CT) or invasive angiography] and the key aim of the applied AI approaches, which include disease detection, phenotyping, outcome prediction, and assistance with clinical decision making. We conclude with the strengths and limitations of AI applications and provide future perspectives.

Plaque burden estimated from optical coherence tomography with deep learning: In vivo validation using co-registered intravascular ultrasound

OBJECTIVES

The objective of the present study was to compare plaque burden (PB) calculated from optical coherence tomography (OCT) using deep learning (DL) with PB derived from co-registered intravascular ultrasound (IVUS).

BACKGROUND

A DL algorithm was developed for automated plaque characterization and PB quantification from OCT images. However, the performance of this algorithm for PB quantification has not been validated.

METHODS

Five-year follow-up OCT and IVUS images from 15 patients implanted with bioresorbable vascular scaffold (BVS) at baseline were analyzed. Precise co-registration for 72 anatomical slices was achieved utilizing unique BVS radiopaque markers. PB derived from OCT DL and IVUS were compared. OCT cross-sections were divided into four subgroups with different media visibility level. The impact of media visibility on the numerical difference between OCT-derived and IVUS-derived PB was investigated. The stent sizes selected by OCT DL and IVUS were compared.

RESULTS

Sixty-four paired OCT and IVUS cross-sections were compared. OCT DL showed good concordance with IVUS for PB assessment (ICC = 0.81, difference = -3.53 ± 6.17%, p < 0.001). The numerical difference between OCT DL-derived PB and IVUS-derived PB was not substantially impacted by missing segments of media visualization (p = 0.21). OCT DL showed a diagnostic accuracy of 92% in identifying PB > 65%. The stent sizes selected by OCT DL were smaller compared to the ones selected by IVUS (difference = 0.30 ± 0.34 mm, p < 0.001).

CONCLUSIONS

The DL algorithm provides a feasible and reliable method for automated PB estimation from OCT, irrespective of media visibility. OCT DL showed good diagnostic accuracy in identifying PB > 65%, revealing its potential to complement conventional OCT imaging.

[Invasive and non-invasive imaging analysis for calcified coronary artery lesions]

Coronary calcifications are frequently identified within coronary lesions as their incidence increases with age and cardiovascular risk factors. Their location can be superficial or deep, according to different pathological process. In all cases, the presence of calcifications within the vascular wall predicts poor clinical prognosis and unfavorable evolution after percutaneous revascularization. Coronary calcifications can be analyzed by angiography, CT or intracoronary imaging (IVUS or OCT) with variable accuracies. Angiography is the most frequently used method but is not very sensitive (sensitivity close to 50%) and insufficient for their precise quantification. The CT scan is a more effective non-invasive method leading to an accurate analysis of the lesion before coronary angiography. IVUS and OCT have an excellent spatial resolution and are the most sensitive methods for the identification (present in nearly 75-80% of lesions) and quantification of calcifications. These intracoronary imaging techniques offer interesting perspectives for identification of the highest-risk lesions, PCI procedures planning (including the choice of an optimal dedicated plaque preparation devices), the monitoring of their execution and the evaluation of the immediate post-stenting results.

A State-of-the-Art Review: The Percutaneous Treatment of Highly Calcified Lesions

Coronary artery calcification is prevalent in coronary heart disease with its progression being predictive of future adverse cardiac events. Its presence is considered to be a marker of interventional procedural complexity. Several adjunctive percutaneous coronary intervention tools, such as modifying balloons, atherectomy devices and intravascular lithotripsy, now exist to successfully treat calcified lesions. In this state-of-the-art review, a step-wise progression of strategies is described to modify coronary plaque, from well-recognised techniques to techniques that should only be considered when standard manoeuvres have proven unsuccessful. Technology has advanced greatly over the past few decades and we discuss how future technologies might shape percutaneous intervention.

Human Coronary Plaque Optical Coherence Tomography Image Repairing, Multilayer Segmentation and Impact on Plaque Stress/Strain Calculations

Coronary vessel layer structure may have a considerable impact on plaque stress/strain calculations. Most current plaque models use single-layer vessel structures due to the lack of available multilayer segmentation techniques. In this paper, an automatic multilayer segmentation and repair method was developed to segment coronary optical coherence tomography (OCT) images to obtain multilayer vessel geometries for biomechanical model construction. Intravascular OCT data were acquired from six patients (one male; mean age: 70.0) using a protocol approved by the local institutional review board with informed consent obtained. A total of 436 OCT slices were selected in this study. Manually segmented data were used as the gold standard for method development and validation. The edge detection method and cubic spline surface fitting were applied to detect and repair the internal elastic membrane (IEM), external elastic membrane (EEM) and adventitia-periadventitia interface (ADV). The mean errors of automatic contours compared to manually segmented contours were 1.40%, 4.34% and 6.97%, respectively. The single-layer mean plaque stress value from lumen was 117.91 kPa, 10.79% lower than that from three-layer models (132.33 kPa). On the adventitia, the single-layer mean plaque stress value was 50.46 kPa, 156.28% higher than that from three-layer models (19.74 kPa). The proposed segmentation technique may have wide applications in vulnerable plaque research.

Optical coherence tomography in coronary atherosclerosis assessment and intervention

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

Radial wall strain: a novel angiographic measure of plaque composition and vulnerability

BACKGROUND

The lipid-to-cap ratio (LCR) and thin-cap fibroatheroma (TCFA) derived from optical coherence tomography (OCT) are indicative of plaque vulnerability.

AIMS

We aimed to explore the association of a novel method to estimate radial wall strain (RWS) from angiography with plaque composition and features of vulnerability assessed by OCT.

METHODS

Anonymised data from patients with intermediate stenosis who underwent coronary angiography (CAG) and OCT were analysed in a core laboratory. Angiography-derived RWSmax was computed as the maximum deformation of lumen diameter throughout the cardiac cycle, expressed as a percentage of the largest lumen diameter. The LCR and TCFA were automatically determined on OCT images by a recently validated algorithm based on artificial intelligence.

RESULTS

OCT and CAG images from 114 patients (124 vessels) were analysed. The average time for the analysis of RWSmax was 57 (39-82) seconds. The RWSmax in the interrogated plaques was 12% (10-15%) and correlated positively with the LCR (r=0.584; p<0.001) and lipidic plaque burden (r=0.411; p<0.001), and negatively with fibrous cap thickness (r= -0.439; p<0.001). An RWSmax >12% was an angiographic predictor for an LCR >0.33 (area under the curve [AUC]=0.86, 95% confidence interval [CI]: 0.78-0.91; p<0.001) and TCFA (AUC=0.72, 95% CI: 0.63-0.80; p<0.001). Lesions with RWSmax >12% had a higher prevalence of TCFA (22.0% versus 1.5%; p<0.001), thinner fibrous cap thickness (71 μm versus 101 μm; p<0.001), larger lipidic plaque burden (23.3% versus 15.4%; p<0.001), and higher maximum LCR (0.41 versus 0.18; p<0.001) compared to lesions with RWSmax ≤12%.

CONCLUSIONS

Angiography-derived RWS was significantly correlated with plaque composition and known OCT features of plaque vulnerability in patients with intermediate coronary stenosis.

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

Background

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Plaque Structural Stress: Detection, Determinants and Role in Atherosclerotic Plaque Rupture and Progression

Atherosclerosis remains a major cause of death worldwide, with most myocardial infarctions being due to rupture or erosion of coronary plaques. Although several imaging modalities can identify features that confer risk, major adverse cardiovascular event (MACE) rates attributable to each plaque are low, such that additional biomarkers are required to improve risk stratification at plaque and patient level. Coronary arteries are exposed to continual mechanical forces, and plaque rupture occurs when plaque structural stress (PSS) exceeds its mechanical strength. Prospective studies have shown that peak PSS is correlated with acute coronary syndrome (ACS) presentation, plaque rupture, and MACE, and provides additional prognostic information to imaging. In addition, PSS incorporates multiple variables, including plaque architecture, plaque material properties, and haemodynamic data into a defined solution, providing a more detailed overview of higher-risk lesions. We review the methods for calculation and determinants of PSS, imaging modalities used for modeling PSS, and idealized models that explore structural and geometric components that affect PSS. We also discuss current experimental and clinical data linking PSS to the natural history of coronary artery disease, and explore potential for refining treatment options and predicting future events.

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

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

Optical Coherence Tomography: An Eye Into the Coronary Artery

Optical coherence tomography (OCT) is slowly but surely gaining a foothold in the hands of interventional cardiologists. Intraluminal and transmural contents of the coronary arteries are no longer elusive to the cardiologist's probing eye. Although the graduation of an interventionalist in imaging techniques right from naked eye angiographies to ultrasound-based coronary sonographies to the modern light-based OCT has been slow, with the increasing regularity of complex coronary cases in practice, such a transition is inevitable. Although intravascular ultrasound (IVUS) due to its robust clinical data has been the preferred imaging modality in recent years, OCT provides a distinct upgrade over it in many imaging and procedural aspects. Better image resolution, accurate estimation of the calcified lesion, and better evaluation of acute and chronic stent failure are the distinct advantages of OCT over IVUS. Despite the obvious imaging advantages of OCT, its clinical impact remains subdued. However, upcoming newer trials and data have been encouraging for expanding the use of OCT to wider indications in clinical utility. During percutaneous coronary intervention (PCI), OCT provides the detailed information (dissection, tissue prolapse, thrombi, and incomplete stent apposition) required for optimal stent deployment, which is the key to successfully reducing the major adverse cardiovascular event (MACE) and stent-related morbidities. The increasing use of OCT in complex bifurcation stenting involving the left main (LM) is being studied. Also, the traditional pitfalls of OCT, such as additional contrast load for image acquisition and stenting involving the ostial and proximal LM, have also been overcome recently. In this review, we discuss the interpretation of OCT images and its clinical impact on the outcome of procedures along with current barriers to its use and newer paradigms in which OCT is starting to become a promising tool for the interventionalist and what can be expected for the immediate future in the imaging world.

Comparison of neoatherosclerosis and a clinical outcomes between bioabsorbable versus durable polymer drug-eluting stent: Verification by optical coherence tomography analysis

BACKGROUND

Neoatherosclerosis after drug-eluting stent (DES) implantation is known to be related with increased risk of late restenosis and stent thrombosis. Neoatherosclerosis and relevant clinical outcomes between bioabsorbable polymer DES (BP-DES) and second-generation durable polymer DES (DP-DES) were evaluated by optical coherence tomography (OCT) analysis.

METHODS

A total of 311 patients (319 lesions) undergoing OCT analysis after DES implantation were enrolled and divided into two groups according to stent type (BP-DES [150 patients, 153 lesions] and DP-DES [161 patients, 166 lesions]). Follow-up OCT analysis was performed at least 9 months after index stent implantation. Neoatherosclerosis was defined as presence of thin-cap fibroatheroma, calcified plaque, and lipid plaque. Primary endpoint was the incidence of neoatherosclerosis, and the secondary endpoints were the occurrence of major adverse cardiac events (MACE), defined as a composite of death, myocardial infarction, target lesion revascularization, or stent thrombosis and to find independent predictors of neoatherosclerosis.

RESULTS

The incidence of neoatherosclerosis was lower in the BP-DES group than the DP-DES group (5.2% vs. 14.5%, p = 0.008), which was driven by lipid plaque. However, the incidence of MACE did not show statistical difference between the two groups in median 4-year follow-up (3.3% vs. 7.8%, hazard ratio 1.964, 95% confidence interval 0.688-5.611, p = 0.207). Less use of angiotensin converting enzyme inhibitors/angiotensin II receptor blockade and higher degree of neointimal hyperplasia remained independent predictors of neoatherosclerosis on Cox regression analysis.

CONCLUSIONS

Patients undergoing BP-DES implantation had lower incidence of neoatherosclerosis than DP-DES, which did not reach statistically better clinical outcomes.

Physiologic and compositional coronary artery disease extension in patients with takotsubo syndrome assessed using artificial intelligence: an optical coherence tomography study

BACKGROUND

Takotsubo syndrome (TTS) is an acute and reversible ventricular motion abnormality without epicardial coronary obstruction. Optical flow ratio (OFR) is an approach to evaluate the coronary stenosis significance based on three-dimensional optical coherence tomography (3D-OCT). The aim of this study is to utilize OCT and an artificial intelligence plaque characterization model to show the prevalence and composition of atherosclerotic disease in coronary vessels of patients with TTS.

METHODS

This is a retrospective and observational study which enrolled patients with TTS who underwent coronary angiography and OCT examination. OCT images were analyzed for tissue characterization and OFR computation using a novel artificial intelligence algorithm.

RESULTS

A total of 37 patients and 49 vessels were studied. All patients were imaged in the left anterior descending coronary artery (LAD) and about two-thirds were also imaged in the left circumflex coronary artery (LCX). Most patients were women (n = 35), and apical was the most common takotsubo type. Tissue composition analysis yielded the following overall plaque types: fibrous (67.1%), lipid (15.5%), and calcium (3.77%). The mean OFR for LAD and LCX was 0.97 ± 0.04 and 0.98 ± 0.02, respectively.

CONCLUSION

Utilizing automatic plaque characterization on OCT images by artificial intelligence, we found that TTS patients have coronary artery disease (i.e. presence of lipid, calcified, or fibrous tissue). The advent of artificial intelligence methods may allow for large-scale studies of patients with TTS.

Artificial Intelligence—A Good Assistant to Multi-Modality Imaging in Managing Acute Coronary Syndrome

Acute coronary syndrome is the leading cause of cardiac death and has a significant impact on patient prognosis. Early identification and proper management are key to ensuring better outcomes and have improved significantly with the development of various cardiovascular imaging modalities. Recently, the use of artificial intelligence as a method of enhancing the capability of cardiovascular imaging has grown. AI can inform the decision-making process, as it enables existing modalities to perform more efficiently and make more accurate diagnoses. This review demonstrates recent applications of AI in cardiovascular imaging to facilitate better patient care.

Optical Coherence Tomography-Derived Changes in Plaque Structural Stress Over the Cardiac Cycle: A New Method for Plaque Biomechanical Assessment

Introduction: Cyclic plaque structural stress has been hypothesized as a mechanism for plaque fatigue and eventually plaque rupture. A novel approach to derive cyclic plaque stress in vivo from optical coherence tomography (OCT) is hereby developed. Materials and Methods: All intermediate lesions from a previous OCT study were enrolled. OCT cross-sections at representative positions within each lesion were selected for plaque stress analysis. Detailed plaque morphology, including plaque composition, lumen and internal elastic lamina contours, were automatically delineated. OCT-derived vessel and plaque morphology were included in a 2-dimensional finite element analysis, loaded with patient-specific intracoronary pressure tracing data, to calculate the changes in plaque structural stress (ΔPSS) on vessel wall over the cardiac cycle. Results: A total of 50 lesions from 41 vessels were analyzed. A significant ΔPSS gradient was observed across the plaque, being maximal at the proximal shoulder (45.7 [32.3, 78.6] kPa), intermediate at minimal lumen area (MLA) (39.0 [30.8, 69.1] kPa) and minimal at the distal shoulder (35.1 [28.2, 72.3] kPa; p = 0.046). The presence of lipidic plaques were observed in 82% of the diseased segments. Larger relative lumen deformation and ΔPSS were observed in diseased segments, compared with normal segments (percent diameter change: 8.2 ± 4.2% vs. 6.3 ± 2.3%, p = 0.04; ΔPSS: 59.3 ± 48.2 kPa vs. 27.5 ± 8.2 kPa, p < 0.001). ΔPSS was positively correlated with plaque burden (r = 0.37, p < 0.001) and negatively correlated with fibrous cap thickness (r = -0.25, p = 0.004). Conclusions: ΔPSS provides a feasible method for assessing plaque biomechanics in vivo from OCT images, consistent with previous biomechanical and clinical studies based on different methodologies. Larger ΔPSS at proximal shoulder and MLA indicates the critical sites for future biomechanical assessment.

A Vision Of Percutaneous Coronary Revascularisation In 2021: How to take advantage of intra-coronary imaging to perform more effective PCI

The use of intracoronary imaging with intravascular ultrasound (IVUS) or optical coherence tomography (OCT) can define vessel architecture and has an established role in guidance and optimisation of percutaneous coronary intervention. Additionally intracoronary imaging has an emerging role in diagnosis, afforded by the ability to depict vessel wall characteristics not seen on angiography alone. Use of intracoronary imaging is recommended by international consensus guidelines from the European Society of Cardiology and two recent expert consensus position statements from the European Association of Percutaneous Coronary Interventions (EAPCI). However, uptake in contemporary practice in the United Kingdom appears to lag behind these recommendations. Imaging is particularly advantageous in complex coronary lesions (such as left main stem coronary artery, bifurcation, or heavily calcified lesions) and in complex patients (acute presentations, atypical presentations, and renal dysfunction). Stent detail to the level of individual struts can be appreciated with intracoronary imaging, which facilitates appropriate stent selection and optimisation of the final stent result. We highlight specific subgroups that benefit from an imaging guided approach to percutaneous coronary intervention. We review the evidence and the role of intracoronary imaging and highlight specific subgroups that show particular benefit from imaging guided percutaneous coronary intervention.

MicroRNA profiles of human peripheral arteries and abdominal aorta in normal conditions: MicroRNAs-27a-5p, -139-5p and -155-5p emerge and in atheroma too

Atherosclerosis may starts early in life and each artery has peculiar characteristics likely affecting atherogenesis. The primary objective of the work was to underpin the microRNA (miR)-profiling differences in human normal femoral, abdominal aortic, and carotid arteries. The secondary aim was to investigate if those identified miRs, differently expressed in normal conditions, may also have a role in atherosclerotic arteries at adult ages. MiR-profiles were performed on normal tissues, revealing that aorta and carotid arteries are more similar than femoral arteries. MiRs emerging from profiling comparisons, i.e., miR-155-5p, -27a-5p, and -139-5p, were subjected to validation by RT-qPCR in normal arteries and also in pathological/atheroma counterparts, considering all the available 20 artery specimens. The three miRs were confirmed to be differentially expressed in normal femoral vs aorta/carotid arteries. Differential expression of those miRs was also observed in atherosclerotic arteries, together with some miR-target proteins, such as vimentin, CD44, E-cadherin and an additional marker SLUG. The different expression of miRs and targets/markers suggests that aorta/carotid and femoral arteries differently activate molecular drivers of pathological condition, thus conditioning the morphology of atheroma in adult life and likely suggesting the future use of artery-specific treatment to counteract atherosclerosis.