Prevalence and Characteristics of TCFA and Degree of Coronary Artery Stenosis

Insights from autopsy-initiated pathological studies of the pathogenesis and clinical manifestations of atherosclerosis and ischemic heart disease: Part II. Ischemic heart disease

CONTEXT

Ischemic heart disease (IHD) due to coronary atherosclerosis constitutes the leading cause of morbidity and mortality worldwide. This review was undertaken to retrospectively analyze the lines of research that generated the evidence for our contemporary understanding of atherosclerosis-based coronary artery disease and to provide a rationale for continued support for autopsy-based research in order to make further progress in reduction of the morbidity and mortaility from IHD.

OBJECTIVES

To analyze the contributions of the autopsy to complement and validate other lines of investigation in determining the complex interactions between coronary artery alterations linked to the major manifestations of coronary atherosclerosis, namely, coronary thrombosis, acute myocardial infarction, and sudden cardiac death.

DATA SOURCES

Systematic search on PubMed to gather relevant studies concerning autopsy studies and reviews of the pathology and pathogenesis of atherosclerosis, ischemic heart disease, coronary atherosclerosis, coronary thrombosis, myocardial infarction and sudden cardiac death.

CONCLUSIONS

An extensive search of the published literature has confirmed the continuing importance of the autopsy as a powerful tool to understand the pathogenesis, clinical features, and therapeutic options for the treatment of atherosclerosis and its major manifestation, ischemic heart disease. This has been described in the Part I companion of the present review. Autopsy-initiated studies have documented the prevalence and clinicopathological significance of atherosclerosis in different human populations and its relationship to risk factors. It has been shown that the clinically silent phase of ischemic heart disease (IHD) begins in the first decades of life. Pathological studies have clarified the complex relationship between coronary atherosclerosis, coronary thrombosis, and myocardial ischemic events. These studies also have elucidated the pathological basis of sudden cardiac death. Insights from these studies also have been important in developing and evaluating strategies for continued progress in reducing the morbidity and mortality attributed to atherosclerosis and IHD.

Long-Term Prognostic Implications of Non-Culprit Lesions in Patients Presenting With an Acute Myocardial Infarction: Is It the Angiographic Stenosis Severity or the Underlying High-Risk Morphology?

BACKGROUND

Patients with acute myocardial infarction and angiographically obstructive non-culprit lesions are at high risk for recurrent major adverse cardiac events (MACEs). However, it remains largely unknown whether events are due to stenosis severity or due to the underlying high-risk lesion morphology.

METHODS

Between January 2017 and December 2021, 1312 patients with acute myocardial infarction underwent optical coherence tomography of all the 3 main epicardial arteries after successful percutaneous coronary intervention. Patients and lesions were categorized according to the presence or absence of (1) 1 or more non-culprit angiographic obstructive stenoses with a visual diameter stenosis of ≥50% and (2) 1 or more lesions with an underlying high-risk morphology defined as an optical coherence tomography thin-cap fibroatheroma (TCFA). Patients were followed for up to 5 years (median 4.1 [interquartile range: 3.0-5.0] years). MACEs comprised cardiac death, non-fatal myocardial infarction, and unplanned coronary revascularization.

RESULTS

Overall, 492 patients had at least 1 obstructive non-culprit lesion, 352 had a single lesion, and 140 had multiple obstructive non-culprit lesions. The presence and number of angiographic obstructive non-culprit lesions correlated with the proportion and number of optical coherence tomography-derived TCFAs. At the lesion level, the prevalence of TCFA was twice as high in obstructive lesions compared with nonobstructive lesions. Patients with obstructive non-culprit lesions had an increased risk of overall MACEs (17.7% versus 12.8%; hazard ratio, 1.39 [95% CI, 1.02-1.91]) and non-culprit lesion-related MACEs (8.7% versus 3.9%; HR, 2.13 [95% CI, 1.26-3.59). Results were similar when patients were categorized on the basis of the underlying TCFA. A proportionally higher rate of overall and non-culprit lesion-related MACEs was observed as the number of obstructive stenoses or TCFAs in non-culprit segments increased. The lesion-specific HRs for obstructive lesion and TCFA were 2.03 (95% CI, 1.06-3.89) and 2.39 (95% CI, 1.29-4.43), respectively. Optical coherence tomography-derived TCFA, but not angiographic obstructive stenosis, was independently predictive of recurrent MACEs in both patient-level and lesion-level multivariable models in which these 2 characteristics were introduced simultaneously.

CONCLUSIONS

The long-term prognostic implications of the presence and extent of angiographic obstructive non-culprit lesions in patients with acute myocardial infarction are primarily due to their correlation with the underlying high-risk morphology, which confers an increased risk of recurrent MACEs.

Vulnerable or High-Risk Plaque: A JACC: Cardiovascular Imaging Position Statement

The concept of high-risk plaque emerged from pathologic and epidemiologic studies 3 decades ago that demonstrated plaque rupture with thrombosis as the predominant mechanism of acute coronary syndrome and sudden cardiac death. Thin-cap fibroatheroma, a plaque with a large lipidic core covered by a thin fibrous cap, is the prototype of the rupture-prone plaque and has been traditionally defined as "vulnerable plaque." Although knowledge on the pathophysiology of plaque instability continues to grow, the risk profile of our patients has shifted and the character of atherosclerotic disease has evolved, partly because of widespread use of lipid-lowering therapies and other preventive measures. In vivo intracoronary imaging studies indicate that superficial erosion causes up to 40% of acute coronary syndromes. This changing landscape calls for broader perspective, expanding the concept of high-risk plaque to the precursors of all major substrates of coronary thrombosis beyond plaque rupture. Other factors to take into consideration include dynamic changes in plaque composition, the importance of plaque burden, inflammatory activation (both local and systemic), healing mechanisms, regional hemodynamic pattern, properties of the fluid phase of blood, and the amount of myocardium at risk subtended by a lesion. Rather than the traditional focus limited to the thin-cap fibroatheroma, the authors advocate a more comprehensive approach that considers both morphologic features and biological activity of plaques and blood. This position paper highlights the challenges to the usual concept of high-risk plaque, proposes a broader definition, and analyzes its key morphologic features, the technological progress of plaque imaging (particularly using intracoronary imaging techniques), advances in pharmacologic therapies for plaque regression and stabilization, and the feasibility and efficacy of focal interventional treatments including preemptive plaque sealing.

Can fast wall shear stress computation predict adverse cardiac events in patients with intermediate non-flow limiting stenoses?

BACKGROUND AND AIMS

Coronary angiography-derived wall shear stress (WSS) may enable identification of vulnerable plaques and patients. A new recently introduced software allows seamless three-dimensional quantitative coronary angiography (3D-QCA) reconstruction and WSS computation within a single user-friendly platform carrying promise for clinical applications. This study examines for the first time the efficacy of this software in detecting vulnerable lesions in patients with intermediate non-flow limiting stenoses.

METHODS

This multicentre retrospective study included patients who had coronary angiography showing at least one lesion with borderline negative fractional flow reserve (FFR: 0.81-0.85). In these lesions, 3D-QCA reconstruction and blood flow simulation were performed using the CAAS Workstation WSS prototype (Pie Medical Imaging, Maastricht, Netherlands). Time averaged and multidirectional WSS were extracted across the lesion at every 3 mm segments. The primary endpoint of the study was lesion-oriented clinical events (LOCE), defined as the composite of cardiac death, target lesion related myocardial infarction (MI) or clinically indicated target lesion revascularization.

RESULTS

352 patients (355 lesions) were included in the analysis. Over a median follow-up of 4.1 years, 57 LOCE were recorded. Lesions causing events had a larger area stenosis (AS) [59.4 (54.6-67.7)% vs 52.8 (43.8-60.1)%, p < 0.001], maximum time averaged WSS (TAWSS) [11.56 (8.25-13.64)Pa vs 7.73 (5.41-11.51)Pa, p < 0.001], mean TAWSS at the minimum lumen area (MLA) [9.30 (5.44-11.94)Pa vs 6.19 (3.96-9.00)Pa, p < 0.001] and maximum transverse WSS [0.30 (0.21-0.45)Pa vs 0.23 (0.17-0.32)Pa, p=0.002] than those remaining quiescent. In multivariable models, AS was the only independent predictor of LOCE. Kaplan-Meier curves demonstrated that lesions with elevated maximum TAWSS and AS had a higher rate of LOCE than those with low TAWSS and AS values (26 % vs 7 %, p < 0.001).

CONCLUSIONS

For non-flow limiting lesions with borderline negative FFR, fast WSS computation using a dedicated software is feasible and holds potential for cardiovascular risk stratification.

High-risk plaques in non-culprit lesions and clinical outcome after NSTEMI vs. STEMI

AIMS

Complete non-culprit (NC) revascularisation may help reduce recurrent events after non-ST-segment elevation myocardial infarction (NSTEMI), especially if NC lesions would harbour high-risk plaque (HRP) features similar to ST-segment elevation myocardial infarction (STEMI). This study aimed to assess differences in fractional flow reserve (FFR)-negative NC plaque morphology in patients presenting with NSTEMI vs. STEMI and assess the association of HRP morphology and clinical outcome.

METHODS AND RESULTS

In the prospective PECTUS-obs study, 438 patients presenting with myocardial infarction (MI) underwent optical coherence tomography (OCT) of all FFR-negative intermediate NC lesions. The primary endpoint was the occurrence of major adverse cardiovascular events (MACE, composite of all-cause mortality, non-fatal MI or unplanned revascularisation) at 2-year follow-up. Four hundred and twenty patients had at least one analysable OCT, including 203 (48.3%) with NSTEMI and 217 (51.7%) with STEMI. The prevalence of HRPs, including thin-cap fibroatheromas, plaque rupture, and thrombus, was comparable between groups. MACE occurred in 29 (14.3%) NSTEMI patients and 16 (7.4%) STEMI patients (Puni-variable = 0.025 and Pmulti-variable = 0.270). Incidence of MACE was numerically higher among patients with HRP, irrespective of the clinical presentation at index (Pinteraction = 0.684). Among HRP criteria, plaque rupture was associated with MACE in both NSTEMI (P < 0.001) and STEMI (P = 0.020).

CONCLUSION

Presence of NC HRP is comparable between NSTEMI and STEMI and leads to numerically higher event rates in both. These results call for additional research on complete revascularisation in NSTEMI and treatment of HRP.

CLINICAL TRIAL REGISTRATION

NCT03857971.

Predictive models for cholesterol crystals and plaque vulnerability in acute myocardial infarction: Insights from an optical coherence tomography study

BACKGROUND

Cholesterol crystals (CCs) are recognized as a risk factor for vulnerable atherosclerotic plaque rupture (PR) and major adverse cardiovascular events. However, their predictive factors and association with plaque vulnerability in patients with acute myocardial infarction (AMI) remain insufficiently explored. Therefore, This study aims to investigate the association between CCs and plaque vulnerability in culprit lesions of AMI patients, identify the factors influencing CCs formation, and develop a predictive model for CCs.

METHODS

A total of 431 culprit lesions from AMI patients who underwent pre-intervention optical coherence tomography (OCT) imaging were analyzed. Patients were divided into groups based on the presence or absence of CCs and PR. The relationship between CCs and plaque vulnerability was evaluated. A risk nomogram for predicting CCs was developed using the least absolute shrinkage and selection operator and logistic regression analysis.

RESULTS

CCs were identified in 64.5 % of patients with AMI. The presence of CCs was associated with a higher prevalence of vulnerable plaque features, such as thin-cap fibroatheroma (TCFA), PR, macrophage infiltration, neovascularization, calcification, and thrombus, compared to patients without CCs. The CCs model demonstrated an area under the curve (AUC) of 0.676 for predicting PR. Incorporating CCs into the TCFA model (AUC = 0.656) significantly enhanced predictive accuracy, with a net reclassification improvement index of 0.462 (95 % confidence interval [CI]: 0.263-0.661, p < 0.001) and an integrated discrimination improvement index of 0.031 (95 % CI: 0.013-0.048, p = 0.001). Multivariate regression analysis identified the atherogenic index of plasma (odds ratio [OR] = 2.417), TCFA (OR = 1.759), macrophage infiltration (OR = 3.863), neovascularization (OR = 2.697), calcification (OR = 1.860), and thrombus (OR = 2.430) as independent risk factors for CCs formation. The comprehensive model incorporating these factors exhibited reasonable discriminatory ability, with an AUC of 0.766 (95 % CI: 0.717-0.815) in the training set and 0.753 (95 % CI: 0.704-0.802) in the internal validation set, reflecting good calibration. Decision curve analysis suggested that the model has potential clinical utility within a threshold probability range of approximately 18 % to 85 %.

CONCLUSIONS

CCs were associated with plaque vulnerability in the culprit lesions of AMI patients. Additionally, this study identified key factors influencing CCs formation and developed a predictive model with potential clinical applicability.

Clinical value of fractional flow reserve in coronary heart disease: A retrospective study

This study investigated the clinical value of coronary arteriography (CAG) combined with fractional flow reserve (FFR) in the treatment of coronary heart disease (CHD) with coronary artery stenosis exceeding 70%. A retrospective analysis was conducted on 344 patients with CHD treated at the Gansu Institute of Cardiovascular Science from January 2020 to May 2022. The patients were divided into the CAG group (n = 138) and the CAG + FFR group (n = 206). Among these patients, those with coronary artery stenosis exceeding 70% underwent an FFR functional examination to accurately determine indicators for coronary intervention. The data collected included demographic information, number of stents, number of vascular lesions, treatment methods, and the occurrence of major adverse cardiovascular events (MACE) at the 6-month follow-up. No significant differences were found between the 2 groups in terms of age, gender, underlying diseases, body mass index (BMI), smoking history, and blood lipid profile. The rate of surgical treatment in the CAG group and the CAG + FFR group was 88.41% and 43.69%, respectively. The CAG + FFR group showed a 44.72% reduction in the need for surgical treatment and a reduced number of stents placed, which helped prevent overtreatment. Additionally, there was no statistical difference between the 2 groups in MACE such as angina pectoris, myocardial infarction, and sudden cardiac death at the 6-month follow-up. After combined CAG examination with FFR measurement, the number of CHD patients with coronary artery stenosis exceeding 70% requiring surgical intervention decreased by 44.72%. FFR could significantly prevent overtreatment and provide more precise guidance for CHD treatments.

Management of vulnerable patient phenotypes and acute coronary syndrome mechanisms

Atherosclerosis is a chronic vascular disease. Its prevalence increases with aging. However, atherosclerosis may also affect young subjects without significant exposure to the classical risk factors. Recent evidence indicates clonal hematopoiesis of indeterminate potential (CHIP) as a novel cardiovascular risk factor that should be suspected in young patients. CHIP represents a link between impaired bone marrow and atherosclerosis. Atherosclerosis may present with an acute symptomatic manifestation or subclinical events that favor plaque growth. The outcome of a plaque relies on a balance of innate and environmental factors. These factors can influence the processes that initiate and propagate acute plaque destabilization leading to intraluminal thrombus formation or subclinical vessel healing. Thirty years ago, the first autopsy study revealed that coronary plaques can undergo rupture even in subjects without a known cardiovascular history. Nowadays, cardiac magnetic resonance studies demonstrate that this phenomenon is not rare. Myocardial infarction is mainly due to plaque rupture and plaque erosion that have different pathophysiological mechanisms. Plaque erosion carries a better prognosis as compared to plaque rupture. Thus, a tailored conservative treatment has been proposed and some studies demonstrated it to be safe. On the contrary, plaque rupture is typically associated with inflammation and anti-inflammatory treatments have been proposed in response to persistently elevate biomarkers of systemic inflammation. In conclusion, atherosclerosis may present in different forms or phenotypes. Vulnerable patient phenotypes, identified by using intravascular imaging techniques, biomarkers, or even genetic analyses, are characterized by distinctive pathophysiological mechanisms. These different phenotypes merit tailored management.

Precision Medicine in Acute Coronary Syndromes

Nowadays, current guidelines on acute coronary syndrome (ACS) provide recommendations mainly based on the clinical presentation. However, greater attention is being directed to the specific pathophysiology underlying ACS, considering that plaque destabilization and rupture leading to luminal thrombotic obstruction is not the only pathway involved, albeit the most recognized. In this review, we discuss how intracoronary imaging and biomarkers allow the identification of specific ACS endotypes, leading to the recognition of different prognostic implications, tailored management strategies, and new potential therapeutic targets. Furthermore, different strategies can be applied on a personalized basis regarding antithrombotic therapy, non-culprit lesion revascularization, and microvascular obstruction (MVO). With respect to myocardial infarction with non-obstructive coronary arteries (MINOCA), we will present a precision medicine approach, suggested by current guidelines as the mainstay of the diagnostic process and with relevant therapeutic implications. Moreover, we aim at illustrating the clinical implications of targeted strategies for ACS secondary prevention, which may lower residual risk in selected patients.

Clinical Impact of Perfusion Balloon for ST-Segment Elevated Myocardial Infarction: RYUSEI Study

Drug-eluting stents have significantly contributed to reducing mortality in patients with ST-segment elevation myocardial infarctions (STEMIs), but slow-flow/no-reflow phenomenon (SFNR) and in-stent restenosis are still clinical problems. In contrast, perfusion balloons (PBs) can compress thrombi and ruptured plaque for long inflation without ischemia and can be used as a delivery device for infusion of nitroprusside to distal risk area during ballooning. We conducted a Reduction of risk bY perfUsion balloon for ST-segment Elevated myocardial Infarction (RYUSEI) study to evaluate whether PBs before stenting are more effective than conventional stenting for STEMIs. We divided consecutive patients with STEMIs who underwent optical coherence tomography (OCT)-guided percutaneous coronary intervention into PB group who were treated with PBs (Ryusei; Kaneka Medix Corporation, Osaka, Japan) before stenting and the conventional percutaneous coronary intervention (CP) group. We compared clinical results including SFNR, OCT findings, and clinical events between the 2 groups. We finally analyzed 34 patients in PB group and 90 in CP group. After propensity score-matching, PB and CP groups consisted of 23 patients, respectively. In the propensity score-matched cohort, SFNR and maximum protrusion area detected by OCT were significantly lower (p = 0.047 and p = 0.019), and thrombolysis in myocardial infarction flow grade 3 was higher (p = 0.022) in the PB group than CP group. Kaplan-Meier analysis revealed a significantly better clinical outcome in PB group than CP group (p = 0.038). In conclusion, the RYUSEI study revealed a pre-stent lesion modification in addition to nitroprusside infusion using PB is useful to achieve better clinical courses in STEMI patients.

Thin-cap fibroatheroma in acute coronary syndrome: Implication for intravascular imaging assessment

Acute coronary syndrome (ACS), a significant cardiovascular disease threat, has garnered increased focus concerning its etiological mechanisms. Thin-cap fibroatheroma (TCFA) are central to ACS pathogenesis, characterized by lipid-rich plaques, profuse foam cells, cholesterol crystals, and fragile fibrous caps predisposed to rupture. While TCFAs may be latent and asymptomatic, their pivotal role in ACS risk is undeniable. High-resolution imaging techniques like Optical coherence tomography (OCT) and Intravascular ultrasound (IVUS) are instrumental for effective TCFA detection. Therapeutic strategies encompass pharmacological and interventional measures, including antiplatelet agents, statins, and Percutaneous Coronary Intervention (PCI), aiding in plaque stabilization, inflammation reduction, and rupture risk mitigation. Despite the strong correlation between TCFAs and adverse prognoses in ACS patients, early detection and rigorous treatment significantly enhance patient prognosis and diminish cardiovascular events. This review aims to encapsulate recent advancements in TCFA research within ACS, covering formation mechanisms, clinical manifestations, and prognostic implications.

Pancoronary plaque characteristics in STEMI patients with rapid plaque progression: An optical coherence tomography study

BACKGROUND

Non-culprit plaque progression is associated with recurrent cardiac ischemic events and worse clinical outcomes. Given that atherosclerosis is a systemic disease, the pancoronary characteristics of patients with rapid plaque progression are unknown. This study aims to identify pancoronary plaque features in patients with ST-segment elevation myocardial infarction (STEMI) with and without rapid plaque progression, focused on the patient level.

METHODS AND RESULTS

From January 2017 to July 2019, 291 patients underwent 3-vessel optical coherence tomography imaging at the time of the primary procedure and a follow-up angiography interval of 12 months. The final analysis included 237 patients. Overall, 308 non-culprit lesions were found in 78 STEMI patients with rapid plaque progression, and 465 non-culprit plaques were found in 159 STEMI patients without rapid plaque progression. These patients had a higher pancoronary vulnerability (CLIMA-defined high-risk plaque: 47.4% vs. 33.3%; non-culprit plaque rupture: 25.6% vs. 14.5%) and a significantly higher prevalence of other vulnerable plaque characteristics (i.e., lipid-rich plaque, cholesterol crystal, microchannels, calcification, spotty calcification, and thrombus) at baseline versus those without rapid plaque progression. Lesions with rapid progression were highly distributed at the LAD, tending to be near the bifurcation. In multivariate analysis, age ≥ 65 years was an independent predictor of subsequent rapid lesion progression at the patient level, whereas microchannel, spotty calcification, and cholesterol crystal were independent predictors for STEMI patients ≥65 years old.

CONCLUSIONS

STEMI patients with subsequent rapid plaque progression had higher pancoronary vulnerability and commonly presented vulnerable plaque morphology. Aging was the only predictor of subsequent rapid plaque progression.

High-Risk Plaques on Coronary Computed Tomography Angiography: Correlation With Optical Coherence Tomography

BACKGROUND

Although patients with high-risk plaque (HRP) on coronary computed tomography angiography (CTA) are reportedly at increased risk for future cardiovascular events, individual HRP features have not been systematically validated against high-resolution intravascular imaging.

OBJECTIVES

The aim of this study was to correlate HRP features on CTA with plaque characteristics on optical coherence tomography (OCT).

METHODS

Patients who underwent both CTA and OCT before coronary intervention were enrolled. Plaques in culprit vessels identified by CTA were evaluated with the use of OCT at the corresponding sites. HRP was defined as a plaque with at least 2 of the following 4 features: positive remodeling (PR), low-attenuation plaque (LAP), napkin-ring sign (NRS), and spotty calcification (SC). Patients were followed for up to 3 years.

RESULTS

The study included 448 patients, with a median age of 67 years and of whom 357 (79.7%) were male, and 203 (45.3%) presented with acute coronary syndromes. A total of 1,075 lesions were analyzed. All 4 HRP features were associated with thin-cap fibroatheroma. PR was associated with all OCT features of plaque vulnerability, LAP was associated with lipid-rich plaque, macrophage, and cholesterol crystals, NRS was associated with cholesterol crystals, and SC was associated with microvessels. The cumulative incidence of the composite endpoint (target vessel nontarget lesion revascularization and cardiac death) was significantly higher in patients with HRP than in those without HRP (4.7% vs 0.5%; P = 0.010).

CONCLUSIONS

All 4 HRP features on CTA were associated with features of vulnerability on OCT. (Massachusetts General Hospital and Tsuchiura Kyodo General Hospital Coronary Imaging Collaboration; NCT04523194).

Evaluation of Nonculprit Coronary Artery Lesions in Patients with Acute ST-Segment Elevation Myocardial Infarction

Background:

Multivessel coronary artery disease is a common finding during the primary percutaneous coronary intervention in patients with acute ST-segment elevation myocardial infarction (STEMI). It might be a cause for recurrent attacks. This study aimed to evaluate nonculprit lesions (NCLs) encountered in the three major epicardial coronary arteries.

Methods:

Patients with STEMI who underwent PPCI and matched the study inclusion criteria were enrolled. They were evaluated clinically, biomedically, and coronary angiographically. The coronary angiography analysis was examined by four cardiologists using the Quantitative Coronary Artery Analysis software. The data was analyzed statistically.

Results:

Of the 154 patients included in the study, 130 (84.4%) were males and 24 (15.6%) were females, with a mean age of 52.92 ± 13.14 years. Five hundred seventy-four NCLs were found in 132 (85.7%) patients. Nonobstructive lesions with stenosis less than 70% of vessel diameter were more frequent than obstructive lesions. The left circumflex coronary artery (LCX) was the first one of the three major arteries to be affected by obstructive NCLs. The obstructive NCLs were 128 in number; found in 78 (50.4%) patients; 65 (50.8%) of them were in LCX; 32 (25%) were in left anterior descending (25%); and 31 (24.2%) were in right coronary artery.

Conclusions:

NCLs are common among STEMI patients. LCX obstructive NCLs are comparable to those in the other two major epicardial coronary arteries, with respect to frequency and severity of luminal stenosis.

Deep learning segmentation of fibrous cap in intravascular optical coherence tomography images

Thin-cap fibroatheroma (TCFA) is a prominent risk factor for plaque rupture. Intravascular optical coherence tomography (IVOCT) enables identification of fibrous cap (FC), measurement of FC thicknesses, and assessment of plaque vulnerability. We developed a fully-automated deep learning method for FC segmentation. This study included 32,531 images across 227 pullbacks from two registries (TRANSFORM-OCT and UHCMC). Images were semi-automatically labeled using our OCTOPUS with expert editing using established guidelines. We employed preprocessing including guidewire shadow detection, lumen segmentation, pixel-shifting, and Gaussian filtering on raw IVOCT (r,θ) images. Data were augmented in a natural way by changing θ in spiral acquisitions and by changing intensity and noise values. We used a modified SegResNet and comparison networks to segment FCs. We employed transfer learning from our existing much larger, fully-labeled calcification IVOCT dataset to reduce deep-learning training. Postprocessing with a morphological operation enhanced segmentation performance. Overall, our method consistently delivered better FC segmentation results (Dice: 0.837 ± 0.012) than other deep-learning methods. Transfer learning reduced training time by 84% and reduced the need for more training samples. Our method showed a high level of generalizability, evidenced by highly-consistent segmentations across five-fold cross-validation (sensitivity: 85.0 ± 0.3%, Dice: 0.846 ± 0.011) and the held-out test (sensitivity: 84.9%, Dice: 0.816) sets. In addition, we found excellent agreement of FC thickness with ground truth (2.95 ± 20.73 µm), giving clinically insignificant bias. There was excellent reproducibility in pre- and post-stenting pullbacks (average FC angle: 200.9 ± 128.0°/202.0 ± 121.1°). Our fully automated, deep-learning FC segmentation method demonstrated excellent performance, generalizability, and reproducibility on multi-center datasets. It will be useful for multiple research purposes and potentially for planning stent deployments that avoid placing a stent edge over an FC.

Cardiac Optical Coherence Tomography: History, Current Status, and Perspective

For more than 2 decades since the first imaging procedure was performed in a living patient, intravascular optical coherence tomography (OCT), with its unprecedented image resolution, has made significant contributions to cardiovascular medicine in the realms of vascular biology research and percutaneous coronary intervention. OCT has contributed to a better understanding of vascular biology by providing insights into the pathobiology of atherosclerosis, including plaque phenotypes and the underlying mechanisms of acute coronary syndromes such as plaque erosion, neoatherosclerosis, stent thrombosis, and myocardial infarction with nonobstructive coronary arteries. Moreover, OCT has been used as an adjunctive imaging tool to angiography for the guidance of percutaneous coronary intervention procedures to optimize outcomes. However, broader application of OCT has faced challenges, including subjective interpretation of the images and insufficient clinical outcome data. Future developments including artificial intelligence-assisted interpretation, multimodality catheters, and micro-OCT, as well as large prospective outcome studies could broaden the impact of OCT on cardiovascular medicine.

Physiology- or Imaging-Guided Strategies for Intermediate Coronary Stenosis

Importance

Treatment strategies for intermediate coronary lesions guided by fractional flow reserve (FFR) and intravascular ultrasonography (IVUS) have shown comparable outcomes. Identifying low-risk deferred vessels to ensure the safe deferral of percutaneous coronary intervention (PCI) and high-risk revascularized vessels that necessitate thorough follow-up can help determine optimal treatment strategies.

Objectives

To investigate outcomes according to treatment types and FFR and IVUS parameters after FFR- or IVUS-guided treatment.

Design, Setting, and Participants

This cohort study included patients with intermediate coronary stenosis from the Fractional Flow Reserve and Intravascular Ultrasound-Guided Intervention Strategy for Clinical Outcomes in Patients With Intermediate Stenosis (FLAVOUR) trial, an investigator-initiated, prospective, open-label, multicenter randomized clinical trial that assigned patients into an IVUS-guided strategy (which recommended PCI for minimum lumen area [MLA] ≤3 mm2 or 3 mm2 to 4 mm2 with plaque burden [PB] ≥70%) or an FFR-guided strategy (which recommended PCI for FFR ≤0.80). Data were analyzed from November to December 2022.

Exposures

FFR or IVUS parameters within the deferred and revascularized vessels.

Main Outcomes and Measures

The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction, and revascularization at 2 years.

Results

A total of 1619 patients (mean [SD] age, 65.1 [9.6] years; 1137 [70.2%] male) with 1753 vessels were included in analysis. In 950 vessels for which revascularization was deferred, incidence of TVF was comparable between IVUS and FFR groups (3.8% vs 4.1%; P = .72). Vessels with FFR greater than 0.92 in the FFR group and MLA greater than 4.5 mm2 or PB of 58% or less in the IVUS group were identified as low-risk deferred vessels, with a decreased risk of TVF (hazard ratio [HR], 0.25 [95% CI, 0.09-0.71]; P = .009). In 803 revascularized vessels, the incidence of TVF was comparable between IVUS and FFR groups (3.6% vs 3.7%; P = .95), which was similar in the revascularized vessels undergoing PCI optimization (4.2% vs 2.5%; P = .31). Vessels with post-PCI FFR of 0.80 or less in the FFR group or minimum stent area of 6.0 mm2 or less or with PB at stent edge greater than 58% in the IVUS group had an increased risk for TVF (HR, 7.20 [95% CI, 3.20-16.21]; P < .001).

Conclusions and Relevance

In this cohort study of patients with intermediate coronary stenosis, FFR- and IVUS-guided strategies showed comparable outcomes in both deferred and revascularized vessels. Binary FFR and IVUS parameters could further define low-risk deferred vessels and high-risk revascularized vessels.

Higher Noncalcified Plaque Volume Is Associated With Increased Plaque Vulnerability and Vascular Inflammation

BACKGROUND

Recently, it was reported that noncalcified plaque (NCP) volume was an independent predictor for cardiac events. Pericoronary adipose tissue (PCAT) attenuation is a marker of vascular inflammation and has been associated with increased cardiac mortality. The aim of this study was to evaluate the relationships between NCP volume, plaque vulnerability, and PCAT attenuation.

METHODS

Patients who underwent preintervention coronary computed tomography angiography and optical coherence tomography were enrolled. Plaque volume was measured by computed tomography angiography, plaque vulnerability by optical coherence tomography, and the level of coronary inflammation by PCAT attenuation. The plaques were divided into 2 groups of high or low NCP volume based on the median NCP volume.

RESULTS

Among 704 plaques in 454 patients, the group with high NCP volume had a higher prevalence of lipid-rich plaque (87.2% versus 75.9%; P<0.001), thin-cap fibroatheroma (38.1% versus 20.7%; P<0.001), macrophage (77.8% versus 63.4%; P<0.001), microvessel (58.2% versus 42.9%; P<0.001), and cholesterol crystal (42.0% versus 26.7%; P<0.001) than the group with low NCP plaque volume. The group with high NCP volume also had higher PCAT attenuation than the group with low NCP volume (-69.6±10.0 versus -73.5±10.6 Hounsfield unit; P<0.001). In multivariable analysis, NCP volume was significantly associated with thin-cap fibroatheroma and high PCAT attenuation. In the analysis of the combination of PCAT attenuation and NCP volume, the prevalence of thin-cap fibroatheroma was the highest in the high PCAT attenuation and high NCP volume group and the lowest in the low PCAT attenuation and low NCP volume group.

CONCLUSIONS

Higher NCP volume was associated with higher plaque vulnerability and vascular inflammation. The combination of PCAT attenuation and NCP volume may help identify plaque vulnerability noninvasively.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04523194.

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.

Coronary Atherosclerosis Phenotypes in Focal and Diffuse Disease

BACKGROUND

The interplay between coronary hemodynamics and plaque characteristics remains poorly understood.

OBJECTIVES

The aim of this study was to compare atherosclerotic plaque phenotypes between focal and diffuse coronary artery disease (CAD) defined by coronary hemodynamics.

METHODS

This multicenter, prospective, single-arm study was conducted in 5 countries. Patients with functionally significant lesions based on an invasive fractional flow reserve ≤0.80 were included. Plaque analysis was performed by using coronary computed tomography angiography and optical coherence tomography. CAD patterns were assessed using motorized fractional flow reserve pullbacks and quantified by pullback pressure gradient (PPG). Focal and diffuse CAD was defined according to the median PPG value.

RESULTS

A total of 117 patients (120 vessels) were included. The median PPG was 0.66 (IQR: 0.54-0.75). According to coronary computed tomography angiography analysis, plaque burden was higher in patients with focal CAD (87% ± 8% focal vs 82% ± 10% diffuse; P = 0.003). Calcifications were significantly more prevalent in patients with diffuse CAD (Agatston score per vessel: 51 [IQR: 11-204] focal vs 158 [IQR: 52-341] diffuse; P = 0.024). According to optical coherence tomography analysis, patients with focal CAD had a significantly higher prevalence of circumferential lipid-rich plaque (37% focal vs 4% diffuse; P = 0.001) and thin-cap fibroatheroma (TCFA) (47% focal vs 10% diffuse; P = 0.002). Focal disease defined by PPG predicted the presence of TCFA with an area under the curve of 0.73 (95% CI: 0.58-0.87).

CONCLUSIONS

Atherosclerotic plaque phenotypes associate with intracoronary hemodynamics. Focal CAD had a higher plaque burden and was predominantly lipid-rich with a high prevalence of TCFA, whereas calcifications were more prevalent in diffuse CAD. (Precise Percutaneous Coronary Intervention Plan [P3]; NCT03782688).

Prognostic value of coronary CT angiography for the prediction of all-cause mortality and non-fatal myocardial infarction: a propensity score analysis

To explore the relationship between comprehensive assessment of coronary atherosclerosis by coronary CT angiography (CCTA) and all-cause mortality and non-fatal myocardial infarction in the Chinese population. Sixty-three patients from the prospective long-term study who experienced major adverse cardiovascular events (MACE) during the follow-up were included. No-MACE patients were 1:1 propensity-matched. Various qualitative and quantitative CCTA parameters, such as coronary artery calcium score (CACS), high-risk plaque, coronary artery disease (CAD) severity, number of obstructive vessels, segment involvement score (SIS), segment stenosis score (SSS), computed tomography-adapt Leaman score (CT-LeSc), and peri-coronary adipose tissue (PCAT) CT attenuation, were compared between both groups. Cox regression analysis was performed to determine the association between CCTA parameters and MACE. The MACE group had higher CACS, more high-risk plaques, more obstructive CAD, more obstructive vessels, higher PCAT CT attenuation, and higher coronary atherosclerotic burden (SIS: 5.76 ± 3.36 vs. 2.84 ± 3.07; SSS: 11.06 ± 8.41 vs. 3.94 ± 4.78; CT-LeSc: 11.25 ± 6.57 vs. 5.49 ± 5.82) than the control group (all p < 0.05). On multivariable analysis, hazard ratios were 1.058 for the SSS (p = 0.004), and 2.152 for the obstructive CAD. When the burden of coronary atherosclerosis was defined as the CT-LeSc, hazard ratios were 1.057 for the CT-LeSc (p = 0.036), and 2.272 for the obstructive CAD. The SSS, CT-LeSc, and presence of obstructive CAD were independently associated with the all-cause mortality and non-fatal myocardial infarction in the suspected CADs in the Chinese population.

Culprit lesion plaque characteristics and angiopoietin like 4 in acute coronary syndrome: A virtual histology-intravascular ultrasound analysis

BACKGROUND

Thin-cap fibroatheroma is a rupture-prone vulnerable plaque that leads to acute coronary syndrome (ACS). However, its underlying mechanisms are not fully understood. Several studies have investigated the clinical association between angiopoietin-like protein 4 (ANGPTL4) and coronary artery disease. Therefore, this study aimed to investigate the correlation of plasma ANGPTL4 in culprit lesion of ACS patients using intravascular ultrasound (IVUS) and virtual-histology IVUS (VH-IVUS).

METHODS

Fifty patients newly diagnosed with ACS between March to September 2021 were selected. Blood samples for baseline laboratory tests, including ANGPTL4, were collected before percutaneous coronary intervention (PCI), and all pre- and post-PCI IVUS examinations were performed of the culprit lesions.

RESULTS

Linear regression analysis between plasma ANGPTL4 and grayscale IVUS/VH-IVUS parameters revealed that plasma ANGPTL4 was strongly correlated with the necrotic core (NC) of the minimal lumen site (r = -0.666, p = 0.003) and largest NC site (r = -0.687, p < 0.001), and patients with lower plasma ANGPTL4 levels showed a significantly higher proportion of TFCA.

CONCLUSION

The present study further demonstrated the protective role of ANGPTL4 in the spectrum of atherosclerotic development in patients with ACS by culprit lesion morphology analysis using IVUS and VH-IVUS.

Automatic lumen and anatomical layers segmentation in IVOCT images using meta learning

Automated analysis of the vessel structure in intravascular optical coherence tomography (IVOCT) images is critical to assess the health status of vessels and monitor coronary artery disease progression. However, deep learning-based methods usually require well-annotated large datasets, which are difficult to obtain in the field of medical image analysis. Hence, an automatic layers segmentation method based on meta-learning was proposed, which can simultaneously extract the surfaces of the lumen, intima, media, and adventitia using a handful of annotated samples. Specifically, we leverage a bi-level gradient strategy to train a meta-learner for capturing the shared meta-knowledge among different anatomical layers and quickly adapting to unknown anatomical layers. Then, a Claw-type network and a contrast consistency loss were designed to better learn the meta-knowledge according to the characteristic of annotation of the lumen and anatomical layers. Experimental results on the two cardiovascular IVOCT datasets show that the proposed method achieved state-of-art performance.

Coronary Physiology-Based Approaches for Plaque Vulnerability: Implications for Risk Prediction and Treatment Strategies

In the catheterization laboratory, the measurement of physiological indexes can help identify functionally significant lesions and has become one of the standard methods to guide treatment decision-making. Plaque vulnerability refers to a coronary plaque susceptible to rupture, enabling risk prediction before coronary events, and it can be detected by defining a certain type of plaque morphology on coronary imaging modalities. Although coronary physiology and plaque vulnerability have been considered different attributes of coronary artery disease, the underlying pathophysiological basis and clinical data indicate a strong correlation between coronary hemodynamic properties and vulnerable plaque. In prediction of coronary events, emerging data have suggested independent and additional implications of a physiology-based approach to a plaque-based approach. This review covers the fundamental interplay between coronary physiology and plaque morphology during disease progression with clinical data supporting this relationship and examines the clinical relevance of physiological indexes in prediction of clinical outcomes and therapeutic decision-making along with plaque vulnerability.

Recent Advances for Dynamic-Based Therapy of Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease, which may lead to high morbidity and mortality. Currently, the clinical treatment strategy for AS is administering drugs and performing surgery. However, advanced therapy strategies are urgently required because of the deficient therapeutic effects of current managements. Increased number of energy conversion-based organic or inorganic materials has been used in cancer and other major disease treatments, bringing hope to patients with the development of nanomedicine and materials. These treatment strategies employ specific nanomaterials with specific own physiochemical properties (external stimuli: light or ultrasound) to promote foam cell apoptosis and cholesterol efflux. Based on the pathological characteristics of vulnerable plaques, energy conversion-based nano-therapy has attracted increasing attention in the field of anti-atherosclerosis. Therefore, this review focuses on recent advances in energy conversion-based treatments. In addition to summarizing the therapeutic effects of various techniques, the regulated pathological processes are highlighted. Finally, the challenges and prospects for further development of dynamic treatment for AS are discussed.

Management of Non-Culprit Lesions in STEMI Patients with Multivessel Disease

Multivessel disease is observed in approximately 50% of patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). Data from randomized clinical trials has shown that complete revascularization in the STEMI setting improves clinical outcomes by reducing the risk of reinfarction and urgent revascularization. However, the timing and modality of revascularization of non-culprit lesions are still debated. PCI of non-culprit lesions can be performed during the index primary PCI or as a staged procedure and can be guided by angiography, functional assessment, or intracoronary imaging. In this review, we summarize the available evidence about the management of non-culprit lesions in STEMI patients with or without cardiogenic shock.

Identification of High-Risk Coronary Lesions by 3-Vessel Optical Coherence Tomography

BACKGROUND

Optical coherence tomography (OCT) may provide a method for detecting histologically defined high-risk plaques in vivo.

OBJECTIVES

The authors aimed to investigate the prognostic value of OCT for identifying patients and lesions that are at risk for adverse cardiac events.

METHODS

Between January 2017 and May 2019, OCT of all the 3 main epicardial arteries was performed in 883 patients with acute myocardial infarction (MI) who were referred for primary percutaneous coronary intervention. The primary endpoint was the composite of cardiac death, nonculprit lesion-related nonfatal MI, and unplanned coronary revascularization. Patients were followed for up to 4 years (median 3.3 years).

RESULTS

The 4-year cumulative rate of the primary endpoint was 7.2%. In patient-level analysis, thin-cap fibroatheroma (TCFA) (adjusted HR: 3.05; 95% CI: 1.67-5.57) and minimal lumen area (MLA) <3.5 mm² (adjusted HR: 3.71; 95% CI: 1.22-11.34) were independent predictors of the primary endpoint. In lesion-level analysis, nonculprit lesions responsible for subsequent events were not angiographically severe at baseline (mean diameter stenosis 43.8% ± 13.4%). TCFA (adjusted HR: 8.15; 95% CI: 3.67-18.07) and MLA <3.5 mm² (adjusted HR: 4.33; 95% CI: 1.81-10.38) were predictive of events arising from each specific lesion. TCFAs with an MLA <3.5 mm² carried a higher risk and were sufficient for identifying patients at risk for the composite of cardiac death and nonculprit lesion-related nonfatal MI.

CONCLUSIONS

OCT imaging of angiographically nonobstructive territories in patients with acute MI can aid in identifying patients and lesions at increased risk for adverse cardiac events.

Diagnostic value of peripheral blood miR-296 combined with vascular endothelial growth factor B on the degree of coronary artery stenosis in patients with coronary heart disease

OBJECTIVE

Coronary heart disease (CHD) is a disorder resulting from organic and functional coronary artery stenosis (CAS), thus causing reduced oxygenated blood in the heart. miRNAs are useful biomarkers in the diagnosis of atherosclerosis, CHD, and acute coronary syndrome. Vascular endothelial growth factor (VEGF) is closely related to CHD. This study explored the correlation of miR-296 and VEGF-B expression levels in peripheral blood with CAS degree in CHD patients.

METHODS

Totally 220 CHD patients were enrolled and classified into mild-(71 cases)/moderate-(81 cases)/severe-CAS (68 cases) groups, with another 80 healthy cases as controls. The serum miR-296 and VEGF-B expression levels were detected using reverse transcription quantitative polymerase chain reaction. The correlation between miR-296 and CAS-related indexes was assessed via Pearson analysis. The binding relationship of miR-296 and VEGF-B was first predicted and their correlation was further analyzed via the Pearson method. The clinical diagnostic efficacy of miR-296 or VEGF-B on CAS degree was evaluated by the receiver operating characteristic curve.

RESULTS

Serum miR-296 was downregulated in CHD patients and was the lowest in patients with severe-CAS. miR-296 was negatively-correlated with high-sensitivity C-reactive protein, brain natriuretic peptide, and cardiac troponin I. miR-296 targeted VEGF-B. VEGF-B was upregulated in CHD patients and inversely-related to miR-296. Low expression of miR-296 and high expression of VEGF-B both had high clinical diagnostic values on CAS degree in CHD patients. miR-296 combined with VEGF-B increased the diagnostic value on CAS.

CONCLUSION

Low expression of miR-296 combined with high expression of its target VEGF-B predicts CAS degree in CHD patients.

Automated analysis of fibrous cap in intravascular optical coherence tomography images of coronary arteries

Thin-cap fibroatheroma (TCFA) and plaque rupture have been recognized as the most frequent risk factor for thrombosis and acute coronary syndrome. Intravascular optical coherence tomography (IVOCT) can identify TCFA and assess cap thickness, which provides an opportunity to assess plaque vulnerability. We developed an automated method that can detect lipidous plaque and assess fibrous cap thickness in IVOCT images. This study analyzed a total of 4360 IVOCT image frames of 77 lesions among 41 patients. Expert cardiologists manually labeled lipidous plaque based on established criteria. To improve segmentation performance, preprocessing included lumen segmentation, pixel-shifting, and noise filtering on the raw polar (r, θ) IVOCT images. We used the DeepLab-v3 plus deep learning model to classify lipidous plaque pixels. After lipid detection, we automatically detected the outer border of the fibrous cap using a special dynamic programming algorithm and assessed the cap thickness. Our method provided excellent discriminability of lipid plaque with a sensitivity of 85.8% and A-line Dice coefficient of 0.837. By comparing lipid angle measurements between two analysts following editing of our automated software, we found good agreement by Bland-Altman analysis (difference 6.7° ± 17°; mean ~ 196°). Our method accurately detected the fibrous cap from the detected lipid plaque. Automated analysis required a significant modification for only 5.5% frames. Furthermore, our method showed a good agreement of fibrous cap thickness between two analysts with Bland-Altman analysis (4.2 ± 14.6 µm; mean ~ 175 µm), indicating little bias between users and good reproducibility of the measurement. We developed a fully automated method for fibrous cap quantification in IVOCT images, resulting in good agreement with determinations by analysts. The method has great potential to enable highly automated, repeatable, and comprehensive evaluations of TCFAs.

The relationships between cholesterol crystals, NLRP3 inflammasome, and coronary atherosclerotic plaque vulnerability in acute coronary syndrome: An optical coherence tomography study

BACKGROUND

Cholesterol crystals (CCs) in lesions are the hallmark of advanced atherosclerotic plaque. Previous studies have demonstrated that CCs could activate NLRP3 inflammasome, which played an important role in atherosclerotic lesion progression. However, the relationship between CCs, NLRP3 inflammasome pathway, and plaque vulnerability in patients with ACS is still not elucidated.

METHODS

Two hundred sixty-nine consecutive acute coronary syndrome (ACS) patients with 269 culprit lesions were included in this study. CCs and other plaque characteristics within the culprit lesion segment were evaluated by optical coherence tomography (OCT) before percutaneous coronary intervention (PCI). The NLRP3 mRNA expression in peripheral blood mononuclear cells (PBMCs) and the serum levels of interleukin (IL)-1β, IL-18, and other biological indices were measured.

RESULTS

Cholesterol crystals were observed in 105 (39%) patients with 105 culprit lesions. There were no significant differences in baseline clinical characteristics between the patients with CCs (CCs group, n = 105) and the patients without CCs (non-CCs group, n = 164) within the culprit lesion segment except for lipoprotein(a) [Lp(a)]. The CCs group had a higher level of NLRP3 mRNA expression in PBMCs and higher levels of serum cytokine IL-1β and IL-18. OCT showed that the CCs group had longer lesion length, more severe diameter stenosis, and less minimum luminal area (MLA) than the non-CCs group (all p < 0.05). The frequency of thin-cap fibroatheroma (TCFA), thrombus, accumulation of macrophages, plaque rupture, micro-channel, calcification, spotty calcification, and layered plaque was higher in the CCs group than in the non-CCs groups (all p < 0.05). Multivariate logistic analysis revealed that the level of NLRP3 expression (OR = 10.204), IL-1β levels (OR = 3.523), IL-18 levels (OR = 1.006), TCFA (OR = 3.593), layered plaque (OR = 5.287), MLA (OR = 1.475), macrophage accumulation (OR = 2.881), and micro-channel (OR = 3.185) were independently associated with CCs.

CONCLUSION

Acute coronary syndrome patients with CCs in culprit lesions had a higher expression of NLRP3, IL-1β, and IL-18, and had more vulnerable plaque characteristics than patients without CCs. CCs might have interacted with NLRP3 inflammasome activation in patients with ACS, which could contribute to plaque vulnerability in culprit lesions.

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.

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.

Prevalence of Healed Plaque and Factors Influencing Its Characteristics Under Optical Coherence Tomography in Patients With Coronary Artery Disease: A Systematic Review, Meta-Analysis, and Meta-Regression

Aim: The purpose of this study was to determine the prevalence of healed plaque and its characteristics under optical coherence tomography (OCT) through a formal systematic review, meta-analysis, and meta-regression. Methods and Results: Thirteen studies were selected from MEDLINE, EMBASE, Cochrane, and online databases. The overall incidence of healed plaques was 40% (95% CI: 39-42), with 37% (95% CI: 35-39) in patients with acute coronary syndrome (ACS) and with 46% (95% CI: 43-49) in patients with stable angina pectoris (SAP). The incidence of healed plaque among culprit plaques (48%, 95% CI: 46-50) was nearly two times higher than that among non-culprit plaques (24%, 95% CI: 21-27). The incidence of thin cap fibroatheroma (TCFA), plaque rupture, microvessel, macrophage accumulation, and calcification was significantly higher in the healed plaque group. Meta-regression revealed an association between smoking (P = 0.033) and healed plaque rupture. Gender (P = 0.047) was independently associated with macrophage accumulation, and mean low-density lipoprotein cholesterol (LDL-C) was independently associated with microvessel. Conclusions: In summary, with a total incidence of 40%, the incidence of healed plaques under OCT was higher in SAP than in ACS, and higher in culprit plaques than in non-culprit plaques. Higher incidence of TCFA, plaque rupture, microvessel, macrophage accumulation, and calcification was found in the healed-plaque group. Smoking, gender, and mean LDL-C level were associated with healed-plaque characteristics.

Interactions Between Morphological Plaque Characteristics and Coronary Physiology: From Pathophysiological Basis to Clinical Implications

High-risk coronary plaque refers to a distinct set of plaque characteristics prone to future coronary events. Coronary physiology represents a group of indexes reflective of the local physiological environment and hemodynamic changes in the macrovascular and microvascular system. Although a large body of evidence has supported the clinical relevance of these 2 factors, currently, identifying plaque morphology cannot reliably capture the lesion subset that causes hard events. Also, the guideline-directed approach based on physiological indexes cannot fully predict and prevent clinical events. In parallel, there is accumulating evidence that these 2 aspects of coronary artery disease influence each other with significant clinical implications, despite traditionally being considered to have separate effects on significances, treatments, and outcomes. In this state-of-the-art review, we explore the clinical evidence of pathophysiological interplay of physiological indexes related to local hemodynamics, epicardial stenosis, and microvascular dysfunction with plaque morphological characteristics that provide a better understanding of the nature of coronary events. Furthermore, we examine the emerging data on the complementary role between plaque morphology and coronary physiology in prognostication and how to apply this concept to overcome the limitations of individual assessment alone. Finally, we propose the potential benefit of integrative assessment of coronary anatomy, plaque quantity and quality, and physiological aspects of a target lesion and vessels for personalized risk profiling and optimized treatment strategy.

Evaluation of coronary stenosis versus plaque burden for atherosclerotic cardiovascular disease risk assessment and management

PURPOSE OF REVIEW

To provide a summary of recent literature on the relative impact of luminal stenosis versus atherosclerotic plaque burden in atherosclerotic cardiovascular disease (ASCVD) risk stratification and management.

RECENT FINDINGS

Recent results from both randomized controlled clinical trials as well as observational cohort studies have demonstrated that ASCVD risk is mediated mainly by the extent of atherosclerotic disease burden rather than by the presence of coronary stenosis or inducible ischemia. Although patients with obstructive CAD are generally at higher risk for ASCVD events than patients with nonobstructive CAD, this is driven by a higher plaque burden in those with obstructive CAD. Accordingly, the ASCVD risk for a given plaque burden is similar in patients with and without obstructive CAD. Accompanying these observations are randomized controlled trial data, which show that optimization of medical therapy instead of early revascularization is most important for improving prognosis in patients with stable obstructive CAD.

SUMMARY

Emerging evidence shows that atherosclerotic plaque burden, and not stenosis per se, is the main driver of ASCVD risk in patients with CAD. This information challenges the current paradigm of selecting patients for intensive secondary prevention measures based primarily on the presence of obstructive CAD.

Using Optical Coherence Tomography to Identify Lipid and Its Impact on Interventions and Clinical Events - A Scoping Review

BACKGROUND

Optical coherence tomographic (OCT) imaging has enabled identification of lipid, with increasing interest in how it may affect coronary interventions and clinical outcomes. This review summarizes the available evidence around OCT identification of lipid and its effect on interventions, clinical events, and the natural history of coronary disease.

METHODS AND RESULTS

We conducted a scoping review using the Medline, HealthStar, and Embase databases for articles published between 1996 and 2021. We screened 1,194 articles and identified 51 for inclusion in this study, summarizing the key findings. The literature supports a common OCT definition of lipid as low-signal regions with diffuse borders, validated against histology and other imaging modalities with acceptable intra- and inter-rater reliability. There is evidence that OCT-identified lipid at the site of stent implantation increases the risk of edge dissection, incomplete stent apposition, in-stent tissue protrusion, decreased coronary flow after stenting, side branch occlusion, and post-procedural cardiac biomarker increases. In mostly retrospective studies, lipid indices measured at non-stented sites are associated with plaque progression and the development of recurrent ischemic events.

CONCLUSIONS

There is extensive literature supporting the ability of OCT to identify lipid and demonstrating a substantial impact of lipid on percutaneous coronary intervention outcomes. Future work to prospectively evaluate the effect of the characteristics of lipid-rich plaques on long-term clinical outcomes is needed.

Association of diabetes mellitus with clinical outcomes in patients with different coronary artery stenosis

Background

It has been demonstrated that patients with type 2 diabetes mellitus (DM) is associated with increased cardiovascular risk. However, little is known regarding the long-term prognosis in diabetic patients who experience mild-to-intermediate coronary artery stenosis (CAS). This study was to assess the clinical outcomes of diabetic patients with different severity of CAS.

Methods

We consecutively enrolled 10,940 patients hospitalized due to angina-like chest pain and followed up for major adverse cardiovascular events (MACEs) covering cardiac death, myocardial infarction, ischemic stroke, unplanned coronary revascularization and angina-related hospitalization. According to coronary angiography, patients were divided into non-obstructive CAS (NOCAS, < 50% stenosis), intermediate CAS (ICAS, 50–69% stenosis), and severe CAS (SCAS, 70–100% stenosis) subgroups, and were further categorized into six groups as NOCAS with DM and non-DM, ICAS with DM and non-DM, and SCAS with DM and non-DM.

Results

During a median follow-up of 40 months, 1,017 (11.1%) MACEs occurred. In patients with ICAS or SCAS, the incidence of events was higher when patients coexisted with DM (p < 0.05, respectively). In subgroup analyses, patients with ICAS and DM, SCAS and non-DM, SCAS and DM had increased risk of events [adjusted hazard ratio (HR): 1.709, 95% confidence interval (CI) 1.106–2.641, p = 0.016; HR: 1.911, 95% CI 1.460–2.501, p < 0.001; HR: 2.053, 95% CI 1.514–2.782, p < 0.001] compared to ones with NOCAS and non-DM. Besides, the Kaplan–Meier curves indicated the highest risk of MACEs in patients with SCAS and DM than others (p < 0.001).

Conclusions

Diabetic patients with ICAS had the worse outcome, which was comparable to patients with SCAS alone.

Coronary Magnetic Resonance Angiography in Chronic Coronary Syndromes

Cardiovascular disease is the leading cause of mortality worldwide, with atherosclerotic coronary artery disease (CAD) accounting for the majority of cases. X-ray coronary angiography and computed tomography coronary angiography (CCTA) are the imaging modalities of choice for the assessment of CAD. However, the use of ionising radiation and iodinated contrast agents remain drawbacks. There is therefore a clinical need for an alternative modality for the early identification and longitudinal monitoring of CAD without these associated drawbacks. Coronary magnetic resonance angiography (CMRA) could be a potential alternative for the detection and monitoring of coronary arterial stenosis, without exposing patients to ionising radiation or iodinated contrast agents. Further advantages include its versatility, excellent soft tissue characterisation and suitability for repeat imaging. Despite the early promise of CMRA, widespread clinical utilisation remains limited due to long and unpredictable scan times, onerous scan planning, lower spatial resolution, as well as motion related image quality degradation. The past decade has brought about a resurgence in CMRA technology, with significant leaps in image acceleration, respiratory and cardiac motion estimation and advanced motion corrected or motion-resolved image reconstruction. With the advent of artificial intelligence, great advances are also seen in deep learning-based motion estimation, undersampled and super-resolution reconstruction promising further improvements of CMRA. This has enabled high spatial resolution (1 mm isotropic), 3D whole heart CMRA in a clinically feasible and reliable acquisition time of under 10 min. Furthermore, latest super-resolution image reconstruction approaches which are currently under evaluation promise acquisitions as short as 1 min. In this review, we will explore the recent technological advances that are designed to bring CMRA closer to clinical reality.

Clinical Impact of Irregular Protrusion Angle After Coronary Stenting at Culprit Lesions With ST-Elevation Myocardial Infarction - An Intravascular Optical Coherence Tomography Study

Background: A recent optical coherence tomography (OCT) registry showed that the presence of irregular protrusion (IP) after coronary stenting was a predictor of worse 1-year cardiovascular events. This study evaluated the clinical impact of OCT-detected IP after coronary stenting at ST-elevation myocardial infarction (STEMI) culprit lesions. Methods and Results: In all, 139 consecutive STEMI patients with OCT-detected IP after stenting were analyzed retrospectively. The maximum IP angles were measured and patients with IP were divided into 2 groups (large IP, maximum IP angle ≥180°; small IP, 0°<angle<180°). The primary endpoints were cardiac death, target vessel myocardial infarction, target lesion revascularization, and stent thrombosis at 1 year after the index percutaneous coronary intervention (PCI). Of STEMI patients with IP, 51.8% had large IP. The incidence of the primary endpoints higher was higher in the large than small IP group (12.5% vs. 1.5%, respectively; P=0.018). The occurrence of plaque rupture was an independent predictor of large IP (odds ratio 4.58; 95% confidential interval 1.86-11.27; P=0.001). Conclusions: Maximum IP angle ≥180° was an independent predictor of clinical events in STEMI patients with IP.

Thrombus aspiration without stenting in a patient with anterior STEMI: Regression and healing of an unstable plaque assessed by OCT at 24 months of follow-up

In selected cases, when STEMI caused by mild or moderate degree lesion with a large concomitant thrombus, additional OCT-guided PCI strategy after thrombus removal allows us to defer stenting with the follow-up natural healing of the vessel wall.

In vivo assessment of endothelial permeability of coronary lesions with variable degree of stenosis using an albumin-binding MR probe

MR imaging with an albumin-binding probe enables the visualization of endothelial permeability and damage in the arterial system. The goal of this study was to compare signal enhancement of lesions with different grades of stenosis segments on molecular CMR in combination with the albumin-binding probe gadofosveset. This prospective clinical study included patients with symptoms suggestive of coronary artery disease (CAD). Patients underwent gadofosveset-enhanced cardiovascular magnetic resonance (CMR) imaging and x-ray angiography (QCA) within 24 h. CMR imaging was performed prior to and 24 h following the administration of gadofosveset. Contrast-to-noise ratios (CNRs) between segments with different grades of stenosis were compared. Overall, n = 203 segments of 26 patients were included. Lesions with more than > 70% stenosis demonstrated significantly higher CNRs compared to lesions < 70% (7.6 ± 8.3 vs. 2.5 ± 4.9; p < 0.001). Post-stenotic segments of lesions > 70% stenosis showed significant higher signal enhancement compared to segments located upstream of these lesions (7.3 ± 8.8 vs. 2.8 ± 2.2; p = 0.02). No difference in signal enhancement between segments proximal and distal of lesions with stenosis greater than 50% was measured (3.3 ± 2.8 vs. 2.4 ± 2.7; p = 0.18). ROC analysis for the detection of lesions ≥ 70% revealed an area under the curve of 0.774 (95% CI 0.681-0.866). This study suggests that relevant coronary stenosis and their down-stream segments are associated with increased signal enhancement on Gadofosveset-enhanced CMR, suggesting a higher endothelial permeability in these lesions. An albumin-binding MR probe could represent a novel in vivo biomarker for the identification and characterization of these vulnerable coronary segments.

Discordance in the diagnostic assessment of vulnerable plaques between radiofrequency intravascular ultrasound versus optical coherence tomography among patients with acute myocardial infarction: insights from the IBIS-4 study

We aimed to evaluate the diagnostic agreement between radiofrequency (RF) intravascular ultrasound (IVUS) and optical coherence tomography (OCT) for thin-cap fibroatheroma (TCFA) in non-infarct-related coronary arteries (non-IRA) in patients with ST-segment elevation myocardial infarction (STEMI). In the Integrated Biomarker Imaging Study (IBIS-4), 103 STEMI patients underwent OCT and RF-IVUS imaging of non-IRA after successful primary percutaneous coronary intervention and at 13-month follow-up. A coronary lesion was defined as a segment with ≥ 3 consecutive frames (≈1.2 mm) with plaque burden ≥ 40% as assessed by grayscale IVUS. RF-IVUS-derived TCFA was defined as a lesion with > 10% confluent necrotic core abutting to the lumen in > 10% of the circumference. OCT-TCFA was defined by a minimum cap thickness < 65 μm. The two modalities were matched based on anatomical landmarks using a dedicated matching software. Using grayscale IVUS, we identified 276 lesions at baseline (N = 146) and follow-up (N = 130). Using RF-IVUS, 208 lesions (75.4%) were classified as TCFA. Among them, OCT identified 14 (6.7%) TCFA, 60 (28.8%) thick-cap fibroatheroma (ThCFA), and 134 (64.4%) non-fibroatheroma. All OCT-TCFA (n = 14) were confirmed as RF-TCFA. The concordance rate between RF-IVUS and OCT for TCFA diagnosis was 29.7%. The reasons for discordance were: OCT-ThCFA (25.8%); OCT-fibrous plaque (34.0%); attenuation due to calcium (23.2%); attenuation due to macrophage (10.3%); no significant attenuation (6.7%). There was a notable discordance in the diagnostic assessment of TCFA between RF-IVUS and OCT. The majority of RF-derived TCFA were not categorized as fibroatheroma using OCT, while all OCT-TCFA were classified as TCFA by RF-IVUS.

ClinicalTrials.gov Identifier NCT00962416.

Characteristics of non-culprit plaques in acute coronary syndrome patients with layered culprit plaque

AIMS

Layered plaques represent signs of previous plaque destabilization. A recent study showed that acute coronary syndrome (ACS) patients with layered culprit plaque have more vulnerability at the culprit lesion and systemic inflammation. We aimed to compare the characteristics of non-culprit plaques between patients with or without layered plaque at the culprit lesion. We also evaluated the characteristics of layered non-culprit plaques, irrespective of culprit plaque phenotype.

METHODS AND RESULTS

We studied ACS patients who had undergone pre-intervention optical coherence tomography (OCT) imaging. The number of non-culprit lesions was evaluated on coronary angiogram and morphological characteristics of plaques were studied by OCT. In 349 patients, 99 (28.4%) had layered culprit plaque. The number of non-culprit plaques in patients with or without layered culprit plaque was similar (3.2 ± 0.8 and 2.8 ± 0.8, P = 0.23). Among 465 non-culprit plaques, 145 from patients with layered culprit plaque showed a higher prevalence of macrophage infiltration (71.0% vs. 60.9%, P = 0.050). When analysed irrespective of culprit plaque phenotype, layered non-culprit plaques showed higher prevalence of lipid (93.3% vs. 86.0%, P = 0.028), thin cap fibroatheroma (29.7% vs. 13.7%, P < 0.001), and macrophage infiltration (82.4% vs. 54.0%, P < 0.001) than non-layered plaques. Plaques with layered phenotype at both culprit and non-culprit lesions had the highest vulnerability.

CONCLUSION

In ACS patients, those with layered phenotype at the culprit lesion demonstrated greater macrophage infiltration at the non-culprit sites. Layered plaque at the non-culprit lesions was associated with more features of plaque vulnerability, particularly when the culprit lesion also had a layered pattern.

Identification of coronary calcifications in optical coherence tomography imaging using deep learning

Coronary calcifications are an obstacle for successful percutaneous treatment of coronary artery disease patients. The optimal method for delineating calcifications extent is coronary optical coherence tomography (OCT). To identify calcification on OCT and subsequently tailor the appropriate treatment, requires expertise in both image acquisition and interpretation. Image acquisition consists from system calibration, blood clearance by a contrast agent along with synchronization of the pullback process. Accurate interpretation demands careful review by the operator of a segment of 50-75 mm of the coronary vessel at steps of 5-10 frames per mm accounting for 375-540 images in each OCT run, which is time consuming and necessitates some expertise in OCT analysis. In this paper we developed a new deep learning algorithm to assist the physician to identify and quantify coronary calcifications promptly, efficiently and accurately. Our algorithm achieves an accuracy of 0.9903 ± 0.009 over the test set at size of 1500 frames and even managed to find calcifications that were not recognized manually by the physician. For the best knowledge of the authors our algorithm achieves high accuracy which was never achieved in the past.

Predicting plaque vulnerability change using intravascular ultrasound + optical coherence tomography image-based fluid-structure interaction models and machine learning methods with patient follow-up data: a feasibility study

BACKGROUND

Coronary plaque vulnerability prediction is difficult because plaque vulnerability is non-trivial to quantify, clinically available medical image modality is not enough to quantify thin cap thickness, prediction methods with high accuracies still need to be developed, and gold-standard data to validate vulnerability prediction are often not available. Patient follow-up intravascular ultrasound (IVUS), optical coherence tomography (OCT) and angiography data were acquired to construct 3D fluid-structure interaction (FSI) coronary models and four machine-learning methods were compared to identify optimal method to predict future plaque vulnerability.

METHODS

Baseline and 10-month follow-up in vivo IVUS and OCT coronary plaque data were acquired from two arteries of one patient using IRB approved protocols with informed consent obtained. IVUS and OCT-based FSI models were constructed to obtain plaque wall stress/strain and wall shear stress. Forty-five slices were selected as machine learning sample database for vulnerability prediction study. Thirteen key morphological factors from IVUS and OCT images and biomechanical factors from FSI model were extracted from 45 slices at baseline for analysis. Lipid percentage index (LPI), cap thickness index (CTI) and morphological plaque vulnerability index (MPVI) were quantified to measure plaque vulnerability. Four machine learning methods (least square support vector machine, discriminant analysis, random forest and ensemble learning) were employed to predict the changes of three indices using all combinations of 13 factors. A standard fivefold cross-validation procedure was used to evaluate prediction results.

RESULTS

For LPI change prediction using support vector machine, wall thickness was the optimal single-factor predictor with area under curve (AUC) 0.883 and the AUC of optimal combinational-factor predictor achieved 0.963. For CTI change prediction using discriminant analysis, minimum cap thickness was the optimal single-factor predictor with AUC 0.818 while optimal combinational-factor predictor achieved an AUC 0.836. Using random forest for predicting MPVI change, minimum cap thickness was the optimal single-factor predictor with AUC 0.785 and the AUC of optimal combinational-factor predictor achieved 0.847.

CONCLUSION

This feasibility study demonstrated that machine learning methods could be used to accurately predict plaque vulnerability change based on morphological and biomechanical factors from multi-modality image-based FSI models. Large-scale studies are needed to verify our findings.