Plaque erosion delays vascular healing after drug eluting stent implantation in patients with acute coronary syndrome: An In Vivo Optical Coherence Tomography Study

Atherosclerotic Plaque Erosion: Mechanisms, Clinical Implications, and Potential Therapeutic Strategies-A Review

Atherosclerosis is an insidious and progressive inflammatory disease characterized by the formation of lipid-laden plaques within the intima of arterial walls with potentially devastating consequences. While rupture of vulnerable plaques has been extensively studied, a distinct mechanism known as plaque erosion (PE) has gained recognition and attention in recent years. PE, characterized by the loss of endothelial cell lining in the presence of intact fibrous cap, contributes to a significant and growing proportion of acute coronary events. However, despite a heterogeneous substrate underlying coronary thrombosis, treatment remains identical. This article provides an overview of atherosclerotic PE characteristics and its underlying mechanisms, highlights its clinical implications, and discusses potential therapeutic strategies.

Coronary Plaque Erosion: Epidemiology, Diagnosis, and Treatment

Plaque erosion (PE), a distinct etiology of acute coronary syndromes (ACSs), is often overshadowed by plaque ruptures (PRs). Concerning its epidemiology, PE has garnered increasing recognition, with recent studies revealing its prevalence to be approximately 40% among ACS patients, challenging earlier assumptions based on autopsy data. Notably, PE exhibits distinct epidemiological features, preferentially affecting younger demographics, particularly women, and often manifesting as a non-ST-segment elevation myocardial infarction. There are seasonal variations, with PE events being less common in winter, potentially linked to physiological changes and cholesterol solidification, while peaking in summer, warranting further investigation. Moving to molecular mechanisms, PE presents a unique profile characterized by a lesser degree of inflammation compared to PR, with endothelial shear stress emerging as a plausible molecular mechanism. Neutrophil activation, toll-like receptor-2 pathways, and hyaluronidase 2 expression are among the factors implicated in PE pathophysiology, underscoring its multifactorial nature. Advancements in intravascular imaging diagnostics, particularly optical coherence tomography and near-infrared spectroscopy coupled with intravascular ultrasound, offer unprecedented insights into plaque composition and morphology. Artificial intelligence algorithms show promise in enhancing diagnostic accuracy and streamlining image interpretation, augmenting clinician decision-making. Therapeutically, the management of PE evolves, with studies exploring less invasive approaches such as antithrombotic therapy without stenting, particularly in cases identified early through intravascular imaging. Additionally, the potential role of drug-coated balloons in reducing thrombus burden and minimizing future major adverse cardiovascular events warrants further investigation. Looking ahead, the integration of advanced imaging modalities, biomarkers, and artificial intelligence promises to revolutionize the diagnosis and treatment of coronary PE, ushering in a new era of personalized and precise cardiovascular care.

"Very" Very Late Stent Thrombosis: The Occurrence of Thrombosis 12.3 Years After Paclitaxel-Eluting Stent Implantation

Very late stent thrombosis (VLST) refers to stent thrombosis occurring beyond one year after coronary intervention. "Very" very or extremely late stent thrombosis (VVLST), occurring after five years of drug-eluting stent (DES) implantation, is extremely rare. We report a case of a 60-year-old male patient with ST-elevation myocardial infarction (STEMI) due to in-stent thrombosis 12.3 years after first-generation DES implantation; we also engage in a brief discussion of its pathogenesis and prevention.

The Usefulness of Intracoronary Imaging in Patients with ST-Segment Elevation Myocardial Infarction

Intracoronary imaging (ICI) modalities, namely intravascular ultrasound (IVUS) and optical coherence tomography (OCT), have shown to be able to reduce major adverse cardiovascular events in patients undergoing percutaneous coronary intervention (PCI). Nevertheless, patients with ST-segment elevation myocardial infarction (STEMI) have been practically excluded from contemporary large randomized controlled trials. The available data are limited and derive mostly from observational studies. Nevertheless, contemporary studies are in favor of ICI utilization in patients who undergo primary PCI. Regarding technical aspects of PCI, ICI has been associated with the implantation of larger stent diameters, higher balloon inflations and lower residual in-stent stenosis post-PCI. OCT, although used significantly less often than IVUS, is a useful tool in the context of myocardial infarction without obstructive coronary artery disease since, due to its high spatial resolution, it can identify the underlying mechanism of STEMI, and, thus, guide therapy. Stent thrombosis (ST) is a rare, albeit a potential lethal, complication that is expressed clinically as STEMI in the vast majority of cases. Use of ICI is encouraged with current guidelines in order to discriminate the mechanism of ST among stent malapposition, underexpansion, uncovered stent struts, edge dissections, ruptured neoatherosclerotic lesions and coronary evaginations. Finally, ICI has been proposed as a tool to facilitate stent deferring during primary PCI based on culprit lesion characteristics.

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

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

Comparisons of Drug-Eluting Balloon versus Drug-Eluting Stent in the Treatment of Young Patients with Acute Myocardial Infarction

BACKGROUND

The incidence of acute myocardial infarction (AMI) in the younger population has been increasing gradually in recent years. The objective of the present study is to investigate the safety and effectiveness of drug-eluting balloons (DEBs) in young patients with AMI.

METHODS

All consecutive patients with AMI aged ≤ 45 years were retrospectively enrolled. The primary endpoint was a device-oriented composite endpoint (DOCE) of cardiac death, target vessel myocardial infarction (MI), or target lesion revascularization (TLR). The secondary study endpoints included heart failure and major bleeding events.

RESULTS

A total of 276 young patients presenting with AMI were finally included. The median follow-up period was 1155 days. Patients treated with DEBs had a trend toward a lower incidence of DOCEs (3.0% vs. 11.0%, p = 0.12) mainly driven by the need for TLR (3.0% vs. 9.1%, p = 0.19) than those treated with DESs. No significant differences between the two groups were detected in the occurrence of cardiac death (0.0% vs. 0.5%, p = 0.69), MI (0.0% vs. 1.4%, p = 0.40), heart failure (0.0% vs. 1.9%, p = 0.39), or major bleeding events (1.5% vs 4.8%, p = 0.30). Multivariate regression analysis showed that DEBs were associated with a trend toward a lower risk of DOCEs (HR 0.13, 95% CI [0.02, 1.05], p = 0.06).

CONCLUSIONS

The findings of the present study suggested that DEBs might be a potential treatment option in young patients with AMI. A larger scale, randomized, multicenter study is required to investigate the safety and effectiveness of DEBs in this setting.

EROSION III: A Multicenter RCT of OCT-Guided Reperfusion in STEMI With Early Infarct Artery Patency

OBJECTIVES

The aim of this study was to test whether optical coherence tomographic (OCT) guidance would provide additional useful information beyond that obtained by angiography and lead to a shift in reperfusion strategy and improved clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI) with early infarct artery patency.

BACKGROUND

Angiography is limited in assessing the underlying pathophysiological mechanisms of the culprit lesion.

METHODS

EROSION III (Optical Coherence Tomography-Guided Reperfusion in ST-Segment Elevation Myocardial Infarction With Early Infarct Artery Patency) is an open-label, prospective, multicenter, randomized, controlled study approved by the ethics committees of participating centers. Patients with STEMI who had angiographic diameter stenosis ≤ 70% and TIMI (Thrombolysis In Myocardial Infarction) flow grade 3 at presentation or after antegrade blood flow restoration were recruited and randomized to either OCT guidance or angiographic guidance. The primary efficacy endpoint was the rate of stent implantation.

RESULTS

Among 246 randomized patients, 226 (91.9%) constituted the per protocol set (112 with OCT guidance and 114 with angiographic guidance). The median diameter stenosis was 54.0% (IQR: 48.0%-61.0%) in the OCT guidance group and 53.5% (IQR: 43.8%-64.0%) in the angiographic guidance group (P = 0.57) before randomization. Stent implantation was performed in 49 of 112 patients (43.8%) in the OCT group and 67 of 114 patients (58.8%) in the angiographic group (P = 0.024), demonstrating a 15% reduction in stent implantation with OCT guidance. In patients treated with stent implantation, OCT guidance was associated with a favorable result with lower residual angiographic diameter stenosis (8.7% ± 3.7% vs 11.8% ± 4.6% in the angiographic guidance group; P < 0.001). Two patients (1 cardiac death, 1 stable angina) met the primary safety endpoint in the OCT guidance group, as did 3 patients (3 cardiac deaths) in the angiographic guidance group (1.8% vs 2.6%; P = 0.67). Reinfarction was not observed in either group. At 1 year, the rates of predefined cardiocerebrovascular events were comparable between the groups (11.6% after OCT guidance vs 9.6% after angiographic guidance; P = 0.66).

CONCLUSIONS

In patients with STEMI with early infarct artery patency, OCT guidance compared with angiographic guidance of reperfusion was associated with less stent implantation during primary percutaneous coronary intervention. These favorable results indicate the value of OCT imaging in optimizing the reperfusion strategy of patients with STEMI. (EROSION III: OCT- vs Angio-Based Reperfusion Strategy for STEMI; NCT03571269).

TNF-α is a Novel Biomarker for Predicting Plaque Rupture in Patients with ST-Segment Elevation Myocardial Infarction

Background and Aims

Patients with plaque rupture (PR) present with different cardiovascular risks, clinical strategies, and outcomes from those with plaque erosion (PE). However, there are lack of noninvasive biomarkers to distinguish PE from PR.

Methods

A prospective analysis of 382 patients with ST-segment elevation myocardial infarction (STEMI) was conducted. Of these patients, 262 and 120 presented with PR and PE, respectively. An additional 83 patients diagnosed with stable angina pectoris were enrolled as control group. Peripheral blood monocytes were collected pre-percutaneous coronary intervention and used to evaluate the mRNA expression of IL-4, IL-10, IL-1β, and TNF-α in all patients.

Results

STEMI patients had higher IL-4, IL-10, IL-1β, and TNF-α expression than the control patients. The mRNA levels of IL-4, IL-1β, and TNF-α were significantly higher in PR patients than PE; however, no significant difference was observed in IL-10 between PE and PR. The areas under the receiver-operating characteristic curves for IL-4, IL-1β, and TNF-α for PR versus PE were 0.685, 0.747, and 0.895, respectively. At the cut-off value of 2.52, TNF-α demonstrated a sensitivity of 70.61% and specificity of 93.33% for discriminating PR from PE patients. When added to the model of established clinical risk factors, TNF-α significantly improved the predictive accuracy of PR. Multivariable logistic regression analysis indicated that TNF-α mRNA level was independently associated with PR (odds ratio, 3.09; 95% confidence interval, 2.29–4.16; p < 0.001).

Conclusion

The inflammatory response of peripheral blood mononuclear cells in patients with PR was higher than that in patients with PE. TNF-α may be a potential biomarker for predicting PR that could facilitate risk stratification and management in STEMI patients.

Case Report: ST-Elevation Myocardial Infarction Secondary to Acute Atherothrombotic Occlusion Treated With No Stent Strategy

Background

Intravascular imaging plays a vital role in the pathophysiology-based diagnosis and treatment of patients with ST-elevation myocardial infarction (STEMI). We present a case of STEMI due to plaque erosion, which was managed with a no stent approach.

Case Summary

A 43-year-old female with a history of tobacco abuse presented with an anterior STEMI. Coronary angiography revealed acute thrombotic occlusion of the left anterior descending artery with spontaneous recanalization. Intravascular imaging with optical coherence tomography (OCT) demonstrated plaque erosion as the underlying etiology for the acute thrombotic occlusion. A no stent strategy with aspiration thrombectomy and dual antiplatelet therapy was used to manage the patient given that there was no evidence of plaque rupture. Repeat coronary imaging was done at 2 months to assess the status of the lesion.

Conclusion

A 43-year-old female with STEMI due to plaque erosion was successfully managed only by thrombus aspiration and not by angioplasty and stent placement. Individualized treatment approaches in patients with acute coronary syndromes, can not only achieve optimal management goals but also avoid unnecessary complications associated with interventions. This case illustrates how intracoronary imaging and pathophysiology-guided treatment can dramatically change management. In this young patient, STEMI was managed purely by thrombus aspiration. Intravascular imaging obviated the need for stent placement possibly preventing stent-related complications including restenosis and thrombosis.

Layered Plaque Characteristics and Layer Burden in Acute Coronary Syndromes

Recently, layered plaque, an optical coherence tomography equivalent of healed plaque, has been gaining attention. However, detailed layered plaque characteristics including the burden of plaque layer have not been investigated. Patients with acute coronary syndromes who underwent preintervention optical coherence tomography imaging of culprit lesion were included. Layer index, a product of the mean layer arc and layer length, was correlated with the pattern of layer and culprit pathology. In addition, layer index was compared between culprit and nonculprit plaques. Finally, predictors for greater layer index were identified using general linear modeling. In 349 patients, 99 culprit plaques had layered phenotype (28.4%), whereas among 465 nonculprit plaques, 165 had layered pattern (35.5%). Layer index was greater in multilayer pattern versus single-layer pattern (1,688.5 vs 996.6, p <0.001), interrupted layer phenotype versus intact layer phenotype (1,276.5 vs 646.8, p <0.001), rupture versus erosion at culprit lesion (1,191.0 vs 861.8, p <0.001), and culprit versus nonculprit plaque (1,475.6 vs 983.4, p <0.001). The general linear modeling revealed that multilayer pattern (regression coefficient b [B] 7.332, p <0.001), interrupted layer phenotype (B 4.624, p <0.001), culprit lesion (B 2.792, p = 0.001), lipid-rich plaque (B 1.953, p = 0.032), and culprit plaque rupture (B: 1.943, p = 0.008) were the significant predictors for greater layer index. In conclusion, layer index (burden of layered plaque) was greater in multilayer pattern, interrupted layer phenotype, at culprit plaque, lipid-rich plaque, and in cases with culprit plaque rupture.

Distinct pathological mechanisms distinguish acute coronary syndrome caused by plaque erosion from plaque rupture

PURPOSE OF REVIEW

The current systematic review aims to provide novel insights into the distinct pathological features of acute coronary syndrome (ACS) with intact fibrous cap, also known as 'plaque erosion'. A more detailed understanding of its underlying pathomechanisms provides the basis for future personalized therapeutic approaches to ACS.

RECENT FINDINGS

In the past years, a mounting proportion of evidence point towards the concept of plaque erosion being responsible for more than one-third of all cases of ACS and representing an autonomous ACS-causing entity driven by biomechanical forces, immunological alternations and systemic elevation of inflammatory mediators. First pilot studies proved a therapeutic paradigm shift from primary PCI at the ACS-causing culprit lesion to systemic therapies in patients with ACS caused by plaque erosion.

SUMMARY

This review provides the current status of the broad basic and clinical studies focused to the topic of plaque erosion: a new ACS-causing pathophysiology with different pathological aspects providing appropriate implications for personalized therapies in ACS.

Plaque erosion and acute coronary syndromes: phenotype, molecular characteristics and future directions

Although acute coronary syndromes (ACS) remain one of the leading causes of death, the clinical presentation has changed over the past three decades with a decline in the incidence of ST-segment elevation myocardial infarction (STEMI) and an increase in non-STEMI. This epidemiological shift is at least partially explained by changes in plaque biology as a result of the widespread use of statins. Historically, atherosclerotic plaque rupture of the fibrous cap was thought to be the main culprit in ACS. However, plaque erosion with an intact fibrous cap is now responsible for about one third of ACS and up to two thirds of non-STEMI. Two major research approaches have enabled a better understanding of plaque erosion. First, advanced intravascular imaging has provided opportunities for an 'optical biopsy' and extensive phenotyping of coronary plaques in living patients. Second, basic science experiments have shed light on the unique molecular characteristics of plaque erosion. At present, patients with ACS are still uniformly treated with coronary stents irrespective of the underlying pathobiology. However, pilot studies indicate that patients with plaque erosion might be treated conservatively without coronary stenting. In this Review, we discuss the patient phenotype and the molecular characteristics in atherosclerotic plaque erosion and provide our vision for a potential major shift in the management of patients with plaque erosion.

Methotrexate Therapy Promotes Cell Coverage and Stability in in-Stent Neointima

PURPOSE

Anti-proliferative drugs released from drug-eluting stents delay cell coverage and vascular healing, which increases the risk of late stent thrombosis. We assessed the potential effects of systemic methotrexate (MTX) on cell coverage, vascular healing and inflammation activation in vivo and in vitro.

METHODS

We applied MTX in the right common carotid artery in a rabbit stenting model to determine the impact on cell coverage and inflammation activation using a serial optical coherence tomography (OCT) analysis and elucidated the molecular mechanism of MTX in human umbilical vein endothelial cells (HUVECs).

RESULTS

Low-dose MTX promoted the development of cell coverage and vascular healing, which was associated with fewer uncovered struts (%) and cross-sections with any uncovered struts (%) at 4 weeks of stenting. The MTX group also exhibited lower rates of heterogeneity, microvessels and per-strut low-signal-intensity layers, indicating neointimal instability at 12 weeks of stenting. In vitro, low-dose MTX strongly inhibited HUVEC apoptosis, promoted proliferation and inhibited inflammatory activation by targeting the phosphoinositide 3-kinase (PI3K)/AKT signalling pathway.

CONCLUSION

Low-dose MTX may be a key means of promoting early cell coverage via the inhibition of the inflammatory response and stability of neointima by targeting inflammatory pathways after stent implantation.

Healed Erosion: The Role of Pre-interventional Optical Coherence Tomography in a Patient Clinically Suspected of Having Unstable Angina with Coronary Spasm

A 46-year-old man complained of chest pain at rest for the past three months. His symptoms gradually exacerbated and were suspected of being due to unstable angina. A coronary angiogram revealed focal tight stenosis at the proximal left anterior descending coronary artery with gross spastic coronary findings. Optical coherence tomography (OCT) revealed layered low-intensity structures with microvessels and the accumulation of macrophages, which indicated progressive stenosis with multiple-layered organized thrombus caused by coronary erosion. We treated the stenosis using a drug-coated balloon instead of drug-eluting stents. There was no restenosis, and OCT revealed good plaque healing at follow-up. This case suggests that the pre-interventional OCT plaque morphology can have a positive impact on the revascularization strategy.

Can OCT change the therapeutic strategy in ACS due to plaque erosion?

The pathophysiology of acute coronary syndromes was thought to be coronary thrombosis over a plaque rupture. Autopsy studies revealed that not all cases were due to plaque rupture, even denuded endothelium or calcific nodule can beget a thrombus. Introduction of OCT made, in vivo recognition of lesion morphology clear. Plaque ruptures are most common and need primary angioplasty. Recent studies established plaque erosion is responsible for ACS in one third of the cases and majority of them present as Non ST elevation myocardial infarction and commonly found in young patients without major risk factors. Evidence from recent studies suggested that stenting can be deferred and they can be managed conservatively with good long term outcomes. More randomized trials are needed comparing plaque rupture and plaque erosion as regards conservative versus invasive management. If these studies substantiate the concept of conservative management, it will lead to a paradigm shift in their management.

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

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

Mean Platelet Volume/Platelet Count Ratio and Culprit Plaque Morphologies: An Optical Coherence Tomography Study in Patients with ST Segment Elevation Myocardial Infarction

This study aimed to investigate the predictive value of mean platelet volume/platelet count ratio (MPR) for coronary plaque features in patients with ST segment elevation myocardial infarction (STEMI). A total of 275 STEMI patients undergoing preintervention optical coherence tomography examination were included, with 142 categorized as plaque rupture (PR) and 133 as plaque erosion (PE). Multivariable logistic regression showed higher MPR was an independent predictor of PR (tertile 3 vs tertile 1, odds ratio: 6.257, 95% confidence interval: 1.586-24.686, P = 0.009). MPR showed better diagnostic performance than other platelet indices. The optimal MPR threshold for diagnosing PR was 0.0473 (sensitivity: 0.721, specificity: 0.647). When added to models of established risk factors, MPR significantly improved the predictive accuracy of PR (area under the curve: 0.767 vs 0.722, P _difference = 0.004). In conclusion, for STEMI patients, MPR was an independent predictor of PR and improved diagnostic performance for PR.

New prediction tools and treatment for ACS patients with plaque erosion

For decades, we have known from autopsy observations that the proximate cause of the majority of acute coronary syndromes ( ACS) is occlusive thrombosis generated by plaque rupture or, less frequently, superficial erosion. Patients with ACS caused by plaque erosion seem to have a better long-term prognosis compared to those with plaque rupture, and may be stabilized by dual antiplatelet therapy without the need for stenting in a non-trivial proportion of cases, limiting the expenses and potential complications of invasive procedures. The accurate prediction of plaque erosion and the identification of specific biomarkers that could be used at the point-of-care without the need of invasive imaging would take us a step closer to the holy grail of precision medicine in patients with ACS.

Influence of Plaque Characteristics on Early Vascular Healing in Patients With ST-Elevation Myocardial Infarction

OBJECTIVES

To compare the early vascular healing of ruptured plaques (RP) and non-ruptured plaques (NRP) one month after primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI), using optical coherence tomography (OCT).

BACKGROUND

Vascular healing and strut coverage are important factors in reducing the risk of stent thrombosis after PCI. Influence of underlying lesion characteristics and differences in healing response between RP and NRP are unknown.

METHODS

Twenty-six STEMI-patients underwent PCI and implantation of a polymer-free drug-coated Biofreedom stent (BF-BES). OCT was performed pre-PCI, post-PCI and at 1-month follow-up. The patients were divided into two groups: RP = 15 and NRP = 11. OCT analyses of culprit lesion, post stent implantation at baseline and follow-up were performed to determine the difference in vascular healing based on presence of uncovered and/or malapposed stent struts and intraluminal filling defects.

RESULTS

The stent coverage did not differ significantly between the two groups at 1-month follow-up with percentage of uncovered struts: RP 26.5% [IQR 15.0-49.0] and NRP 28.1% [IQR 15.5-38.8] for NRP (p = 0.78). At 1-month, RP showed an increased percentage of late acquired malapposed struts (1.4% [IQR 0.8-2.4] vs. 0.0% [IQR 0.0-1.4], p = 0.03) and a larger total malapposition area (1.3 mm² [IQR 0.4-2.5] vs. 0.0 mm² [IQR 0.0-0.9], p = 0.01), compared to NRP.

CONCLUSION

Three out of four struts were covered within one month after stenting. The vascular healing was comparable in RP and NRP on stent coverage. However, RP had more and larger late acquired malapposition areas.

Smooth muscle cells-derived CXCL10 prevents endothelial healing through PI3Kγ-dependent T cells response

AIMS

Defects in efficient endothelial healing have been associated with complication of atherosclerosis such as post-angioplasty neoatherosclerosis and plaque erosion leading to thrombus formation. However, current preventive strategies do not consider re-endothelialization in their design. Here, we investigate mechanisms linking immune processes and defect in re-endothelialization. We especially evaluate if targeting phosphoinositide 3-kinase γ immune processes could restore endothelial healing and identify immune mediators responsible for these defects.

METHODS AND RESULTS

Using in vivo model of endovascular injury, we showed that both ubiquitous genetic inactivation of PI3Kγ and hematopoietic cell-specific PI3Kγ deletion improved re-endothelialization and that CD4+ T-cell population drives this effect. Accordingly, absence of PI3Kγ activity correlates with a decrease in local IFNγ secretion and its downstream interferon-inducible chemokine CXCL10. CXCL10 neutralization promoted re-endothelialization in vivo as the same level than those observed in absence of PI3Kγ suggesting a role of CXCL10 in re-endothelialization defect. Using a new established ex vivo model of carotid re-endothelialization, we showed that blocking CXCL10 restore the IFNγ-induced inhibition of endothelial healing and identify smooth muscle cells as the source of CXCL10 secretion in response to Th1 cytokine.

CONCLUSION

Altogether, these findings expose an unforeseen cellular cross-talk within the arterial wall whereby a PI3Kγ-dependent T-cell response leads to CXCL10 production by smooth muscle cells which in turn inhibits endothelial healing. Therefore, both PI3Kγ and the IFNγ/CXCL10 axis provide novel strategies to promote endothelial healing.

Plaque erosion: a new in vivo diagnosis and a potential major shift in the management of patients with acute coronary syndromes

Pathology and in vivo imaging studies have identified superficial plaque erosion as a frequent and important mechanism underlying acute coronary syndromes (ACS). In contrast with plaque rupture, the pathophysiological mechanisms leading to plaque erosion remain poorly understood. The advent of intravascular imaging techniques, particularly optical coherence tomography, has aided understanding of this mode of ACS in vivo by complementing previous insights from pathology studies. Appreciation of the distinct biological and clinical mechanisms of plaque erosion points to the possibility of tailored management strategies for patients presenting with ACS.

EROSION Study (Effective Anti-Thrombotic Therapy Without Stenting: Intravascular Optical Coherence Tomography-Based Management in Plaque Erosion): A 1-Year Follow-Up Report

BACKGROUND

The initial EROSION study (Effective Anti-Thrombotic Therapy Without Stenting: Intravascular Optical Coherence Tomography-Based Management in Plaque Erosion) demonstrated that patients with acute coronary syndrome caused by plaque erosion might be stabilized with aspirin and ticagrelor without stenting for ≤1 month. However, a long-term evaluation of outcomes is lacking. The aim of this study was to assess whether the initial benefit of noninterventional therapy for patients with acute coronary syndrome caused by plaque erosion is maintained for ≤1 year.

METHODS AND RESULTS

Among 53 patients who completed clinical follow-up, 49 underwent repeat optical coherence tomography imaging at 1 year. Median residual thrombus volume decreased significantly from 1 month to 1 year (0.3 mm³ (0.0-2.0 mm³] versus 0.1 mm³ [0.0-2.0 mm³]; P=0.001). Almost half of the patients (46.9%) had no residual thrombus at 1 year. Minimal effective flow area remained unchanged (2.1 mm² [1.5-3.8 mm²] versus 2.1 mm² [1.6-4.0 mm²]; P=0.152). Among 53 patients, 49 (92.5%) remained free from major adverse cardiovascular event for ≤1 year: 3 (5.7%) patients required revascularization because of exertional angina and 1 (1.9%) patient had gastrointestinal bleeding.

CONCLUSIONS

One-year follow-up optical coherence tomography demonstrated a further decrease in thrombus volume between 1-month and 1-year follow-up. A majority (92.5%) of patients with acute coronary syndrome caused by plaque erosion managed with aspirin and ticagrelor without stenting remained free of major adverse cardiovascular event for ≤1 year.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02041650.