Pathophysiology of acute coronary syndrome assessed by optical coherence tomography

Vasa vasorum enhancement on optical coherence tomography in Kawasaki disease

BACKGROUND

Patients with Kawasaki disease (KD) prone to develop coronary artery aneurysm (CAA) with unknown etiology. We aimed to disclose the relationship between vasa vasorum (VV) and intimal thickening using optical coherence tomography (OCT) in KD.

METHODS

Forty-three coronary artery branches of 21 patients with KD were examined by OCT. The coronary arteries were classified into three groups: the CAA group (n = 9) in which CAAs remained since the acute phase, the regressed group (n = 16) in which CAAs were regressed, and the no CAA group (n = 18). The number and distribution of VV, and intimal thickening in coronary arteries were evaluated on OCT.

RESULTS

Intimal thickening was significantly more severe in the CAA and regressed groups than in the no CAA group (median: 481, 474, and 218 μm, p = 0.001 and p < 0.001, respectively). The number of VV in the regressed group was significantly higher than that in the CAA and no CAA groups. The numbers of adventitial VV and internal VV were positively correlated with the intimal thickness (R = 0.64, p < 0.001; R = 0.62, p < 0.001, respectively). In the no CAA group, no internal VV were observed.

CONCLUSIONS

VV enhances according to intimal thickening, suggesting that VV may have some link to the healing process, such as CAA regression and intimal thickening.

IMPACT

Kawasaki disease (KD) is a vasculitis syndrome developing coronary artery aneurysm, however its etiology still remains unclear. Coronary artery imaging using optical coherence tomography (OCT) can reveal coronary arterial wall pathology, however OCT studies are limited in patients with KD. Using OCT, we disclosed the closed relationship between vasa vasorum enhancement and regressed coronary arterial lesions. Vasa vasorum enhancement is involved in the pathomechanism of the convalescent phase of KD.

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

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

Percutaneous coronary intervention for a healed erosion with excimer laser coronary angioplasty and drug-coated balloon angioplasty: a case report

Background

Healed plaque, characterized by distinct layers of organizing thrombus and collagen, is the hallmark of tissue self-repair. However, the efficacy of excimer laser coronary angioplasty (ELCA) followed by drug-coated balloon (DCB) angioplasty in patients with healed plaques is not fully understood.

Case summary

A 42-year-old woman with a history of anxiety disorder was admitted to our institution with worsening chest pain and subsequently diagnosed with anterior non-ST-elevation myocardial infarction. Coronary angiography revealed severe stenosis in the proximal left anterior descending artery (LAD) despite Thrombolysis in Myocardial Infarction (TIMI) grade 3. Optical coherence tomography (OCT) showed healed plaques with partial macrophage accumulation and no fresh thrombus. Plaque disruption and thin-cap fibrous atheroma were not identified in the culprit lesions. Intravascular ultrasound (IVUS) confirmed high-intensity marginal irregular masses at the culprit site, suggesting that the thrombus was formed by plaque erosion rather than lipid plaque or necrotic tissue. With lesion modification using ELCA prior to DCB angioplasty, OCT examination of the LAD after ELCA showed a significant reduction in plaque burden and preserved lumen size. Post-percutaneous coronary intervention angiography revealed no stenosis with TIMI grade 3. A follow-up coronary computed tomography scan showed no angiographic restenosis, and the patient remained symptom-free.

Conclusions

Here we describe a case in which OCT and IVUS evaluation suggested organizing thrombus due to erosion healing, and a favorable outcome was achieved with the combination of ELCA and DCB. The combination use of ELCA and DCB might be a potential strategy for acute coronary syndrome patients with organizing thrombus.

Case Report: Structural Changes in the Coronary Vessel Wall in a Patient With Incomplete Kawasaki Disease

BACKGROUND

Kawasaki disease (KD) is an acute systemic vasculitis of infants and young children that affects medium-sized vessels. Conventional cardiac imaging techniques, such as cardiac catheterization, are useful for characterizing the coronary arterial lesion (CAL) size and luminal diameter of the diseased coronary artery segment in patients with KD, but there are limitations to the visualization of the detailed vascular anatomy. Optical coherence tomography (OCT) is a high-resolution intracoronary arterial imaging modality that can distinguish the three layers of the coronary arterial wall. Several studies have reported coronary artery wall abnormalities in KD patients with coronary arterial aneurysm or regressed aneurysm. However, there have been no reports on changes in the coronary artery wall in cases of incomplete KD without CAL.

CASE PRESENTATION

We herein report an 11-year-old girl with a history of incomplete KD without coronary arterial aneurysms. She had been diagnosed with perimembranous ventricular septal defect (VSD) after birth and had experienced incomplete KD at 1 year old. During her hospitalization for KD, she did not receive intravenous immunoglobulin (IVIG), because she did not meet the Harada score or criteria for treatment in patients with incomplete KD established by the American Heart Association. No dilatation or coronary artery aneurysm were observed on transthoracic echocardiography in the acute or follow-up period. At 11 years old, she received cardiac catheterization and coronary angiography (CAG) for the evaluation of a VSD and follow-up of KD. CAG demonstrated no aneurysm, dilatation, or significant stenosis of the coronary arteries. We performed an OCT study, which revealed the presence of intimal thickening, disruption of the media, and neovascularization in the left anterior descending artery.

CONCLUSION

OCT demonstrates the structural changes of CA even in the patient with incomplete KD who have not been treated with IVIG.

Intimal thickening and disruption of the media occur in the arterial walls of coronary arteries not associated with coronary arterial aneurysms in patients with Kawasaki disease

Background

Coronary artery aneurysm (CAA) is an important complication of Kawasaki disease (KD) that is associated with arterial structure damage. However, few studies have examined structural changes in coronary arteries that are not associated with CAA.

Methods

We examined coronary arteries in KD patients with CAAs who underwent follow-up coronary angiography (CAG) and optical coherence tomography (OCT). Coronary arterial branches with no abnormal findings during the most recent CAG were classified into two groups. Arteries with an acute-phase CAA that later regressed were classified as group R; arteries with no abnormal findings on either acute or convalescent phase CAG were classified as group N. Coronary arterial wall structural changes were compared between groups using OCT.

Results

Fifty-seven coronary arterial branches in 23 patients were evaluated by OCT. Thirty-six branches showed no abnormality during the most recent CAG. Both groups R and N comprised 18 branches. Maximum intimal thicknesses in groups R and N were 475 and 355 µm, respectively (p = 0.007). The incidences of media disruption were 100% and 67%, respectively (p = 0.02). Calcification, macrophage accumulation, and thrombus were not found in either group.

Conclusions

Intimal thickening and disruption of the media occur in coronary arteries with acute phase CAAs that later regress in the convalescent phase, as well as in arteries with normal CAG findings in the acute and convalescent phases.

Optical Coherence Tomography based treatment approach for patients with Acute Coronary Syndrome

INTRODUCTION

Areas covered:In this review, we outline the underlying causes of acute coronary syndrome (ACS) as evaluated by optical coherence tomography (OCT). We report both the definitions of each mechanism and its frequency as reported in the literature to date. Finally, we present an algorithm based on the findings in the review that gives an outlined approach to perform intervention on ACS patients.Expert opinion:Although the most common and most accepted intervention in ACS cases is stent implantation, data suggest a stentless approach in cases of plaque erosion, which generally occurs in younger patients presenting with an acute coronary syndrome that have TIMI flow of 2/3 and either a small or large burden of thrombus and underlying stenosis of less than 50%.

Accuracy of Physicians in Differentiating Type 1 and Type 2 Myocardial Infarction Based on Clinical Information

Background

Physicians commonly judge whether a myocardial infarction (MI) is type 1 (thrombotic) vs type 2 (supply/demand mismatch) based on clinical information. Little is known about the accuracy of physicians’ clinical judgement in this regard. We aimed to determine the accuracy of physicians’ judgement in the classification of type 1 vs type 2 MI in perioperative and nonoperative settings.

Methods

We performed an online survey using cases from the Optical Coherence Tomographic Imaging of Thrombus (OPTIMUS) Study, which investigated the prevalence of a culprit lesion thrombus based on intracoronary optical coherence tomography (OCT) in patients experiencing MI. Four MI cases, 2 perioperative and 2 nonoperative, were selected randomly, stratified by etiology. Physicians were provided with the patient’s medical history, laboratory parameters, and electrocardiograms. Physicians did not have access to intracoronary OCT results. The primary outcome was the accuracy of physicians' judgement of MI etiology, measured as raw agreement between physicians and intracoronary OCT findings. Fleiss’ kappa and Gwet’s AC1 were calculated to correct for chance.

Results

The response rate was 57% (308 of 536). Respondents were 62% male; median age was 45 years (standard deviation ± 11); 45% had been in practice for > 15 years. Respondents’ overall accuracy for MI etiology was 60% (95% confidence interval [CI] 57%-63%), including 63% (95% CI 60%-68%) for nonoperative cases, and 56% (95% CI 52%-60%) for perioperative cases. Overall chance-corrected agreement was poor (kappa = 0.05), consistent across specialties and clinical scenarios.

Conclusions

Physician accuracy in determining MI etiology based on clinical information is poor. Physicians should consider results from other testing, such as invasive coronary angiography, when determining MI etiology.

Innovative invasive management without stent implantation guided by optical coherence tomography in acute coronary syndrome

BACKGROUND

A two-step strategy of invasive management without stenting, guided by optical coherence tomography (OCT), in selected patients with acute coronary syndrome (ACS), might avoid systematic stent implantation and allow medical therapy alone.

AIMS

To assess the feasibility and safety of such a procedure, and to define coronary imaging characteristics in a specific population.

METHODS

This single-centre proof-of-concept study included all patients with ACS who benefited from a two-step revascularization procedure with optimal reperfusion during primary percutaneous coronary intervention followed by delayed angiography and OCT. OCT imaging determined medical therapy treatment alone without stenting in case of absence of vulnerable plaque rupture and <70% stenosis. Follow-up consisted of screening for major adverse cardiac events (MACE) at 12months.

RESULTS

Forty-six patients were included, mainly men (86.9%) and smokers (65.2%), with a mean age of 47.1years. Most cases (80.4%) were large thrombus burden lesions. Delayed angiography and OCT were performed in a median period of 6 [3-10] days. No adverse events occurred between the initial and second angiograms. Plaque rupture was detected in 39.1% of patients, plaque erosion in 54.3% and calcified nodule in 6.5%. Twenty-three patients benefited from systematic delayed OCT over a median period of 171days, showing an increase in minimal lumen area. At 12months, two patients (4.3%) presented MACE and were stented. No sudden death or myocardial infarction recurrence occurred.

CONCLUSIONS

Analysing ACS mechanisms by OCT might facilitate treatment decisions in patients with ST-segment elevation myocardial infarction managed by a two-step procedure. Conservative treatment with antithrombotic therapy without stenting seems to be a reliable option in a selected population.

Stabilization of high-risk plaques

The prevalence of atherosclerotic cardiovascular diseases (ASCVDs) is increasing globally and they have become the leading cause of death in most countries. Numerous experimental and clinical studies have been conducted to identify major risk factors and effective control strategies for ASCVDs. The development of imaging modalities with the ability to determine the plaque composition enables us to further identify high-risk plaque and evaluate the effectiveness of different treatment strategies. While intensive lipid-lowering by statins can stabilize or even regress plaque by various mechanisms, such as the reduction of lipid accumulation in a necrotic lipid core, the reduction of inflammation, and improvement of endothelial function, there are still considerable residual risks that need to be understood. We reviewed important findings regarding plaque vulnerability and some encouraging emerging approaches for plaque stabilization.

[ST segment elevation myocardial infarction in a young patient: special physiopathology and unusual management]

We report the case of a 24-year-old patient admitted for anterior ST segment elevation myocardial complicated by ventricular fibrillation and revealing thrombotic sub occlusion of the left anterior descending coronary artery. Revascularization is achieved by manual thrombectomy and use of Glycoprotein GPIIbIIIa inhibitors and permits to restore TIMI 3 flow. Given the large thrombotic burden, the patient is initially treated medically (optimal anti thrombotic therapy without stenting) and benefits from angiographic control 48 hours later with imaging by Optical Coherence Tomography (OCT). It shows a reduction of thrombus burden and lack of significant underlying organic lesion (no organic stenosis or plaque rupture). In view of these data, it was decided to continue medical treatment alone without stenting. OCT imaging at 6 months shows atheroma without stenosis, thrombus or plaque rupture. This young patient remains asymptomatic and recovered normal left ventricular function with a 2-year follow-up.

Atherosclerosis and atheroma plaque rupture: imaging modalities in the visualization of vasa vasorum and atherosclerotic plaques

Invasive angiography has been widely accepted as the gold standard to diagnose cardiovascular pathologies. Despite its superior resolution of demonstrating atherosclerotic plaque in terms of degree of lumen stenosis, the morphological assessment for the plaque is insufficient for the analysis of plaque components, and therefore, unable to predict the risk status or vulnerability of atherosclerotic plaque. There is an increased body of evidence to show that the vasa vasorum play an important role in the initiation, progression, and complications of atherosclerotic plaque leading to major adverse cardiac events. This paper provides an overview of the evidence-based reviews of various imaging modalities with regard to their potential value for comprehensive characterization of the composition, burden, and neovascularization of atherosclerotic plaque.

Association Between High Serum Matrix Metalloproteinase-9 and MMP-9 (-1562C>T) Polymorphism in Patients With ST-Elevation Acute Myocardial Infarction

Background

Matrix metalloproteinase (MMP)-9 is excessively expressed in frail region of atherosclerotic plaque and released in circulation following plaque rupture. High MMP-9 level associated with severity of occluded thrombus and subsequent myocardial infarction. MMP-9 (-1562C>T) polymorphism associated with acute myocardial infarction, however conflicting data present regarding impact of MMP-9 (-1562C>T) polymorphism on circulating MMP-9 level in acute myocardial infarction with ST-elevation (STEMI), clinical entity represents totally occluded coronary thrombus.

Methods

We enrolled consecutively subjects with acute coronary syndrome treated in intensive coronary care unit. Acute coronary syndrome diagnosis were classified into STEMI and non-ST-elevation acute coronary syndrome (NSTEACS). Seventy consecutive subjects were enrolled for this study, 31 subjects with STEMI and 39 subjects with NSTEACS.

Results

On admission serum MMP-9 level, measured with sandwich enzyme immunoassay, were higher in STEMI as compared with NSTEACS (1,574.2 ± 604.1 ng/mL vs. 1,104.4 ± 591.5 ng/mL, P < 0.01). Proportion of subjects with MMP-9 (-1562C>T) polymorphism, analyzed with PCR-RFLP, were higher in STEMI as compared with NSTEACS (66.7% vs. 33.3%, P = 0.15). T allele frequency was almost twice in STEMI as compared to in NSTEACS. Almost all (83%) subjects with MMP-9 (-1562C>T) polymorphism had high serum MMP-9 level (> 1,334.5 ng/mL) during STEMI, whereas in NSTEACS all subjects had low level.

Conclusion

MMP-9 (-1562C>T) polymorphism associated with high serum MMP-9 level in patients with STEMI.

Optical coherence tomography imaging in acute coronary syndromes

Optical coherence tomography (OCT) is a high-resolution imaging technique that offers microscopic visualization of coronary plaques. The clear and detailed images of OCT generate an intense interest in adopting this technique for both clinical and research purposes. Recent studies have shown that OCT is useful for the assessment of coronary atherosclerotic plaques, in particular the assessment of plaque rupture, erosion, and intracoronary thrombus in patients with acute coronary syndrome. In addition, OCT may enable identifying thin-cap fibroatheroma, the proliferation of vasa vasorum, and the distribution of macrophages surrounding vulnerable plaques. With its ability to view atherosclerotic lesions in vivo with such high resolution, OCT provides cardiologists with the tool they need to better understand the thrombosis-prone vulnerable plaques and acute coronary syndromes. This paper reviews the possibility of OCT for identification of vulnerable plaques in vivo.

Invasive imaging technologies: can we reconcile light and sound?

Since the introduction of intravascular, catheter-based invasive imaging and diagnostic tools in the catheterization laboratories two decades ago, the functional assessment of angiographically moderate or ambiguous lesions by fractional flow reserve measurements represents the established standard of care today. Likewise, intravascular ultrasound (IVUS) is widely accepted to guide treatment strategy in complex lesions, such as long or left main stem lesions. Developments are driven by the clinical interest to optimize treatment, prevent periprocedural complications, understand treatment failure and understand progression of atherosclerosis. As a result, a variety of devices are now clinically available that enable detection and monitoring of specific plaque features over time, such as the presence of necrotic core by IVUS-VH, a lipid-core plaque by near infrared (NIR) spectroscopy or a thin fibrous cap atheroma by optical coherence tomography (OCT). As the physical boundaries for both light and sound are different, these imaging technologies offer different advantages and limitations. Light-based technologies offer unparalleled high image resolution (OCT) or unparalleled high sensitivity and specificity for distinct plaque components (NIR spectroscopy), whereas conventional IVUS offers a much better tissue penetration. From a clinical perspective, both types of information are valuable. Ideally, this information should easily and in real time be available in the catheterization laboratory, consisting of co-registered datasets gained during a single catheter pullback. On this background, a combined NIR spectroscopy and IVUS catheter has recently been introduced for clinical use. The article discusses the potential and limitations of these different technologies. They may allow advanced coronary plaque diagnosis in a fast, accurate, reliable, user- and patient-friendly manner and, as such, can help to improve clinical practice today and therapeutic options in the future.

Impact of out-stent plaque volume on in-stent intimal hyperplasia: results from serial volumetric analysis with high-gain intravascular ultrasound

BACKGROUND

Changes in out-stent plaque volume can be related to in-stent intimal hyperplasia. However, few data exist regarding the impact of out-stent plaque volume on in-stent intimal hyperplasia.

METHODS

We prospectively performed volumetric intravascular ultrasound in 46 stable coronary patients (34 males, mean age of 66 years) immediately as well as 18 months after stenting. From the high-gain ultrasound images, out-stent plaque volume was calculated by extracting the stent volume from the external elastic membrane volume. Volumes of in-stent intimal hyperplasia and reference plaque were also evaluated.

RESULTS

Out-stent plaque volume increased from 177.3 ± 100.8mm(3) to 190.7 ± 111.1mm(3) (p<0.05) in correlation with increases in-stent intimal hyperplasia (r=0.536, p<0.05). Under these conditions, changes in reference plaque volume correlated with those in LDL-C, which decreased from 121.2 ± 48.0mg/dl to 103.3 ± 48.9 mg/dl (r=0.43, p<0.05). Interestingly, increases in out-stent plaque volume in the silorimus-eluting stent (2.7 ± 1.2%) were lesser than those in the bare-metal stent (14.0 ± 11.0%, p<0.05).

CONCLUSIONS

These results indicate that irrespective of LDL-C level, changes in out-stent plaque volume correlate with those in in-stent intimal hyperplasia. We suggest that silorimus-eluting stent can suppress in-stent intimal hyperplasia partially by affecting out-stent plaque, although further large-scale studies are required to define the role of out-stent plaque in the occurrence of in-stent intimal hyperplasia.