Coronary Intravascular Imaging Research Articles

In-Stent Restenosis: Achilles’ Heel of Post-PCI Era

Despite advancements in stent design and polymer coatings over the past two decades, 1% to 2% of patients annually still experience instent restenosis (ISR). ISR reduces myocardial perfusion, may develop symptoms of myocardial ischemia, and thus leads to a high risk of myocardial infarction and cardiac death. Given that millions of drug-eluting stents (DES) are implanted globally every year, ISR remains a prevalent clinical issue with significant public health implications. Coronary intravascular imaging, includes intravascular ultrasound (IVUS) and optical coherence tomography (OCT), can help physicians gain deeper insights into the potential mechanisms of ISR. The preferred treatment strategy hinges on an accurate diagnosis and better understanding of etiology. The mechanism of ISR is multifaceted, and its treatment is challenging. Although the risk of ISR continues to decrease with advancements in DES application, further research is still needed to enrich the treatment options for ISR.

Intracoronary Imaging and Physiology to Guide PCI: Are We Ready for a Class I Guideline Recommendation?

Over the last decade, there has been a plethora of evidence to support the utilization of intravascular coronary imaging and physiological assessment to guide percutaneous coronary interventions (PCI). While there is a class I recommendation for the use of coronary physiology to guide PCI, the use of intravascular coronary imaging remains a class IIa recommendation. Herein, we aimed to review the recent scientific evidence from major trials highlighting the consideration for a future class I guideline recommendation for the use of intracoronary imaging. The benefits of intravascular ultrasound (IVUS) and optical coherence tomography (OCT) to guide and optimize PCI have been demonstrated in several large trials. These trials have demonstrated that IVUS reduces major adverse cardiovascular events. Similarly, intracoronary physiology has been demonstrated to be an important tool to guide revascularization decision-making and been associated with a lower incidence of death, non-fatal myocardial infarction, and repeat revascularization compared with angiography alone. With existing clinical outcomes data on the benefit of intracoronary physiology and imaging-guided PCI as well as forthcoming data from ongoing trials regarding the use of these modalities, the interventional cardiology community is bound to transition from routine PCI to precision-, image-, and physiology-guided PCI.

Noninvasive Plaque Imaging to Accelerate Coronary Artery Disease Drug Development.

Coronary artery disease (CAD) remains the leading cause of adult mortality globally. Targeting known modifiable risk factors has had substantial benefit, but there remains a need for new approaches. Improvements in invasive and noninvasive imaging techniques have enabled an increasing recognition of distinct quantitative phenotypes of coronary atherosclerosis that are prognostically relevant. There are marked differences in plaque phenotype, from the high-risk, lipid-rich, thin-capped atheroma to the low-risk, quiescent, eccentric, nonobstructive calcified plaque. Such distinct phenotypes reflect different pathophysiologic pathways and are associated with different risks for acute ischemic events. Noninvasive coronary imaging techniques, such as computed tomography, positron emission tomography, and coronary magnetic resonance imaging, have major potential to accelerate cardiovascular drug development, which has been affected by the high costs and protracted timelines of cardiovascular outcome trials. This may be achieved through enrichment of high-risk phenotypes with higher event rates or as primary end points of drug efficacy, at least in phase 2 trials, in a manner historically performed through intravascular coronary imaging studies. Herein, we provide a comprehensive review of the current technology available and its application in clinical trials, including implications for sample size requirements, as well as potential limitations. In its effort to accelerate drug development, the US Food and Drug Administration has approved surrogate end points for 120 conditions, but not for CAD. There are robust data showing the beneficial effects of drugs, including statins, on CAD progression and plaque stabilization in a manner that correlates with established clinical end points of mortality and major adverse cardiovascular events. This, together with a clear mechanistic rationale for using imaging as a surrogate CAD end point, makes it timely for CAD imaging end points to be considered. We discuss the importance of global consensus on these imaging end points and protocols and partnership with regulatory bodies to build a more informed, sustainable staged pathway for novel therapies.

Myocardial infarction with non-obstructive coronary arteries (MINOCA).

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is evident in up to 15% of all acute myocardial infarctions (AMI) and disproportionally affects females. Despite younger age, female predominance, and fewer cardiovascular risk factors, MINOCA patients have a worse prognosis than patients without cardiovascular disease and a similar prognosis compared to patients with MI and obstructive coronary artery disease (CAD). MINOCA is a syndrome with a broad differential diagnosis that includes both ischemic [coronary artery plaque disruption, coronary vasospasm, coronary microvascular dysfunction, spontaneous coronary artery dissection (SCAD), and coronary embolism/thrombosis] and non-ischemic mechanisms (Takotsubo cardiomyopathy, myocarditis, and non-ischemic cardiomyopathy)-the latter called MINOCA mimickers. Therefore, a standardized approach that includes multimodality imaging, such as coronary intravascular imaging, cardiac magnetic resonance, and in selected cases, coronary reactivity testing, including provocation testing for coronary vasospasm, is necessary to determine underlying etiology and direct treatment. Herein, we review the prevalence, characteristics, prognosis, diagnosis, and treatment of MINOCA -a syndrome often overlooked.

Pénétration de l'imagerie endocoronaire en France (données de France PCI) : l'exception française

PurposeEvaluate intravascular coronary imaging (ICI) utilization in France and compare it with other countries. MethodologyWe included in our study all PCI performed between 2014 and 2021 in all participating centers of France PCI registry. ResultsThe percentage of ICI use during PCI varied from 1.2% to 1% between 2014 and 2020 in the France PCI Registry. In 2021, among 45,227 PCI procedures performed at the 41 participating centers, 768 (1.7%) had an ICI, including 329 (0.7%) with OCT, 341 (0.8%) with IVUS, and 98 (0.2%) undetermined. In "all-comers" PCI, the rate of ICI use was 1.7% in France, 2.5% in the United States, 10% in Sweden, 16.2% in the United Kingdom, and 84.4% in Japan. In left main PCI, the rate was 5.8% in France, 62.3% in Sweden, 66.6% in the UK, and 96.6% in Japan. In the France PCI registry, the rate of ICI use ranged from 0% to 9.5% in all PCI and from 0% to 30% in left main PCI. ConclusionICI techniques are exceptionally used in France in routine practice, in contrast to our European neighbors such as Swede or the United Kingdom. Obtaining reimbursement in certain recommended indications and participation in a national interventional cardiology registry with incentive practice indicators should improve this situation.

Vulnerable atherosclerotic plaque features: findings from coronary imaging.

Pathological studies have suggested that features of vulnerable atherosclerotic plaques likely to progress and lead to acute cardiovascular events have specific characteristics. Given the progress of intravascular coronary imaging technology, some large prospective studies have detected features of vulnerable atherosclerotic plaques using these imaging modalities. However, the rate of cardiovascular events, such as acute coronary syndrome, has been found to be considerably reduced in the limited follow-up period available in the statin era. Additionally, not all disrupted plaques lead to thrombus formation with clinical presentation. If sub-occlusive or occlusive thrombus formation does not occur, a thrombus on a disrupted plaque will organize without any symptoms, forming a “healed plaque”. Although vulnerable plaque detection using intracoronary imaging is focused on “thin-cap fibroatheroma” leading to plaque rupture, superficial plaque erosion is increasingly recognized; however, the underlying mechanism of thrombus formation on eroded plaques is not well understood. One of intravascular imaging, optical coherence tomography (OCT) has the highest image resolution and has enabled detailed characterization of the plaque in vivo. Here, we reviewed the status and limitations of intravascular imaging in terms of detecting vulnerable plaque through mainly OCT studies. We suggested that vulnerable plaque should be reconsidered in terms of eroded plaque and healed plaque and that both plaque and circulating blood should be assessed in greater detail accordingly.

A016 Optical Coherence Tomography (OCT) for Intravascular Coronary Imaging at Middlemore Hospital (MMH) Over the Last Two Years – A Retrospective Audit

A016 Optical Coherence Tomography (OCT) for Intravascular Coronary Imaging at Middlemore Hospital (MMH) Over the Last Two Years – A Retrospective Audit

IVUS and OCT: Current State-of-the-Art in Intravascular Coronary Imaging

To summarize the current state-of-the-art of intracoronary imaging with a focus on clinical outcomes, novel approaches, and anticipated future developments. Multiple randomized trials have demonstrated that intravascular ultrasound (IVUS) guidance of percutaneous coronary intervention (PCI) significantly reduces major cardiac adverse events (MACE), and in particular, rates of target lesion failure or clinical restenosis. High-definition IVUS enhances the ability to visualize stent struts and plaque components. Optical coherence tomography (OCT) offers a greater resolution and can image many plaque morphology and stent characteristics that are not visualized with IVUS. Image guidance should be considered strongly in complex PCI lesions and potentially in all-comers. Multimodality imaging using near-infrared spectroscopy or fluorescence, combined with IVUS or OCT, is an exciting new approache to image plaque lipid, intraplaque hemorrhage, inflammation, and fibrin deposition. Intravascular imaging guidance of PCI utilizing IVUS or OCT definitively improves outcomes in many patient subsets but remains heavily underutilized. Emerging intravascular imaging modalities, such as near-infrared spectroscopy and near-infrared fluorescence imaging, will allow for improved plaque and stent characterization. As cath lab integration, automated image segmentation, and x-ray co-registration evolve further, we envision that intravascular imaging will become a routine for the vast majority of PCI patients, with resultant benefits in clinical outcomes.

Impact and trends of intravascular imaging in diagnostic coronary angiography and percutaneous coronary intervention in inpatients in the United States.

Intravascular imaging with intravascular ultrasound (IVUS) and optical coherence tomography (OCT) is an important adjunct to invasive coronary angiography. The primary objective was to examine the frequency of intravascular coronary imaging, trends in imaging use, and outcomes of patients undergoing angiography and/or percutaneous coronary intervention (PCI) in the United States. Adult patients ≥18 years of age undergoing in-hospital cardiac catheterization from January 2004 to December 2014 were identified from the National Inpatient Sample (NIS). International Classification of Diseases, Ninth Revision (ICD-9) diagnosis and procedure codes were used to identify IVUS and OCT use during diagnostic angiography and PCI. Among 3,211,872 hospitalizations with coronary angiography, intracoronary imaging was performed in 88,775 cases (4.8% of PCI and 1.0% of diagnostic procedures), with IVUS in 98.9% and OCT in 1.1% of cases. Among patients undergoing PCI, the rate of intravascular coronary imaging increased from 2.1% in 2004-2005 to 6.6% in 2013-2014 (P < 0.001 for trend). Use of intravascular coronary imaging was associated with lower in-hospital mortality in patients undergoing PCI (adjusted OR 0.77; 95% CI 0.71-0.83). There was marked variability in intravascular imaging by hospital, with 63% and 13% of facilities using intravascular imaging in <5% and >15% of PCIs, respectively. In a large administrative database from the United States, intravascular imaging use was low, increased over time, and imaging was associated with reduced in-hospital mortality. Substantial variation in the frequency of intravascular imaging by hospital was observed. Additional investigation to determine clinical benefits of IVUS and OCT are warranted.

Acute Coronary Syndrome due to In-Stent Neoatherosclerosis 14 years after Bare-Metal Stent Implantation: Findings of Intravascular Imaging Modalities

In recent years, neoatherosclerosis and very late stent thrombosis in the extended follow-up period after baremetal stent (BMS) implantation have been recognized. We experienced a case of in-stent restenosis (ISR) detected in a BMS implanted 14 years prior. An 86-year-old man who had a history of BMS implantation because of angina pectoris in the proximal left anterior descending coronary artery (LAD) 14 years previously was referred to our hospital because of worsening chest pain on exertion for 1 month. A coronary angiogram revealed severe stenosis in the previously implanted BMS. Seven days later, percutaneous coronary intervention (PCI) for the LAD lesion was performed. Prior to intervention, intravascular ultrasound (IVUS), optical coherence tomography (OCT), and intracoronary angioscopy were performed, which showed diffuse heterogeneous plaque throughout the stent, various types of imaging in plaques including thrombi and fibrous plaque, and yellow plaques with respective imaging devices. We deployed two drug-eluting stents to cover all the plaque using a filter device in order to protect from distal embolism, and verified the good result by final angiography. From observations obtained with intravascular coronary imaging modalities in this case and knowledge that some past studies revealed, this case was considered as an acute coronary syndrome since neoatherosclerosis rupture in the BMS lesion happened in the extended follow-up period. Therefore we emphasize that physicians have to follow patients who have undergone BMS implantation carefully, even if ISR is not detected in the post early phase.

Role of near-infrared spectroscopy in intravascular coronary imaging.

Near-infrared spectroscopy is an intracoronary imaging modality that has been validated in preclinical and clinical studies to help quantify the lipid content of the coronary plaque and provide information regarding its vulnerability. It has the potential to develop into a valuable tool for the risk stratification of a vulnerable plaque and, furthermore, a vulnerable patient. In addition, in the future this technology may help in the development of novel therapies that impact vascular biology.

The basics of intravascular optical coherence tomography.

Optical coherence tomography (OCT) has opened new horizons for intravascular coronary imaging. It utilizes near-infrared light to provide a microscopic insight into the pathology of coronary arteries in vivo. Optical coherence tomography is also capable of identifying the chemical composition of atherosclerotic plaques and detecting traits of their vulnerability. At present it is the only tool to measure the thickness of the fibrous cap covering the lipid core of the atheroma, and thus it is an exceptional modality to detect plaques that are prone to rupture (thin fibrous cap atheromas). Moreover, it facilitates distinguishing between plaque rupture and plaque erosion as a cause of acute intracoronary thrombosis. Optical coherence tomography is applied to guide angioplasties of coronary lesions and to assess outcomes of percutaneous coronary interventions broadly. It identifies stent malapposition, dissections, and thrombosis with unprecedented precision. Furthermore, OCT helps to monitor vessel healing after stenting. It evaluates the coverage of stent struts by the neointima and detects in-stent neoatherosclerosis. With so much potential, new studies are warranted to determine OCT's clinical impact. The following review presents the technical background, basics of OCT image interpretation, and practical tips for adequate OCT imaging, and outlines its established and potential clinical application.

The diagnostic value of intracoronary optical coherence tomography

Optical coherence tomography (OCT) is a novel light-based imaging modality for application in the coronary circulation. Compared to conventional intravascular ultrasound, OCT has a ten-fold higher image resolution. This advantage has seen OCT successfully applied in the assessment of atherosclerotic plaque, stent apposition, and tissue coverage, heralding a new era in intravascular coronary imaging. The present article discusses the diagnostic value of OCT, both in cardiovascular research as well as in potential clinical application.The unparalleled high image resolution and strong contrast between the coronary lumen and the vessel wall structure enable fast and reliable image interpretation. OCT makes it possible to visualize the presence of atherosclerotic plaque in order to characterize the structure and extent of coronary plaque and to quantify lumen dimensions, as well as the extent of lumen narrowing, in unprecedented detail. Based on optical properties, OCT is able to distinguish different tissue types, such as fibrous, lipid-rich, necrotic, or calcified tissue. Furthermore, OCT is able to cover the visualization of a variety of features of atherosclerotic plaques that have been associated with rapid lesion progression and clinical events, such as thin cap fibroatheroma, fibrous cap thickness, dense macrophage infiltration, and thrombus formation. These unique features allow the use of OCT to assess patients with acute coronary syndrome and to study the dynamic nature of coronary atherosclerosis in vivo and over time. This permits new insights into plaque progression, regression, and rupture, as well as the study of effects of therapies aimed at modulating these developments.Today's OCT technology allows high detail resolution as well as fast and safe clinical image acquisition. These unique features have established OCT as the gold standard for the assessment of coronary stents. This technique makes it possible to study stent expansion, peri-procedural vessel trauma, and the interaction of the stent with the vessel wall down to the level of individual stent struts, both acutely as well as in the long term, where it is has proven extremely sensitive to the detection of even minor amounts of tissue coverage. These qualities render OCT indispensable to addressing vexing clinical questions such as the relationship of drug-eluting stent deployment, vascular healing, the true time course of endothelial stent coverage, and late stent thrombosis. This may also better guide the optimal duration of dual anti-platelet therapy that currently remains unclear and relatively empirical.In the future, OCT might emerge, parallel to its undisputed position in research, as the tool of choice in all clinical scenarios where angiography is limited by its nature as a two-dimensional luminogram.