Current Management of In-Stent Restenosis

In-stent restenosis (ISR) remains the primary cause of target lesion failure following percutaneous coronary intervention (PCI), resulting in 10-year incidences of target lesion revascularization at a rate of approximately 20%. The treatment of ISR is challenging due to its inherent propensity for recurrence and varying susceptibility to available strategies, influenced by a complex interplay between clinical and lesion-specific conditions. Given the multiple mechanisms contributing to the development of ISR, proper identification of the underlying substrate, especially by using intravascular imaging, becomes pivotal as it can indicate distinct therapeutic requirements. Among standalone treatments, drug-coated balloon (DCB) angioplasty and drug-eluting stent (DES) implantation have been the most effective. The main advantage of a DCB-based approach is the avoidance of an additional metallic layer, which may otherwise enhance neointimal hyperplasia, provide the substratum for developing neoatherosclerosis, and expose the patient to a persistently higher risk of coronary ischemic events. On the other hand, target vessel scaffolding by DES implantation confers relevant mechanical advantages over DCB angioplasty, generally resulting in larger luminal gain, while drug elution from the stent surface ensures the inhibition of neointimal hyperplasia. Nevertheless, repeat stenting with DES also implies an additional permanent metallic layer that may reiterate and promote the mechanisms leading to ISR. Against this background, the selection of either DCB or DES on a patient- and lesion-specific basis as well as the implementation of adjuvant treatments, including cutting/scoring balloons, intravascular lithotripsy, and rotational atherectomy, hold the potential to improve the effectiveness of ISR treatment over time. In this review, we comprehensively assessed the available evidence from randomized trials to define contemporary interventional treatment of ISR and provide insights for future directions.

Long-term clinical outcomes of intravascular imaging-guided percutaneous coronary intervention versus angiography-guided percutaneous coronary intervention in complex coronary lesions: a systematic review and meta-analysis

Background: In this study, we aim to discuss the long-term clinical outcomes of intravascular ultrasound imaging-guided percutaneous intervention (IVUS-PCI) versus angiography-guided percutaneous coronary intervention (PCI) in complex coronary lesions over a mean period of 2 years. Methods: A systematic search and meta-analysis were conducted to assess the efficacy of using intravascular ultrasound or optical coherence tomography guidance in coronary artery stenting compared to angiography. Results: A total of 11 randomized controlled trials with 6740 patients were included. For the primary outcome, a pooled analysis (3.2 vs 5.6%). For secondary outcomes, the risk was significantly low in image-guided percutaneous intervention compared with angiography. Conclusion: Intravascular imaging-guided PCI is significantly more effective than angiography-guided PCI in reducing the risk of target lesion revascularization, target vessel revascularization, cardiac death, major adverse cardiovascular events and stent thrombosis.

Coronary Angiography, Intravascular Ultrasound, and Optical Coherence Tomography for Guiding of Percutaneous Coronary Intervention: A Systematic Review and Network Meta-Analysis

BACKGROUND

Results from multiple randomized clinical trials comparing outcomes after intravascular ultrasound (IVUS)- and optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) with invasive coronary angiography (ICA)-guided PCI as well as a pivotal trial comparing the 2 intravascular imaging (IVI) techniques have provided mixed results.

METHODS

Major electronic databases were searched to identify eligible trials evaluating at least 2 PCI guidance strategies among ICA, IVUS, and OCT. The 2 coprimary outcomes were target lesion revascularization and myocardial infarction. The secondary outcomes included ischemia-driven target lesion revascularization, target vessel myocardial infarction, death, cardiac death, target vessel revascularization, stent thrombosis, and major adverse cardiac events. Frequentist random-effects network meta-analyses were conducted. The results were replicated by Bayesian random-effects models. Pairwise meta-analyses of the direct components, multiple sensitivity analyses, and pairwise meta-analyses IVI versus ICA were supplemented.

RESULTS

The results from 24 randomized trials (15 489 patients: IVUS versus ICA, 46.4%, 7189 patients; OCT versus ICA, 32.1%, 4976 patients; OCT versus IVUS, 21.4%, 3324 patients) were included in the network meta-analyses. IVUS was associated with reduced target lesion revascularization compared with ICA (odds ratio [OR], 0.69 [95% CI, 0.54-0.87]), whereas no significant differences were observed between OCT and ICA (OR, 0.83 [95% CI, 0.63-1.09]) and OCT and IVUS (OR, 1.21 [95% CI, 0.88-1.66]). Myocardial infarction did not significantly differ between guidance strategies (IVUS versus ICA: OR, 0.91 [95% CI, 0.70-1.19]; OCT versus ICA: OR, 0.87 [95% CI, 0.68-1.11]; OCT versus IVUS: OR, 0.96 [95% CI, 0.69-1.33]). These results were consistent with the secondary outcomes of ischemia-driven target lesion revascularization, target vessel myocardial infarction, and target vessel revascularization, and sensitivity analyses generally did not reveal inconsistency. OCT was associated with a significant reduction of stent thrombosis compared with ICA (OR, 0.49 [95% CI, 0.26-0.92]) but only in the frequentist analysis. Similarly, the results in terms of survival between IVUS or OCT and ICA were uncertain across analyses. A total of 25 randomized trials (17 128 patients) were included in the pairwise meta-analyses IVI versus ICA where IVI guidance was associated with reduced target lesion revascularization, cardiac death, and stent thrombosis.

CONCLUSIONS

IVI-guided PCI was associated with a reduction in ischemia-driven target lesion revascularization compared with ICA-guided PCI, with the difference most evident for IVUS. In contrast, no significant differences in myocardial infarction were observed between guidance strategies.

In-Stent Restenosis Overview: From Intravascular Imaging to Optimal Percutaneous Coronary Intervention Management

Despite ongoing progress in stent technology and deployment techniques, in-stent restenosis (ISR) still remains a major issue following percutaneous coronary intervention (PCI) and accounts for 10.6% of all interventions in the United States. With the continuous rise in ISR risk factors such as obesity and diabetes, along with an increase in the treatment of complex lesions with high-risk percutaneous coronary intervention (CHIP), a substantial growth in ISR burden is expected. This review aims to provide insight into the mechanisms, classification, and management of ISR, with a focus on exploring innovative approaches to tackle this complication comprehensively, along with a special section addressing the approach to complex calcified lesions.

The Evolving Field of Acute Coronary Syndrome Management: A Critical Appraisal of the 2023 European Society of Cardiology Guidelines for the Management of Acute Coronary Syndrome

Acute coronary syndromes (ACS), encompassing conditions like ST-elevation myocardial infarction (STEMI) and non-ST-elevation acute coronary syndromes (NSTE-ACS), represent a significant challenge in cardiovascular care due to their complex pathophysiology and substantial impact on morbidity and mortality. The 2023 European Society of Cardiology (ESC) guidelines for ACS management introduce several updates in key areas such as invasive treatment timing in NSTE-ACS, pre-treatment strategies, approaches to multivessel disease, and the use of imaging modalities including computed tomography (CT) coronary angiography, magnetic resonance imaging (MRI), and intracoronary imaging techniques, such as optical coherence tomography (OCT) and intravascular ultrasound (IVUS). They also address a modulation of antiplatelet therapy, taking into consideration different patient risk profiles, and introduce new recommendations for low-dose colchicine. These guidelines provide important evidence-based updates in practice, reflecting an evolution in the understanding and management of ACS, yet some potentially missed opportunities for more personalized care and technology adoption are discussed.

Intravascular Ultrasound Use in Peripheral Arterial and Deep Venous Interventions: Multidisciplinary Expert Opinion From SCAI/AVF/AVLS/SIR/SVM/SVS

Percutaneous revascularization is the primary strategy for treating lower extremity venous and arterial disease. Angiography is limited by its ability to accurately size vessels, precisely determine the degree of stenosis and length of lesions, characterize lesion morphology, or correctly diagnose postintervention complications. These limitations are overcome with use of intravascular ultrasound (IVUS). IVUS has demonstrated the ability to improve outcomes following percutaneous coronary intervention, and there is increasing evidence to support its benefits in the setting of peripheral vascular intervention. At this stage in its evolution, there remains a need to standardize the use and approach to peripheral vascular IVUS imaging. This manuscript represents considerations and consensus perspectives that emerged from a roundtable discussion including 15 physicians with expertise in interventional cardiology, interventional radiology, and vascular surgery, representing 6 cardiovascular specialty societies, held on February 3, 2023. The roundtable's aims were to assess the current state of lower extremity revascularization, identify knowledge gaps and need for evidence, and determine how IVUS can improve care and outcomes for patients with peripheral arterial and deep venous pathology.

Intrastent Restenosis: A Comprehensive Review

The primary objective of this paper is to delineate and elucidate the contemporary advancements, developments, and prevailing trajectories concerning intrastent restenosis (ISR). We aim to provide a thorough overview of the most recent developments in this area, covering various aspects such as pathophysiological insights, therapeutic approaches, and new strategies for tackling the complex challenges of ISR in modern clinical settings. The authors have undertaken a study to address a relatively new medical challenge, recognizing its significant impact on the morbidity and mortality of individuals with cardiovascular diseases. This effort is driven by the need to fully understand, analyze, and possibly improve the outcomes of this emerging medical issue within the cardiovascular disease field. We acknowledge its considerable clinical implications and the necessity for innovative methods to mitigate its effects on patient outcomes. Therefore, our emphasis was directed towards elucidating the principal facets of the condition's prevalence, expounding upon the foundational mechanisms underscoring conspicuous restenosis, and delineating the risk factors relevant in shaping the contemporary landscape of diagnostic and therapeutic modalities. This thorough examination aims to provide a comprehensive understanding of the various dimensions of the condition, including epidemiological data, pathophysiological complexities, and clinical considerations critical for evaluating and enhancing current diagnostic and treatment approaches.

Intravascular Imaging-Guided Percutaneous Coronary Intervention Before and After Standardized Optimization Protocols

BACKGROUND

Although benefits of intravascular imaging (IVI) in percutaneous coronary intervention (PCI) have been observed in previous studies, it is not known whether changes in contemporary practice, especially with application of standardized optimization protocols, have improved clinical outcomes.

OBJECTIVES

The authors sought to investigate whether clinical outcomes of IVI-guided PCI are different before and after the application of standardized optimization protocols in using IVI.

METHODS

2,972 patients from an institutional registry (2008-2015, before application of standardized optimization protocols, the past group) and 1,639 patients from a recently published trial (2018-2021 after application of standardized optimization protocols, the present group) were divided into 2 groups according to use of IVI. The primary outcome was 3-year target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction, or target vessel revascularization.

RESULTS

Significant reduction of TVF was observed in the IVI-guided PCI group compared with the angiography-guided PCI group (10.0% vs 6.7%; HR: 0.77; 95% CI: 0.61-0.97; P = 0.027), mainly driven by reduced cardiac death or myocardial infarction in both past and present IVI-guided PCI groups. When comparing past IVI and present IVI groups, TVF was significantly lower in the present IVI group (8.5% vs 5.1%; HR: 0.63; 95% CI: 0.42-0.94; P = 0.025), with the difference being driven by reduced target vessel revascularization in the present IVI group. Consistent results were observed in inverse-probability-weighting adjusted analysis.

CONCLUSIONS

IVI-guided PCI improved clinical outcomes more than angiography-guided PCI. In addition, application of standardized optimization protocols when using IVI further improved clinical outcomes after PCI. (Intravascular Imaging- Versus Angiography-Guided Percutaneous Coronary Intervention For Complex Coronary Artery Disease [RENOVATE-COMPLEX-PCI]; NCT03381872; and the institutional cardiovascular catheterization database of Samsung Medical Center: Long-Term Outcomes and Prognostic Factors in Patient Undergoing CABG or PCI; NCT03870815).

Fractional flow reserve versus intravascular imaging to guide decision-making for percutaneous coronary intervention in intermediate lesions: A meta-analysis

BACKGROUND

Both fractional flow reserve (FFR) and intravascular imaging (IVI) have been used to guide the decision-making for percutaneous coronary intervention (PCI) in intermediate coronary stenosis. Nevertheless, studies that directly compared the prognostic significance of these two strategies are scarce.

AIMS

The aim of this meta-analyses was to evaluate the impact of FFR versus IVI to guide the decision-making in PCI for intermediate stenosis on clinical outcomes.

METHODS

We systematically searched PubMed, Embase, Cochrane, and relevant database from inception date to September 2022 for observational studies and randomized clinical trials (RCTs) which compared FFR and IVI-based decision-making in PCI for intermediate stenosis. The primary outcome was a composite of major adverse cardiac event (MACE). Pooled risk ratios (RR) were calculated using random effects models and heterogeneity were evaluated with the I2 statistic.

RESULTS

We identified 5 studies (3 RCTs and 2 observational studies) with 3208 patients. The follow-up duration ranged from 12 to 24 months. Among five studies, four compared FFR with intravascular ultrasound while one compared FFR with optical coherence tomography. There was no statistically difference between FFR and IVI in the incidence of MACE (RR: 1.19; 95% confidence interval: 0.85-1.68; p = 0.31) and its individual components. These results were consistent regardless of various cut-off value of PCI across the studies. Compared with IVI, FFR was associated with a lower PCI rate (37.0% vs. 60.3%; p < 0.001).

CONCLUSIONS

The decision to perform PCI for intermediate stenosis guided by FFR or IVI showed a similar clinical outcome. The use of FFR significantly reduced the need for PCI.

Role of Intravascular Imaging in Complex Percutaneous Coronary Intervention: A Meta-Analysis of Randomized Controlled Trials

Intravascular imaging (IVI) during percutaneous coronary intervention (PCI) has been shown to improve clinical outcomes. However, data is limited in complex PCI and the adoption remains low. We aimed to conduct a meta-analysis of all available randomized controlled trials comparing IVI with conventional angiography in patients who underwent complex PCI. The primary outcomes of interest were major adverse cardiovascular events, all-cause death, cardiovascular death, myocardial infarction, stent thrombosis, target lesion revascularization and target vessel revascularization. Random-effects model was used to calculate pooled risk ratios (RRs) and 95% confidence intervals (CIs). A total of 10 randomized controlled trials comprising 6,368 patients with 3,452 in the IVI group and 2,916 in the angiography group were included. The mean duration of follow up was 2 years, mean age was 65 years and 73% of patients were men. As compared with PCI with routine angiography, the IVI-guided PCI group had significantly lower risks of major adverse cardiovascular events (RR 0.65, 95% CI 0.56 to 0.75, p <0.00001), stent thrombosis (RR 0.57, 95% CI 0.36 to 0.92, p = 0.02), cardiovascular deaths (RR 0.46, 95% CI 0.31 to 0.68, p = 0.0001), target lesion revascularization (RR 0.61, 95% CI 0.48 to 0.78, p <0.0001) and target vessel revascularization (RR 0.62, 95% CI 0.48 to 0.80, p = 0.0003). All-cause deaths and MI were similar in the 2 groups. In conclusion, among patients who underwent complex PCI, IVI reduces adverse events, importantly stent thrombosis and repeat revascularizations, compared with angiography alone guided PCI.

Trends and Inhospital Outcomes of Intravascular Imaging on Single-Vessel Coronary Chronic Total Occlusion Treated With Percutaneous Coronary Intervention

Intravascular imaging (IVI), including intravascular ultrasound (IVUS) and optical coherence tomography (OCT), improves outcomes of percutaneous coronary intervention (PCI) for chronic total occlusions (CTOs). We sought to quantify temporal trends in the uptake of IVI for CTO-PCI in the United States. We identified adults who underwent single-vessel PCI for CTO between 2008 and 2020. We quantified yearly trends in the number of IVUS-guided and OCT-guided single-vessel CTO-PCIs by Cochran-Armitage and linear regression tests. We also examined the rates of inhospital mortality and other prespecified inhospital outcomes in patients who underwent CTO-PCIs with and without IVI, using logistic regression. Our study included a total of 151,998 PCIs on single-vessel CTOs, with the absolute number of CTO-PCIs decreasing from 12,345 in 2008 to 8,525 in 2020 (p trend <0.001). IVUS use has increased dramatically from 6% in 2008 to 18% in 2020 for single-vessel CTO-PCIs (p trend <0.001). Rates of OCT use have increased as well, from 0% in 2008 to 7% in 2020 (p trend <0.001). There was no difference in inhospital mortality between patients who underwent CTO-PCI with and without IVI (p logistic = 0.60). In the largest national analysis of single-vessel CTO-PCI trends to date, we found that the use of IVUS has increased substantially accompanied by a similar but lesser increase in the use of OCT. There were no differences in rates of inhospital mortality between patients who underwent single-vessel CTO-PCIs with and without IVI.

Intracoronary imaging guided percutaneous coronary intervention outcomes among individuals with cardiogenic shock

BACKGROUND

Limited data exist around the utility of intracoronary imaging (ICI) during percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS) and cardiogenic shock (CS), who are inherently at a high risk of stent thrombosis (ST).

METHODS

All PCI procedures for ACS patients with CS in England and Wales between 2014 and 2020 were retrospectively analysed, stratified into two groups: ICI and angiography-guided groups. Multivariable logistic regression analyses were performed to examine odds ratios (OR) of in-hospital outcomes, including major adverse cardiovascular and cerebrovascular events (MACCE; composite of all-cause mortality, acute stroke/transient ischaemic attack (TIA), and reinfarction) and major bleeding, in the ICI-guided group compared with angiography-guided PCI.

RESULTS

Of 15,738 PCI procedures, 1240(7.9%) were ICI-guided. The rate of ICI use amongst those with CS more than doubled from 2014 (5.7%) to 2020 (13.3%). The ICI-guided group were predominantly younger, males, with a higher proportion of non-ST-elevation ACS and ST. MACCE was significantly lower in the ICI-guided group compared with the angiography-guided group (crude: 29.8% vs. 38.2%, adjusted odds ratio (OR) 0.65 95% confidence interval [CI] 0.56-0.76), driven by lower all-cause mortality (28.6% vs. 37.0%, OR 0.65 95% CI 0.55-0.75). There were no differences in other secondary outcomes between groups.

CONCLUSION

ICI use among CS patients has more than doubled over 6 years but remains significantly under-utilized, with less than 1-in-6 patients in receipt of ICI-guided PCI by 2020. ICI-guided PCI is associated with prognostic benefits in CS patients and should be more frequently utilized to increase their long-term survival.

Invasive imaging modalities in a spontaneous coronary artery dissection: when "believing is seeing"

Spontaneous coronary artery dissection (SCAD) is a rare but increasingly recognized cause of acute coronary syndrome (ACS) with recent advancements in cardiac imaging facilitating its identification. However, SCAD is still often misdiagnosed due to the absence of angiographic hallmarks in a significant number of cases, highlighting the importance of meticulous interpretation of angiographic findings and, when necessary, additional usage of intravascular imaging to verify changes in arterial wall integrity and identify specific pathoanatomical features associated with SCAD. Accurate diagnosis of SCAD is crucial, as the optimal management strategies for patients with SCAD differ from those with atherosclerotic coronary disease. Current treatment strategies favor a conservative approach, wherein intervention is reserved for cases with persistent ischemia, patients with high-risk coronary anatomy, or patients with hemodynamic instability. In this paper, we provide a preview of invasive imaging modalities and classical angiographic and intravascular imaging hallmarks that may facilitate proper SCAD diagnosis.

Acute Coronary Syndrome with Non-Obstructive Plaque on Angiography and Features of Vulnerable Plaque on Intracoronary Optical Coherence Tomography

Optical coherence tomography (OCT) has a high spatial resolution and is useful in identifying coronary lesions with high-risk features (vulnerable plaques). These plaques are strongly associated with acute coronary syndrome (ACS). In this report, we present the case of a 43-year-old male patient presenting with typical chest pain that began three hours prior to admission. The patient exhibited an elevation of the ST segments of the anterior and lateral walls. Invasive stratification revealed a 40% lesion in the middle segment of the left anterior descending (LAD) artery. The patient was given optimized clinical treatment as he had a nonobstructive lesion in the LAD at the time of angiography. During the treatment, the patient continued to complain of angina on exertion. A follow-up coronary angiography, along with OCT analysis of the middle-to-moderate lesion in the LAD, revealed a plaque predominantly rich in lipids with signs of vulnerability. A percutaneous coronary intervention was performed. The patient's recovery was uneventful, and he was discharged the day after the procedure. This case illustrates the evolution of intravascular imaging, particularly OCT, in the detection of vulnerable plaques.

Missed Coronary Artery Dissection Post-Blunt Chest Trauma

Cardiac contusion is rarely diagnosed in patients with blunt chest trauma in the emergency department, especially if patients are asymptomatic. We present a case of a 43-year-old man whose diagnosis of left anterior descending artery (LAD) dissection after blunt chest trauma was delayed. The patient presented to the emergency department of a remote district hospital after a motorcycle accident, asymptomatic with a mildly reduced level of consciousness due to a very small subdural hemorrhage. Ten days later, when he developed a syncopal attack due to a massive pulmonary embolism (PE), his first performed electrocardiogram (ECG) showed sinus rhythm with QS waves and slight ST elevation in leads V2-V6. The subsequent coronary angiography showed left anterior descending artery dissection, and the diagnosis was nicely depicted with optical coherence tomography (OCT). A drug-eluting stent was implanted with a good angiographic result. This case highlights the significance of early recognition of traumatic coronary dissection, which should be excluded even in asymptomatic patients with a plain ECG acquisition, for the appropriate management and prevention of unfavorable outcomes.

The role of intravascular imaging in chronic total occlusion percutaneous coronary intervention

Chronic total occlusions (CTOs) represent the most complex subset of coronary artery disease and therefore careful planning of CTO percutaneous coronary recanalization (PCI) strategy is of paramount importance aiming to achieve procedural success, and improve patient's safety and post CTO PCI outcomes. Intravascular imaging has an essential role in facilitating CTO PCΙ. First, intravascular ultrasound (IVUS), due to its higher penetration depth compared to optical coherence tomography (OCT), and the additional capacity of real-time imaging without need for contrast injection is considered the preferred imaging modality for CTO PCI. Secondly, IVUS can be used to resolve proximal cap ambiguity, facilitate wire re-entry when dissection and re-entry strategies are applied and most importantly to guide stent deployment and optimization post implantation. The role of OCT during CTO PCI is currently limited to stent sizing and optimization, however, due to its high spatial resolution, OCT is ideal for detecting stent edge dissections and strut malapposition. In this review, we describe the use of intravascular imaging for lesion crossing, plaque characterization and wire tracking, extra- or intra-plaque, and stent sizing and optimization during CTO PCI and summarize the findings of the major studies in this field.

Clinical and Procedural Outcomes of IVUS-Guided vs. Angiography-Guided CTO-PCI: A Systematic Review and Meta-Analysis

Chronic total occlusions (CTO) in coronary angiographies present a significant challenge nowadays. Intravascular ultrasound (IVUS) is a valuable tool during CTO-PCI, aiding in planning and achieving procedural success. However, the impact of IVUS on clinical and procedural outcomes in CTO-PCI remains uncertain. This meta-analysis aimed to compare IVUS-guided and angiography-guided approaches in CTO-PCI. The study included five studies and 2320 patients with stable coronary artery disease (CAD) and CTO. The primary outcome of major adverse cardiac events (MACE) did not significantly differ between the groups (p = 0.40). Stent thrombosis was the only secondary clinical outcome that showed a significant difference, favoring the IVUS-guided approach (p = 0.01). Procedural outcomes revealed that IVUS-guided procedures had longer stents, larger diameters, and longer procedure and fluoroscopy times (p = 0.007, p < 0.001, p = 0.03, p = 0.002, respectively). Stent number and contrast volume did not significantly differ between the approaches (p = 0.88 and p = 0.33, respectively). In summary, routine IVUS use did not significantly improve clinical outcomes, except for reducing stent thrombosis. Decisions in CTO-PCI should be individualized based on patient characteristics and supported by a multi-parametric approach.

Intravascular Imaging Use in Percutaneous Coronary Interventions of Chronic Total Occlusions

BACKGROUND

Intravascular ultrasound (IVUS) can assist percutaneous coronary intervention (PCI) of chronic total occlusions (CTO).

METHODS

We analyzed 8,983 CTO PCIs performed in 8,771 patients between 2012 and 2022 at 39 centers.

RESULTS

Overall, IVUS was used in 44.5% of the cases, for crossing in 11.5% and for stent optimization in 33.1%. IVUS for stent optimization was used more often for complex lesions with higher prevalence of calcification (51.2% vs 34.3%; P<.001); was associated with lower air kerma radiation dose (1.78 [1.00, 3.09] vs 2.30 (1.35, 3.91) min, P<.001) and contrast volume (190 [138, 258] vs 220 [160, 300] ml, P<.001). Among cases with successful guidewire crossing, those that used IVUS for stent optimization had higher technical (99.3% vs 96.3%; P<.001) and procedural (96.1% vs 94.6%, P=.002) success rates and similar major adverse complication event rates (2.04% vs 1.62%; P=.176). The use of IVUS for stent optimization significantly increased over time.

CONCLUSION

In a contemporary, multicenter registry, IVUS was used in 44.5% and its use for stent optimization significantly increased over time. Cases where IVUS was used for stent optimization had higher technical and procedural success and similar risk of complications compared with cases where IVUS was not used for stent optimization.

Accounting for blood attenuation in intravascular near-infrared fluorescence-ultrasound imaging using a fluorophore-coated guidewire

Significance

Intravascular near-infrared fluorescence (NIRF) imaging aims to improve the inspection of vascular pathology using fluorescent agents with specificity to vascular disease biomarkers. The method has been developed to operate in tandem with an anatomical modality, such as intravascular ultrasound (IVUS), and complements anatomical readings with pathophysiological contrast, enhancing the information obtained from the hybrid examination.

Aim

However, attenuation of NIRF signals by blood challenges NIRF quantification. We propose a new method for attenuation correction in NIRF intravascular imaging based on a fluorophore-coated guidewire that is used as a reference for the fluorescence measurement and provides a real-time measurement of blood attenuation during the NIRF examination.

Approach

We examine the performance of the method in a porcine coronary artery ex vivo and phantoms using a 3.2F NIRF-IVUS catheter.

Results

We demonstrate marked improvement over uncorrected signals of up to 4.5-fold and errors of < 11 % for target signals acquired at distances up to 1 mm from the catheter system employed.

Conclusions

The method offers a potential means of improving the accuracy of intravascular NIRF imaging under in vivo conditions.

Zero-contrast IVUS-guided complex PCI in a patient with NSTE-ACS and severe renal impairment

A 76-year-old male with severe comorbidities and multiple cardiovascular risk factors including stage IV chronic kidney disease presents with non-ST-elevation myocardial infarction. An ultra-low contrast invasive coronary angiography using the DyeVert system and iso-osmolar contrast agent revealed a multivessel disease with heavy calcifications involving the left main stem and its bifurcation requiring a complex percutaneous coronary intervention. Because of the high risk of contrast-induced acute kidney injury, a zero-contrast intervention was performed using intravascular ultrasound guidance and dedicated stenting techniques with optimal imaging, clinical, and renal outcomes. Zero-contrast policies can be safely implemented even in complex clinical scenarios but at least two orthogonal angiographic projections should always be acquired to rule out distal complications.

Intravascular Imaging of Atherosclerosis by Using Engineered Nanoparticles

Atherosclerosis is a leading cause of morbidity and mortality, and high-risk atherosclerotic plaques can result in myocardial infarction, stroke, and/or sudden death. Various imaging and sensing techniques (e.g., ultrasound, optical coherence tomography, fluorescence, photoacoustic) have been developed for scanning inside blood vessels to provide accurate detection of high-risk atherosclerotic plaques. Nanoparticles have been utilized in intravascular imaging to enable targeted detection of high-risk plaques, to enhance image contrast, and in some applications to also provide therapeutic functions of atherosclerosis. In this paper, we review the recent progress on developing nanoparticles for intravascular imaging of atherosclerosis. We discuss the basic nanoparticle design principles, imaging modalities and instrumentations, and common targets for atherosclerosis. The review is concluded and highlighted with discussions on challenges and opportunities for bringing nanoparticles into in vivo (pre)clinical intravascular applications.

Intravascular Imaging During Percutaneous Coronary Intervention: JACC State-of-the-Art Review

Coronary angiography has historically served as the gold standard for diagnosis of coronary artery disease and guidance of percutaneous coronary intervention (PCI). Adjunctive use of contemporary intravascular imaging (IVI) technologies has emerged as a complement to conventional angiography-to further characterize plaque morphology and optimize the performance of PCI. IVI has utility for preintervention lesion and vessel assessment, periprocedural guidance of lesion preparation and stent deployment, and postintervention assessment of optimal endpoints and exclusion of complications. The role of IVI in reducing major adverse cardiac events in complex lesion subsets is emerging, and further studies evaluating broader use are underway or in development. This paper provides an overview of currently available IVI technologies, reviews data supporting their utilization for PCI guidance and optimization across a variety of lesion subsets, proposes best practices, and advocates for broader use of these technologies as a part of contemporary practice.

Educational Experience of Interventional Cardiology Fellows in the United States and Canada

BACKGROUND

The COVID-19 pandemic and iodinated contrast shortage may have affected interventional cardiology (IC) fellowship training.

OBJECTIVES

The aim of this study was to investigate the educational experience of first-year IC fellows in the United States and Canada.

METHODS

A 59-question online survey was conducted among 2021-2022 first-year IC fellows in the United States and Canada.

RESULTS

Of the 360 IC fellows invited to participate, 111 (31%) responded; 95% were from the United States, and 79% were men. Participants were mostly from university programs (70%), spent 61 to 70 hours/week in the hospital, and had an annual percutaneous coronary intervention case number of <200 (5%), 200 to 249 (8%), 250 to 349 (33%), 350 to 499 (39%), 500 to 699 (12%), or ≥700 (3%). For femoral access, a micropuncture needle was used regularly by 89% and ultrasound-guided puncture by 81%, and 43% used vascular closure devices in most cases (>80%). Intravascular ultrasound was performed and interpreted very comfortably by 62% and optical coherence tomography (OCT) by 32%, and 20% did not have access to OCT. Approximately one-third felt very comfortable performing various atherectomy techniques. Covered stents, fat embolization, and coil embolization were used very comfortably by 14%, 4%, and 3%, respectively. Embolic protection devices were used very comfortably by 11% to 24% of IC fellows. Almost one-quarter of fellows (24%) were warned about their high radiation exposure. Eighty-four percent considered IC fellowship somewhat or very stressful, and 16% reported inadequate psychological support.

CONCLUSIONS

This survey highlights opportunities for improvement with regard to the use of intravascular imaging, atherectomy techniques, complication prevention and management strategies, radiation awareness and mitigation, and psychological support.

Efficacy of a new generation intracoronary optical coherence tomography imaging system with fast pullback

OBJECTIVES

We sought to investigate whether a novel, fast-pullback, high-frequency optical coherence tomography (HF-OCT) imaging system enables data acquisition with a reduced amount of contrast agents while retaining the same qualitative and quantitative lesion assessment to conventional OCT.

BACKGROUND

The increased amount of administered contrast agents is a major concern when performing intracoronary OCT.

METHODS

The present study is a single-center, prospective, observational study including 10 patients with stable coronary artery disease. A total of 28 individual coronary arteries were assessed by both fast-pullback HF-OCT and by conventional OCT.

RESULTS

The contrast volume used in each OCT run for the HF-OCT system was significantly lower than for the conventional OCT system (5.0 ± 0.0 mL vs. 7.8 ± 0.7 mL, respectively, with a mean difference of -2.84 [95% confidence interval [CI]: -3.10 to -2.58]). No significant difference was found in the median value of the clear image length between the two OCT systems (74 mm [interquartile range [IQR]; 63, 81], 74 mm [IQR; 71, 75], p = 0.89). Fast-pullback HF-OCT showed comparable measurements to conventional OCT, including minimum lumen area (3.27 ± 1.53 mm² vs. 3.21 ± 1.53 mm² , p = 0.27), proximal reference area (7.03 ± 2.28 mm² vs. 7.03 ± 2.34 mm² , p = 0.96), and distal reference area (5.93 ± 1.96 mm² vs. 6.03 ± 2.02 mm² , p = 0.23). Qualitative OCT findings were comparable between the fast-pullback HF-OCT runs and conventional OCT with respect to identifying lipid-rich plaques, calcifications, layered plaques, macrophages, and cholesterol crystals.

CONCLUSION

With the fast pullback function of a novel HF-OCT imaging system, we acquired OCT images using a significantly lower amount of contrast volume while retaining a comparable qualitative and quantitative lesion assessment to conventional OCT.

Thrombosis and myocardial infarction: the role of bioresorbable scaffolds

Coronary stents have dramatically improved the treatment of coronary artery stenosis. In-stent-restenosis (ISR) and stent thrombosis (ST) pose major obstacles to the success of coronary stenting. Drug-eluting stents (DES) emerged as a major breakthrough in stenting and significantly reduced ISR. Despite taking dual antiplatelet therapy (DAPT), very late ST has remained a major obstacle in the success of DES. This occurs regardless of the type of polymer or antiproliferative agent in the contemporary stents. Such adverse events occur at a rate of approximately 2% to 3% per year after first year, which have been attributed to the strut fractures, loss of vessel compliance and vasomotion, and neoatherosclerosis. Fully bioresorbable scaffolds (BRS) have emerged in an effort to overcome these limitations leading to a "leave nothing behind" approach. While appealing, the initial experience with BRS technology was hampered by increased rates of BRS thrombosis compared with DES. In this review, we summarized underlying mechanisms leading to BRS failure and provided insights into optimizing BRS deployment with intravascular imaging. In addition, we outlined the perspectives of new generations BRS with thinner struts and new designs as well as alternative materials to improve outcome.

Long-term outcomes following intravascular lithotripsy (IVL) for calcified coronary lesions: A Real-World Multicenter European Study

OBJECTIVES

To explore the long-term clinical outcomes following intravascular lithotripsy (IVL) in calcified coronary lesions from a real-world population.

BACKGROUND

IVL is a relatively new but promising modality for treating coronary calcified lesions, but there is a dearth of long-term outcome data from real-world patients.

METHODS

This was a multicenter, observational study in which we enrolled all patients treated with IVL from November 2018 to February 2021 from eight centers in Europe and the United Kingdom. Procedural success, complications, and clinical outcomes (cardiac death, target vessel myocardial infarction [TVMI], target lesion revascularization [TLR], and MACE [major adverse cardiac events, the composite of cardiac death, TVMI, and TLR]) were assessed.

RESULTS

In total, 273 patients with a mean age of 72 ± 9.1 years were treated with IVL. Major comorbidities included diabetes mellitus (n = 110, 40%) and chronic kidney disease (n = 45, 16%). Acute coronary syndrome accounted for 48% (n = 132) of patients, while 52% (n = 141) had stable angina. De novo lesions and in-stent restenosis accounted for 79% and 21% of cases, respectively. Intravascular imaging was used in 33% (n = 90) of patients. An upfront IVL strategy was adopted in 34% (n = 92), while the rest were bailout procedures. Adjuvant rotational atherectomy ("RotaTripsy") was required in 11% (n = 31) of cases. The procedural success was 99%. During a median follow-up of 687 days (interquartile range: 549-787), cardiac death occurred in 5% (n = 14), TVMI in 3% (n = 8), TLR in 6% (n = 16), and MACE rate was 11% (n = 30).

CONCLUSION

This is the largest multicenter registry with a long-term follow-up showing the remarkably high procedural success of IVL use in calcified coronary lesions with low rates of hard endpoints and MACE.

Pulmonary Vascular Remodeling and Prognosis in Patients Evaluated for Heart Transplantation: Insights from the OCTOPUS-CHF Study

OBJECTIVE

In patients with advanced heart failure, the intravascular optical coherence tomography (OCT) of subsegmental pulmonary artery measurements is correlated with right heart catheterization parameters. Our aim was to study the prognostic value of pulmonary OCT, right heart catheterization data, and the echocardiographic estimation of pulmonary pressure in patients studied for elective heart transplants.

METHODS

This research is an observational, prospective, multicenter study involving 90 adults with a one-year follow-up.

RESULTS

A total of 10 patients (11.1%) died due to worsening heart failure before heart transplantation, 50 underwent a heart transplant (55.6%), and 9 died in the first year after the transplant. The patients with and without events (mortality or heart failure-induced hospitalization) had similar data regarding echocardiography, right heart catheterization, and pulmonary OCT (with a median estimated pulmonary artery systolic pressure of 42.0 mmHg, interquartile range (IQR) of 30.3-50.0 vs. 47.0 mmHg, IQR 34.6-59.5 and p = 0.79, median pulmonary vascular resistance of 2.2 Wood units, IQR 1.3-3.7 vs. 2.0 Wood units, IQR 1.4-3.2 and p = 0.99, and a median pulmonary artery wall thickness of 0.2 ± 0.5 mm vs. 0.2 ± 0.6 mm and p = 0.87).

CONCLUSION

Pulmonary vascular remodeling (evaluated with echocardiography, right heart catheterization, and pulmonary OCT) was not associated with prognosis in a selected sample of adults evaluated for elective heart transplants. Pulmonary OCT is safe and feasible for the evaluation of these patients.

Intravascular imaging for left main stem assessment: An update on the most recent clinical data

Left main (LM) stem has different structural and anatomical characteristics compared to all of the other segments of the coronary tree, thus its management through percutaneous coronary intervention (PCI) is a challenge and is associated with worse clinical outcome and higher need for revascularization as compared to other lesion settings. Intravascular imaging, by means of intravascular ultrasound (IVUS) or optical coherence tomography (OCT), is an important tool for LM PCI guidance, aiming at improving the immediate performance and the long term outcome of this procedure. Following current guidelines and recent scientific findings, IVUS becomes important to firstly assess, and finally evaluate the result of LM stenting, according to the experience and preferences of the operator. The role of OCT still remains to be defined, but recent data is shedding light also on this imaging technique. The aim of this review is to highlight the latest scientific advancements regarding intravascular imaging in LM coronary artery disease.

Decision-Making During Percutaneous Coronary Intervention Guided by Optical Coherence Tomography: Insights From the LightLab Initiative

BACKGROUND

Use of intracoronary imaging is associated with improved outcomes in patients undergoing percutaneous coronary intervention (PCI). Yet, the impact of intracoronary imaging on real-time physician decision-making during PCI is not fully known.

METHODS

The LightLab Initiative is a multicenter, prospective, observational study designed to characterize the use of a standardized optical coherence tomography (OCT) workflow during PCI. Participating physicians performed pre-PCI and post-PCI OCT in accordance with this workflow and operator assessments of lesion characteristics and treatment plan were recorded for each lesion based on angiography alone and following OCT. Physicians were categorized as having low (n=15), intermediate (n=13), or high (n=14) OCT use in the year preceding participation.

RESULTS

Among 925 patients with 1328 lesions undergoing PCI, the prescribed OCT workflow was followed in 773 (84%) of patients with 836 lesions. Operator lesion assessment and decision-making during PCI changed with OCT use in 86% (721/836) of lesions. Pre-PCI OCT use changed operator decision-making in 80% of lesions, including lesion assessment (45%), vessel preparation strategy (27%), stent diameter (37%), and stent length (36%). Post-PCI OCT changed stent optimization decision-making in 31% of lesions. These findings were consistent across strata of physician prior OCT experience.

CONCLUSIONS

A standardized OCT workflow impacted PCI decision-making in 86% of lesions, with a predominant effect on pre-PCI lesion assessment and planning of treatment strategy. This finding was consistent regardless of operator experience level and provides insight into mechanisms by which intravascular imaging might improve PCI outcomes.

Intracoronary Imaging of Vulnerable Plaque-From Clinical Research to Everyday Practice

The introduction into clinical practice of intravascular imaging, including intravascular ultrasound (IVUS), optical coherence tomography (OCT) and their derivatives, allowed for the in vivo assessment of coronary atherosclerosis in humans, including insights into plaque evolution and progression process. Intravascular ultrasound, the most commonly used intravascular modality in many countries, due to its low resolution cannot assess many features of vulnerable plaque such as lipid plaque or thin-cap fibroatheroma. Thus, novel methods were introduced to facilitate this problem including virtual histology intravascular ultrasound and later on near-infrared spectroscopy and OCT. Howbeit, none of the currently used modalities can assess all known characteristics of plaque vulnerability; hence, the idea of combining different intravascular imaging methods has emerged including NIRS-IVUS or OCT-IVUS imaging. All of those described methods may allow us to identify the most vulnerable plaques, which are prone to cause acute coronary syndrome, and thus they may allow us to introduce proper treatment before plaque destabilization.

Determinants and long-term outcomes of largely uncovered struts in thin-struts drug-eluting stents assessed by optical coherence tomography

BACKGROUND

Uncovered struts are a determinant of stent failure. The impact of plaque composition and procedural factors on the occurrence, evolution, and outcomes of uncovered struts in a high-risk setting has not been investigated.

OBJECTIVE

To investigate the determinants and long-term clinical impact of largely uncovered struts (LUS) in thin-struts drug-eluting stents (DES) implanted in complex lesions by intracoronary optical coherence tomography (OCT).

METHODS

Ninety patients with multivessel disease undergoing staged complete revascularization were randomly assigned to bioabsorbable or durable polymer DES. OCT were serially performed during the index procedure, at 3- and 18-month follow-up, and analyzed by an independent core lab. Struts were defined uncovered by OCT if no tissue was visible above the struts. LUS were defined as ≥30% of uncovered struts at 3-month follow-up. Clinical outcomes were the occurrence of target vessel failure (TVF) and major adverse cardiac and cerebrovascular events (MACCE) at 5-year follow-up.

RESULTS

LUS occurred in 31 patients (34.4%) regardless of stent platform. At 5 years, no differences were observed in the rate of TVF (12.7% vs. 13.4%; p = 0.91) and MACCE (23.9% vs. 24.9%; p = 0.88) between the two groups. At multivariate logistic regression, plaque rupture, mean lumen diameter, proximal reference vessel area, and maximum stent deployment pressure were independent predictors of LUS.

CONCLUSIONS

LUS are a frequent finding in complex coronary lesions treated with thin-struts DES, especially in the presence of plaque rupture. However, in this study, no significant safety signal related to LUS emerged in long-term follow-up.

Quantitative Flow Ratio Is Related to Anatomic Left Main Stem Lesion Parameters as Assessed by Intravascular Imaging

Introduction: Previously, an association between anatomic left main stem (LMS) lesion parameters, as described by intravascular ultrasound (IVUS) and fractional flow reserve (FFR), was shown. Quantitative flow ratio (QFR) is a novel, promising technique which can assess functional stenosis relevance based only on angiography. However, as little is known about the relationship between anatomic LMS parameters and QFR, it was thus investigated in this study. Methods: In 53 patients with LMS disease, we tested the association between anatomic assessment using OCT (n = 28) or IVUS (n = 25) on the one hand and functional assessment as determined by QFR on the other hand. LMS-QFR was measured using a dedicated approach, averaging QFR over left anterior descending (LAD) and circumflex (LCX) and manually limiting segment of interest to LMS. Results: The minimal luminal area of the LMS (LMS-MLA) as measured by intravascular imaging showed a consistent correlation with QFR (R = 0.61, p < 0.001). QFR could predict a LMS-MLA < 6 mm2 with very good diagnostic accuracy (AUC 0.919) and a LMS-MLA < 4.5 mm2 with good accuracy (AUC 0.798). Similar results were obtained for other stenosis parameters. Conclusions: QFR might be a valuable tool to assess LMS disease. Further studies focusing on patient outcomes are needed to further validate the effectiveness of this approach.

Contemporary Management of Severely Calcified Coronary Lesions

Coronary artery calcification is increasingly prevalent in our patient population. It significantly limits the procedural success of percutaneous coronary intervention and is associated with a higher risk of adverse cardiovascular events both in the short-term and long-term. There are several modalities for modifying calcified plaque, such as balloon angioplasty (including specialty balloons), coronary atheroablative therapy (rotational, orbital, and laser atherectomy), and intravascular lithotripsy. We discuss each modality’s relative advantages and disadvantages and the data supporting their use. This review also highlights the importance of intravascular imaging to characterize coronary calcification and presents an algorithm to tailor the calcium modification therapy based on specific coronary lesion characteristics.

Optical coherence tomography in the diagnosis of myocardial infarction with non-obstructive coronary arteries

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a working diagnosis and requires identification of the underlying causes to optimize treatment, improve prognosis, and prevent the recurrence of myocardial infarction. According to the literature, the prognosis of patients diagnosed with MINOCA is comparable to the group of patients with myocardial infarction (MI) and significant stenosis of the coronary arteries. Intracoronary imaging is a crucial diagnostic tool used in identifying epicardial causes of MINOCA that are not visible in coronary angiography. Optical coherence tomography (OCT) provides the highest spatial resolution, simultaneously allowing detailed visualization of plaque pathology in individuals with MINOCA and identifying the cause of MI in up to 80% of patients. Common causes of a MINOCA may include plaque disruption, spontaneous coronary artery dissection (SCAD), coronary artery spasm, and coronary thromboembolism. The optimization of pharmacological treatment in this group of patients, especially dual antiplatelet therapy and statins, improves the prognosis. Data on the indications for invasive treatment of patients with MINOCA based on OCT findings are insufficient. There is a strong need for research comparing treatment strategies, especially in high-risk lesions visualized in OCT. The main aim of this review is to demonstrate the usefulness of OCT in determining the mechanism of MINOCA.

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

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

Framework for lumen-based nonrigid tomographic coregistration of intravascular images

Purpose: Modern medical imaging enables clinicians to effectively diagnose, monitor, and treat diseases. However, clinical decision-making often relies on combined evaluation of either longitudinal or disparate image sets, necessitating coregistration of multiple acquisitions. Promising coregistration techniques have been proposed; however, available methods predominantly rely on time-consuming manual alignments or nontrivial feature extraction with limited clinical applicability. Addressing these issues, we present a fully automated, robust, nonrigid registration method, allowing for coregistering of multimodal tomographic vascular image datasets using luminal annotation as the sole alignment feature. Approach: Registration is carried out by the use of the registration metrics defined exclusively for lumens shapes. The framework is primarily broken down into two sequential parts: longitudinal and rotational registration. Both techniques are inherently nonrigid in nature to compensate for motion and acquisition artifacts in tomographic images. Results: Performance was evaluated across multimodal intravascular datasets, as well as in longitudinal cases assessing pre-/postinterventional coronary images. Low registration error in both datasets highlights method utility, with longitudinal registration errors-evaluated throughout the paired tomographic sequences-of 0.29 ± 0.14    mm ( < 2 longitudinal image frames) and 0.18 ± 0.16    mm ( < 1 frame) for multimodal and interventional datasets, respectively. Angular registration for the interventional dataset rendered errors of 7.7 ° ± 6.7 ° , and 29.1 ° ± 23.2 ° for the multimodal set. Conclusions: Satisfactory results across datasets, along with additional attributes such as the ability to avoid longitudinal over-fitting and correct nonlinear catheter rotation during nonrigid rotational registration, highlight the potential wide-ranging applicability of our presented coregistration method.

Dual-modality fluorescence lifetime imaging-optical coherence tomography intravascular catheter system with freeform catheter optics

SIGNIFICANCE

Intravascular imaging is key to investigations into atherosclerotic plaque pathobiology and cardiovascular diagnostics overall. The development of multimodal imaging devices compatible with intracoronary applications has the potential to address limitations of currently available single-modality systems.

AIM

We designed and characterized a robust, high performance multimodal imaging system that combines optical coherence tomography (OCT) and multispectral fluorescence lifetime imaging (FLIm) for intraluminal simultaneous assessment of structural and biochemical properties of coronary arteries.

APPROACH

Several shortcomings of existing FLIm-OCT catheter systems are addressed by adopting key features, namely (1) a custom fiber optic rotary joint based on an air bearing, (2) a broadband catheter using a freeform reflective optics, and (3) integrated solid-state FLIm detectors. Improvements are quantified using a combination of experimental characterization and simulations.

RESULTS

Excellent UV and IR coupling efficiencies and stability (IR: 75.7 % ± 0.4 % , UV: 45.7 % ± 0.35 % ) are achieved; high FLIm optical performance is obtained (UV beam FWHM: 50 μm) contemporaneously with excellent OCT beam quality (IR beam FWHM: 17 μm). High-quality FLIm OCT image of a human coronary artery specimen was acquired.

CONCLUSION

The ability of this intravascular imaging system to provide comprehensive structural and biochemical properties will be valuable to further our understanding of plaque pathophysiology and improve cardiovascular diagnostics.

Outcomes of Intravascular Ultrasound-Guided Versus Angiography-Guided Percutaneous Coronary Interventions in Chronic Total Occlusions: A Systematic Review and Meta-Analysis

BACKGROUND

Percutaneous coronary interventions (PCI) with intravascular ultrasound (IVUS) guidance have been associated with better long-term outcomes, but adoption remains limited. There are limited data on the impact of IVUS on chronic total occlusion (CTO)-PCI.

OBJECTIVES

To examine the impact of IVUS guidance on the outcomes of CTO-PCI.

METHODS

We performed a systematic review and study-level meta-analysis of IVUS vs angiography-guided CTO-PCI. Electronic databases were systematically searched for all pertinent studies from inception through January 2021. Randomized controlled trials (RCT), registry data, and abstracts published in peer-reviewed indexed journals were included. We examined the following in-hospital and long-term outcomes: major adverse cardiac events; all-cause mortality; cardiovascular mortality; myocardial infarction (MI); target-vessel revascularization (TVR); target-lesion revascularization (TLR); and stent thrombosis (ST). We also evaluated the following procedural metrics: procedure time; fluoroscopy time; contrast volume; total stent length; and total number of stents. Random-effects models were used to pool individual study results.

RESULTS

Four (2 observational, 2 randomized) studies including 1975 patients (IVUS-guided PCI, 861 patients; angiography-guided PCI, 1114 patients) were included in the analysis. IVUS-guided CTO-PCI had similar all-cause mortality, major adverse cardiac events, cardiovascular mortality, MI, TVR, and TLR compared with angiography-guided CTO-PCI, but lower risk of stent thrombosis (odds ratio, 0.24; 95% confidence interval, 0.08-0.76; P=.02; I²=0%), shorter procedure time (P<.001; I²=88%), shorter fluoroscopy time (P<.001; I²=63%), and less contrast volume use (P<.001; I²=59%). Total stent length (P<.001; I²=39%) and total number of stents (P<.001; I²=72%) were lower with IVUS-guided CTO-PCI.

CONCLUSION

IVUS-guided CTO-PCI is associated with lower risk of ST.

An Ex Vivo Study of Outward Electrical Impedance Tomography (OEIT) for Intravascular Imaging

OBJECTIVE

Atherosclerosis is a chronic immuno-inflammatory condition emerging in arteries and considered the cause of a myriad of cardiovascular diseases. Atherosclerotic lesion characterization through invasive imaging modalities is essential in disease evaluation and determining intervention strategy. Recently, electrical properties of the lesions have been utilized in assessing its vulnerability mainly owing to its capability to differentiate lipid content existing in the lesion, albeit with limited detection resolution. Electrical impedance tomography is the natural extension of conventional spectrometric measurement by incorporating larger number of interrogating electrodes and advanced algorithm to achieve imaging of target objects and thus provides significantly richer information. It is within this context that we develop Outward Electrical Impedance Tomography (OEIT), aimed at intravascular imaging for atherosclerotic lesion characterization.

METHODS

We utilized flexible electronics to establish the 32-electrode OEIT device with outward facing configuration suitable for imaging of vessels. We conducted comprehensive studies through simulation model and ex vivo setup to demonstrate the functionality of OEIT.

RESULTS

Quantitative characterization for OEIT regarding its proximity sensing and conductivity differentiation was achieved using well-controlled experimental conditions. Imaging capability for OEIT was further verified with phantom setup using porcine aorta to emulate in vivo environment.

CONCLUSION

We have successfully demonstrated a novel tool for intravascular imaging, OEIT, with unique advantages for atherosclerosis detection.

SIGNIFICANCE

This study demonstrates for the first time a novel electrical tomography-based platform for intravascular imaging, and we believe it paves the way for further adaptation of OEIT for intravascular detection in more translational settings and offers great potential as an alternative imaging tool for medical diagnosis.

Review on Laser Technology in Intravascular Imaging and Treatment

Blood vessels are one of the most essential organs, which nourish all tissues in our body. Once there are intravascular plaques or vascular occlusion, other organs and circulatory systems will not work properly. Therefore, it is necessary to detect abnormal blood vessels by intravascular imaging technologies for subsequent vascular treatment. The emergence of lasers and fiber optics promotes the development of intravascular imaging and treatment. Laser imaging techniques can obtain deep vascular images owing to light scattering and absorption properties. Moreover, photothermal and photomechanical effects of laser make it possible to treat vascular diseases accurately. In this review, we present the research progress and applications of laser techniques in intravascular imaging and treatment. Firstly, we introduce intravascular optical coherent tomography and intravascular photoacoustic imaging, which can obtain various information of plaques. Multimodal intravascular imaging techniques provide more information about intravascular plaques, which have an essential influence on intravascular imaging. Secondly, two laser techniques including laser angioplasty and endovenous laser ablation are discussed for the treatment of arterial and venous diseases, respectively. Finally, the outlook of laser techniques in blood vessels, as well as the integration of laser imaging and treatment are prospected in the section of discussions.