Intracoronary optical coherence tomography: state of the art and future directions

Emerging opportunities to target inflammation: myocardial infarction and type 2 diabetes

After myocardial infarction (MI), patients with type 2 diabetes have an increased rate of adverse outcomes, compared to patients without. Diabetes confers a 1.5-2-fold increase in early mortality and, importantly, this discrepancy has been consistent over recent decades, despite advances in treatment and overall survival. Certain assumptions have emerged to explain this increased risk, such as differences in infarct size or coronary artery disease severity. Here, we re-evaluate that evidence and show how contemporary analyses using state-of-the-art characterization tools suggest that the received wisdom tells an incomplete story. Simultaneously, epidemiological and mechanistic biological data suggest additional factors relating to processes of diabetes-related inflammation might play a prominent role. Inflammatory processes after MI mediate injury and repair and are thus a potential therapeutic target. Recent studies have shown how diabetes affects immune cell numbers and drives changes in the bone marrow, leading to pro-inflammatory gene expression and functional suppression of healing and repair. Here, we review and re-evaluate the evidence around adverse prognosis in patients with diabetes after MI, with emphasis on how targeting processes of inflammation presents unexplored, yet valuable opportunities to improve cardiovascular outcomes in this vulnerable patient group.

Bifurcation detection in intravascular optical coherence tomography using vision transformer based deep learning

Objective. Bifurcation detection in intravascular optical coherence tomography (IVOCT) images plays a significant role in guiding optimal revascularization strategies for percutaneous coronary intervention (PCI). We propose a bifurcation detection method using vision transformer (ViT) based deep learning in IVOCT.Approach. Instead of relying on lumen segmentation, the proposed method identifies the bifurcation image using a ViT-based classification model and then estimate bifurcation ostium points by a ViT-based landmark detection model.Main results. By processing 8640 clinical images, the Accuracy and F1-score of bifurcation identification by the proposed ViT-based model are 2.54% and 16.08% higher than that of traditional non-deep learning methods, are similar to the best performance of convolutional neural networks (CNNs) based methods, respectively. The ostium distance error of the ViT-based model is 0.305 mm, which is reduced 68.5% compared with the traditional non-deep learning method and reduced 24.81% compared with the best performance of CNNs based methods. The results also show that the proposed ViT-based method achieves the highest success detection rate are 11.3% and 29.2% higher than the non-deep learning method, and 4.6% and 2.5% higher than the best performance of CNNs based methods when the distance section is 0.1 and 0.2 mm, respectively.Significance. The proposed ViT-based method enhances the performance of bifurcation detection of IVOCT images, which maintains a high correlation and consistency between the automatic detection results and the expert manual results. It is of great significance in guiding the selection of PCI treatment strategies.

Investigations of injection strategies to use heparinized normal saline instead of contrast media for intracoronary optical coherence tomography imaging

BACKGROUND

The benefits of intravascular imaging-guided percutaneous coronary interventions (PCI) are well established. Intravascular imaging guidance improves short- and long-term outcomes, especially in complex PCI. Optical coherence tomography (OCT) has a higher resolution than intravascular ultrasound. However, the usage of OCT is mainly limited by the need to use contrast for flushing injections, which increases the risk of contrast-induced acute kidney injury, especially in patients with underlying chronic kidney disease. The aim of this study was to prove that flushing techniques with normal saline instead of contrast can be used in OCT imaging and can generate high-quality images.

METHODS

This prospective single-center observational study included patients with indications for OCT-guided PCI. For OCT pullbacks, heparinized saline was injected by an automatic pump injector at different rates, and additional extension catheters for selective coronary artery engagement were used at the operator's discretion. Recordings were made using the Ilumien Optis OCT system (Abbott) and the Dragonfly (Abbott) catheter and were analyzed at 1-mm intervals by two operators. Pullbacks were categorized as having optimal, acceptable, or unacceptable imaging quality. A clinically usable run was determined if >75% of the region of interest length was described as having optimal or acceptable imaging quality.

RESULTS

A total of 32 patients were enrolled in the study; 47 different lesions were assessed before and after PCI. In total, 91.5% of runs were described as clinically suitable for use.

CONCLUSION

Heparinized saline injections for OCT imaging are effective in generating good-quality OCT images suitable for clinical use.

Long-term clinical outcomes of image-guided percutaneous coronary intervention in acute myocardial infarction from the Korea Acute Myocardial Infarction Registry

Imaging modalities for percutaneous coronary intervention (PCI), such as intravascular ultrasound (IVUS) or optical coherence tomography (OCT), have increased in the current PCI era. However, their clinical benefits in acute myocardial infarction (AMI) have not been fully elucidated. This study investigated the long-term outcomes of image-guided PCI in patients with AMI using data from the Korean Acute Myocardial Infarction Registry. A total of 9,271 patients with AMI, who underwent PCI with second-generation drug-eluting stents between November 2011 and December 2015, were retrospectively examined, and target lesion failure (TLF) at 3 years (defined as the composite of cardiac death, target vessel myocardial infarction, and ischemia-driven target lesion revascularization) was evaluated. From the registry, 2,134 patients (23.0%) underwent image-guided PCI (IVUS-guided: n = 1,919 [20.6%]; OCT-guided: n = 215 patients [2.3%]). Based on propensity score matching, image-guided PCI was associated with a significant reduction in TLF (hazard ratio: 0.76; 95% confidence interval: 0.59-0.98, p = 0.035). In addition, the TLF incidence in the OCT-guided PCI group was comparable to that in the IVUS-guided PCI group (5.3% vs 4.7%, p = 0.903). Image-guided PCI, including IVUS and OCT, is associated with favorable clinical outcomes in patients with AMI at 3 years post-intervention. Additionally, OCT-guided PCI is not inferior to IVUS-guided PCI in patients with AMI.

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

ABSTRACT

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

Renal Dysfunction Increases Risk of Adverse Cardiovascular Events in 5-Year Follow-Up Study of Intermediate Coronary Artery Lesions

BACKGROUND Progression of chronic coronary syndrome (CCS) is influenced by chronic kidney disease (CKD). This 5-year follow-up study aimed to assess 100 patients with 118 intermediate coronary artery lesions evaluated by fractional flow reserve (FFR) and intravascular imaging stratified according to renal function. MATERIAL AND METHODS This prospective study enrolled patients with intermediate coronary stenosis identified by coronary angiogram. Patients with severe renal dysfunction (estimated glomerular filtration rate (eGFR) <45 ml/min/1.73 m²) were excluded from the study. The remaining were divided into 2 groups according to eGFR: 45-60 ml/min/1.73 m² for mild-to-moderate renal dysfunction and >60 ml/min/1.73 m² for no renal dysfunction. We analyzed intermediate-grade stenoses (40-80% as assessed in coronary angiography) with the use of optical coherence tomography (OCT), FFR, and intravascular ultrasound (IVUS). RESULTS Renal dysfunction patients were older (67.7±8.1 vs 63.6±9.7 years, P=0.044). Lesion characteristics, including plaque type and minimal lumen area in OCT, showed no significant differences between the renal dysfunction and no renal dysfunction groups. Thin-cap fibroatheroma, calcific plaques, lipidic plaques, and fibrous plaques had similar prevalence. FFR values and IVUS parameters did not significantly differ between the groups. Over a 5-year follow-up, individuals with mild-to-moderate renal dysfunction had an elevated risk of all-cause mortality and major adverse cardiovascular events in multivariate analyses adjusted for age and sex. CONCLUSIONS Mild-to-moderate renal dysfunction was not associated with significant differences in OCT- and IVUS-derived plaque morphology nor with functional indices characterizing intermediate-grade coronary stenoses. Renal dysfunction was related to a higher risk of all-cause mortality and major adverse cardiovascular events prevalence in 5-year follow-up.

Invasive and Non-invasive Assessment of Non-culprit Coronary Lesions in Patients with ST-segment Elevation Myocardial Infarction

The angiographic evidence of coronary multivessel disease (MVD) increases significantly the risk of recurrent ischemic events in patients with ST-segment elevation myocardial infarction (STEMI). Recent evidence suggests that a complete revascularization strategy should be considered the standard of care in these patients and performed for significant non-culprit lesions (NCLs) after careful assessment of the individual risk-benefit ratio. However, the optimal timing and the modality for the assessment of NCLs is not fully standardized. This brief review aims to summarise the management of MVD in patients with STEMI and to provide an overview of the principal techniques used to guide revascularisation in this high-risk clinical setting.

Same-day discharge after percutaneous coronary procedures-Consensus statement of the working group of interventional cardiology (AGIK) of the Austrian Society of Cardiology

INTRODUCTION

Percutaneous coronary intervention is a well-established revascularization strategy for patients with coronary artery disease. Recent technical advances such as radial access, third generation drug-eluting stents and highly effective antiplatelet therapy have substantially improved the safety profile of coronary procedures. Despite several practice guidelines and a clear patient preference of early hospital discharge, the percentage of coronary procedures performed in an outpatient setting in Austria remains low, mostly due to safety concerns.

METHODS

The aim of this consensus statement is to provide a practical framework for the safe and effective implementation of coronary outpatient clinics in Austria. Based on a structured literature review and an in-depth analysis of available practice guidelines a consensus statement was developed and peer-reviewed within the working group of interventional cardiology (AGIK) of the Austrian Society of Cardiology.

RESULTS

Based on the available literature same-day discharge coronary procedures show a favorable safety profile with no increase in the risk of major adverse events compared to an overnight stay. This document provides a detailed consensus in various clinical settings. The most important prerequisite for same-day discharge is, however, adequate selection of suitable patients and a structured peri-interventional and postinterventional management plan.

CONCLUSION

Based on the data analysis this consensus document provides detailed practice guidelines for the safe operation of daycare cathlab programs in Austria.

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.

Dual modality intravascular catheter system combining pulse-sampling fluorescence lifetime imaging and polarization-sensitive optical coherence tomography

The clinical management of coronary artery disease and the prevention of acute coronary syndromes require knowledge of the underlying atherosclerotic plaque pathobiology. Hybrid imaging modalities capable of comprehensive assessment of biochemical and morphological plaques features can address this need. Here we report the first implementation of an intravascular catheter system combining fluorescence lifetime imaging (FLIm) with polarization-sensitive optical coherence tomography (PSOCT). This system provides multi-scale assessment of plaque structure and composition via high spatial resolution morphology from OCT, polarimetry-derived tissue microstructure, and biochemical composition from FLIm, without requiring any molecular contrast agent. This result was achieved with a low profile (2.7 Fr) double-clad fiber (DCF) catheter and high speed (100 fps B-scan rate, 40 mm/s pullback speed) console. Use of a DCF and broadband rotary junction required extensive optimization to mitigate the reduction in OCT performance originating from additional reflections and multipath artifacts. This challenge was addressed by the development of a broad-band (UV-visible-IR), high return loss (47 dB) rotary junction. We demonstrate in phantoms, ex vivo swine coronary specimens and in vivo swine heart (percutaneous coronary access) that the FLIm-PSOCT catheter system can simultaneously acquire co-registered FLIm data over four distinct spectral bands (380/20 nm, 400/20 nm, 452/45 nm, 540/45 nm) and PSOCT backscattered intensity, birefringence, and depolarization. The unique ability to collect complementary information from tissue (e.g., morphology, extracellular matrix composition, inflammation) with a device suitable for percutaneous coronary intervention offers new opportunities for cardiovascular research and clinical diagnosis.

Artificial Intelligence for the Interventional Cardiologist: Powering and Enabling OCT Image Interpretation

Intravascular optical coherence tomography (IVOCT) is a form of intra-coronary imaging that uses near-infrared light to generate high-resolution, cross-sectional, and 3D volumetric images of the vessel. Given its high spatial resolution, IVOCT is well-placed to characterise coronary plaques and aid with decision-making during percutaneous coronary intervention. IVOCT requires significant interpretation skills, which themselves require extensive education and training for effective utilisation, and this would appear to be the biggest barrier to its widespread adoption. Various artificial intelligence-based tools have been utilised in the most contemporary clinical IVOCT systems to facilitate better human interaction, interpretation and decision-making. The purpose of this article is to review the existing and future technological developments in IVOCT and demonstrate how they could aid the operator.

Segmentation of anatomical layers and imaging artifacts in intravascular polarization sensitive optical coherence tomography using attending physician and boundary cardinality losses

Intravascular ultrasound and optical coherence tomography are widely available for assessing coronary stenoses and provide critical information to optimize percutaneous coronary intervention. Intravascular polarization-sensitive optical coherence tomography (PS-OCT) measures the polarization state of the light scattered by the vessel wall in addition to conventional cross-sectional images of subsurface microstructure. This affords reconstruction of tissue polarization properties and reveals improved contrast between the layers of the vessel wall along with insight into collagen and smooth muscle content. Here, we propose a convolutional neural network model, optimized using two new loss terms (Boundary Cardinality and Attending Physician), that takes advantage of the additional polarization contrast and classifies the lumen, intima, and media layers in addition to guidewire and plaque shadows. Our model segments the media boundaries through fibrotic plaques and continues to estimate the outer media boundary behind shadows of lipid-rich plaques. We demonstrate that our multi-class classification model outperforms existing methods that exclusively use conventional OCT data, predominantly segment the lumen, and consider subsurface layers at most in regions of minimal disease. Segmentation of all anatomical layers throughout diseased vessels may facilitate stent sizing and will enable automated characterization of plaque polarization properties for investigation of the natural history and significance of coronary atheromas.

Comparison between optical coherence tomography-guided and intravascular ultrasound-guided primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

Objective

To examine the clinical outcomes of optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) in patients presenting with ST-segment elevation myocardial infarction (STEMI).

Methods

We retrospectively investigated 533 consecutive patients who underwent primary PCI for STEMI between June 2016 and December 2020. The primary endpoint was a target lesion failure (TLF; defined as a composite of cardiac death, target vessel myocardial infarction, or target lesion revascularization). Propensity score (PS) matching was performed to allow direct comparison of OCT-guided and intravascular ultrasound (IVUS)-guided PCI.

Results

Patients in the OCT group (n=166) were younger than those in the IVUS group (n=367) and had a significantly higher left ventricular ejection fraction and estimated glomerular filtration rate. Killip class IV and left main stem disease were more common in the IVUS group. The median peak creatine kinase level was comparable between the two groups (1953 U/L vs 1603 U/L). A significantly larger amount of contrast was used in the OCT group (200 mL vs 165 mL; p<0.001). The cumulative incidence of TLF during a median follow-up of 2.2 years did not differ significantly between OCT and IVUS groups (9.6% vs 13.6%; p=0.221) but cardiac mortality was significantly higher in the IVUS group (8.7% vs 3.6%; p=0.047). After PS matching (n=161 in each group), there was no significant between-group difference in TLF or any other clinical outcome measures.

Conclusions

OCT-guided PCI demonstrated clinical outcomes in patients with STEMI that were comparable to those of IVUS-guided PCI despite considerable differences in background characteristics.

Does artificial intelligence enhance physician interpretation of optical coherence tomography: insights from eye tracking

Background and objectives

The adoption of optical coherence tomography (OCT) in percutaneous coronary intervention (PCI) is limited by need for real-time image interpretation expertise. Artificial intelligence (AI)-assisted Ultreon™ 2.0 software could address this barrier. We used eye tracking to understand how these software changes impact viewing efficiency and accuracy.

Methods

Eighteen interventional cardiologists and fellows at McMaster University, Canada, were included in the study and categorized as experienced or inexperienced based on lifetime OCT use. They were tasked with reviewing OCT images from both Ultreon™ 2.0 and AptiVue™ software platforms while their eye movements were recorded. Key metrics, such as time to first fixation on the area of interest, total task time, dwell time (time spent on the area of interest as a proportion of total task time), and interpretation accuracy, were evaluated using a mixed multivariate model.

Results

Physicians exhibited improved viewing efficiency with Ultreon™ 2.0, characterized by reduced time to first fixation (Ultreon™ 0.9 s vs. AptiVue™ 1.6 s, p = 0.007), reduced total task time (Ultreon™ 10.2 s vs. AptiVue™ 12.6 s, p = 0.006), and increased dwell time in the area of interest (Ultreon™ 58% vs. AptiVue™ 41%, p < 0.001). These effects were similar for experienced and inexperienced physicians. Accuracy of OCT image interpretation was preserved in both groups, with experienced physicians outperforming inexperienced physicians.

Discussion

Our study demonstrated that AI-enabled Ultreon™ 2.0 software can streamline the image interpretation process and improve viewing efficiency for both inexperienced and experienced physicians. Enhanced viewing efficiency implies reduced cognitive load potentially reducing the barriers for OCT adoption in PCI decision-making.

Optical Coherence Tomography as a Tool for Imaging the Sinonasal Mucosa in Patients: A Systematic Review

Objectives: To summarize the current applications and potential uses of optical coherence tomography (OCT), a noninvasive imaging modality that uses near-infrared light to produce cross-sectional, high-resolution images of biologic tissues, for evaluating the sinonasal mucosa in patients. Methods: Original articles utilizing OCT to image the sinonasal mucosa in patients were identified from the PubMed, Embase, Cochrane Library, Web of Science, and Scopus databases using the search phrase: "Optical Coherence Tomography" AND (sinonasal OR intranasal OR sinus OR nose OR sinusitis OR rhinitis OR olfactory). Strength of evidence, quality of evidence, and risk of bias were measured using validated scales. Study results were qualitatively assessed. Results: Out of 1662 original records identified through database searching, 9 studies were included in the systematic review. Levels of evidence ranged from III to IV and quality of evidence ranged from moderate to very low. Endoscopic OCT systems as well as OCT systems integrated with surgical microscopes were described in the literature. Applications of OCT for imaging the sinonasal mucosa included identifying morphological patterns unique to individual diseases, detecting mucosal structural changes after medical therapies and procedures, and evaluating mucociliary clearance. Conclusions: Most studies investigating OCT imaging of the sinonasal mucosa featured small sample sizes and lacked control groups. While OCT imaging could be a useful adjunct for diagnosing sinonasal disorders and monitoring response to treatment in the future, additional high-quality studies are necessary to determine if the use of OCT imaging can lead to improved diagnostic accuracy and health outcomes for patients with sinonasal pathologies.

ISR vs De Novo Lesion Treatment During OCT-Guided PCI: Insights From the LightLab Initiative

Background

Long-term outcomes after percutaneous coronary intervention (PCI) for in-stent restenosis (ISR) are poor, yet limited granular procedural data exist evaluating lesion assessment, vessel treatment, and acute procedural outcomes.

Methods

The LightLab Initiative was a multicenter, prospective, observational study with contemporaneous procedural data collection during PCI procedures. Data were collected during PCIs performed by 48 interventional cardiologists at 17 US hospitals (2019-2021). Optical coherence tomography (OCT) was performed pre-PCI for lesion assessment and post-PCI for stent optimization, and results were compared between ISR and de novo lesion PCI.

Results

In total, 2592 OCT-guided PCIs involving 2944 lesions were included, of which 458 procedures (17.7%) were ISR PCI. Compared with de novo lesion PCI, ISR lesions were more commonly type C (64.8% vs 52.9%) and performed via femoral artery access (46.4% vs 37.7%). Use of OCT changed operator assessment and treatment decisions more frequently in ISR PCI (94.2% vs 85.2%; P = .002). Scoring balloons (21.8% vs 2.5%), cutting balloons (16.4% vs 3.4%), and atherectomy (26.3% vs 9.9%) were used more commonly in ISR PCI (all P < .0001), and ISR PCI procedures were longer (62 vs 51 min). Moreover, the final achieved minimum stent area and percent expansion (4.4 vs 5.1 mm2 and 80% vs 83%, respectively; both P < .0001) were lower in ISR PCI.

Conclusions

In this real-world cohort of patients who underwent OCT-guided PCI, ISR procedures were longer and final minimum stent area and percent expansion were lower despite greater use of advanced lesion modification. OCT frequently altered physician decision making, emphasizing its utility in potentially reducing recurrent stent failure in this high-risk population.

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.

Computed Tomography-Based Coronary Artery Calcium Score Calculation at a Reduced Tube Voltage Utilizing Iterative Reconstruction and Threshold Modification Techniques: A Feasibility Study

BACKGROUND

The coronary artery calcium score (CACS) indicates cardiovascular health. A concern in this regard is the ionizing radiation from computed tomography (CT). Recent studies have tried to introduce low-dose CT techniques to assess CACS. We aimed to investigate the accuracy of iterative reconstruction (IR) and threshold modification while applying low tube voltage in coronary artery calcium imaging.

METHODS

The study population consisted of 107 patients. Each subject underwent an electrocardiogram-gated CT twice, once with a standard voltage of 120 kVp and then a reduced voltage of 80 kVp. The standard filtered back projection (FBP) reconstruction was applied in both voltages. Considering Hounsfield unit (HU) thresholds other than 130 (150, 170, and 190), CACS was calculated using the FBP-reconstructed 80 kVp images. Moreover, the 80 kVp images were reconstructed utilizing IR at different strength levels. CACS was measured in each set of images. The intraclass correlation coefficient (ICC) was used to compare the CACSs.

RESULTS

A 64% reduction in the effective dose was observed in the 80 kVp protocol compared to the 120 kVp protocol. Excellent agreement existed between CACS at high-level (strength level = 5) IR in low-kVp images and the standard CACS protocol in scores ≥ 11 (ICC > 0.9 and p < 0.05). Increasing the threshold density to 190 HU in FBP-reconstructed low-kVp images yielded excellent agreement with the standard protocol in scores ≥ 11 (ICC > 0.9 and p < 0.05) and good agreement in score zero (ICC = 0.84 and p = 0.02).

CONCLUSIONS

The modification of the density threshold and IR provides an accurate calculation of CACS in low-voltage CT with the potential to decrease patient radiation exposure.

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.

Impact of acute and persistent stent malapposition after percutaneous coronary intervention on adverse cardiovascular outcomes

INTRODUCTION

The association of coronary stent malapposition (SM) and adverse clinical outcomes after percutaneous coronary intervention (PCI) remains unclear. We aimed to perform a systematic review and meta-analysis of randomized and observational studies to assess the association between acute and persistent SM detected using intravascular ultrasound (IVUS) or optical coherence tomography (OCT) and adverse cardiovascular outcomes.

EVIDENCE ACQUISITION

Available studies were identified through a systematic search of PubMed, reference lists of relevant articles, and Medline. Main efficacy outcomes of interest were: device-oriented composite endpoint (DoCE, including cardiac death, myocardial infarction [MI], target lesion revascularization [TLR], and stent thrombosis [ST]), major safety events (MSE, including cardiac death, MI and ST), TLR, and ST. A sensitivity analysis regarding the impact of major malapposition was also performed.

EVIDENCE SYNTHESIS

A total of 9 studies enrolling 6497 patients were included in the meta-analysis. After a mean follow-up of 24±14 months, overall acute and/or persistent malapposition was not significantly associated with the occurrence of all the outcomes of interest, including DoCE (risk ratio [RR] 1.00, 95% confidence interval [CI, 0.79-1.26], P=0.99), MSE (RR 1.42, 95%CI [0.81-2.50], P=0.22), TLR (RR 0.84, 95%CI [0.59-1.19], P=0.33), and ST (RR 1.16, 95%CI [0.48-2.85], P=0.74). In the sensitivity analysis, we found a significant increase of MSE in patients with major malapposition (RR 2.97, 95%CI [1.51-5.87], P=0.001).

CONCLUSIONS

Acute and persistent SM were not overall associated with adverse cardiovascular clinical outcomes at follow-up. However, major malapposition was associated with an increased risk of major safety events, including cardiac death, MI and ST. These findings should be taken into account during stent implantation and PCI optimization.

Trajectory-Aware Adaptive Imaging Clue Analysis for Guidewire Artifact Removal in Intravascular Optical Coherence Tomography

Guidewire Artifact Removal (GAR) involves restoring missing imaging signals in areas of IntraVascular Optical Coherence Tomography (IVOCT) videos affected by guidewire artifacts. GAR helps overcome imaging defects and minimizes the impact of missing signals on the diagnosis of CardioVascular Diseases (CVDs). To restore the actual vascular and lesion information within the artifact area, we propose a reliable Trajectory-aware Adaptive imaging Clue analysis Network (TAC-Net) that includes two innovative designs: (i) Adaptive clue aggregation, which considers both texture-focused original (ORI) videos and structure-focused relative total variation (RTV) videos, and suppresses texture-structure imbalance with an active weight-adaptation mechanism; (ii) Trajectory-aware Transformer, which uses a novel attention calculation to perceive the attention distribution of artifact trajectories and avoid the interference of irregular and non-uniform artifacts. We provide a detailed formulation for the procedure and evaluation of the GAR task and conduct comprehensive quantitative and qualitative experiments. The experimental results demonstrate that TAC-Net reliably restores the texture and structure of guidewire artifact areas as expected by experienced physicians (e.g., SSIM: 97.23%). We also discuss the value and potential of the GAR task for clinical applications and computer-aided diagnosis of CVDs.

Current Management of Highly Calcified Coronary Lesions: An Overview of the Current Status

The amount of coronary calcium strongly correlates with the degree of atherosclerosis and, therefore, with the rate of future cardiac events. Calcified coronary lesions still represent a challenge for interventional cardiologists, bringing not only a higher risk of immediate complications during percutaneous coronary interventions (PCI), but also a higher risk of late stent failure due to under-expansion and/or malapposition, and therefore, have a relevant prognostic impact. Accurate identification of the calcified plaques together with the analysis of their distribution pattern within the vessel wall by intracoronary imaging is important to improve the successful treatment of these lesions. The aim of this review is to guide readers through the assessment of the calcified plaque distribution using intracoronary imaging in order to select the best devices and strategies for plaque debulking and lesion preparation.

Effectiveness and safety of optical coherence tomography-guided PCI in Indian patients with complex lesions: A multicenter, prospective registry

BACKGROUND

Optical coherence tomography (OCT) is reported to be a feasible and safe imaging modality for the guidance of percutaneous coronary intervention (PCI) of complex lesions.

METHODS

This multicenter, prospective registry assessed the minimum stent area (MSA) achieved under OCT guidance. A performance goal of 24% improvement in MSA over and above the recommendation set by the European Association of Percutaneous Cardiovascular Interventions Consensus 2018 (4.5 mm2 MSA for non-left main and 3.5 mm2 for small vessels). The incidence of contrast-induced nephropathy was also assessed. Core lab analysis was conducted.

RESULTS

Five hundred patients (average age: 59.4 ± 10.1 years; 83% males) with unstable angina (36.8%), NSTEMI (26.4%), and STEMI (22%) were enrolled. The primary endpoint was achieved in 93% of lesions with stent diameter ≥2.75 mm (average MSA: 6.44 mm2) and 87% of lesions with stent diameter ≤2.5 mm (average MSA: 4.56 mm2). The average MSA (with expansion ≥80% cutoff) was 6.63 mm2 and 4.74 mm2 with a stent diameter ≥2.75 mm and ≤2.5 mm, respectively. According to the core lab analysis, the average MSA achieved with a stent diameter ≥2.75 mm and ≤2.5 mm was 6.23 mm2 and 3.95 mm2, respectively (with expansion ≥80% cutoff). Clinically significant serum creatinine was noted in two patients (0.45%). Major adverse cardiac events at 1 year were noted in 1.2% (n = 6) of the patients; all were cardiac deaths.

CONCLUSION

PCI under OCT guidance improves procedural and long-term clinical outcomes in patients with complex lesions not just in a controlled trial environment but also in routine clinical practice.

Multimodality OCT, IVUS and FFR evaluation of coronary intermediate grade lesions in women vs. men

Background

The pathophysiology of atherosclerotic plaque formation and its vulnerability seem to differ between genders due to contrasting risk profiles and sex hormones, however this process is still insufficiently understood. The aim of the study was to compare the differences between sexes regarding the optical coherence tomography (OCT), intravascular ultrasound (IVUS) and fractional flow reserve (FFR)-derived coronary plaque indices.

Methods

In this single-center multimodality imaging study patients with intermediate grade coronary stenoses identified in coronary angiogram (CAG) were evaluated using OCT, IVUS and FFR. Stenoses were considered significant when the FFR value was ≤0.8. Minimal lumen area (MLA), was analyzed by OCT in addition to plaque stratification into fibrotic, calcific, lipidic and thin-cap fibroatheroma (TCFA). IVUS was used for evaluation of lumen-, plaque- and vessel volume, as well as plaque burden.

Results

A total of 112 patients (88 men and 24 women) with chronic coronary syndromes (CCS), who underwent CAG were enrolled. No significant differences in baseline characteristics were present between the study groups. The mean FFR was 0.76 (0.73-0.86) in women and 0.78 ± 0.12 in men (p = 0.695). OCT evaluation showed a higher prevalence of calcific plaques among women than men p = 0.002 whereas lipid plaques were more frequent in men (p = 0.04). No significant differences regarding minimal lumen diameter and minimal lumen area were found between the sexes. In IVUS analysis women presented with significantly smaller vessel area, plaque area, plaque volume, vessel volume (11.1 ± 3.3 mm² vs. 15.0 ± 4.6 mm² p = 0.001, 6.04 ± 1.7 mm² vs. 9.24 ± 2.89 mm² p < 0.001, 59.8 ± 35.2 mm³ vs. 96.3 (52.5-159.1) mm³ p = 0.005, 106.9 ± 59.8 mm³ vs. 153.3 (103-253.4) mm³ p = 0.015 respectively). At MLA site plaque burden was significantly greater for men than women (61.50 ± 7.7% vs. 55.5 ± 8.0% p = 0.005). Survival did not differ significantly between women and men (94.6 ± 41.9 months and 103.51 ± 36.7 months respectively; p = 0.187).

Conclusion

The presented study did not demonstrate significant differences in FFR values between women and men, yet a higher prevalence of calcific plaques by OCT and lower plaque burden at the MLA site by IVUS was found in women vs. men.

ST-elevation myocardial infarction complicated by ventricular tachycardia revealing coronary artery ectasia: a case report

BACKGROUND

Coronary artery ectasia is a rare angiographic finding and results from a disease process that compromises the integrity of the vessel wall. Its prevalence ranges between 0.3% and 5% of patients undergoing coronary angiography (Swaye et al. in Circulation 67:134-138, 1983). Coronary artery ectasia in patients with ST-elevation myocardial infarction is associated with an increased risk of cardiovascular events and death after percutaneous coronary intervention.

CASE PRESENTATION

We report the case of a 50-year-old male Caucasian patient, admitted for ventricular tachycardia at 200 beats per minute hemodynamically not tolerated that was reduced by external electric shock. Electrocardiogram after cardioversion showed a sinus rhythm with anterior ST-elevation myocardial infarction. Thrombolytic therapy was chosen after exposure to dual antiplatelet therapy and heparin since the expected time to percutaneous coronary intervention was greater than 120 minutes from first medical contact and the patient presented within 12 hours of onset of ischemic symptoms. The electrocardiogram after thrombolysis showed the resolution of the ST segment. The echocardiogram showed a dilated left ventricle with severe dysfunction with left ventricle ejection fraction at 30%. Coronary angiography revealed non-obstructive giant ecstatic coronaries without any thrombus. A check-up to look for possible etiologies for coronary artery ectasia was carried out and returned normal. Since no etiology for coronary artery ectasia was found at the limit of available exams in our center, the patient was discharged with antiplatelet therapy (aspirin 100 mg once a day) and heart failure treatment with an indication for an implantable cardiac defibrillator.

CONCLUSIONS

Coronary artery ectasia in the context of acute myocardial infarction is a rare condition that may have dangerous complications, especially when an optimal treatment for ecstatic culprit vessels is still controversial.

Intravascular Ultrasound and Optical Coherent Tomography Combined Catheter

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are established intravascular imaging tools for evaluating plaque characteristics and volume, together with guiding percutaneous coronary interventions. The high tissue penetration of IVUS facilitates assessment of the entire vessel wall, whereas the higher resolution of OCT allows detailed assessment of endoluminal structures. A combined IVUS-OCT probe works synergistically, facilitating a greater understanding of de novo coronary artery disease and a better correlation with pathological specimens. In this review, we discuss the rationale and potential roles of the combined IVUS-OCT catheter system.

OCT Emerging Technologies: Coronary Micro-optical Coherence Tomography

Optical coherence tomography (OCT) is an imaging modality that is used in a significant number of interventional cardiology procedures. Key structural changes occurring within the vessel wall, including presence of neutrophils, macrophages, monocytes, and vascular smooth muscle cells, are below the resolution of clinical intracoronary OCT. To address this challenge, a new form of OCT with 1 to 2 μm resolution, termed micro-OCT (μOCT), has been developed. This review article summarizes the ability of μOCT technology to visualize coronary microstructures and discusses its clinical implications.

Intracoronary Imaging of Coronary Atherosclerotic Plaque: From Assessment of Pathophysiological Mechanisms to Therapeutic Implication

Atherosclerotic cardiovascular disease is the leading cause of morbidity and mortality worldwide. Several cardiovascular risk factors are implicated in atherosclerotic plaque promotion and progression and are responsible for the clinical manifestations of coronary artery disease (CAD), ranging from chronic to acute coronary syndromes and sudden coronary death. The advent of intravascular imaging (IVI), including intravascular ultrasound, optical coherence tomography and near-infrared diffuse reflectance spectroscopy has significantly improved the comprehension of CAD pathophysiology and has strengthened the prognostic relevance of coronary plaque morphology assessment. Indeed, several atherosclerotic plaque phenotype and mechanisms of plaque destabilization have been recognized with different natural history and prognosis. Finally, IVI demonstrated benefits of secondary prevention therapies, such as lipid-lowering and anti-inflammatory agents. The purpose of this review is to shed light on the principles and properties of available IVI modalities along with their prognostic significance.

Clinical use of optical coherence tomography during percutaneous coronary intervention and coronary procedures in Southeast Asia: a survey-based expert consensus summary

Optical coherence tomography (OCT), an established intravascular imaging technique, enables rapid acquisition of high-resolution images during invasive coronary procedures to assist physician decision-making. OCT has utility in identifying plaque/lesion morphology (e.g., thrombus, degree of calcification, and presence of lipid) and vessel geometry (lesion length and vessel diameter) and in guiding stent optimisation through identification of malapposition and underexpansion. The use of OCT guidance during percutaneous coronary interventions (PCI) has demonstrated improved procedural and clinical outcomes in longitudinal registries, although randomised controlled trial data remain pending. Despite growing data and guideline endorsement to support OCT guidance during PCI, its use in different countries is not well established. This article is based on an advisory panel meeting that included experts from Southeast Asia (SEA) and is aimed at understanding the current clinical utility of intracoronary imaging and OCT, assessing the barriers and enablers of imaging and OCT adoption, and mapping a path for the future of intravascular imaging in SEA. This is the first Southeast Asian consensus that provides insights into the use of OCT from a clinician's point of view.

OCT Guidance in Bifurcation Percutaneous Coronary Intervention

Coronary bifurcation is defined by the European Bifurcation Consensus as a coronary artery stenosis adjacent to the origin of a significant side branch. Its anatomy is composed of 3 different segments: proximal main vessel, distal main vessel and side branch. Coronary artery bifurcation lesions are encountered in approximately 15-20% of all percutaneous coronary interventions and constitute a complex subgroup of lesions characterized by lower procedural success rates and higher rates of adverse outcomes. In recent years, a growing focus in the European and Japanese bifurcation club meetings has been the emerging role of intravascular imaging, in guiding successful bifurcation percutaneous coronary interventions (PCI). In this review we will present the main ways optical coherence tomography (OCT) can be used to improve outcomes during bifurcation PCI.

Safety and efficiency of percutaneous coronary intervention using a standardised optical coherence tomography workflow

BACKGROUND

While intravascular imaging guidance during percutaneous coronary intervention (PCI) improves outcomes, routine intravascular imaging usage remains low, in part due to perceived inefficiency and safety concerns.  Aims: The LightLab (LL) Initiative was designed to evaluate whether implementing a standardised optical coherence tomography (OCT) workflow impacts PCI safety metrics and procedural efficiency.

METHODS

In this multicentre, prospective, observational study, PCI procedural data were collected over 2 years from 45 physicians at 17 US centres. OCT-guided PCI incorporating the LL workflow (N=264), a structured algorithm using routine pre- and post-PCI OCT imaging, was compared with baseline angiography-only PCI (angio) (N=428). Propensity score analysis identified 207 matched procedures. Outcomes included procedure time, radiation exposure, contrast volume, device utilisation, and treatment strategy.

RESULTS

Compared with angiography alone, LL workflow OCT-guided PCI increased the median procedural time by 9 minutes but reduced vessel preparation time (2 min LL workflow vs 3 min angio; p<0.001) and resulted in less unplanned additional treatment (4% LL workflow vs 10% angio; p=0.01). With LL workflow OCT guidance, fewer cineangiography views were needed compared to angiography guidance, leading to decreased radiation exposure (1,133 mGy LL workflow vs 1,269 mGy angio; p=0.02), with no difference in contrast utilisation between groups (p=0.28). Furthermore, LL workflow OCT guidance resulted in fewer predilatation balloons and stents being used, more direct stent placement, and greater stent post-dilatation than angiography-guided PCI.

CONCLUSIONS

The incorporation of a standardised pre- and post-PCI OCT imaging workflow improves procedural efficiency and safety metrics, at a cost of a modestly longer procedure time.

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.

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.

Plaque burden estimated from optical coherence tomography with deep learning: In vivo validation using co-registered intravascular ultrasound

OBJECTIVES

The objective of the present study was to compare plaque burden (PB) calculated from optical coherence tomography (OCT) using deep learning (DL) with PB derived from co-registered intravascular ultrasound (IVUS).

BACKGROUND

A DL algorithm was developed for automated plaque characterization and PB quantification from OCT images. However, the performance of this algorithm for PB quantification has not been validated.

METHODS

Five-year follow-up OCT and IVUS images from 15 patients implanted with bioresorbable vascular scaffold (BVS) at baseline were analyzed. Precise co-registration for 72 anatomical slices was achieved utilizing unique BVS radiopaque markers. PB derived from OCT DL and IVUS were compared. OCT cross-sections were divided into four subgroups with different media visibility level. The impact of media visibility on the numerical difference between OCT-derived and IVUS-derived PB was investigated. The stent sizes selected by OCT DL and IVUS were compared.

RESULTS

Sixty-four paired OCT and IVUS cross-sections were compared. OCT DL showed good concordance with IVUS for PB assessment (ICC = 0.81, difference = -3.53 ± 6.17%, p < 0.001). The numerical difference between OCT DL-derived PB and IVUS-derived PB was not substantially impacted by missing segments of media visualization (p = 0.21). OCT DL showed a diagnostic accuracy of 92% in identifying PB > 65%. The stent sizes selected by OCT DL were smaller compared to the ones selected by IVUS (difference = 0.30 ± 0.34 mm, p < 0.001).

CONCLUSIONS

The DL algorithm provides a feasible and reliable method for automated PB estimation from OCT, irrespective of media visibility. OCT DL showed good diagnostic accuracy in identifying PB > 65%, revealing its potential to complement conventional OCT imaging.

Intravascular molecular imaging: translating pathophysiology of atherosclerosis into human disease conditions

Progression of atherosclerotic plaque in coronary arteries is characterized by complex cellular and non-cellular molecular interactions. Within recent years, atherosclerosis has been recognized as inflammation-driven disease condition, where progressive stages are characterized by morphological changes in plaque composition but also relevant molecular processes resulting in increased plaque vulnerability. While existing intravascular imaging modalities are able to resolve key morphological features during plaque progression, they lack capability to characterize the molecular profile of advanced atherosclerotic plaque. Because hybrid imaging modalities may provide incremental information related to plaque biology, they are expected to provide synergistic effects in detecting high risk patients and lesions. The aim of this article is to review existing literature on intravascular molecular imaging approaches, and to provide clinically oriented proposals of their application. In addition, we assembled an overview of future developments in this field geared towards detection of patients at risk for cardiovascular events.

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.

The MLD MAX OCT algorithm: An imaging-based workflow for percutaneous coronary intervention

Although extensive clinical data support the utility of intravascular imaging to guide and optimize outcomes following percutaneous coronary interventions (PCI), clinical adoption remains limited. One of the primary reasons for limited utilization may be a lack of standardization on how to best integrate the data provided by intravascular imaging practically. Optical coherence tomography (OCT) offers a high-resolution intravascular imaging modality with integrated software automation that allows for incorporation of OCT into the routine workflow of PCIs. We suggest use of an algorithm called MLD MAX to incorporate OCT for imaging-guided interventions: the baseline OCT imaging run is intended to facilitate procedural planning and strategizing, consisting of assessment for predominant lesion morphology (M), measurement for stent length (L) and determination of stent diameter (D); the post-PCI OCT imaging run is designated for assessment of need for further optimization of stent result, and consists of analysis for medial dissections (M), adequate stent apposition (A) and stent expansion (X). Incorporation of the MLD MAX algorithm into daily practice guides an efficient and easily-memorable workflow for optimized PCI procedures.

Improving efficiency and operator proficiency during percutaneous coronary interventions utilizing a standardized optical coherence tomography workflow

OBJECTIVES

This study was designed to compare efficiency and quality metrics between percutaneous coronary intervention (PCI) procedures using optical coherence tomography (OCT) guided by a variable workflow versus a standardized workflow in a real-world population.

BACKGROUND

The LightLab (LL) Initiative was designed to evaluate the impact of a standardized OCT workflow during PCI to address barriers to adoption.

METHODS

The LL Initiative was a multicenter, prospective, observational study. PCI efficiency data were collected from 1/21/19 to 1/8/21 from 45 physicians at 17 US centers. OCT-guided PCIs were compared between baseline phase (variable workflow; N = 383) and the LL workflow utilization phase (N = 447). The LL workflow uses OCT to assess lesion Morphology, Length and Diameter, and then optimize outcomes by correcting for Medial dissection, stent mal-Apposition, and under-eXpansion (MLD MAX). Matching based on propensity scores was used to control for differences between PCIs.

RESULTS

After propensity matching, 291 paired procedures were included. Integration of the LL versus variable workflow resulted in no difference in procedure time (51 min vs. 51 min, p = 0.93). There was a reduction in radiation exposure (1124 mGy vs. 1493 mGy, p < 0.0001) and contrast volume (160 cc vs. 172 cc, p < 0.001). The LL workflow decreased the proportion of underexpanded lesions (34% vs. 54%, p < 0.0001) and improved minimum stent expansion (85% vs. 79%, p < 0.0001). Number of noncompliant balloons used was reduced with the LL workflow. (2.0 vs. 1.7, p < 0.01).

CONCLUSIONS

These data suggest that standardizing imaging with the LL workflow may overcome barriers to imaging and improve PCI outcomes without prolonging procedures.

Immersive educational curriculum on intracoronary optical coherence tomography image analysis among naïve readers

BACKGROUND

Optical coherence tomography (OCT) is an intravascular imaging modality for analysing coronary vessels. Image interpretation remains an obstacle for novice readers due to technical artefacts and uncertainty in tissue characterization. Despite an expanding clinical and research role for OCT, few training efforts exist, and there is an absence of a national standardized educational curriculum. We sought to determine whether an interactive, feedback-based OCT curriculum improved image interpretation among naive readers.

METHODS

Naive OCT readers completed both a Standard curriculum, comprised of self-directed didactics and consensus statements, and an Augmented curriculum, which provided real-time digital feedback of feature identification and measurements. Modules were separated by a minimum one-week washout period. After each module, and blinded to the exam answers, subjects completed an identical expert-designed 413-item exam to assess technical knowledge and ability to identify and measure vessel features. Performances were compared using Exact Wilcoxon signed-rank tests.

RESULTS

Among the 7 included subjects were 3 medical students, 3 internal medicine residents, and 1 cardiovascular medicine fellow with no prior OCT experience. The technical knowledge score (maximum 13) was significantly higher with the Augmented compared with the Standard curriculum (median 11 vs. 7, p = 0.03). After undergoing the Augmented curriculum, all 7 subjects were able to identify features of plaque rupture (Standard curriculum: 5/7 subjects, p = 0.5) and macrophages (Standard curriculum: 6/7 subjects, p = 0.99), differentiate the components between red and white thrombus (Standard curriculum: 6/7 subjects, p = 0.99), and characterize lipid plaque by attenuation, signal, homogeneity, and borders (Standard curriculum: 5/7 subjects, p = 0.5). Performances on the remaining exam portions did not differ between curricula.

CONCLUSIONS

The need for standardized, effective training in OCT image interpretation is increasingly essential as the intravascular imaging modality becomes widely utilized among interventional cardiologists and trainees. A novel interactive OCT curriculum enhanced naive readers' technical knowledge and may supplement traditional self-learning in refining analytic skills.

Impact of Intracoronary Imaging-Guided Percutaneous Coronary Intervention on Procedural Outcomes Among Complex Patient Groups

Background Intracoronary imaging (ICI) has been shown to improve survival after percutaneous coronary intervention (PCI). Whether this prognostic benefit is sustained across different indications remains unclear. Methods and Results All PCI procedures performed in England and Wales between April, 2014 and March 31, 2020, were retrospectively analyzed. The association between ICI use and in-hospital major acute cardiovascular and cerebrovascular events; composite of all-cause mortality, stroke, and reinfarction and mortality was examined using multivariable logistic regression analysis for different imaging-recommended indications as set by European Association for Percutaneous Cardiovascular Interventions consensus. Of 555 398 PCI procedures, 10.8% (n=59 752) were ICI-guided. ICI use doubled between 2014 (7.8%) and 2020 (17.5%) and was highest in left main PCI (41.2%) and lowest in acute coronary syndrome (9%). Only specific European Association for Percutaneous Cardiovascular Interventions imaging-recommended indications were associated with reduced major acute cardiovascular and cerebrovascular events and mortality, including left main PCI (odds ratio [OR], 0.45 [95% CI, 0.39-0.52] and 0.41 [95% CI, 0.35-0.48], respectively), acute coronary syndrome (OR, 0.76 [95% CI, 0.70-0.82] and 0.70 [95% CI, 0.63-0.77]), and stent length >60 mm (OR, 0.75 [95% CI, 0.59-0.94] and 0.72 [95% CI, 0.54-0.95]). Stent thrombosis and renal failure were associated with lower mortality (OR, 0.69 [95% CI, 0.52-0.91]) and major acute cardiovascular and cerebrovascular events (OR, 0.77 [95% CI, 0.60-0.99]), respectively. Conclusions ICI use has more than doubled over a 7-year period at a national level but remains low, with <1 in 5 procedures performed under ICI guidance. In-hospital survival was better with ICI-guided than angiography-guided PCI, albeit only for specific indications.

Structural and Functional Evaluation of Coronary Arteries Treated With ABSORB Bioresorbable Vascular Scaffold at 5-Year Follow-Up

Although complete bioresorbable vascular scaffold (BVS) resorption has been demonstrated at 5-year follow-up, whether corresponding vasomotor function restoration occurs remains unknown. The objective was to simultaneously assess the structural healing response along with vasomotor responses at 5-year follow-up of BVS implantation. We studied consecutive patients treated with ABSORB-BVS at 5-year follow-up (n = 31), who were recruited from a multicenter registry and were contacted to undergo a research protocol-driven repeat coronary angiogram involving intracoronary optical coherence tomography (OCT) and invasive coronary endothelial function testing. Epicardial endothelium-dependent vasomotion was defined as any vasodilatation after intracoronary acetylcholine (ACh), whereas endothelium-independent vasomotion was defined as any vasodilatation after intracoronary nitroglycerine (NTG), using quantitative coronary angiography. The mean implantation time point was 60.5 ± 4.6 months. OCT imaging demonstrated complete scaffold resorption in all patients. New coronary lesions (stenosis >50%) were found in 5 patients (16.1%), 3 of them underwent ad hoc percutaneous revascularization (9.7%). Intracoronary ACh (27 patients) and NTG testing (30 patients) was performed. Quantitative coronary angiography analysis demonstrated vasoconstriction after ACh administration and lack of response to NTG in BVS segments (mean lumen diameter = 2.00 ± 0.61 mm at baseline vs 1.74 ± 0.70 mm post-ACh, p <0.001; 2.05 ± 0.54 mm at baseline vs 2.03 ± 0.50 mm post-NTG, p = 0.69). OCT lumen analysis demonstrated similar vasoconstrictive responses to ACh (mean lumen area = 5.31 ± 2.26 mm² at baseline vs 5.12 ± 2.55 mm² post-ACh, p = 0.007) but had a vasodilatory response to NTG (5.96 ± 2.35 mm² at baseline vs 6.17 ± 2.55 mm² post-NTG, p<0.001). In conclusion, complete ABSORB-BVS resorption was demonstrated at 5-year follow-up. However, this healing response was associated with endothelium-dependent vasomotor dysfunction within the BVS segment.

Comparative Appraisal of Intravascular Ultrasound and Optical Coherence Tomography in Invasive Coronary Imaging: 2022 Update

Although coronary angiography has been well established as a standard modality for percutaneous coronary intervention guidance, recent developments in intravascular imaging techniques, such as intravascular ultrasound and optical coherence tomography, have become increasingly adopted, enabling direct detailed lesion visualization, including lesions beyond the scope of assessment using exclusively angiography. Intravascular imaging modalities have been reported to potentially improve both short- and long-term percutaneous intervention outcomes. This review aims to provide a comparative summary of recent advancements in research regarding the clinical applications and outcomes of intravascular ultrasound and optical coherence tomography.

Comprehensive Assessment of Coronary Calcification in Intravascular OCT Using a Spatial-Temporal Encoder-Decoder Network

Coronary calcification is a strong indicator of coronary artery disease and a key determinant of the outcome of percutaneous coronary intervention. We propose a fully automated method to segment and quantify coronary calcification in intravascular OCT (IVOCT) images based on convolutional neural networks (CNN). All possible calcified plaques were segmented from IVOCT pullbacks using a spatial-temporal encoder-decoder network by exploiting the 3D continuity information of the plaques, which were then screened and classified by a DenseNet network to reduce false positives. A novel data augmentation method based on the IVOCT image acquisition pattern was also proposed to improve the performance and robustness of the segmentation. Clinically relevant metrics including calcification area, depth, angle, thickness, volume, and stent-deployment calcification score, were automatically computed. 13844 IVOCT images with 2627 calcification slices from 45 clinical OCT pullbacks were collected and used to train and test the model. The proposed method performed significantly better than existing state-of-the-art 2D and 3D CNN methods. The data augmentation method improved the Dice similarity coefficient for calcification segmentation from 0.615±0.332 to 0.756±0.222, reaching human-level inter-observer agreement. Our proposed region-based classifier improved image-level calcification classification precision and F1-score from 0.725±0.071 and 0.791±0.041 to 0.964±0.002 and 0.883±0.008, respectively. Bland-Altman analysis showed close agreement between manual and automatic calcification measurements. Our proposed method is valuable for automated assessment of coronary calcification lesions and in-procedure planning of stent deployment.

Towards standardizing retinal optical coherence tomography angiography: a review

The visualization and assessment of retinal microvasculature are important in the study, diagnosis, monitoring, and guidance of treatment of ocular and systemic diseases. With the introduction of optical coherence tomography angiography (OCTA), it has become possible to visualize the retinal microvasculature volumetrically and without a contrast agent. Many lab-based and commercial clinical instruments, imaging protocols and data analysis methods and metrics, have been applied, often inconsistently, resulting in a confusing picture that represents a major barrier to progress in applying OCTA to reduce the burden of disease. Open data and software sharing, and cross-comparison and pooling of data from different studies are rare. These inabilities have impeded building the large databases of annotated OCTA images of healthy and diseased retinas that are necessary to study and define characteristics of specific conditions. This paper addresses the steps needed to standardize OCTA imaging of the human retina to address these limitations. Through review of the OCTA literature, we identify issues and inconsistencies and propose minimum standards for imaging protocols, data analysis methods, metrics, reporting of findings, and clinical practice and, where this is not possible, we identify areas that require further investigation. We hope that this paper will encourage the unification of imaging protocols in OCTA, promote transparency in the process of data collection, analysis, and reporting, and facilitate increasing the impact of OCTA on retinal healthcare delivery and life science investigations.

Treatment and Outcome of Patients With Coronary Artery Ectasia: Current Evidence and Novel Opportunities for an Old Dilemma

Coronary artery ectasia (CAE) is defined as a diffuse or focal dilation of an epicardial coronary artery, which diameter exceeds by at least 1. 5 times the normal adjacent segment. The term ectasia refers to a diffuse dilation, involving more than 50% of the length of the vessel, while the term aneurysm defines a focal vessel dilation. CAE is a relatively uncommon angiographic finding and its prevalence ranges between 0.3 and 5% of patients undergoing coronary angiography. Although its pathophysiology is still unclear, atherosclerosis seems to be the underlying mechanism in most cases. The prognostic role of CAE is also controversial, but previous studies reported a high risk of cardiovascular events and mortality in these patients after percutaneous coronary intervention. Despite the availability of different options for the interventional management of patients with CAE, including covered stent implantation and stent-assisted coil embolization, there is no one standard approach, as therapy is tailored to the individual patient. The abnormal coronary dilation, often associated with high thrombus burden in the setting of acute coronary syndromes, makes the interventional treatment of CAE patients challenging and often complicated by distal thrombus embolization and stent malapposition. Moreover, the optimal antithrombotic therapy is debated and includes dual antiplatelet therapy, anticoagulation, or a combination of them. In this review we aimed to provide an overview of the pathophysiology, classification, clinical presentation, natural history, and management of patients with CAE, with a focus on the challenges for both clinical and interventional cardiologists in daily clinical practice.