Optical Coherence Tomography Research Articles

Plaque phenotyping using deep learning in optical coherence tomography imaging

Abstract Background Artificial intelligence (AI) techniques have emerged as powerful tools in various computer vision tasks, particularly in classification, detection, and segmentation. Purpose This study aimed to develop a deep learning model for categorizing optical coherence tomography (OCT) frames into different plaque phenotypes, including thin-cap fibroatheroma (TCFA) and fibroatheroma. Methods A prospective multicenter observational study enrolled 168 patients who underwent percutaneous coronary intervention (PCI) and received OCT imaging for non-target lesions with angiographically estimated diameter stenosis greater than 30% (177 vessels). Among them, 129 patients (135 vessels) underwent follow-up OCT imaging at 1 year. A total of 45,072 OCT frames were randomly divided into training and validation sets in a 4:1 ratio. An EfficientNet-B3 convolutional neural network model was developed to classify OCT frames into TCFA, thick-cap fibroatheroma, non-fibroatheroma, adaptive intimal thickening, and normal vessel categories. Results A confusion matrix comparing manually assessed plaque phenotypes with AI-predicted phenotypes was presented in Table. In the validation datasets (9,015 frames), the overall accuracy of the model was 85.1%. For predicting the presence of TCFA, sensitivity was 81.1%, specificity was 98.8%, positive predictive value was 63.9%, and negative predictive value was 99.5%. Regarding the presence of fibroatheroma, sensitivity was 90.3%, specificity was 89.4%, positive predictive value was 93.1%, and negative predictive value was 85.4%. Conclusions The deep learning algorithm demonstrated high accuracy in detecting TCFA and fibroatheroma with excellent reproducibility. This automated process enables operators to promptly identify high-risk lesions during PCI, potentially leading to improved clinical outcomes.

Speckle decorrelation rate as a robust indicator for visualizing the therapeutic thermal field with OCT

Optical coherence tomography (OCT) is evolving from a diagnostic imaging modality to one that also facilitates therapeutic procedures. However, visualizing the therapeutic thermal field during minimally invasive thermal treatments such as laser or radio frequency ablation is challenging. This difficulty arises because tissues show minimal optical property changes until they reach the coagulation threshold at approximately 50∘C. To address this, we introduce the speckle decorrelation rate as a new, to our knowledge, contrast mechanism for OCT, enhancing the visualization of the therapeutic thermal field. Through ex vivo tissue experiments on a laser ablation-OCT surveillance system, we demonstrate that the speckle decorrelation rate offers superior sensitivity to detect subtle temperature changes and is less sensitive to the selection of time intervals for decorrelation calculations compared to existing speckle decorrelation methods. Our approach, which is label-free and compatible with various OCT systems, has been validated across diverse biological tissues, showing potential to augment the precision and safety of thermal therapies. Additionally, we propose a GPU-accelerated pipeline to expedite processing time, making real-time thermal field visualization feasible.

Comparison of different calcium modification strategies for coronary calcified nodules: insights from optical coherence tomography

Abstract Background The optimal treatment strategy for coronary calcified nodules (CN) remains uncertain. Purpose We sought to compare the safety and efficacy of different calcium modification strategies for managing CN using optical coherence tomography (OCT). Methods In this single-center retrospective cohort study, consecutive patients undergoing OCT-guided percutaneous coronary intervention (PCI) for severely calcified lesions using rotational atherectomy (RA), orbital atherectomy (OA), or intravascular lithotripsy (IVL) between January 2017 and December 2022 were included. OCT analysis was performed through our institutional core-laboratory to identify CN, assess plaque characteristics, and evaluate post-stent optimization. Primary outcomes were minimum stent area (MSA) and MSA at CN site post-PCI. One-year target vessel failure (TVF), defined as a composite of cardiac death, target-vessel myocardial infarction, or ischemia-driven target vessel revascularization, was also recorded. Results Among a total of 154 patients with 158 lesions, CN was identified in 54 lesions (34.2%) and managed with RA (39%, n=21), OA (33%, n=18), or IVL (28%, n=15). The IVL group exhibited a larger minimal lumen diameter, maximum calcium arc, and maximum calcium thickness at baseline. Post-PCI OCT demonstrated comparable MSA (RA: 5.91 ± 0.33mm², OA: 5.94 ± 0.38mm², IVL: 6.46 ± 0.45mm²; p=0.61) and MSA at CN site (6.77 ± 0.49mm², 6.71 ± 0.51mm², 7.13 ± 0.59mm², respectively; p=0.87) after adjusting for procedural and morphologic factors among the groups. The incidence of TVF at one year was similar among the groups. Conclusions In patients undergoing PCI for severely calcified lesions with CN, comparable procedural and clinical outcomes can be achieved using RA, OA, or IVL. The equivalence across these techniques underscores a role for individualized decision-making integrating patient- and lesion-specific characteristics, as well as center expertise when selecting a treatment strategy for CN.OCT findings and clinical outcomes

Application of Artificial Intelligence Models to Predict the Onset or Recurrence of Neovascular Age-Related Macular Degeneration

Neovascular age-related macular degeneration (nAMD) is one of the major causes of vision impairment that affect millions of people worldwide. Early detection of nAMD is crucial because, if untreated, it can lead to blindness. Software and algorithms that utilize artificial intelligence (AI) have become valuable tools for early detection, assisting doctors in diagnosing and facilitating differential diagnosis. AI is particularly important for remote or isolated communities, as it allows patients to endure tests and receive rapid initial diagnoses without the necessity of extensive travel and long wait times for medical consultations. Similarly, AI is notable also in big hubs because cutting-edge technologies and networking help and speed processes such as detection, diagnosis, and follow-up times. The automatic detection of retinal changes might be optimized by AI, allowing one to choose the most effective treatment for nAMD. The complex retinal tissue is well-suited for scanning and easily accessible by modern AI-assisted multi-imaging techniques. AI enables us to enhance patient management by effectively evaluating extensive data, facilitating timely diagnosis and long-term prognosis. Novel applications of AI to nAMD have focused on image analysis, specifically for the automated segmentation, extraction, and quantification of imaging-based features included within optical coherence tomography (OCT) pictures. To date, we cannot state that AI could accurately forecast the therapy that would be necessary for a single patient to achieve the best visual outcome. A small number of large datasets with high-quality OCT, lack of data about alternative treatment strategies, and absence of OCT standards are the challenges for the development of AI models for nAMD.

The impact of SYNTAX score on culprit lesion morphology of acute coronary syndrome

Abstract Background The SYNTAX score quantifies the complexity of coronary artery morphology and is useful in determining the indication for CABG (Coronary Artery Bypass Grafting) or PCI (Percutaneous Coronary Intervention), which often reflect coronary artery disease severity. However, how SYNTAX score affects etiology of ACS (Acute Coronary Syndrome) patients observed by OCT (Optical Coherence Tomography) has been unclear. Methods This is a sub study of TACTICS OCT registry (n=702) which include ACS patients who underwent OCT guided PCI. Based on SYNTAX score, patients were divided into low-SYNTAX-group (1-22 points) and high-SYNTAX-group (23 points or higher). ACS culprit lesions were classified into plaque rupture (PR), plaque erosion (PE), and calcified nodule (CN). We compared patient characteristics and culprit lesions in low-group and high-group. Results High-SYNTAX-group was significantly younger with relatively greater prevalence of diabetes and lower body mass index. Peak CK, LVEF, Multi vessel and TIMI grade were also significantly greater in high-SYNTAX-group than low-SYNTAX-group. Although PR and PE were 2 most common etiologies of ACS in both groups, proportion of CN was much greater in high-SYNTAX-group than low-SYNTAX-group. Conclusion High-SYNTAX score was likely to have impact on ACS etiology increasing proportion of CN.

Prognostic value of diffuse high-risk plaque in patients with acute myocardial infarction: a three-vessel optical coherence tomography study

Abstract Background Existing evidence has identified that high-risk plaque (HRP) characterized by a thin-cap fibroatheroma and/or a minimal lumen area ≤ 3.5 mm² were indicative of future cardiovascular events. Diffuse coronary artery disease also contributes to the poor prognosis. Purpose The present study aims to assess the prognostic value of diffuse HRP in patients with acute myocardial infarction (AMI) by using three-vessel optical coherence tomography (OCT). Methods A total of 674 patients with AMI who underwent OCT examination of three major epicardial arteries between January 2017 and December 2018 were consecutively studied. Among 2843 nonculprit lesions detected by OCT, 1375 (48.4%) HRPs were identified and divided into diffuse HRP group (lesion length >20mm, n=443) and focal HRP group (lesion length ≤20mm, n=932). Patients were followed up for a median period of 5 years. Major adverse cardiovascular event (MACE) was defined as the composite of cardiac death, nonculprit lesion-related nonfatal myocardial infarction, and unplanned coronary revascularization. Results The average age of all enrolled patients is 56.7±11.4 years, with 74.9% of male. As compared with focal HRP group, diffuse HRP group had longer lesion length [25.8(23.0,30.8) mm vs. 13.2(9.8,16.1) mm, P<0.001], longer lipid length [18.6(12.3,24.9) mm vs. 7.0(4.5,10.5) mm, P<0.001], and thinner minimal fibrous cap thickness [73.3(53.3,106.7) μm vs. 93.3(60.0,130.0) μm, P<0.001], whereas mean lipid arc was comparable between the two groups. The prevalence of nonculprit plaque rupture (14.2% vs. 7.8%, P<0.001) was significantly higher in diffuse HRP group than that in the focal HRP group. Nonculprit lesions in diffuse HRP group had higher incidence of macrophage accumulation, microvessels, cholesterol crystals, calcification, and layered plaque phenotype than those in focal HRP group (all P<0.001). The incidence of nonculprit lesion-related MACE was 4.7% in diffuse HRP group and 1.7% in focal HRP group [HR: 3.155, 95% confidence interval: 1.579 to 6.301, P=0.002]. Conclusions In patients with AMI, diffuse HRP at nonculprit segment has higher levels of plaque vulnerability and is predictive of future adverse cardiovascular events. Further studies are warranted to investigate the individual treatment strategy of diffuse and focal HRP.Figure 1.Nonculprit plaque vulnerabilityFigure 2.MACE

Preclinical assessment of transcatheter-delivered expandable endoluminal polymeric graft fabricated by electrospinning of microfiber

Abstract Background Matrix fabricated from electrospinning of micro fibre of polyester is porous and permeable to blood, facilitates cell infiltration and late resorption of the biodegradable material. This biomaterial opens an avenue of research in recreating a novel and favourable endoluminal lining in diseased vessel. Previous preclinical work has shown that implants in aorta of rodents generate layers of endoluminal elastin. In humans, one of the most impervious arteries to atherosclerosis is the intra-thoracic artery; therefore, an attempt to induce similar structures with an implantable device was made. Methods For this study, novel tissue-engineered vascular grafts (T-TEVGs) were used in a preclinical rabbit iliac artery model. It was made of resorbable polyester biomaterial processed into fibrous tubular conduits. These T-TEVGs were implanted percutaneously. In total, twelve T-TEVGs in iliac arteries of nine rabbits were implanted. Follow-up were conducted on five rabbits with eight T-TEVGs at three months, two rabbits with two T-TEVGs at six months, and two rabbits with two T-TEVGs at twelve months. At follow-up, percutaneous optical coherence tomography (OCT) was performed, and OCT-derived luminal vessel wall dimensions and fractional flow reserve (OFR) derived from OCT were assessed. Results The overall pooled analysis at different timepoints on follow-up, documented an average MLA of 1.74±0.48mm2, average of proximal and distal reference area of 4.55±0.99 mm2, average area stenosis of 61±12%, and mean OFR value of 0.96±0.03 (OFR ranging from 0.89 to 0.99). There was a moderate positive correlation between minimum lumen area and OFR (r=0.590, p< 0.01). There was a strong negative correlation between percentage area stenosis and OFR (r= - 0.846, p< 0.01). At no timepoint in follow-up and in every vessel analysed, OFR value was lower than 0.89, suggesting that none of these vessels exhibited flow-limiting narrowing. Our study has a few limitations. 1) The preclinical model is a non-atherosclerotic rabbit; 2) There was no barotrauma prior to the implantation of the device; 3) Limited sample size, short and medium follow-up duration, and pooling of assessment at different timepoints. Conclusion The current study shows the durability and favourable hemodynamics of this bioresorbable fibrillated scaffold at short and medium term follow-up, supporting the potential utility of T-TEVEGs for peripheral human artery revascularisation. Long-term follow-ups are mandatory to confirm the durability of these results. Histopathology of this preclinical model should confirm the endoluminal elastin as previously documented in rodents (rats) and will be presented at the time of the congress.

Association of polarimetric signatures with coronary plaque composition in patients with acute and chronic coronary syndrome: an intravascular polarization-sensitive optical coherence tomography study

Abstract Background Intravascular polarimetry with polarization-sensitive (PS-) optical coherence tomography (OCT) measures polarization properties, birefringence and depolarization, in parallel with structural features available with conventional OCT (Figure 1). Birefringence is elevated in collagen and collagen-synthesizing smooth muscle cells, which imparts mechanical integrity to fibrous caps. Depolarization is elevated in the presence of macrophages and lipid/necrotic core. Purpose This study aimed to investigate polarimetric signatures of coronary lesions in patients with acute coronary syndrome (ACS) and chronic coronary syndrome (CCS). Furthermore, we aimed to investigate diagnostic value for birefringence and depolarization of ACS culprit lesions discriminating from CCS target lesions. Methods This was the first-in-human study of intracoronary PS-OCT in Japan, consisting of 17 patients with ACS (n = 5) or CCS (n = 12) who underwent intravascular PS-OCT. ACS culprit lesions (ACS-lesions) and CCS target lesions (CCS-lesions) were included in the analysis, resulting in a total of 862 cross-sections. In the cross-sectional images, lumen segmentation and guidewire artifact were automatically segmented. The median value of birefringence and depolarization were automatically analyzed using depolarization cut-off value (cross-sectional level). Birefringence and depolarization of ACS- and CCS-lesions were compared by using a generalized estimating equation model. Receiver operating characteristic (ROC) analysis was used to investigate diagnostic performance of polarimetric signatures for the identification of ACS-lesions. Results Compared to CCS-lesions, ACS-lesions featured higher lipid-burden index and maximum lipid arc (both p < 0.05). Compared to the CCS-lesions, ACS-lesions exhibited significantly lower birefringence (p < 0.05) and higher depolarization (p < 0.05) (Figure 2). In the ROC analysis for differentiating ACS-lesions from CCS-lesions, area under the curves (AUC) for birefringence and depolarization were 0.712 and 0.672, respectively. In the multivariable ROC analysis in diagnosing ACS lesions, combination of birefringence with depolarization improved the AUC to 0.755 (p ＝ 0.025). Conclusions Intravascular PS-OCT provides quantitative compositional assessment of coronary lesions. Decreased birefringence and pronounced depolarization within the ACS-lesions indicate increased collagenolytic activity and the presence of macrophage infiltration, respectively. These results suggest that polarization properties may serve as quantitative imaging markers for assessing natural history of coronary atherosclerosis.

Arterial stiffness characterization of patients with different ACS-causing plaque morphologies quantified by optical coherence tomography

Abstract Background Optical coherence tomography (OCT) has refined acute coronary syndrome (ACS)-management by enabling in-depth characterization of culprit lesions. Differentiating between plaques with ruptured (RFC) and intact fibrous cap (IFC) has shaped clinical decision making. However, the systemic vascular changes associated with different plaque morphologies remain unexplored. Purpose To investigate arterial stiffness among different ACS-causing plaque morphologies (RFC vs. IFC) and its prognostic value post-ACS. Methods We conducted a secondary analysis of a prospective registry study, including patients who underwent OCT-characterization of the ACS-causing culprit lesion and received arterial stiffness assessment 90 days post-index event. The association between arterial stiffness parameters, such as pulse wave velocity (PWV), aortic pulse pressure (APP), heart rate-corrected augmentation index (AIx@75) and plaque morphologies was assessed using logistic regression, adjusted for age, sex, hypertension, presence of diabetes mellitus, smoking status, LDL-C and discharge medications (ACE-inhibitors/ARBs, beta blockers, calcium-channel blockers and diuretics). A multiparameter model additionally included intima-media-thickness and all arterial stiffness metrics. Cox regression, further adjusted for stroke history, prior percutaneous coronary intervention or stable coronary artery disease and Killip class, evaluated the link between arterial stiffness parameters and major adverse cardiovascular events plus (MACE+). Results In total, 110 patients with arterial stiffness and OCT data were included. Of these, 78 (70.9%) patients had RFC- and 32 (29.1%) IFC-ACS. The median age was 61.5 years and 80.0% of patients were male. Patients with RFC- had significantly higher PWV (8.35 vs. 7.50 m/s, p=0.015) compared to IFC-ACS. Both groups received similar regimens of antihypertensive, diuretic and lipid-lowering pharmacological therapy at discharge (p>0.1). After multivariable adjustment, increased PWV (4th Quartile [Q4] vs. 1st Quartile [Q1] Adjusted Hazard Ratio [aHR]: 1.38 [95% Confidence Interval (CI) 1.02-1.88], p=0.043) was associated with RFC- while high APP was significantly associated with IFC-ACS as the underlying plaque morphology (Q4 vs. Q1 aHR: 0.65 [95% CI 0.48-0.87], p=0.005) (Figure 1). Furthermore, per one-unit increment in APP we observed a 10% increase in risk for MACE+ in patients with RFC-ACS (aHR: 1.10 [95% CI 1.02-1.19], p=0.016) but not IFC-ACS (aHR: 0.95 [95% CI 0.82-1.11], p=0.54). No risk modification with increases in PWV and AIx@75 were observed, regardless of underlying plaque pathology (p>0.05). Conclusion There are distinct differences in arterial stiffness between patients with RFC- and IFC-ACS. These results underscore the value of a patient-specific approach that integrates invasive and non-invasive vascular characterization for identifying high-risk individuals and guiding therapy to enhance clinical outcomes.

Serial optical coherence tomography assessment of coronary atherosclerosis and long-term clinical outcomes

Abstract Background The impact of high-risk coronary artery plaques identified using optical coherence tomography (OCT) on late luminal narrowing and clinical events remains poorly understood. Methods This multicenter prospective study included 176 patients who underwent percutaneous coronary intervention (PCI) and serial OCT at baseline and 1-year follow-up to investigate non-target regions with angiographically intermediate stenosis. The primary outcome measure was luminal narrowing within the matched regions of interest in the non-target regions over a 1-year period. The secondary outcome measures included all-cause death, cardiac death, nonfatal myocardial infarction, and ischemia-driven coronary artery revascularization within 3 years. Results At 1 year after PCI, the coronary artery lumen area in non-target regions significantly decreased from 6.06 (95% confidence interval [CI], 5.60–6.53) to 5.88 (95% CI, 5.41–6.35) mm2, with a difference of -0.18 (95% CI, -0.22 to -0.14 mm2; P<0.001). This decrease was pronounced in thin-cap fibroatheromas (TCFAs), thick-cap fibroatheromas, mixed plaques, and fibrous plaques. The prevalence of TCFAs decreased from 3.4% to 3.3% (P<0.001), whereas that of thick-cap fibroatheromas also decreased from 35% to 33% (P<0.001). Patients with TCFA had a significantly higher risk of ischemia-driven non-target vessel revascularization (hazard ratio [HR], 2.42; 95% CI, 1.03–5.71; P=0.04), primarily due to revascularization in the imaged region. The higher prevalence of fibroatheroma was associated with a numerically increased risk of imaged region revascularization (HR per 10%, 1.38; 95% CI, 0.97–1.97; P=0.07). The prevalence of coronary artery calcium significantly increased from 31% at baseline to 34% at 1-year follow-up (P<0.001), accompanied by a significant increase in calcium thickness and angle. Diabetes and current smoking habits were independently associated with increasing calcium prevalence. No significant association was observed between the prevalence of coronary artery calcium and clinical outcomes within 3 years. Conclusions Coronary artery lumen area significantly decreased over a 1-year interval, particularly in TCFAs, thick-cap fibroatheromas, mixed plaques, and fibrous plaques. Although no significant association was noted between coronary artery calcium prevalence and clinical outcomes within 3 years, the interaction between calcium progression and long-term clinical events necessitates further investigation.

Novel Approaches for the Early Detection of Glaucoma Using Artificial Intelligence

Background: If left untreated, glaucoma—the second most common cause of blindness worldwide—causes irreversible visual loss due to a gradual neurodegeneration of the retinal ganglion cells. Conventional techniques for identifying glaucoma, like optical coherence tomography (OCT) and visual field exams, are frequently laborious and dependent on subjective interpretation. Through the fast and accurate analysis of massive amounts of imaging data, artificial intelligence (AI), in particular machine learning (ML) and deep learning (DL), has emerged as a promising method to improve the early detection and management of glaucoma. Aims: The purpose of this study is to examine the current uses of AI in the early diagnosis, treatment, and detection of glaucoma while highlighting the advantages and drawbacks of different AI models and algorithms. In addition, it aims to determine how AI technologies might transform glaucoma treatment and suggest future lines of inquiry for this area of study. Methods: A thorough search of databases, including Web of Science, PubMed, and Scopus, was carried out to find pertinent papers released until August 2024. The inclusion criteria were limited to research published in English in peer-reviewed publications that used AI, ML, or DL to diagnose or treat glaucoma in human subjects. Articles were chosen and vetted according to their quality, contribution to the field, and relevancy. Results: Convolutional neural networks (CNNs) and other deep learning algorithms are among the AI models included in this paper that have been shown to have excellent sensitivity and specificity in identifying glaucomatous alterations in fundus photos, OCT scans, and visual field tests. By automating standard screening procedures, these models have demonstrated promise in distinguishing between glaucomatous and healthy eyes, forecasting the course of the disease, and possibly lessening the workload of physicians. Nonetheless, several significant obstacles remain, such as the requirement for various training datasets, outside validation, decision-making transparency, and handling moral and legal issues. Conclusions: Artificial intelligence (AI) holds great promise for improving the diagnosis and treatment of glaucoma by facilitating prompt and precise interpretation of imaging data and assisting in clinical decision making. To guarantee wider accessibility and better patient results, future research should create strong generalizable AI models validated in various populations, address ethical and legal matters, and incorporate AI into clinical practice.

Significant stenosis without thrombus may be the third most common etiology of acute coronary syndrome

Abstract Background Plaque rupture (PR), plaque erosion (PE) and calcified nodule (CN) are known as major etiologies of acute coronary syndrome (ACS). On the other hand, significant stenosis without thrombus (SSWT) can be sometimes observed in culprit plaque of ACS. However, incidence and clinical feature of SSWT in ACS patients are not well known in Japanese. Method This is a sub study of TACTICS registry which include ACS patients (n=702) undergoing primary percutaneous coronary intervention (PCI) under optical coherence tomography (OCT) in Japan. Using this registry data, we compared the clinical features and OCT findings of SSWT in ACS patients in comparison with PR, PE and CN. Major adverse cardiac event (MACE) was defined as death, non-fatal myocardial infarction, heart failure, or ischemia-driven revascularization at 1-year. Results Plaque rupture (PR: n=411, 61%) and plaque erosion (PE: n=178, 26%) were 2 major etiologies, which was followed by SSWT (n=59, 9%) and calcified nodule (CN: n=28, 4%). Clinical characteristics are shown in table 1. Patients with SSWT was slightly older than PR and PE but younger than CN. Proportion of male was fewer than PR and PE but greater than CN. In terms of traditional coronary risk factors, there were significant differences in prevalences of diabetes, active smoking, and hemodialysis among different etiologies. In SSWT, non-ST elevation myocardial infarction was the main type of ACS followed by unstable angina and ST elevation myocardial infarction (51%, 39% and 10%, respectively), which may be associated with the least CK level and greater TIMI flow. Lesion was less complex with lower proportion of type B2 or C, shorter procedure time, lower proportion of multivessel disease and lower syntax score. OCT findings are shown in table 2. Regarding lipid component and calcification, SSWT showed similar finding as PE. Cholesterol crystal was relatively less as compared to PR and PE. Kaplan-Meier survival curve showing MACE and ischemia driven-TLR are shown in figure 1 and 2. MACE and TLR was the least in SSWT. Conclusion SSWT was the third most common etiology of ACS with different feature from PR, PE and CN.

A meta-analysis of randomised controlled trials comparing optical coherence tomography-guided against angiography-guided revascularisation

Abstract Optical coherence tomography (OCT)-guided percutaneous coronary intervention (PCI) offers more in-depth assessment of plaque morphology, vessel sizing and post-PCI stent deployment characteristics than angiography guidance alone. Previous studies have demonstrated superiority of OCT-guided compared to angiography-guided PCI in stent implantation and expansion, with no difference in safety outcomes. Despite this, adoption of OCT-guided PCI remains low in clinical practice due to its increased procedural time, larger contrast volume, and added cost. Two large multicentre international randomised controlled trials (RCTs) were recently published. We therefore aimed to perform an up-to-date meta-analysis of RCTs comparing OCT-guided revascularisation against angiography-guided revascularisation on hard clinical outcomes. A comprehensive search of PubMed/MEDLINE and Ovid/Embase was performed, of which only RCTs were included. Two authors identified relevant articles and extracted the data independently. Any disagreements were resolved by a third author. Clinical outcome data was extracted from each study and then pooled to determine the overall risk ratio (RR) and confidence interval (CI) collectively. This was calculated with random-effects model using the Mantel-Haenszel method. All reported P values are two-sided, with significance set at P<0.05. A total of ten RCTs involving a total of 5062 patients were included. After an average follow-up of 20 months, there was no significant difference in the trial-defined composite endpoint between OCT-guided versus angiography guided revascularisation [6.8% versus 7.9%, RR 0.85, 95% CI (0.69 to 1.03), P=0.10, heterogeneity (I2)=0%]. There was also no significant difference in cardiac death [1.0% versus 1.6%, RR 0.61, 95% CI (0.36 to 1.02), P=0.06, heterogeneity (I2)=0%, Figure 1a], myocardial infarction [3.2% versus 3.7%, RR 0.86, 95% CI (0.65 to 1.15), P=0.31, I2=0%, Figure 1b] and target lesion or vessel repeat revascularisation [3.8% versus 4.1%, RR 0.95, 95% CI (0.72 to 1.25), P=0.70, I2=0%, Figure 1c] between the two arms. However, the OCT-guided revascularisation arm was associated with a significantly lower rate of stent thrombosis [0.8% versus 1.5%, RR 0.57, 95% CI (0.33 to 0.97), P=0.04, I2=0%, Figure 1d] than the angiography-guided revascularisation arm. The number-needed-to-treat (NNT) by OCT-guided revascularisation to reduce one additional stent thrombosis event was 143. In conclusion, our findings show the use of OCT-guided revascularisation led to a significant reduction in stent thrombosis compared to angiography-guided revascularisation, but there was no difference in cardiac death, myocardial infarction and repeat revascularisation. The NNT for stent thrombosis was 143 patients. Further research is needed to identity those subgroups most likely to benefit from OCT-guided revascularisation before it can be more widely adopted to significantly impact on clinical care.

Very short-term effects of single dose of proprotein convertase subtilisin kexin 9 inhibitor therapy before percutaneous coronary intervention

Abstract Introduction Several pioneering studies have reported that continuous administration of proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitor reduces cardiovascular events and plaque volume on intravascular ultrasound and increase the thickness of the fibrous-cap on optical coherence tomography after 52-76 weeks.[1,2] However, the effect of PCSK9 inhibitors in very short period of time has not adequately been evaluated. Purpose This study aimed to investigate the effect of the single dose of PCSK9 inhibitor in regard to serial change of plaque composition in very short period with near-infrared spectroscopy with intravascular ultrasound (NIRS-IVUS). Methods This prospective, single arm, single-center, interventional study included 27 consecutive coronary artery disease patients (silent myocardial ischemia and stable angina) who performed NIRS-IVUS at the time of coronary angiography for diagnosis between June 2021 and August 2023. Maximal lipid-core burden index over any 4-mm segment (max-LCBI4mm) and total lipid-core burden index (T-LCBI) at the target lesions were assessed with NIRS-IVUS and they were administered evolocumab 420mg. After 2 to 6 weeks, percutaneous coronary intervention (PCI) was performed on a standby basis and repeat NIRS-IVUS were performed at PCI. Results The median max-LCBI4mm showed a significant decrease from 387 to 315 (IQR: 268 to 572 and IQR: 221 to 488, respectively; p = 0.02) in a lesion-wise analysis. The median T-LCBI also showed a significant decrease from 160 to 117 (IQR: 105 to 263 and IQR: 65 to 226, respectively; p = 0.02). Minimum lumen area and minimum lumen diameter showed no significant changes. Conclusions Single dose of PCSK9 inhibitor therapy before PCI resulted in significant degression of lipid core plaques identified by NIRS at the target lesion in very short period of time.Changes of max-LCBI4mmChanges of T-LCBI

Differences in non-flow limiting non-culprit plaque characteristics after myocardial infarction in patients with versus without chronic kidney disease

Abstract Background Patients with chronic kidney disease (CKD) are at increased risk for recurrent cardiovascular events after myocardial infarction compared to patients with preserved renal function. This disparity may be related to differences in plaque morphology. Purpose To compare non-flow limiting non-culprit (NC) plaque characteristics as assessed by optical coherence tomography in patients with versus without chronic kidney disease presenting with myocardial infarction. Methods 438 patients presenting with myocardial infarction with additional non-flow limiting (defined as a fractional flow reserve >0.80) NC lesions were included in the prospective observational PECTUS-obs study after treatment of the infarct related artery. An independent core laboratory performed all quantitative and qualitative OCT analyses. For the present subgroup analysis, patients were grouped according to the presence or absence of CKD, which was defined as an estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m². Baseline characteristics were compared between groups on a patient-level and OCT characteristics were compared on a lesion-level while accounting for within-patient clustering. Results Out of 420 patients with at least one analyzable OCT, baseline renal function was known in 416. Among them, there were 55 patients with and 361 patients without CKD (mean eGFR 47.4 ± 9.2 vs 84.7 ± 15.0 ml/min/1.73 m², p<0.001). Patients with CKD were older (mean age 73 ± 9 vs 62 ± 10 years, p<0.001), more frequently were female (29.1% vs 17.2%, p=0.035) and predominantly presented with a non-ST-segment elevation myocardial infarction (72.2% vs 44.9%, p<0.001). Comorbid disease was more prevalent among patients with CKD, including a higher prevalence of hypertension (p=0.010), hypercholesterolemia (p=0.020), diabetes (p<0.001), history of myocardial infarction (p<0.001), carotid artery disease (p=0.019) and peripheral artery disease (p=0.002). Coronary lesions in patients with CKD on average had a larger maximal calcium arc (188 ± 114 vs 137 ± 87º, p=0.003) and length (11.9 ± 10.3 vs 8.4 ± 7.4 mm, p=0.021). Lipid plaques were less prevalent among lesions in patients with CKD (63.6% vs 78.0%, p=0.016) and less frequently had a lipid arc ≥90º (60.6% vs 76.1%, p=0.018). Although the mean minimal fibrous cap thickness was lower in patients with CKD (p=0.025), no difference was observed in the prevalence of thin-cap fibroatheromas (p=0.984) or high-risk plaques according to the PECTUS-obs criteria (p=0.665). Conclusion Non-flow limiting NC lesions in patients with CKD differ from those in patients without CKD in a cohort of patients presenting with myocardial infarction. Overall, plaques in patients with CKD show more extensive calcification, whereas lesions in patients without CKD more often consist of lipid plaques, but the prevalence of high-risk plaques was comparable.

Epiretinal membrane: an overview and update.

Epiretinal membrane (ERM) is a frequently diagnosed macular disease associated with aging, characterized by a fibrous membrane forming on the internal limiting membrane (ILM) and leading to visual dysfunctions such as metamorphopsia. Various hypotheses regarding the pathology of metamorphopsia have been proposed; however, the complete pathophysiologic mechanism underlying ERM remains unclear. Optical coherence tomography (OCT) provides detailed images enabling precise diagnosis and characterization of ERM, with several recent studies using the latest OCT imaging techniques. Surgical removal of ERM is the only treatment option; however, criteria for surgical intervention are not established, complicating the decision-making processes. Furthermore, the debate on whether simultaneous peeling of the ILM during ERM surgery enhances outcomes or poses unnecessary risks is ongoing, with no definite conclusion having yet been reached. This review also focuses on epiretinal proliferation, which is different from ERM and is characteristic of lamellar macular hole (LMH). Recently, diagnostic criteria for LMH and related diseases were proposed. Reports on effective surgical procedures for LMH exist, although more research is needed to confirm the long-term outcomes. Thus, this review article aims to provide an overview and updated knowledge of ERM, LMH, and related diseases.

Impact of sex and age on culprit plaque type of acute coronary syndrome in Japanese patients from TACTICS registry

Abstract Background In acute coronary syndrome (ACS), plaque rupture (PR) is the most frequent etiology followed by plaque erosion (PE) while calcified nodule (CN) is the least etiology. These three are known as major etiologies of ACS. Traditionally, it has been believed that sex and age have impact on etiology of ACS. For example, plaque erosion was thought to often occur in young female while calcified nodule often occur in elderly patients. However, impact of sex and age have not been well described. Methods This is a sub-study from TACTICS registry which consist of 702 Japanese ACS patients who underwent primary percutaneous coronary intervention under optical coherence tomography (OCT) from multicenter. Based on the OCT findings, patients were divided into PR, PE, CN and others. These data were stratified by sex and ages (<50, 50s, 60s, 70s, 80 or over). In this sub-study, we mainly focused on 3 major etiologies of ACS (PR, PE, CN) and compared incidence and clinical characteristics based on sex and ages. Results Distribution of culprit plaque type in ACS patients are shown in figure 1A (male) and 1B (female). PR remained top etiology of ACS in any sex and any age category. However, trend of PE was different between male and female. In male, as patients get younger, incidence of PE increased. In male patients under 50, incidence of PE was almost similar as PR. On the other hand, in female, incidence of PE was greatest in 70s followed by 80 or over. Surprisingly, young female showed the least incidence of PE. CN was the least etiology of three but increased especially from 80. Clinical characteristics are shown in table 1A (male) and 1B (female). In male, most of the baseline characteristics differ between different ages while in female, most of the baseline characteristic did not differ between different ages. Conclusion In our data, PE was more distinct in younger male ACS patients while PE was not that distinct in younger female ACS patients. The impact of sex and age on culprit plaque type of ACS might be variable depending on population.

Coronary stent edge segments as determinant of clinical outcomes: An OCTOBER Trial Substudy

Abstract Background Small lumen dimensions and high plaque burden in stent edge segments are known risk factors for subsequent clinical events after percutaneous coronary intervention (PCI). The evidence using intravascular optical coherence tomography is scarce. Purpose This study aimed to characterize edge segments after PCI and the relation to clinical outcomes in the randomized OCTOBER trial on bifurcation PCI optimized using optical coherence tomography. Methods This is a predefined substudy of the OCTOBER Trial. Edge segments were analysed in detail for degree of stenosis and plaque composition using a dedicated software. Data was planned to be analysed using multi-level cox regression analysis, but descriptive statistics was applied due to very low event rates after OCT-guided PCI. Main endpoints were OCT-detected edge residual stenosis, lipid plaque, calcification, and dissections. Post PCI coronary angiography was analysed for diameter stenosis, edge segment length and minimal lumen diameter. Patients with cardiac events were diagnosed with angiography duringt the two-year follow-up period. Results A total of 597 patients were treated with OCT-guided PCI. Analysable final OCT scans with no additional treatment was available for 505 patients in the main vessel and for the side branch in 289 cases. At deadline for abstract submission 242 scans with 474 edges were analysed and included in preliminary results.Lesions with ≥30% diameter stenosis was found in 20% of proximal edges, 24% of distal edges and 37% of side branch (SB) edges. A plaque burdenOCT ≥180° was found in 74% of proximal edges, 48% of distal edges, and 52% of SB edges. A lipid plaque wafound in 35%, 11% and 14%, dissections in 15%, 6% and 12%, and ≥180° calcium was found in 7%, 4% and 4% of edges respectively. Six patients (1%) of the total OCT-guided population had an edge-related event during the median two-year follow-up. Only two of these 6 patients had post-procedural OCT-scans of the event-related edge, thus 4 of the cases were effectively angiographic guided. Conclusion Only a small fraction of edge segments in the OCTOBER Trial were left with residual edge disease exceeding protocol thresholds. This resulted in historically very low rate of edge related events. No evaluation of a stent edge by OCT in otherwise OCT guided patients appeared to be the main predictor of edge related events. Final results are presented at ESC 2024.

Lesion-level changes induced by low-density lipoprotein cholesterol lowering therapy in patients with acute myocardial infarction: the pre-specified PACMAN-AMI lesion-level analysis

Abstract Background Previous intracoronary imaging studies investigated atherosclerotic changes induced by lipid-lowering therapy in extensive coronary segments, based on anatomical landmarks and irrespective of the baseline atheroma burden. The effects of lipid-lowering therapy focusing on coronary lesions with advanced atherosclerotic features and at presumably higher risk for future events remains largely unknown. Purpose To provide a lesion-level analysis reporting changes in high-risk atherosclerotic features and plaque phenotypes induced by alirocumab versus placebo in addition to high-intensity statin therapy in nonculprit coronary lesions of patients admitted with acute myocardial infarction (AMI). Methods In this pre-specified lesion-level analysis of the PACMAN-AMI trial, coronary lesions were identified as segments with plaque burden ≥40% defined by intravascular ultrasound (IVUS). IVUS, near-infrared spectroscopy (NIRS) and optical coherence tomography (OCT) images at baseline and 52-week follow-up were manually matched and lesion-level imaging outcome measures were calculated by analysts blinded to treatment allocation and patient clinical data. The evolution of high-risk plaque phenotypes as defined by each imaging modality (IVUS-defined plaque burden ≥70%, NIRS-defined maximum LCBI 4 mm ≥400, OCT-defined thin-cap fibroatheroma <65µm) was investigated. Results Overall, 591 lesions with available baseline and follow-up imaging were included. Of these, 287 were identified in 118 patients (214 vessels) in the alirocumab arm, and 304 lesions were identified in 127 patients (239 vessels) in the placebo arm. At lesion-level, mean change in percent atheroma volume (PAV) by IVUS was -4.86% with alirocumab vs -2.78% with placebo (difference, -2.02 [-3.00 to -1.05], p<.001), substantially greater than that at vessel-level (Figure 1). At the minimum lumen area (MLA) site, mean change in PAV was -10.14% with alirocumab vs -6.70% with placebo (difference, -3.36 (-4.98 to -1.75, p<0.001). MLA increased by 0.15 mm2 with alirocumab and decreased by 0.07 mm2 in the placebo arm (difference, +0.21, 0.01 to 0.41, p=0.036), whereas arterial remodeling was similar between arms (-0.73±1.61 in alirocumab vs -0.63±1.31 in placebo group, p=0.482). Among lesions with high-risk plaque phenotypes at baseline, those in the alirocumab arm more frequently showed a more stable and less lipid-rich plaque phenotype at follow-up than those in the placebo arm (Figure 2). Conclusions At lesion-level, intense lipid-lowering therapy with alirocumab in addition to high-intensity statin therapy induced extensive PAV regression, substantially greater than described in previous vessel-level analyses. Compared to statin therapy alone, alirocumab treatment was associated with a greater enlargement of the lesion MLA, similar negative arterial remodeling, and a more frequent transition of high-risk plaque phenotypes into more stable, less lipid-rich plaque phenotypes.Figure 1.Figure 2

The relationship between atherogenic index of plasma and plaque vulnerabilities: an optical coherence tomography study

Abstract Background Atherogenic index of plasma (AIP) has been recommended as a marker of plasma atherogenicity. The impact of AIP on plaque characteristics is not fully understood. Purpose The study investigates the relationship between AIP and coronary plaque features in patients with acute coronary syndrome (ACS). Methods From January 2015 to June 2017 pre-intervention optical coherence tomography (OCT) was performed in 522 ACS patients. AIP was defined as the base 10 logarithm of the ratio of the concentrations of triglyceride to high-density lipoprotein cholesterol. Patients were divided into four groups according to AIP quartiles. Results A total of 332 patients were included for the analysis. The incidence of thin-cap fibroatheroma (TCFA) (group I [lowest] 9.09% vs group II 16.5% vs group III 44.7% vs group IV [highest] 52.9%), macrophage accumulation (group I 18.2% vs group II 22.4% vs group III 31.8% vs group IV 47.1%), plaque rupture (group I 10.4% vs group II 14.1% vs group III 17.6% vs group IV 34.1%) and plaque erosion (group I 2.6% vs group II 2.4% vs group III 14.1% vs group IV 12.9%) were significantly different among AIP quartiles. Multivariate logistic regression revealed the risk of TCFA (odds ratio 11.938, 95% confidence interval 4.723-30.174, p<0.001) and plaque rupture (OR 4.976, 95% CI 1.993-12.424, p<0.001) increased in group IV compared to group I. Receiver operating characteristics curve showed the predictive value of AIP for TCFA and plaque rupture were 0.720 and 0.669 respectively. Conclusions AIP is an independent predictor for vulnerable plaques beyond traditional factors. It can be integrated in clinical practice for risk stratification of ACS patients.Multivariate logistic analysisROC curves