Optical coherence tomography in coronary atherosclerosis assessment and intervention

Automated comprehensive evaluation of coronary artery plaque in IVOCT using deep learning

The process of manually characterizing and quantifying coronary artery plaque tissue in intravascular optical coherence tomography (IVOCT) images is both time-consuming and subjective. We have developed a deep learning-based semantic segmentation model (EDA-UNet) designed specifically for characterizing and quantifying coronary artery plaque tissue in IVOCT images. IVOCT images from two centers were utilized as the internal dataset for model training and internal testing. Images from another independent center employing IVOCT were used for external testing. The Dice coefficients for fibrous plaque, calcified plaque, and lipid plaque in external tests were 0.8282, 0.7408, and 0.7052 respectively. The model demonstrated strong correlation and consistency with the ground truth in the quantitative analysis of calcification scores and the identification of thin-cap fibroatheroma (TCFA). The median duration for each callback analysis was 18 s. EDA-UNet model serves as an efficient and accurate technological tool for plaque characterization and quantification.

Long-Term Prognostic Implications of Non-Culprit Lesions in Patients Presenting With an Acute Myocardial Infarction: Is It the Angiographic Stenosis Severity or the Underlying High-Risk Morphology?

BACKGROUND

Patients with acute myocardial infarction and angiographically obstructive non-culprit lesions are at high risk for recurrent major adverse cardiac events (MACEs). However, it remains largely unknown whether events are due to stenosis severity or due to the underlying high-risk lesion morphology.

METHODS

Between January 2017 and December 2021, 1312 patients with acute myocardial infarction underwent optical coherence tomography of all the 3 main epicardial arteries after successful percutaneous coronary intervention. Patients and lesions were categorized according to the presence or absence of (1) 1 or more non-culprit angiographic obstructive stenoses with a visual diameter stenosis of ≥50% and (2) 1 or more lesions with an underlying high-risk morphology defined as an optical coherence tomography thin-cap fibroatheroma (TCFA). Patients were followed for up to 5 years (median 4.1 [interquartile range: 3.0-5.0] years). MACEs comprised cardiac death, non-fatal myocardial infarction, and unplanned coronary revascularization.

RESULTS

Overall, 492 patients had at least 1 obstructive non-culprit lesion, 352 had a single lesion, and 140 had multiple obstructive non-culprit lesions. The presence and number of angiographic obstructive non-culprit lesions correlated with the proportion and number of optical coherence tomography-derived TCFAs. At the lesion level, the prevalence of TCFA was twice as high in obstructive lesions compared with nonobstructive lesions. Patients with obstructive non-culprit lesions had an increased risk of overall MACEs (17.7% versus 12.8%; hazard ratio, 1.39 [95% CI, 1.02-1.91]) and non-culprit lesion-related MACEs (8.7% versus 3.9%; HR, 2.13 [95% CI, 1.26-3.59). Results were similar when patients were categorized on the basis of the underlying TCFA. A proportionally higher rate of overall and non-culprit lesion-related MACEs was observed as the number of obstructive stenoses or TCFAs in non-culprit segments increased. The lesion-specific HRs for obstructive lesion and TCFA were 2.03 (95% CI, 1.06-3.89) and 2.39 (95% CI, 1.29-4.43), respectively. Optical coherence tomography-derived TCFA, but not angiographic obstructive stenosis, was independently predictive of recurrent MACEs in both patient-level and lesion-level multivariable models in which these 2 characteristics were introduced simultaneously.

CONCLUSIONS

The long-term prognostic implications of the presence and extent of angiographic obstructive non-culprit lesions in patients with acute myocardial infarction are primarily due to their correlation with the underlying high-risk morphology, which confers an increased risk of recurrent MACEs.

Defining "Vulnerable" in Coronary Artery Disease: Predisposing Factors and Preventive Measures

The likelihood of a plaque to cause an acute coronary syndrome (ACS) depends on several factors, both lesion- and patient-related. One of the most investigated and established contributing factors is the presence of high-risk or "vulnerable plaque" characteristics, which have been correlated with increased incidence of major adverse cardiovascular events (MACE). The recognition, however, that a significant percentage of vulnerable plaques do not result in causing clinical events has led the scientific community towards the more multifaceted concept of "vulnerable patients". Incorporating the morphological features of an atherosclerotic plaque into its hemodynamic surroundings can better predict the chance of its disruption, as altered fluid dynamics play a significant role in plaque destabilization. The advances in coronary imaging and the field of computational fluid dynamics (CFD) can contribute to develop more accurate lesion- and patient-related ACS prediction models that take into account both the morphology of a plaque and the forces applied upon it. The aim of this review is to provide the latest data regarding the aforementioned predictive factors as well as relevant preventive measures.

Free carrier-enhanced Bi/Bi2S3 nanoparticles enable precise OCT catheter-guided interventional photothermal therapy for colorectal cancer

Current clinical colorectal cancer treatments usually possess unsatisfactory effects, mainly because of unavoidable surgical trauma and multidrug resistance. Precise and minimally invasive theragnostic technology has advanced through miniaturized catheter intervention with imaging-guided treatment methods; however, previously reported approaches cannot simultaneously perform in situ real-time imaging and therapy. We proposed a strategy of 0.9 mm catheter-based optical coherence tomography imaging-guided interventional photothermal therapy at 1310 nm for orthotopic colorectal cancer. Specifically, folate-modified Bi/Bi2S3 nanoparticles showed intense scattering signals and local hyperpyrexia under 1310 nm laser irradiation in vitro and in vivo due to the localized surface plasmon resonance effect, enabling imaging-guided precise tumor treatment. Histopathological and blood biochemistry analyses confirmed the high biosafety and negligible long-term toxicity of Bi/Bi2S3 nanoparticles. This new method offers a feasible methodology for catheter-based precise interventional photon theragnostics. STATEMENT OF SIGNIFICANCE: : Emerging minimally invasive techniques have been explored for the treatment of colorectal cancer (CRC); however, these reported approaches cannot reach the requirement of precise orthotopic cancer treatment due to the lack of in situ real-time imaging guidance. This study proposes a 0.9 mm catheter-based OCT imaging-guided interventional photothermal therapy (IPTT) strategy at 1310 nm for treating orthotopic CRC. Folate-modified plasmonic Bi/Bi2S3 nanoparticles enable real-time imaging-guided IPTT by providing strong scattering signals and local hyperthermia. This approach allows simultaneous transmission of imaging and therapy light in the same optical fiber, offering a promising method for precise CRC theragnostics and addressing the gap of in situ real-time imaging during IPTT.

Inflammation in coronary atherosclerosis: diagnosis and treatment

Coronary atherosclerosis is a chronic condition characterised by the development of an atherosclerotic plaque in the inner layer of the coronary artery, mainly associated with cholesterol accumulation and favoured by endothelial dysfunction related to other cardiovascular risk factors, such as smoking, diabetes and hypertension. A key actor in this process is the systemic inflammatory response, which can make plaques either grow slowly over the course of years (like a 'mountain'), obstructing coronary flow, and causing stable coronary artery disease, or make them explode (like a 'volcano') with subsequent abrupt thrombosis causing an acute coronary syndrome. This central role of inflammation in coronary atherosclerosis has led to its consideration as a modifiable cardiovascular risk factor and a therapeutic target. Classic anti-inflammatory drugs have been tested in clinical trials with some encouraging results, and new drugs specifically designed to tackle inflammation are currently being under investigation in ongoing trials. The objectives of this review are to (1) summarise the role of inflammatory biomarkers and imaging techniques to detect inflammation at each stage of plaque progression, and (2) explore currently available and upcoming anti-inflammatory therapies.

Clinical characteristics and prognosis of myocardial infarction with nonobstructive coronary arteries evaluated by optical coherence tomography

Myocardial infarction with nonobstructive coronary artery (MINOCA) is a heterogeneous disease with different pathophysiological mechanisms and prognosis. In recent years, it has been found that the incidence of major cardiovascular adverse events in MINOCA is similar to that of myocardial infarction with coronary artery disease (MI-CAD), and it is difficult to clarify the pathogenesis of both through coronary angiography (CAG). Therefore, the aim of this study is to investigate the clinical features, plaque characteristics and prognosis of patients with MINOCA and MI-CAD through optical coherence tomography (OCT). A total of 553 culprit lesions from AMI patients who underwent CAG and OCT were retrospectively analysed. Patients were subsequently divided into two groups: the MINOCA group and the MI-CAD group. The clinical characteristics, plaque characteristics and prognosis of the two groups were compared. The primary endpoint was defined as a composite of major adverse cardiac events (MACE), including cardiac death, non-fatal myocardial infarction, target lesion revascularization, stroke, and rehospitalisation for angina or heart failure. (1) Patients with MINOCA exhibited a lower incidence of ST-segment elevated myocardial infarction (STEMI) and a less frequent history of combined drug-eluting stent (DES) compared to those with MI-CAD. Additionally, they demonstrated lower levels of low density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides (TG), peak troponin T (peak TnT) and peak creatine kinase (peak CK). The MINOCA group had more lesions in the left anterior descending (LAD) and fewer in the left circumflex (LCX). Additionally, they demonstrated a lower prevalence of multibranch vasculopathy and a diminished post-discharge use of aspirin, P2Y12 receptor inhibitors, beta-blockers, angiotensin converting enzyme inhibitor/angiotensin receptor blockers (ACEI/ARBs), and a higher proportion of conservative treatment compared to DES. The frequency of plaque rupture, calcified plaque, cholesterol crystals, macrophages infiltration, microvessels, thin-cap fibroatheroma (TCFA), and thrombus were found to be lower in the MINOCA group than in the MI-CAD group, with these differences being statistically significant (P < 0.05); (2) No significant difference was observed in the incidence of MACE at 30-days and 1 year between patients in the MINOCA and MI-CAD groups (P > 0.05). Compared with MI-CAD patients, MINOCA patients had fewer high-risk plaques on OCT and were more likely to be treated conservatively, with lower rates of stenting and less post-discharge pharmacological treatment. Both groups had similar rates of MACE at 30-day and 1 year, highlighting the importance of individualising treatment for MINOCA patients. Patients with MINOCA who develop MACE are more likely to exhibit high-risk OCT plaque features, with macrophage infiltration identified as an independent risk factor. OCT plaque features such as plaque rupture, plaque erosion, cholesterol crystals, macrophages, microvessels, TCFA may have played different roles in the progression of the two groups of patients.

Glycemic control and coronary plaque characteristics in patients with acute myocardial infarction

BACKGROUND

The impact of glycemic control on the morphological characteristics of non-culprit lesions (NCLs) in patients with acute myocardial infarction (AMI) remains unclear.

METHODS AND RESULTS

A total of 800 AMI patients who underwent 3-vessel OCT were divided into three groups based on their serum glycated hemoglobin (HbA1c) levels: poorly controlled diabetes mellitus (DM) (HbA1c ≥8.0 %, n = 79), well controlled DM (6.5 % ≤ HbA1c < 8.0 %, n = 105), and non-DM (HbA1c <6.5 %, n = 616). OCT imaging was performed on all NCLs and plaque characteristics were assessed at both the patient and lesion level, including high-risk features. Separate covariate-adjusted multivariate models were performed to determine whether glycemic control was associated with high-risk plaque features in NCLs. Patients with poorly controlled DM had higher NCL vulnerability compared to those with well controlled DM and non-DM, both at the patient level [thin-cap fibroatheroma (TCFA): 63.3 % vs. 32.4 % vs. 27.1 %] and the lesion level [TCFA: 22.1 % vs. 11.6 % vs. 9.5 %; non-culprit plaque rupture (PR): 8.4 % vs. 4.6 % vs. 4.6 %]. Vulnerable plaque features, including TCFA, non-culprit PR, macrophages, microchannels, cholesterol crystals, layered plaque and calcification, were more prevalent with increasing HbA1c levels. Multivariate analysis revealed that at the patient level, poorly controlled DM was an independent predictor of TCFA and microchannels, whereas at the lesion level it independently predicted TCFA and non-culprit PR.

CONCLUSIONS

In AMI patients, poor glycemic control is associated with increased vulnerability of NCLs. As HbA1c levels increase, there is a worsening of plaque characteristics, including greater plaque burden and more advanced features of vulnerability.

Thrombus rooting in the pulmonary arteriovenous fistula in a patient with cryptogenic stroke, a case report

BACKGROUND

Cryptogenic stroke constitutes approximately 40% of ischemic strokes in young adults, imposing a significant socioeconomic burden. However, the source of embolus has been specifically investigated in a few number of studies. In this report, We document the first case of a cryptogenic stroke associated with a pulmonary arteriovenous fistula (PAVF), providing evidence of mural thrombus formation within the PAVF vessel.

CASE PRESENTATION

A 52-year-old woman present with sudden-onset blurriness, right-sided numbness and paresthesia, speech difficulties, and salivation. It was confirmed as embolic stroke with magnetic resonance imaging. No evidence of cerebral arteriosclerosis or stenosis was identified, and cardiogenic embolism was ruled out. Further investigation was conducted to determine the cause of the anomalous embolism. A right-to-left shunt was detected using trans-cranial Doppler and transthoracic echocardiogram. Pulmonary arteriography revealed a simple PAVF. Optical coherence tomography (OCT) was used to examine the interior structure of the fistula vessel, revealing the presence of mural thrombus and a rough endangium.

CONCLUSIONS

This case provides the initial evidence regarding the location of thrombus formation assessed and raises the awareness of a potential emboligenic mechanism in PAVF.

Recent advances and clinical implications of intravascular imaging

Coronary artery disease (CAD) remains a major contributor to the global mortality rate. Accurate and detailed evaluation of atherosclerotic plaque characteristics is essential for effective risk assessment and treatment planning. Although conventional coronary angiography excels at quantifying luminal stenosis, information on plaque composition and structure remains limited. Recent advances in intravascular imaging (IVI) have bridged this gap by enabling high-resolution visualization of the vessel wall and plaque morphology, thereby enhancing treatment strategies and facilitating comprehensive risk stratification. Among the principal IVI modalities, intravascular ultrasound (IVUS), optical coherence tomography (OCT), and near-infrared spectroscopy (NIRS) provide distinct benefits. IVUS accurately measures vessel diameter and plaque burden, offering critical guidance for managing complex lesions and left main artery disease. The extremely high spatial resolution of OCT allows precise identification of high-risk plaque features, such as thin fibrous caps. NIRS complements these techniques by quantitatively assessing lipid components within plaques, making it particularly useful in predicting future cardiovascular events. In this review, we summarize the latest evidence on applying IVI modalities to the evaluation and treatment of CAD. We focus on the assessment of plaque morphology, identification of high-risk lesions, and the role of IVI-guided percutaneous coronary intervention (PCI). The continued development of hybrid imaging systems and artificial intelligence-based image analysis may produce more precise and safer PCI approaches. Consequently, IVI is poised to become indispensable in managing CAD, paving the way for more personalized treatment strategies tailored to the specific lesion characteristics of each patient.

Optical coherence tomography-guided vs. coronary angiography-guided percutaneous coronary intervention: a systematic review and meta-analysis

Background

The superiority of optical coherence tomography (OCT) guidance over coronary angiography (CA) guidance in optimizing therapy in patients undergoing percutaneous coronary intervention (PCI) remains uncertain. Consequently, we conducted a comprehensive meta-analysis with the objective of providing a higher level of evidence.

Methods

The databases of PubMed/Medline, Embase, and Cochrane Central were searched in March 2024. The outcomes of this meta-analysis included all-cause death, cardiovascular death, major adverse cardiovascular events (MACE), restenosis, myocardial infarction (MI), target lesion revascularization (TLR), target vessel revascularization (TVR), post-intervention minimum stent area (MSA), post-intervention minimum lumen diameter (MLD), and follow-up MLD. Statistical analysis was conducted using RevMan 5.3 and STATA version 18. The degree of heterogeneity was evaluated using the I2 statistical test. When I2 exceeded 50%, heterogeneity was deemed to be substantial, prompting the application of a random effects model; conversely, a fixed effects model was employed. The results were expressed as risk ratio (RR) and mean deviation (MD) with their corresponding 95% confidence interval (CI).

Results

A total of 25 articles were included in the study. In terms of clinical outcomes, OCT-guided PCI was associated with a significant reduction in all-cause death (RR =0.62; 95% CI: 0.47-0.83; P=0.001), cardiovascular death (RR =0.47; 95% CI: 0.32-0.69; P<0.0001), and MACE (RR =0.65; 95% CI: 0.54-0.77; P<0.00001). Meanwhile, no statistically significant differences were observed for restenosis (RR =0.91; 95% CI: 0.73-1.13; P=0.38), MI (RR =0.83; 95% CI: 0.69-1.00; P=0.05), TLR (RR =0.86; 95% CI: 0.66-1.10; P=0.23), and TVR (RR =0.82; 95% CI: 0.63-1.07; P=0.15). In terms of surrogate endpoints, OCT-guided PCI was associated with a significant enhancement of MSA (MD =0.30; 95% CI: 0.04-0.56; P=0.03) and MLD at follow-up (MD =0.12; 95% CI: 0.02-0.22; P=0.02). Nevertheless, no significant increase in the post-intervention MLD was observed (MD =0.04; 95% CI: -0.02 to 0.10; P=0.19).

Conclusions

Compared with CA, the use of OCT for PCI guidance may be an effective strategy to optimize treatment.

Feasibility and safety of intracranial carotid implantation with covered stents for advanced head and neck squamous cell carcinoma involving the carotid artery: A preliminary investigation

Objective

The aim of this study was to assess the feasibility and safety of implanting covered stents in cases of advanced head and neck squamous cell carcinoma (ASCCHN) where the carotid artery was involved.

Methods

A total of 30 patients (29 males and one female) were included in this study, with ages ranging from 40 to 79 years. Among these patients, 28 patients had received radiotherapy and 17 received subsequent adjuvant therapy, while one was receiving treatment for the first time. Eighteen were treated with covered stent implantation in conjunction with surgery, and the remaining 12 received stent implantation alone. The study evaluated and compared the stent implantation's success rate, overall survival (OS), and associated complications.

Results

Successful implantation of covered stents was achieved in all 30 cases. No instances of significant hemorrhage or thromboembolic cerebral infarction occurred during surgery. Of the patients in the salvage surgical group, 15 underwent complete tumor resection with a success rate of 83.3% (15/18), of which four experienced tumor recurrence with a local recurrence rate of 26.7% (4/15). The OS rates at 6 months for all patients, the salvage surgical group, the 15 patients with complete tumor resection, and the nonsurgical group were 64.0%, 66.8%, 75.5%, and 58.6%, respectively. At 12 months, the OS rates were 21.4%, 29.3%, 43.2%, and 11.8%, respectively. Notably, the OS of the 15 patients who underwent complete tumor resection was significantly higher than that of the 12 patients who received stent implantation alone (p = 0.044). All cerebrovascular accidents occurred in patients with radiotherapy history, and subsequent adjuvant therapy had no significant effect on the OS time in the salvage surgical and nonsurgical groups (p = 0.935; p = 0.526).

Conclusion

In cases of ASCCHN involving the carotid artery, the implantation of covered stents is a safe and feasible procedure.

Artificial intelligence for the analysis of intracoronary optical coherence tomography images: a systematic review

Intracoronary optical coherence tomography (OCT) is a valuable tool for, among others, periprocedural guidance of percutaneous coronary revascularization and the assessment of stent failure. However, manual OCT image interpretation is challenging and time-consuming, which limits widespread clinical adoption. Automated analysis of OCT frames using artificial intelligence (AI) offers a potential solution. For example, AI can be employed for automated OCT image interpretation, plaque quantification, and clinical event prediction. Many AI models for these purposes have been proposed in recent years. However, these models have not been systematically evaluated in terms of model characteristics, performances, and bias. We performed a systematic review of AI models developed for OCT analysis to evaluate the trends and performances, including a systematic evaluation of potential sources of bias in model development and evaluation.

Efficacy and Safety of High-Frequency Optical Coherence Tomography (HF-OCT) for Coronary Imaging: A Multicenter Study

Background

Optical coherence tomography (OCT) has emerged as an essential tool in coronary atherosclerosis research and has shown clinical value in optimizing percutaneous coronary intervention. Its capability to identify coronary plaque pathology and accurately detect intervention results, often overlooked by angiography, serves as a guide in managing patients with acute coronary syndromes, myocardial infarction due to nonobstructing coronary artery disease, calcified arteries, and in-stent restenosis, thus contributing to improved clinical outcomes. However, the current technology of intracoronary imaging catheters has a size approaching 3F, limiting its adoption preintervention. Furthermore, the image field of view of current OCT technologies cannot consistently offer complete visualization of coronary arteries ≥5 mm.

Methods

In this multicenter, single-arm study, we evaluated the efficacy and safety of a novel imaging catheter and system called high-frequency optical coherence tomography (HF-OCT). This system features a reduced-size, rapid-exchange imaging catheter with a diameter of 1.8F. HF-OCT captures 100 mm long segments of coronary arteries in just 1 second. In addition, HF-OCT provides an expanded field of view greater than 14 mm in diameter, enabling complete imaging of large coronary arteries.

Results

After conducting 143 imaging acquisitions in 81 unique coronary arteries across 75 patients at 3 institutions, we obtained an average clear image length of 68.8 ± 18.8 mm. Coronary arteries of varying sizes, including cases with severe stenosis, were evaluated. Comparing preintervention HF-OCT acquisitions-taken prior to any arterial manipulation-to postintervention acquisitions, no significant difference in image quality was observed (t test, P = .901).

Conclusions

The results of this study illustrate that a lower HF-OCT catheter profile, larger field of view, and faster pullback capabilities provide reliable imaging of coronary arteries in an all-comers, multicenter population.

Association between the ratio of high-density lipoprotein cholesterol to apolipoprotein A-I and in-stent neoatherosclerosis: an optical coherence tomography study

Background

In-stent neoatherosclerosis (ISNA) is an important cause of in-stent restenosis (ISR) with drug-eluting stent (DES) implants. High-density lipoprotein cholesterol (HDL-C) is associated with ISNA. However, few studies have focused on the functionalities of HDL-C composition, and till date, optical coherence tomography (OCT) has not been used to analyze the relationship between ISNA incidence and HDL-C-to-apolipoprotein A-I ratio (HAR) in patients with DES implants and ISR (DES-ISR). This study aimed to clarify the association between HAR and ISNA.

Methods

This single-center, retrospective study included patients admitted to the Affiliated Hospital of Zunyi Medical University. A total of 216 patients with 220 ISR lesions who underwent OCT for the culprit stent were included between July 2018 and November 2022. Based on HAR at admission, 33rd and 66th percentiles were identified as the cut-off points, and all eligible patients were divided into three groups: Tertile 1 (HAR ≤0.836; n=71), Tertile 2 (0.836< HAR <0.932; n=73), and Tertile 3 (HAR ≥0.932; n=72). Baseline characteristics and angiographic and OCT features were compared between the different groups. In addition, univariate and multivariate logistic regression models were used to assess the association of HAR with ISNA and in-stent thin-cap fibroatheroma (TCFA).

Results

Angiographic characteristics and quantitative OCT assessment values did not differ significantly among the groups. The incidences of ISNA (62.0% vs. 52.1% vs. 37.5%, P=0.01) and in-stent TCFA (35.2% vs. 27.4% vs. 15.3%, P=0.02) were significantly lower in the third tertile of the HAR group than in the first or second tertiles. The multifactor logistic regression model revealed that the highest tertile group had a reduced risk of ISNA [hazard ratio (HR) =0.185, 95% confidence interval (CI): 0.081-0.421; P<0.001] and TCFA (HR =0.197, 95% CI: 0.075-0.517; P<0.001) compared with the lowest tertile group.

Conclusions

OCT revealed high HAR levels to be negatively correlated with the incidences of ISNA and TCFA in patients with ISR. HAR is a better indicator of ISNA and plaque fragility than HDL-C itself, thus providing a marker and pathway for better prevention of ISNA.

Discussion on the comparison of Raman spectroscopy and cardiovascular disease-related imaging techniques and the future applications of Raman technology: a systematic review

Cardiovascular disease (CVD) is a major cause of unnatural death worldwide, so timely diagnosis of CVD is crucial for improving patient outcomes. Although the traditional diagnostic tools can locate plaque and observe inner wall of blood vessel structure, they commonly have radioactivity and cannot detect the chemical composition of the plaque accurately. Recently emerging Raman techniques can detect the plaque composition precisely, and have the advantages of being fast, high-resolution and marker-free. This makes Raman have great potential for detecting blood samples, understanding disease conditions, and real-time monitoring. This review summarizes the origin and state-of-art of Raman techniques, including the following aspects: (a) the principle and technical classification of Raman techniques; (b) the applicability of Raman techniques and its comparison with traditional diagnostic tools at different diagnosis targets; (c) the applicability of Raman spectroscopy in advanced CVD. Lastly, we highlight the possible future applications of Raman techniques in CVD diagnosis.

Management of Coronary Stent Underexpansion

Coronary stent underexpansion is an important problem and limitation of percutaneous coronary intervention, adversely affecting both short- and long-term patient outcomes. Stent underexpansion occurs when a stent fails to expand adequately compared with the adjacent reference segment, resulting in inadequate luminal gain. Multiple studies suggest that stent underexpansion is associated with increased risks of in-stent restenosis, stent thrombosis, and myocardial infarction, resulting in recurrent symptoms, readmissions, repeat interventions, and increased mortality. Contributing factors for stent underexpansion include severe calcification, inadequate lesion preparation, suboptimal stent deployment, and preexisting in-stent restenosis. Calcific plaques, especially when present behind a previously implanted, underexpanded stent, pose a significant challenge for further stent optimization. These lesions are often resistant to high-pressure balloon dilatation and may require advanced techniques that carry increased risks of complications. Intravascular imaging modalities, such as intravascular ultrasound and optical coherence tomography, have emerged as essential tools in diagnosing and managing stent underexpansion. These techniques provide a more detailed evaluation of the vessel and previously implanted stent, enabling the clinician to understand the exact mechanism of stent failure, and assess plaque burden and morphology, which ultimately helps guide appropriate treatment strategies. Despite the clinical importance of stent underexpansion, there is currently no consensus on its optimal treatment, largely because of the absence of large prospective studies in this area. This comprehensive review aims to summarize the existing evidence, clinical experience, and treatment strategies for coronary stent underexpansion, with the goal of providing practical guidance to clinicians to help optimize percutaneous coronary intervention and patient outcomes.

Functional or anatomical assessment of non-culprit lesions in acute myocardial infarction

BACKGROUND

Previous studies have reported the value of quantitative flow ratio (QFR) to assess the physiological significance of non-culprit lesions (NCLs) in acute myocardial infarction (AMI) patients and of optical coherence tomography (OCT)-defined thin-cap fibroatheroma (TCFA) to identify non-culprit vulnerable plaques.

AIMS

We sought to systematically compare long-term NCL-related clinical prognosis in an AMI population utilising acute Murray fractal law-based QFR (μQFR) values and OCT-defined TCFA.

METHODS

Three-vessel OCT imaging and μQFR assessment were conducted in 645 AMI patients, identifying 1,320 intermediate NCLs in non-infarct-related arteries. The primary endpoint was a composite of cardiac death, NCL-related non-fatal myocardial infarction (MI), and NCL-related unplanned coronary revascularisation, with follow-up lasting up to 5 years.

RESULTS

The primary endpoint occurred in 59 patients (11.1%). OCT-defined TCFA independently predicted patient-level (adjusted hazard ratio [HR] 3.05, 95% confidence interval [CI]: 1.80-5.19) and NCL-specific primary endpoints (adjusted HR 4.46, 95% CI: 2.33-8.56). The highest event rate of 29.6% was observed in patients with NCLs that were TCFA (+) with μQFR ≤0.80, compared to 16.3% in those that were also TCFA (+) but with μQFR>0.80, 6.0% in those that were TCFA (-) with μQFR ≤0.80, and 6.6% in those that were TCFA (-) with μQFR>0.80 (log-rank p<0.001). TCFA was an independent predictor for the primary endpoint in ST-segment elevation MI (STEMI; adjusted HR 3.27, 95% CI: 1.67-6.41) and non-STEMI (adjusted HR 3.26, 95% CI: 1.24-8.54) patients, whereas μQFR ≤0.80 was not.

CONCLUSIONS

When assessing NCLs during the index procedure in AMI patients, OCT-defined TCFA serves as the dominant prognostic predictor for long-term clinical outcomes, rather than μQFR-determined physiological significance.

Mapping the distribution of radial artery atherosclerosis by optical coherence tomography

BACKGROUND

Radial artery plaque (RAP) can influence the function of arterial conduits after revascularization and hinder the maturation of arteriovenous fistulas in patients undergoing hemodialysis patients. However, the preferred in vivo sites for RAP development have not been systematically investigated. This study measured and evaluated RAP to map the distribution of RAP in the radial artery (RA) using optical coherence tomography (OCT).

METHODS

OCT images of the entire RA in 300 patients at 1 mm intervals were analyzed to assess RAP phenotypes and measure the distance of RAP from the radial artery ostium. The RA was evenly divided into three segments: proximal, middle, and distal. Patients were categorized into two groups: the RAP group (n = 68) and the non-RAP group (n = 232).

RESULTS

Among the 300 patients with 300 radial arteries studied, 68 patients (22.7%) developed 180 distinct RAPs. The distal segment was the most susceptible to RAP formation (51 patients; 17.0%).In plaque level analysis, Most RAPs (55%) were located ≥ 150 mm from the RA ostium. The distal segment exhibited a significantly higher median cumulative plaque index compared with the proximal and middle segments (p = 0.031). Logistic regression analysis identified aging, smoking, diabetes mellitus, and multi-vessel coronary disease (MVCD) as independent risk factors for RAP occurrence.

CONCLUSIONS

RAP was observed in 22.7% of patients with acute coronary syndrome (ACS), with a predominant localization in the distal segment, both at the patient and plaque level. Significant risk factors included aging, smoking, diabetes mellitus, and MVCD.

Vulnerable or High-Risk Plaque: A JACC: Cardiovascular Imaging Position Statement

The concept of high-risk plaque emerged from pathologic and epidemiologic studies 3 decades ago that demonstrated plaque rupture with thrombosis as the predominant mechanism of acute coronary syndrome and sudden cardiac death. Thin-cap fibroatheroma, a plaque with a large lipidic core covered by a thin fibrous cap, is the prototype of the rupture-prone plaque and has been traditionally defined as "vulnerable plaque." Although knowledge on the pathophysiology of plaque instability continues to grow, the risk profile of our patients has shifted and the character of atherosclerotic disease has evolved, partly because of widespread use of lipid-lowering therapies and other preventive measures. In vivo intracoronary imaging studies indicate that superficial erosion causes up to 40% of acute coronary syndromes. This changing landscape calls for broader perspective, expanding the concept of high-risk plaque to the precursors of all major substrates of coronary thrombosis beyond plaque rupture. Other factors to take into consideration include dynamic changes in plaque composition, the importance of plaque burden, inflammatory activation (both local and systemic), healing mechanisms, regional hemodynamic pattern, properties of the fluid phase of blood, and the amount of myocardium at risk subtended by a lesion. Rather than the traditional focus limited to the thin-cap fibroatheroma, the authors advocate a more comprehensive approach that considers both morphologic features and biological activity of plaques and blood. This position paper highlights the challenges to the usual concept of high-risk plaque, proposes a broader definition, and analyzes its key morphologic features, the technological progress of plaque imaging (particularly using intracoronary imaging techniques), advances in pharmacologic therapies for plaque regression and stabilization, and the feasibility and efficacy of focal interventional treatments including preemptive plaque sealing.

From Mechanisms to Management: Tackling In-Stent Restenosis in the Drug-Eluting Stent Era

PURPOSE OF REVIEW

Drug-eluting stent (DES) technology has greatly enhanced the safety and effectiveness of percutaneous coronary interventions (PCI). The aim of the present paper is to provide a comprehensive review of in-stent restenosis (ISR), focusing on the contemporary DES era, including its incidence, mechanisms, and imaging characterization.

RECENT FINDINGS

Despite the widespread use of DES and numerous improvements, recent clinical data indicate that ISR still occurs in 5-10% of PCI procedures, posing a considerable public health issue. The incidence, morphology, and clinical implications of ISR are determined by a complex interplay of several factors: the patient, stent, procedure, and vessel and lesion-related factors. Advancements in intracoronary imaging have provided greater insight into its patterns and underlying causes. Over time, treatment strategies have evolved, and current guidelines recommend an individualized approach using intracoronary imaging to characterize ISR's underlying substrate.

Visualization of Atherosclerotic Plaques Paired with Joheksol 350 (Omnipaque)

Background: Cardiovascular disease is one of the leading causes of death around the globe. Atherosclerosis, a chronic inflammatory blood vessel disease that takes years to develop, is its primary cause. Instability and further plaque buildup are caused by chronic inflammation, which creates the conditions for possible rupture. The visualization of arterial lesions in situ can enhance understanding of atherosclerosis progression and potentially improve experimental therapies. Conventional histology methods for assessing atherosclerotic lesions are robust but are destructive and may prevent further tissue analysis. Objectives: The objective of the current study was to evaluate a novel, nondestructive method for the visualization and characterization of atherosclerotic lesions. Methods and Results: Thus, we tested the hypothesis that MRI paired with an iodine-based radiopaque stain would effectively characterize atherosclerotic plaques in a manner comparable to routine histology while maintaining sample integrity and providing whole-volume data.

TEAD1-Mediated Trans-Differentiation of Vascular Smooth Muscle Cells into Fibroblast-Like Cells Contributes to the Stabilization and Repair of Disrupted Atherosclerotic Plaques

Atherosclerotic plaque rupture mainly contributes to acute coronary syndrome (ACS). Insufficient repair of these plaques leads to thrombosis and subsequent ACS. Central to this process is the modulation of vascular smooth muscle cells (VSMCs) phenotypes, emphasizing their pivotal role in atherosclerotic plaque stability and healing post-disruption. Here, an expansion of FSP1+ cells in a tandem stenosis (TS) model of atherosclerotic mice is unveiled, predominantly originating from VSMCs through single-cell RNA sequencing (scRNA-seq) analyses and VSMC lineage tracing studies. Further investigation identified TEA domain transcription factor 1 (TEAD1) as the key transcription factor driving the trans-differentiation of VSMCs into fibroblast-like cells. In vivo experiments using a TS model of plaque rupture demonstrated that TEAD1 played a crucial role in promoting plaque stability and healing post-rupture through pharmacological or TEAD1-AAV treatments. Mechanistically, it is found that TEAD1 promoted the expression of fibroblast markers through the Wnt4/β-Catenin pathway, facilitating the trans-differentiation. Thus, this study illustrated that TEAD1 played a critical role in promoting the trans-differentiation of VSMCs into fibroblast-like cells and subsequent extracellular matrix production through the Wnt4/β-Catenin pathway. Consequently, this process enhanced the healing mechanisms following plaque rupture, elucidating potential therapeutic avenues for managing atherosclerotic instability.

Development of a label-free, functional, molecular and structural imaging system combining optical coherence tomography and Raman spectroscopy for in vivo measurement of rat retina

In vivo access to molecular information of retinal tissue is considered to play a critical role in enabling early diagnosis of ophthalmic and neurodegenerative diseases. The current gold standard of retina imaging, optical coherence tomography and angiography provides only the retinal morphology and blood perfusion, missing the full spectrum of molecular information. Raman spectroscopy addresses this gap while keeping the investigation non-invasive and label-free. Although previous studies have demonstrated the huge diagnostic potential of combining both modalities for in vivo biological tissue measurement, some have either employed unsafe optical power levels for in vivo retinal measurements or presented results that were negative or contradictory. In this study, we have developed an eye-safe multimodal in vivo label-free imaging system and demonstrate the potential of this device by investigating the retina of a living albino rat. The acquired Raman spectra showed relevant Raman bands in comparison with the previous ex vivo studies. Using this multimodal imaging system for non-invasive retina measurements of transgenic rodents holds the potential to advance the understanding of the pathophysiology of both ophthalmic and neurodegenerative diseases.

FFR-Negative Nonculprit High-Risk Plaques and Clinical Outcomes in High-Risk Populations: An Individual Patient-Data Pooled Analysis From COMBINE (OCT-FFR) and PECTUS-obs

BACKGROUND

Despite fractional flow reserve (FFR)-guided deferral of revascularization, recurrent events in patients with diabetes or after myocardial infarction remain common. This study aimed to assess the association between FFR-negative but high-risk nonculprit lesions and clinical outcomes.

METHODS

This is a patient-level pooled analysis of the prospective natural-history COMBINE (OCT-FFR) study (Optical Coherence Tomography Morphologic and Fractional Flow Reserve Assessment in Diabetes Mellitus Patients) and PECTUS-obs study (Identification of Risk Factors for Acute Coronary Events by OCT After STEMI and NSTEMI Patients With Residual Non- Flow Limiting Lesions). Optical coherence tomography was performed on all FFR-negative (FFR >0.80) native nonculprit lesions. Patients or lesions with a high-risk plaque were compared with those without a high-risk plaque. A high-risk plaque was defined in the presence of at least 2 prespecified criteria: (1) lipid arc ≥90o, (2) minimum fibrous cap thickness <65 µm, and (3) presence of either plaque rupture or thrombus. The primary end points were native major adverse cardiovascular events (composite of all-cause mortality, nonfatal myocardial infarction, or unplanned revascularization excluding stent-failure-related events and nonattributable events) and target lesion failure (composite of cardiac death, target vessel myocardial infarction, or target lesion revascularization).

RESULTS

Among 810 patients, 450 (55.6%) had a history of diabetes and 482 (59.5%) presented with myocardial infarction. At least 1 high-risk plaque was identified in 271 (33.5%) patients and 287 (30.6%) lesions. Over a median follow-up of 761 (interquartile range, 731-1175) days, the presence of a high-risk plaque was associated with patient-level native major adverse cardiovascular events (hazard ratio, 2.127 [95% CI, 1.451-3.120]; P<0.001) and lesion-level target lesion failure (hazard ratio, 2.623 [95% CI, 1.559-4.414]; P<0.001). The risk of adverse outcomes increased with the copresence of multiple high-risk features.

CONCLUSIONS

FFR-negative but high-risk nonculprit lesions are associated with adverse patient- and lesion-level clinical outcomes. These findings emphasize the additional value of intracoronary imaging in patients with FFR-negative nonculprit lesions.

REGISTRATION

URL: https://clinicaltrials.gov; Unique identifier: NCT02989740; Unique identifier: NCT03857971.

Non-culprit plaque healing on serial OCT imaging and future outcome in patients with acute coronary syndromes

BACKGROUND AND AIMS

Histologic studies indicated that healed plaque, characterized by a multilayered pattern, is indicative of prior atherothrombosis and subsequent healing. However, longitudinal in vivo data on healed plaque formation in non-culprit plaques are limited. This study aimed to investigate serial changes and clinical significance of new layered pattern formation in non-culprit plaques in patients with acute coronary syndromes (ACS) using serial optical coherence tomography (OCT) imaging.

METHODS

ACS patients who underwent two OCTs at baseline and 1-year follow-up were included. Serial changes in morphologic characteristics of non-culprit plaques were evaluated. New layered pattern was defined as a new signal-rich layer on the plaque surface at follow-up that was not present at baseline.

RESULTS

Among 553 non-culprit plaques observed in 222 patients, 82 (14.8 %) exhibited a new layered pattern at follow-up. Thin-cap fibroatheroma, macrophage, and thrombus were identified as independent predictors of the new layered pattern. Plaques with new layered pattern formation showed a greater significant reduction in luminal area and lipid content, as well as a greater increase in fibrous cap thickness compared to those without. The incidence of 6-year non-culprit-related major adverse cardiac events was higher in patients with new layered pattern than in those without (25.4 % vs. 10.8 %, p = 0.011), mainly due to clinically driven coronary revascularization.

CONCLUSIONS

Plaque destabilization and subsequent healing frequently occur in non-culprit plaques after ACS. The formation of a new layered pattern may contribute to temporary plaque stabilization, but results in luminal stenosis and worse clinical outcomes.

Effect of Intensive Lipid-Lowering Therapy on Coronary Plaque Stabilization Derived from Optical Coherence Tomography: a Meta-analysis and Meta-regression

PURPOSE

The definitive impacts of intensive lipid-lowering therapy (LLT) on plaque stabilization and the relationship between the key markers during LLT and plaque stability remain unquestioned. Thus, these meta-analysis and meta-regression intend to holistically evaluate the influence exerted by rigorous LLT on the minimum fibrous cap thickness (FCT) and maximum lipid arc as discerned through optical coherence tomography (OCT). This study further scrutinizes the correlation of this impact with variations in high-sensitivity C-reactive protein (hs-CRP), low-density lipoprotein cholesterol (LDL-C), or additional parameters within patients diagnosed with coronary artery disease (CAD).

METHODS

Comprehensive searches were conducted on platforms including PubMed, Embase, and the Cochrane Library for randomized controlled trials (RCTs) published until June 1, 2023. The search was language agnostic and targeted RCTs elaborating on the correlation between high-intensity statin therapy or statins used concomitantly with other lipid-lowering medications and the minimum FCT and maximum lipid arc as assessed by OCT. The meta-analyses were executed employing a standard mean difference (SMD) algorithm with random-effects on continuous variables. These methodologies align with the Preferred Reporting Items for Systematic and Meta-analysis (PRISMA) guidelines.

RESULTS

A spectrum of 12 RCTs engaging 972 patients were identified and mobilized for these analyses. Meta-analysis outcomes depicted a conspicuous correlation between intensive LLT and an enhanced minimum FCT (12 studies with 972 participants; SMD, 0.87; 95% CI, 0.54 to 1.21; P < 0.01), reduced maximum lipid arc (9 studies with 564 participants; SMD, -0.43; 95% CI, -0.58 to -0.29; P < 0.01). Meta-regression analysis has determined an association of elevated minimum FCT with decreased LDL-C (β, -0.0157; 95% CI, -0.0292 to -0.0023; P = 0.025), total cholesterol (TC) (β, -0.0154; 95% CI, -0.0303 to -0.0005; P = 0.044), and apolipoprotein B (ApoB) (β, -0.0209; 95% CI, -0.0361 to -0.0057; P = 0.022). However, no significant association was discerned relative to variations in hs-CRP/CRP (β, -0.1518; 95% CI, -1.3766 to -1.0730; P = 0.772), triglyceride (TG) (β, -0.0030; 95% CI, -0.0258 to -0.0318; P = 0.822), and high-density lipoprotein cholesterol (HDL-C) (β, 0.0313; 95% CI, -0.0965 to 0.1590; P = 0.608). Subsequent subgroup meta-analysis demonstrated that high-intensity statin therapy (5 studies with 204 participants; SMD, 1.03; 95% CI, 0.67 to 1.39; P < 0.01), as well as a combinative approach including PCSK9 antibodies and statins (3 studies with 522 participants; SMD, 1.17; 95% CI, 0.62 to 1.73; P < 0.01) contributed to an increase in minimum FCT. Parallelly, high-intensity statin therapy (4 studies with 183 participants; SMD, -0.42; 95% CI, -0.65 to -0.19; P < 0.01) or the combined application of PCSK9 antibodies and statins (2 studies with 222 participants; SMD, -0.98; 95% CI, -1.26 to -0.70; P < 0.01) was evidenced to decrease the maximum lipid arc.

CONCLUSIONS

Intensive LLT, mainly high-intensity statin therapy and combined PCSK9 antibody with statin, has a beneficial effect on coronary plaque stabilization derived from OCT in patients with CAD. Coronary plaque stabilization is primarily due to lipid-lowering effect, not anti-inflammatory effect. Moreover, the lipid-lowering effect has nothing to do with the changes in HDL-C and TG, but is mainly related to the reduction of LDL-C, TC, and ApoB.

High-risk plaques in non-culprit lesions and clinical outcome after NSTEMI vs. STEMI

AIMS

Complete non-culprit (NC) revascularisation may help reduce recurrent events after non-ST-segment elevation myocardial infarction (NSTEMI), especially if NC lesions would harbour high-risk plaque (HRP) features similar to ST-segment elevation myocardial infarction (STEMI). This study aimed to assess differences in fractional flow reserve (FFR)-negative NC plaque morphology in patients presenting with NSTEMI vs. STEMI and assess the association of HRP morphology and clinical outcome.

METHODS AND RESULTS

In the prospective PECTUS-obs study, 438 patients presenting with myocardial infarction (MI) underwent optical coherence tomography (OCT) of all FFR-negative intermediate NC lesions. The primary endpoint was the occurrence of major adverse cardiovascular events (MACE, composite of all-cause mortality, non-fatal MI or unplanned revascularisation) at 2-year follow-up. Four hundred and twenty patients had at least one analysable OCT, including 203 (48.3%) with NSTEMI and 217 (51.7%) with STEMI. The prevalence of HRPs, including thin-cap fibroatheromas, plaque rupture, and thrombus, was comparable between groups. MACE occurred in 29 (14.3%) NSTEMI patients and 16 (7.4%) STEMI patients (Puni-variable = 0.025 and Pmulti-variable = 0.270). Incidence of MACE was numerically higher among patients with HRP, irrespective of the clinical presentation at index (Pinteraction = 0.684). Among HRP criteria, plaque rupture was associated with MACE in both NSTEMI (P < 0.001) and STEMI (P = 0.020).

CONCLUSION

Presence of NC HRP is comparable between NSTEMI and STEMI and leads to numerically higher event rates in both. These results call for additional research on complete revascularisation in NSTEMI and treatment of HRP.

CLINICAL TRIAL REGISTRATION

NCT03857971.

Prevalence of intracerebral thrombus detected by optical coherence tomography in patients with posterior circulation stroke or transient ischemic attack

BACKGROUND

The incidence of thrombosis in patients with intracranial atherosclerotic stenosis (ICAS) remains unclear. Optical coherence tomography (OCT) has the potential to explore the vessel wall structure of posterior-circulation ICAS because of its relatively straight anatomical structure compared with that of the anterior cerebral arteries. This study aimed to determine the prevalence and characteristics of thrombosis in the posterior-circulation ICAS using OCT.

METHODS

This prospective study was conducted on 135 patients with posterior-circulation arterial stenosis who underwent OCT. All patients were symptomatic and had a severely stenotic lesion (70-99%) in the vetebrobasilar artery. The enrolled patients were classified according to the presence of in situ thrombus as defined by OCT. Clinical data and OCT characteristics were compared.

RESULTS

Eighty-two patients diagnosed with posterior-circulation ICAS were enrolled. In situ thrombi were identified in 34 patients. Clinically, patients with in situ thrombus were more prone to cerebral infarctions than transient ischemic attacks. The percentage area of stenosis in the non-thrombus group was significantly lower than that in the thrombus group. The thrombus burden, mean flow area, mean thrombus area, maximum lipid arc, and mean lumen area were significantly different among white, red, and mixed thrombi.

CONCLUSIONS

We achieved in vivo vessel wall structural analysis of posterior-circulation ICAS with the largest sample size. We also revealed the true incidence of in situ thrombosis and potential corresponding clinical events of posterior-circulation ICAS for the first time.

Macrophage-based pathogenesis and theranostics of vulnerable plaques

Vulnerable plaques, which are high-risk features of atherosclerosis, constitute critical elements in the disease's progression due to their formation and rupture. Macrophages and macrophage-derived foam cells are pivotal in inducing vulnerability within atherosclerotic plaques. Thus, understanding macrophage contributions to vulnerable plaques is essential for advancing the comprehension of atherosclerosis and devising novel therapeutic and diagnostic strategies. This review provides an overview of the pathological characteristics of vulnerable plaques, emphasizes macrophages' critical role, and discusses advanced strategies for their diagnosis and treatment. It aims to present a comprehensive macrophage-centered perspective for addressing vulnerable plaques in atherosclerosis.

Predictive models for cholesterol crystals and plaque vulnerability in acute myocardial infarction: Insights from an optical coherence tomography study

BACKGROUND

Cholesterol crystals (CCs) are recognized as a risk factor for vulnerable atherosclerotic plaque rupture (PR) and major adverse cardiovascular events. However, their predictive factors and association with plaque vulnerability in patients with acute myocardial infarction (AMI) remain insufficiently explored. Therefore, This study aims to investigate the association between CCs and plaque vulnerability in culprit lesions of AMI patients, identify the factors influencing CCs formation, and develop a predictive model for CCs.

METHODS

A total of 431 culprit lesions from AMI patients who underwent pre-intervention optical coherence tomography (OCT) imaging were analyzed. Patients were divided into groups based on the presence or absence of CCs and PR. The relationship between CCs and plaque vulnerability was evaluated. A risk nomogram for predicting CCs was developed using the least absolute shrinkage and selection operator and logistic regression analysis.

RESULTS

CCs were identified in 64.5 % of patients with AMI. The presence of CCs was associated with a higher prevalence of vulnerable plaque features, such as thin-cap fibroatheroma (TCFA), PR, macrophage infiltration, neovascularization, calcification, and thrombus, compared to patients without CCs. The CCs model demonstrated an area under the curve (AUC) of 0.676 for predicting PR. Incorporating CCs into the TCFA model (AUC = 0.656) significantly enhanced predictive accuracy, with a net reclassification improvement index of 0.462 (95 % confidence interval [CI]: 0.263-0.661, p < 0.001) and an integrated discrimination improvement index of 0.031 (95 % CI: 0.013-0.048, p = 0.001). Multivariate regression analysis identified the atherogenic index of plasma (odds ratio [OR] = 2.417), TCFA (OR = 1.759), macrophage infiltration (OR = 3.863), neovascularization (OR = 2.697), calcification (OR = 1.860), and thrombus (OR = 2.430) as independent risk factors for CCs formation. The comprehensive model incorporating these factors exhibited reasonable discriminatory ability, with an AUC of 0.766 (95 % CI: 0.717-0.815) in the training set and 0.753 (95 % CI: 0.704-0.802) in the internal validation set, reflecting good calibration. Decision curve analysis suggested that the model has potential clinical utility within a threshold probability range of approximately 18 % to 85 %.

CONCLUSIONS

CCs were associated with plaque vulnerability in the culprit lesions of AMI patients. Additionally, this study identified key factors influencing CCs formation and developed a predictive model with potential clinical applicability.

Timing of multivessel revascularization in stable patients with STEMI: a systematic review and network meta-analysis

INTRODUCTION AND OBJECTIVES

Multivessel percutaneous coronary intervention (MV-PCI) is recommended in patients with ST-segment elevation myocardial infarction (STEMI) and multivessel coronary artery disease (CAD) without cardiogenic shock. The present network meta-analysis investigated the optimal timing of MV-PCI in this context.

METHODS

We pooled the aggregated data from randomized trials investigating stable STEMI patients with multivessel CAD treated with a strategy of either MV-PCI or culprit vessel-only PCI. The primary outcome was all-cause death. The main secondary outcomes were cardiovascular death, myocardial infarction, and unplanned ischemia-driven revascularization.

RESULTS

Among 11 trials, a total of 10 507 patients were randomly assigned to MV-PCI (same sitting, n=1683; staged during the index hospitalization, n=3460; staged during a subsequent hospitalization within 45 days, n=3275) or to culprit vessel-only PCI (n=2089). The median follow-up was 18.6 months. In comparison with culprit vessel-only PCI, MV-PCI staged during the index hospitalization significantly reduced all-cause death (risk ratio, 0.73; 95%CI, 0.56-0.92; P=.008) and ranked as possibly the best treatment option for this outcome compared with all other strategies. In comparison with culprit vessel-only PCI, a MV-PCI reduced cardiovascular mortality without differences dependent on the timing of revascularization. MV-PCI within the index hospitalization, either in a single procedure or staged, significantly reduced myocardial infarction and unplanned ischemia-driven revascularization, with no significant difference between each other.

CONCLUSIONS

In patients with STEMI and multivessel CAD without cardiogenic shock, multivessel PCI within the index hospitalization, either in a single procedure or staged, represents the safest and most efficacious approach. The different timings of multivessel PCI did not result in any significant differences in all-cause death. This study is registered at PROSPERO (CRD42023457794).

Relationship Between Coronary Artery Calcium Score and Vulnerability of Culprit Plaque Assessed by OCT in Patients With Established Coronary Artery Disease

BACKGROUND

Coronary artery calcium score (CACS) is widely used for risk stratification. However, in patients with established coronary artery disease, its clinical implication and relationship with plaque vulnerability are unclear. We sought to correlate the CACS and plaque vulnerability assessed by optical coherence tomography.

METHODS

Patients with coronary artery disease who had CACS and optical coherence tomography before percutaneous coronary intervention were included. Patients were divided into 5 groups based on CACS: CACS of 0, 1 to 99, 100 to 399, 400 to 999, and ≥1000. Optical coherence tomography-derived vulnerable features in culprit plaque were compared between the groups.

RESULTS

In 460 patients, the prevalence of lipid-rich plaque, macrophage, and cholesterol crystal significantly differed among the 5 groups, being lowest in the patients with a CACS of 0. The prevalence of thin-cap fibroatheroma tended to be lower in those with a CACS of 0. No significant difference in vulnerable features was observed between the 4 groups with CACS >0. In the 2-group comparison between the group with a CACS of 0 and the other 4 groups combined, the prevalence of lipid-rich plaque (60.5% versus 85.9%; P<0.001), macrophage (48.8% versus 74.1%; P<0.001), thin-cap fibroatheroma (16.3% versus 35.0%; P=0.013), and cholesterol crystal (11.6% versus 32.9%; P=0.004) was significantly lower in the patients with CACS of 0. CACS of 0 was independently negatively associated with lipid-rich plaque, macrophage, thin-cap fibroatheroma, and cholesterol crystal after adjustment for patient characteristics.

CONCLUSIONS

Patients with a CACS of 0 have a significantly lower prevalence of vulnerable plaque features compared with those with CACS >0 in patients with established coronary artery disease.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04523194.

Ten-year clinical outcomes after drug-eluting stents implantation according to clinical presentation-Insights from the DECADE cooperation

BACKGROUND

Investigations of very long-term outcomes after percutaneous coronary intervention (PCI) with drug-eluting stents (DES) according to clinical presentation are scarce. Here, we investigated the 10-year clinical outcomes of patients undergoing DES-PCI according to clinical presentation.

METHODS

Patient-level data from five randomized trials with 10-year follow-up after DES-PCI were pooled. Patients were dichotomized into acute coronary syndrome (ACS) or chronic coronary syndrome (CCS) groups as per clinical presentation. The primary outcome was all-cause death. Secondary outcomes were cardiovascular death, myocardial infarction (MI), definite stent thrombosis (ST) and repeat revascularization involving the target lesion (TLR), target vessel (TVR) or non-target vessel (nTVR).

RESULTS

Of the 9700 patients included in this analysis, 4557 presented with ACS and 5143 with CCS. Compared with CCS patients, ACS patients had a higher risk of all-cause death and nTVR in the first year, but comparable risk thereafter. In addition, ACS patients had a higher risk of MI [adjusted hazard ratio 1.21, 95% confidence interval (1.04-1.41)] and definite ST [adjusted hazard ratio 1.48, 95% confidence interval (1.14-1.92)], while the risk of TLR and TVR was not significantly different up to 10-year follow-up.

CONCLUSIONS

Compared to CCS patients, ACS patients treated with PCI and DES implantation have an increased risk of all-cause death and repeat revascularization of remote vessels up to 1 year, with no significant differences thereafter and up to 10-year follow-up. ACS patients have a consistently higher risk of MI and definite ST. Whether these differences persist with current antithrombotic and secondary prevention therapies requires further investigation.

Role of optical coherence tomography in clinical management of myocardial infarction with nonobstructive coronary arteries

Myocardial infarction without angiographic moderate to severe stenosis (> 50%) and any other related diagnosis on clinical presentation is defined as myocardial infarction with nonobstructive coronary arteries (MINOCA). Common causes of MINOCA working diagnosis includes plaque disruption, spontaneous coronary artery dissection, coronary artery spasm, coronary thromboembolism, Takotsubo cardiomyopathy, and myocarditis. Clinical history, assay of myocardial enzymes, electrocardiogram, echocardiography, coronary angiography, and left ventriculography facilitate the initial diagnosis of MINOCA and reveal the underlying causes, while cardiovascular magnetic resonance and optical coherence tomography (OCT) are used to confirm the diagnosis. Although cardiovascular magnetic resonance is the gold standard noninvasive diagnostic tool for MINOCA, its ability to diagnose the cause and mechanism underlying this condition in the coronary arteries is limited because of its image resolution. Observational studies have demonstrated that OCT can be used to determine the underlying cause of MINOCA by investigating the characteristics of the culprit lesions and to predict the prognosis of the patients. In this article, we review the current diagnostic approach for MINOCA focusing on each imaging tool. Furthermore, we reevaluate the role of OCT in the clinical management of MINOCA. Identifying the cause of MINOCA through OCT might help select optimal and effective drug treatments and improve prognosis.

Synthetic polarization-sensitive optical coherence tomography using contrastive unpaired translation

Polarization-sensitive optical coherence tomography (PS-OCT) measures the polarization state of backscattered light from tissues and provides valuable insights into the birefringence properties of biological tissues. Contrastive unpaired translation (CUT) was used in this study to generate a synthetic PS-OCT image from a single OCT image. The challenges related to extensive data requirements relying on labeled datasets using only pixel-wise correlations that make it difficult to efficiently regenerate the periodic patterns observed in PS-OCT images were addressed. The CUT model captures birefringence patterns by leveraging patch-wise correlations from unpaired data, which allows learning of the underlying structural features of biological tissues responsible for birefringence. To demonstrate the performance of the proposed approach, three generative models (Pix2pix, CycleGAN, and CUT) were compared on an in vivo dataset of injured mouse tendons over a six-week healing period. CUT outperformed Pix2pix and CycleGAN by producing high-fidelity synthetic PS-OCT images that closely matched the original PS-OCT images. Pearson correlation and two-way ANOVA tests confirmed the superior performance of CUT (p-value < 0.0001) over the comparison models. Additionally, a ResNet-152 classification model was used to assess tissue damage, which achieved an accuracy of up to 90.13% compared to the original PS-OCT images. This research demonstrates that CUT is superior to conventional methods for generating high-quality synthetic PS-OCT images and offers better improvements in most scenarios, in terms of efficiency and image fidelity.

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

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 2016 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 prevalence 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 11.130, 95% confidence interval 4.186-29.593, p < 0.001) and plaque rupture (OR 5.332, 95% CI 2.040-13.937, 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.

CONCLUSION(S)

AIP is an independent predictor for vulnerable plaques beyond traditional factors. It can be integrated in clinical practice for risk stratification of ACS patients.

TRIAL REGISTRATION

All patients gave their consent to participate in the study and the Ethics Committee of Beijing Anzhen Hospital, Capital Medical University approved it (2020047X).

Photothermal optical coherence microscopy for studying lipid architecture in human carotid arteries

Photothermal optical coherence microscopy (PT-OCM) combines the high-resolution, label-free morphological imaging of OCM with the ability to discriminate tissue composition through phase-sensitive photothermal imaging. In this study, we perform 2D imaging of human carotid endarterectomies to spectrally determine lipid distribution, with verification via histologically stained samples. The structural information from OCM is combined with the spectral information gained from measuring the resulting sample surface displacement from thermoelastic expansion, following light irradiation. PT-OCM is thus demonstrated as a potential tool in the investigation of atherosclerotic plaque lipids, contributing towards the understanding of plaque instability.

Extracellular RIPK3 Acts as a Damage-Associated Molecular Pattern to Exaggerate Cardiac Ischemia/Reperfusion Injury

BACKGROUND

Cardiac ischemia/reperfusion (I/R) injury has emerged as an important therapeutic target for ischemic heart disease. Currently, there is no effective therapy for reducing cardiac I/R injury. Damage-associated molecular patterns are endogenous molecules released after cellular damage to exaggerate tissue inflammation and injury. RIPK3 (receptor-interacting protein kinase 3), a well-established intracellular mediator of cell necroptosis and inflammation, serves as a circulating biomarker of multiple diseases. However, whether extracellular RIPK3 also exerts biological functions in cardiac I/R injury remains totally unknown.

METHODS

Patients with acute myocardial infarction receiving percutaneous coronary intervention (PCI) were recruited independently in the discovery cohort (103 patients) and validation cohort (334 patients), and major adverse cardiovascular events were recorded. Plasma samples were collected before and after PCI (6 and 24 h) for RIPK3 concentration measurement. Cultured neonatal rat ventricular myocytes, macrophages and endothelial cells, and in vivo mouse models with myocardial injury induced by I/R (or hypoxia/reoxygenation) were used to investigate the role and mechanisms of extracellular RIPK3. Another cohort including patients with acute myocardial infarction receiving PCI and healthy volunteers was recruited to further explore the mechanisms of extracellular RIPK3.

RESULTS

In the discovery cohort, elevated plasma RIPK3 levels after PCI are associated with poorer short- and long-term outcomes in patients with acute myocardial infarction, as confirmed in the validation cohort. In both cultured cells and in vivo mouse models, recombinant RIPK3 protein exaggerated myocardial I/R (or hypoxia/reoxygenation) injury, which was alleviated by the RIPK3 antibody. Mechanistically, RIPK3 acted as a damage-associated molecular pattern and bound with RAGE (receptor of advanced glycation end-products), subsequently activating CaMKII (Ca2+/calmodulin-dependent kinase II) to elicit the detrimental effects. The positive correlation between plasma RIPK3 concentrations and CaMKII phosphorylation in human peripheral blood mononuclear cells was confirmed.

CONCLUSIONS

We identified the positive relationship between plasma RIPK3 concentrations and the risk of major adverse cardiovascular events in patients with acute myocardial infarction receiving PCI. As a damage-associated molecular pattern, extracellular RIPK3 plays a causal role in multiple pathological conditions during cardiac I/R injury through RAGE/CaMKII signaling. These findings expand our understanding of the physiological and pathological roles of RIPK3, and also provide a promising therapeutic target for myocardial I/R injury and the associated complications.

Unlocking the Secrets of Acute Coronary Syndromes Using Intravascular Imaging: From Pathophysiology to Improving Outcomes

Acute coronary syndrome (ACS) represents the most severe manifestation of coronary artery disease. Intravascular imaging, both intravascular ultrasound (IVUS) and optical coherence tomography (OCT), have played crucial roles for the impressive reduction in mortality of ACS. Intravascular imaging is useful for the detection of atherosclerotic mechanism (plaque rupture, calcified nodules, or plaque erosions) and for the evaluation of nonatherosclerotic and nonobstructive types of ACS. In addition, IVUS and OCT play a crucial role in the optimization of the PCI. The aim of the current review is to present the role of intravascular imaging in identifying the mechanisms of ACS and its prognostic role in future events, to review the current guidelines suggesting intravascular imaging use in ACS, to summarize its role in PCI in patients with ACS, and to compare IVUS and OCT.

Management of vulnerable patient phenotypes and acute coronary syndrome mechanisms

Atherosclerosis is a chronic vascular disease. Its prevalence increases with aging. However, atherosclerosis may also affect young subjects without significant exposure to the classical risk factors. Recent evidence indicates clonal hematopoiesis of indeterminate potential (CHIP) as a novel cardiovascular risk factor that should be suspected in young patients. CHIP represents a link between impaired bone marrow and atherosclerosis. Atherosclerosis may present with an acute symptomatic manifestation or subclinical events that favor plaque growth. The outcome of a plaque relies on a balance of innate and environmental factors. These factors can influence the processes that initiate and propagate acute plaque destabilization leading to intraluminal thrombus formation or subclinical vessel healing. Thirty years ago, the first autopsy study revealed that coronary plaques can undergo rupture even in subjects without a known cardiovascular history. Nowadays, cardiac magnetic resonance studies demonstrate that this phenomenon is not rare. Myocardial infarction is mainly due to plaque rupture and plaque erosion that have different pathophysiological mechanisms. Plaque erosion carries a better prognosis as compared to plaque rupture. Thus, a tailored conservative treatment has been proposed and some studies demonstrated it to be safe. On the contrary, plaque rupture is typically associated with inflammation and anti-inflammatory treatments have been proposed in response to persistently elevate biomarkers of systemic inflammation. In conclusion, atherosclerosis may present in different forms or phenotypes. Vulnerable patient phenotypes, identified by using intravascular imaging techniques, biomarkers, or even genetic analyses, are characterized by distinctive pathophysiological mechanisms. These different phenotypes merit tailored management.

Diagnostic and therapeutic optical imaging in cardiovascular diseases

Cardiovascular disease (CVD) is one of the most prevalent health threats globally. Traditional diagnostic methods for CVDs, including electrocardiography, ultrasound, and cardiac magnetic resonance imaging, have inherent limitations in real-time monitoring and high-resolution visualization of cardiovascular pathophysiology. In recent years, optical imaging technology has gained considerable attention as a non-invasive, high-resolution, real-time monitoring solution in the study and diagnosis of CVD. This review discusses the latest advancements, and applications of optical techniques in cardiac imaging. We compare the advantages of optical imaging over traditional modalities and especially scrutinize techniques such as optical coherence tomography, photoacoustic imaging, and fluorescence imaging. We summarize their investigations in atherosclerosis, myocardial infarction, and heart valve disease, etc. Additionally, we discuss challenges like deep-tissue imaging and high spatiotemporal resolution adjustment, and review existing solutions such as multimodal integration, artificial intelligence, and enhanced optical probes. This article aims to drive further development in optical imaging technologies to provide more precise and efficient tools for early diagnosis, pathological mechanism exploration, and treatment of CVD.

Optical coherence tomography predictors of clinical outcomes after stent implantation: the ILUMIEN IV trial

BACKGROUND AND AIMS

Observational registries have suggested that optical coherence tomography (OCT) imaging-derived parameters may predict adverse events after drug-eluting stent (DES) implantation. The present analysis sought to determine the OCT predictors of clinical outcomes from the large-scale ILUMIEN IV trial.

METHODS

ILUMIEN IV was a prospective, single-blind trial of 2487 patients with diabetes or high-risk lesions randomized to OCT-guided versus angiography-guided DES implantation. All patients underwent final OCT imaging (blinded in the angiography-guided arm). From more than 20 candidates, the independent OCT predictors of 2-year target lesion failure (TLF; the primary endpoint), cardiac death or target-vessel myocardial infarction (TV-MI), ischaemia-driven target lesion revascularization (ID-TLR), and stent thrombosis were analysed by multivariable Cox proportional hazard regression in single treated lesions.

RESULTS

A total of 2128 patients had a single treated lesion with core laboratory-analysed final OCT. The 2-year Kaplan-Meier rates of TLF, cardiac death or TV-MI, ID-TLR, and stent thrombosis were 6.3% (n = 130), 3.3% (n = 68), 4.3% (n = 87), and 0.9% (n = 18), respectively. The independent predictors of 2-year TLF were a smaller minimal stent area (per 1 mm2 increase: hazard ratio 0.76, 95% confidence interval 0.68-0.89, P < .0001) and proximal edge dissection (hazard ratio 1.77, 95% confidence interval 1.20-2.62, P = .004). The independent predictors of cardiac death or TV-MI were smaller minimal stent area and longer stent length; of ID-TLR were smaller intra-stent flow area and proximal edge dissection; and of stent thrombosis was smaller minimal stent expansion.

CONCLUSIONS

In the ILUMIEN IV trial, the most important OCT-derived post-DES predictors of both safety and effectiveness outcomes were parameters related to stent area, expansion and flow, proximal edge dissection, and stent length.

The clinical relevance of the reversal of coronary atherosclerotic plaque

Atherosclerotic cardiovascular disease (ASCVD) remains a leading cause of death globally despite advances in preventive therapies. Understanding of the initiation and progression of atherosclerosis, the interplay between lipoproteins, endothelial dysfunction, inflammation, and immune responses is critical to treating this disease. The development of vulnerable coronary plaques prone to thrombosis, can lead to acute coronary syndromes, for these reasons, the potential plaque stabilization and regression through pharmacological interventions, particularly lipid-lowering agents like statins and PCSK9 inhibitors is crucial. The imaging techniques such as intravascular ultrasound (IVUS), near-infrared spectroscopy (NIRS), and optical coherence tomography (OCT) play a key role in assessing plaque composition and guiding interventional therapeutic strategies. Clinical evidence supports the efficacy of intensive lipid-lowering therapy in inducing plaque regression, with studies demonstrating reductions in plaque volume and improvements in plaque morphology assessed by IVUS, OCT and NIRS. While pharmacological interventions show promise in promoting plaque regression and stabilization, their impact on long-term cardiovascular events requires further investigation. Multimodality imaging and comprehensive outcome trials are proposed as essential tools for elucidating the relationship between plaque modification and clinical benefit in coronary atherosclerosis. The stabilization or regression of atherosclerotic plaque might serve as the phenomenon linking the reduction in LDL-C levels to the decrease in cardiovascular events. Overall, this review emphasizes the ongoing efforts to advance our understanding of ASCVD pathophysiology and optimize therapeutic approaches for improving patient outcomes.

Differences in total plaque burden between plaque rupture and plaque erosion: A combined computed tomography angiography and optical coherence tomography study

BACKGROUNDS

Coronary computed tomography angiography (CTA) allows for the assessment of atherosclerotic plaque burden across the entire coronary vasculature. No studies have examined the relationship between the underlying pathology of the culprit lesion and total plaque burden in patients with acute coronary syndromes. The aim of this study was to compare the total plaque burden between patients with plaque rupture versus plaque erosion.

METHODS

A total of 232 patients who presented with their first non-ST-segment elevation acute coronary syndrome and underwent both CTA and optical coherence tomography imaging before intervention were selected. Quantitative analysis was performed using semi-automated software (Autoplaque version 3.0, Cedars-Sinai Medical Center). An attenuation of <30 Hounsfield units defined low-density non-calcified plaque (LDNCP). All 3 vessels were assessed using the modified 17-segment American Heart Association model for coronary segment classification.

RESULTS

Among 232 patients, 125 (53.9%) had plaque rupture and 107 (46.1%) had plaque erosion. Total plaque burden (48.2 [39.8-54.9] % vs. 44.1 [38.6-50.0] %, P ​= ​0.006), total non-calcified plaque (NCP) burden (46.6 [39.1-53.3] % vs. 43.0 [37.6-49.2] %, P ​= ​0.013), total LDNCP burden (2.3 [1.4-3.0] % vs. 1.7 [1.2-2.6] %, P ​= ​0.016), and total calcified plaque (CP) burden (0.8 [0.1-1.6] % vs. 0.4 [0.0-1.4] %, P ​= ​0.047) were significantly greater in patients with culprit plaque rupture than in those with culprit plaque erosion.

CONCLUSION

Patients with plaque rupture, compared with those with plaque erosion, had a greater total plaque burden, NCP burden, LDNCP burden, and CP burden.

CLINICAL TRIAL REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04523194.

Relationship between plaque burden and plaque vulnerability: Acute coronary syndromes versus chronic coronary syndrome

BACKGROUND

The relationship between plaque burden and microscopic characterization of plaque features as it pertains to clinical presentation has not been fully investigated. The aim of this study was to compare the relationship between plaque burden and plaque vulnerability in patients with acute coronary syndromes (ACS) versus chronic coronary syndrome (CCS).

METHODS

Patients who underwent both coronary computed tomography angiography (CTA) and optical coherence tomography (OCT) before coronary intervention were enrolled. All plaques were detected in culprit vessels using CTA, and total plaque volume (TPV) and OCT features were assessed at the corresponding sites. All plaques were divided into three groups according to the tertile levels of TPV (low TPV: <96.5 ​mm3, moderate TPV: 96.5-164.7 ​mm3, high TPV: ≥164.8 ​mm3).

RESULTS

A total of 990 plaques were imaged by OCT in 419 patients: 445 plaques in 190 (45.3%) patients with ACS and 545 in 229 (54.7%) with CCS. Macrophage was more prevalent in plaques with greater TPV in patients who presented with ACS but not in those who presented with CCS (low vs. moderate vs. high TPV group: macrophage 57.4% vs. 71.8% vs. 82.4% in ACS; 63.4% vs. 67.8% vs. 66.7% in CCS; interaction P ​= ​0.004). Lipid arc increased as TPV increased, especially in patients who presented with ACS. Conversely, the layer index increased as TPV increased in patients with CCS.

CONCLUSION

Greater plaque burden was closely related to higher levels of plaque vulnerability in ACS and greater volume of layered plaque in CCS.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT04523194.

Polarization-insensitive optical coherence tomography using pseudo-depolarized reference light for mitigating birefringence-related image artifacts

Significance

Optical coherence tomography (OCT) images are prone to image artifacts due to the birefringence of the sample or the optical system when a polarized light source is used for imaging. These artifacts can lead to degraded image quality and diagnostic information.

Aim

We aim to mitigate these birefringence-related artifacts in OCT images by adding a depolarizer module in the reference arm of the interferometer.

Approach

We investigated different configurations of liquid crystal patterned retarders as pseudo-depolarizers in the reference arm of OCT setups. We identified the most effective depolarization module layout for polarization artifact suppression for a spectral-domain OCT system based on a Michelson and a Mach-Zehnder interferometer.

Results

The performance of our approach was demonstrated in an achromatic quarter-wave plate allowing the selection of a variety of sample polarization states. A substantial improvement of the OCT signal magnitude was observed after placing the optimal depolarizer configuration, reducing the cross-polarization artifact from 5.7 to 1.8 dB and from 8.0 to 1.0 dB below the co-polarized signal for the fiber-based Michelson and Mach-Zehnder setup, respectively. An imaging experiment in the birefringent scleral tissue of a post-mortem alpine marmot eye and a mouse tail specimen further showcased a significant improvement in the detected signal intensity and an enhanced OCT image quality followed by a drastic elimination of the birefringence-related artifacts.

Conclusions

Our study presents a simple yet cost-effective technique to mitigate birefringence-related artifacts in OCT imaging. This method can be readily implemented in existing OCT technology and improve the effectiveness of various OCT imaging applications in biomedicine.

Three-dimensional optical coherence tomography for guidance of percutaneous coronary intervention for coronary bifurcation disease: a review of current clinical applications

Percutaneous coronary intervention (PCI) for coronary bifurcation disease remains one of the most challenging situations in interventional cardiology in terms of procedural success rates and long-term cardiac events. Optical coherence tomography (OCT), with a higher signal-to-noise ratio and the ability to distinguish plaque components, can display the true condition of bifurcation lesions without overlapping or shortening and achieve detailed visualization of vascular structures, which is superior to those of other imaging modalities. Three-dimensional (3D) reconstruction of OCT images (3D-OCT) helps to gain a more informed understanding of the geometry and morphology of bifurcation lesions and provide additive information on plaque distribution. Following stent implantation, 3D-OCT can also guide the re-crossing of guide wires through stent struts jailing the side branch (SB) ostium and more clearly display the jailing strut configuration, as well as the ideal position of the guidewire recrossing point and stent struct link connection, to confirm the optimal guidewire position and understand interactions between stents and vessel walls, which may improve clinical results after PCI. The present review provides an up-to-date overview of the clinical use of 3D-OCT for accurate assessment of bifurcation anatomy, guiding the optimal guidewire rewiring into SB during bifurcation stenting, and evaluation of post-PCI results, offering novel information about atherosclerotic disease or stenting process.

Predictors of Optical Coherence Tomography-Defined Calcified Nodules in Patients With Acute Coronary Syndrome - A Substudy From the TACTICS Registry

BACKGROUND

Recent studies suggest that the presence of calcified nodules (CN) is associated with worse prognosis in patients with acute coronary syndrome (ACS). We investigated clinical predictors of optical coherence tomography (OCT)-defined CN in ACS patients in a prospective multicenter registry.

METHODS AND RESULTS

We investigated 695 patients enrolled in the TACTICS registry who underwent OCT assessment of the culprit lesion during primary percutaneous coronary intervention. OCT-CN was defined as calcific nodules erupting into the lumen with disruption of the fibrous cap and an underlying calcified plate. Compared with patients without OCT-CN, patients with OCT-CN (n=28) were older (mean [±SD] age 75.0±11.3 vs. 65.7±12.7 years; P<0.001), had a higher prevalence of diabetes (50.0% vs. 29.4%; P=0.034), hemodialysis (21.4% vs. 1.6%; P<0.001), and Killip Class III/IV heart failure (21.4% vs. 5.7%; P=0.003), and a higher preprocedural SYNTAX score (median [interquartile range] score 15 [11-25] vs. 11 [7-19]; P=0.003). On multivariable analysis, age (odds ratio [OR] 1.072; P<0.001), hemodialysis (OR 16.571; P<0.001), and Killip Class III/IV (OR 4.466; P=0.004) were significantly associated with the presence of OCT-CN. In non-dialysis patients (n=678), age (OR 1.081; P<0.001), diabetes (OR 3.046; P=0.014), and Killip Class III/IV (OR 4.414; P=0.009) were significantly associated with the presence of OCT-CN.

CONCLUSIONS

The TACTICS registry shows that OCT-CN is associated with lesion severity and poor clinical background, which may worsen prognosis.