OCT compared with IVUS in a coronary lesion assessment: the OPUS-CLASS study

Optical coherence tomography to guide percutaneous coronary intervention

Percutaneous coronary intervention (PCI) has been most commonly guided by coronary angiography. However, to overcome the inherent limitations of conventional coronary angiography, there has been an increasing interest in the adjunctive tools of intracoronary imaging for PCI guidance. Recently, optical coherence tomography (OCT) has garnered substantial attention as a valid intravascular imaging modality for guiding PCI. However, despite the unparalleled high-resolution imaging capability of OCT, which offers detailed anatomical information on coronary lesion morphology and PCI optimisation, its broad application in routine PCI practice remains limited. Several factors may have curtailed the widespread adoption of OCT-guided PCI in daily practice, including the transitional challenge from intravascular ultrasound (IVUS), the experienced skill required for image acquisition and interpretation, the lack of a uniform algorithm for OCT-guided PCI optimisation, and the limited clinical evidence. Herein, we provide an in-depth review of OCT-guided PCI, involving the technical aspects, optimal strategies for OCT-guided PCI, and the wide application of OCT-guided PCI in various anatomical subsets. Special attention is given to the latest clinical evidence from recent randomised clinical trials with respect to OCT-guided PCI.

Comparison of Long-Term Outcomes Between Intravascular Ultrasound-, Optical Coherence Tomography- and Angiography-Guided Stent Implantation: A Meta-Analysis

Intravascular ultrasonography (IVUS) and optical coherence tomography (OCT) guided percutaneous coronary interventions (PCI) are alternative techniques to angiography-guided (ANG-g) PCI in patients with coronary artery disease (CAD), especially for optimal stent deployment in coronary arteries. We conducted a network meta-analysis including studies comparing those three techniques. We searched databases for studies that compared IVUS, OCT, and ANG-g PCI in patients with CAD. Overall, 52 studies with 231,137 patients were included in this meta-analysis. ANG-g PCI had higher major adverse cardiovascular events (MACEs), all-cause death, cardiac death, myocardial infarction (MI), target lesion revascularization (TLR), and stent thrombosis (ST) than IVUS-guided PCI. Of note, both OCT-guided and IVUS-guided PCI had similar outcomes. The frequency of MACEs, cardiac death, and MI were higher in ANG-g PCI than in OCT-guided PCI. The highest benefit was established with OCT for MACEs (P-score=.973), MI (P-score=.823), and cardiac death (P-score=.921) and with IVUS for all-cause death (P-score=.792), TLR (P -score=.865), and ST (P-score=.930). This network meta-analysis indicated that using OCT or IVUS for optimal stent implantation provides better outcomes in comparison with ANG-g in patients with CAD undergoing PCI.

The impact of high intensity training and sports on recipients of solid organ transplants: a narrative review

Objectives

High intensity exercise in individuals post solid organ transplant (SOT) remains a largely understudied phenomenon, with potential risks and benefits. Additionally, the optimal training protocols are still unclear. This narrative review aimed to explore the impact of high-intensity exercise training and strenuous sports on solid organ transplant recipients (SOTRs).

Methods

We conducted a narrative review of intervention studies of any design that included high-intensity exercise training and cross-sectional studies of strenuous sports and activities. Additionally, we reviewed individual reports documenting post-SOT performance at highly competitive or physiological levels. We used MEDLINE to search for relevant articles followed by a manual search for additional articles. Data were extracted and results were summarized.

Results

High-intensity and strenuous exercise appears to be safe among stable SOTRs. High-intensity protocols consistently demonstrated improvements in VO2peak and a reduction in coronary artery disease prevalence, though findings related to body composition, health-related quality of life outcomes, and cardiovascular exercise variables were inconsistent. Pre-transplant athletes showcase notable achievements and physiological adaptations post-transplantation, highlighting the capacity for athletic performance among this population. However, caution is warranted in interpreting the findings from these studies due to limitations in generalizability and other methodological limitations.

Conclusion

As evidenced by current literature, high intensity exercise emerges as a promising exercise method for safely improving various physiological parameters, and reducing the prevalence of coronary heart disease in SOTRs. It can induce similar or greater effects to moderate intensity exercise, however follow-up studies indicate low retention. Further research of higher methodological rigor is warranted in this field to advance understanding, and to guide evidence-based practice.

Comparison of intravascular ultrasound-guided with optical coherence tomography-guided percutaneous coronary intervention for left main distal bifurcation lesions: Rationale and design of the ISOLEDS trial

BACKGROUND

Percutaneous coronary intervention (PCI) can provide benefits for anatomically suitable left main coronary artery (LMCA) lesions. When compared to traditional coronary angiography (CAG) -guided PCI, the use of intravascular ultrasound (IVUS) guidance has shown significant long-term prognostic improvements in LMCA PCI. Optical coherence tomography (OCT) offers a higher axial resolution than IVUS. However, there is currently a lack of relevant randomized controlled trials investigating the use of OCT specifically for left main distal bifurcation lesions.

METHODS

The ISOLEDS trial is an ongoing multicenter study that aims to compare IVUS-guided PCI with OCT-guided PCI for patients with true LMCA distal bifurcation lesions. This prospective, randomized, controlled, non-inferiority trial will enroll a total of 664 patients with visually-defined Medina 1,1,1 or 0,1,1 classification of left main distal bifurcation lesions. The patients will be randomly assigned in a 1:1 ratio to either IVUS-guided or OCT-guided PCI. The primary endpoint is to assess the occurrence of target lesion failure (TLF) within 12 months after the procedure. After undergoing PCI, patients are required to visit the hospital for a 12-month clinical follow-up. During this clinical assessment, CAG can be performed to evaluate the status of target lesions.

DISCUSSION

The ISOLEDS trial represents the first attempt to compare two distinct intracoronary imaging techniques for guiding PCI in patients with true LMCA distal bifurcation lesions. By evaluating and comparing the outcomes of these two imaging techniques, the trial results will aid operators in selection of the most effective approach for guiding PCI in these patients.

Emerging Hybrid Intracoronary Imaging Technologies and Their Applications in Clinical Practice and Research

Intravascular ultrasound and optical coherence tomography are used with increasing frequency for the care of coronary patients and in research studies. These imaging tools can identify culprit lesions in acute coronary syndromes, assess coronary stenosis severity, guide percutaneous coronary intervention (PCI), and detect vulnerable plaques and patients. However, they have significant limitations that have stimulated the development of multimodality intracoronary imaging catheters, which provide improvements in assessing vessel wall pathology and guiding PCI. Prototypes combining 2 or even 3 imaging probes with complementary attributes have been developed, and several multimodality systems have already been used in patients, with near-infrared spectroscopy intravascular ultrasound-based studies showing promising results for the identification of high-risk plaques. Moreover, postmortem histology studies have documented that hybrid imaging catheters can enable more accurate characterization of plaque morphology than standalone imaging. This review describes the evolution in the field of hybrid intracoronary imaging; presents the available multimodality catheters; and discusses their potential role in PCI guidance, vulnerable plaque detection, and the assessment of endovascular devices and emerging pharmacotherapies targeting atherosclerosis.

Percutaneous coronary intervention for bifurcation coronary lesions using optimised angiographic guidance: the 18th consensus document from the European Bifurcation Club

The 2023 European Bifurcation Club (EBC) meeting took place in Warsaw in October, and the latest evidence for the use of intravascular ultrasound (IVUS) and optical coherence tomography (OCT) to optimise percutaneous coronary interventions (PCI) on coronary bifurcation lesions (CBLs) was a major focus. The topic generated deep discussions and general appraisal on the potential benefits of IVUS and OCT in PCI procedures. Nevertheless, despite an increasing recognition of IVUS and OCT capabilities and their recognised central role for guidance in complex CBL and left main PCI, it is expected that angiography will continue to be the primary guidance modality for CBL PCI, principally due to educational and economic barriers. Mindful of the restricted access/adoption of intracoronary imaging for CBL PCI, the EBC board decided to review and describe a series of tips and tricks which can help to optimise angiography-guided PCI for CBLs. The identified key points for achieving an optimal angiography-guided PCI include a thorough analysis of pre-PCI images (computed tomography angiography, multiple angiographic views, quantitative coronary angiography vessel estimation), a systematic application of the technical steps suggested for a given selected technique, an intraprocedural or post-PCI use of stent enhancement and a low threshold for bailout use of intravascular imaging.

Computed tomography coronary angiography assessment of left main coronary artery stenosis severity

BACKGROUND

Angiographic assessment of left main coronary artery (LMCA) stenosis severity can be unreliable. In cases of ambiguity, intravascular ultrasound (IVUS) can be utilised with a minimal lumen area (MLA) of ≥6 ​mm2 an accepted threshold for safe deferral of revascularization. We sought to assess whether quantitative computer tomography coronary angiography (CTCA) measures could assist clinicians making LMCA revascularization decisions when compared with IVUS as gold standard.

METHODS

Consecutive patients undergoing IVUS assessment of angiographically intermediate LMCA stenosis were included. All patients had undergone 320-slice CTCA <90 days prior to IVUS imaging. Offline quantitative assessment of IVUS- and CT-derived measures were undertaken with the cohort divided into those with significant (s-LMCA) versus non-significant (ns-LMCA) disease using the accepted IVUS threshold.

RESULTS

Fifty-eight patients were included, with no difference in mean age (61.5 ​± ​12.2 vs. 59.7 ​± ​11.9 years, p ​= ​0.57), diabetic status (24.2% vs 16.0%, p ​= ​0.44) or other baseline demographics between groups. Patients with ns-LMCA had larger CT luminal area (8.64 ​± ​3.91 vs. 5.41 ​± ​1.54 ​mm2, p ​< ​0.001), larger minimal lumen diameter (MLD) (3.25 ​± ​0.74 vs. 2.56 ​± ​0.38 ​mm, p ​< ​0.001) and lower area stenosis (45.74 ​± ​18.10 vs. 60.93 ​± ​14.68%, p ​= ​0.001). There was a significant positive correlation between CTCA and IVUS MLA (r ​= ​0.68, p ​< ​0.001) and MLD (r ​= ​0.67, p ​< ​0.001). ROC analysis demonstrated CTCA MLA cut-off <8.29 ​mm2 provides the greatest negative predictive value and sensitivity in predicting the presence of significant LMCA disease.

CONCLUSION

CTCA derived MLA and MLD have a strong correlation with IVUS. A CTCA derived MLA cut-off <8.29 ​mm2 showed greatest clinical utility for predicting the need for further assessment, based on IVUS gold standard.

Innovations in Intracoronary Imaging: Present Clinical Practices and Future Outlooks

Engaging intracoronary imaging (IC) techniques such as intravascular ultrasound or optical coherence tomography enables the precise description of vessel architecture. These imaging modalities have well-established roles in providing guidance and optimizing percutaneous coronary intervention (PCI) outcomes. Furthermore, IC is increasingly recognized for its diagnostic capabilities, as it has the unique capacity to reveal vessel wall characteristics that may not be apparent through angiography alone. This manuscript thoroughly reviews the contemporary landscape of IC in clinical practice. Focused on current methodologies, the review explores the utility and advancements in IC techniques. Emphasizing their role in clarifying coronary pathophysiology, guiding PCI, and optimizing patient outcomes, the manuscript critically evaluates the strengths and limitations of each modality. Additionally, the integration of IC into routine clinical workflows and its impact on decision-making processes are discussed. By synthesizing the latest evidence, this review provides valuable insights for clinicians, researchers, and healthcare professionals involved in the dynamic field of interventional cardiology.

Stent sizing by coronary CT angiography compared with optical coherence tomography

BACKGROUND

Coronary CT angiography (CCTA) is well-established for diagnosis and stratification of coronary artery disease (CAD). Its usefulness in guiding percutaneous coronary interventions (PCI) and stent sizing is unknown.

METHODS

This is a sub-analysis of the Precise Percutaneous Coronary Intervention Plan (P3) study (NCT03782688). We analyzed 65 vessels with matched CCTA and pre-PCI optical coherence tomography (OCT) assessment. The CCTA-guided stent size was defined by the mean distal reference lumen diameter rounded up to the nearest stent diameter. The OCT lumen-guided stent size was the mean distal reference lumen diameter rounded to the closest stent diameter. The agreement on stent diameters was determined with Kappa statistics, Passing-Bablok regression analysis, and the Bland-Altman method.

RESULTS

The distal reference lumen diameter by CCTA and OCT were 2.75 ​± ​0.53 ​mm and 2.72 ​± ​0.55 ​mm (mean difference 0.06, limits of agreement -0.7 to 0.82). There were no proportional or systematic differences (coefficient A 1.06, 95% CI 0.84 to 1.3 and coefficient B -0.22, 95% CI -0.83 to 0.36) between methods. The agreement between the CCTA and OCT stent size was substantial (Cohen's weighted Kappa 0.74, 95% CI 0.64 to 0.85). Compared to OCT stent diameter, CCTA stent size was concordant in 52.3% of the cases; CCTA overestimated stent size in 20.0% and underestimated in 27.7%.

CONCLUSION

CCTA accurately assessed the reference vessel diameter used for stent sizing. CCTA-based stent sizing showed a substantial agreement with OCT. CCTA allows for PCI planning and may aid in selecting stent diameter.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Optical coherence tomography-guided vs. intravascular ultrasound-guided percutaneous coronary intervention: a systematic review and meta-analysis of randomized controlled trials

Background

Optical coherence tomography (OCT) and intravascular ultrasound (IVUS) are superior to coronary angiography for guiding percutaneous coronary intervention (PCI). However, whether one technique is superior to the other is inconclusive.

Methods

We searched PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov from inception to November 2023 for randomized controlled trials (RCTs) comparing OCT and IVUS in patients undergoing PCI. RevMan 5.4 was used to pool outcomes with risk ratio (RR) as the effect measure.

Results

Six RCTs (4,402 patients) were included in this meta-analysis. There was no significant difference between the OCT- and IVUS-guided PCI groups in the risk of major adverse cardiovascular events (RR 0.87, 95% CI: 0.65, 1.16; I2 = 0%) and cardiac mortality (RR 0.73, 95% CI: 0.24, 2.21; I2 = 0%). The results were consistent across the subgroups of the presence or absence of left main disease (P interaction >0.1). There were no significant differences between OCT and IVUS in the risk of target lesion revascularization (RR 0.78, 95% CI: 0.47, 1.30; I2 = 0%), target vessel revascularization (RR 1.06, 95% CI: 0.69, 1.62; I2 = 0%), target-vessel myocardial infarction (RR 0.79, 95% CI: 0.40, 1.53; I2 = 0%), stent thrombosis (RR 0.59, 95% CI: 0.12, 2.97; I2 = 0%), and all-cause mortality (RR 1.01, 95% CI: 0.53, 1.90; I2 = 0%).

Conclusions

Our meta-analysis demonstrated similar clinical outcomes in OCT- and IVUS-guided PCI. New large-scale multicenter RCTs with long-term follow-up are required to confirm or refute our findings and provide more reliable results.

Systematic Review Registration

PROSPERO, identifier, CRD42023486933.

Quantitative Coronary Angiography vs Intravascular Ultrasonography to Guide Drug-Eluting Stent Implantation: A Randomized Clinical Trial

Importance

Although intravascular ultrasonography (IVUS) guidance promotes favorable outcomes after percutaneous coronary intervention (PCI), many catheterization laboratories worldwide lack access.

Objective

To investigate whether systematic implementation of quantitative coronary angiography (QCA) to assist angiography-guided PCI could be an alternative strategy to IVUS guidance during stent implantation.

Design, Setting, and Participants

This randomized, open-label, noninferiority clinical trial enrolled adults (aged ≥18 years) with chronic or acute coronary syndrome and angiographically confirmed native coronary artery stenosis requiring PCI. Patients were enrolled in 6 cardiac centers in Korea from February 23, 2017, to August 23, 2021, and follow-up occurred through August 25, 2022. All principal analyses were performed according to the intention-to-treat principle.

Interventions

After successful guidewire crossing of the first target lesion, patients were randomized in a 1:1 ratio to receive either QCA- or IVUS-guided PCI.

Main Outcomes and Measures

The primary outcome was target lesion failure at 12 months, defined as a composite of cardiac death, target vessel myocardial infarction, or ischemia-driven target lesion revascularization. The trial was designed assuming an event rate of 8%, with the upper limit of the 1-sided 97.5% CI of the absolute difference in 12-month target lesion failure (QCA-guided PCI minus IVUS-guided PCI) to be less than 3.5 percentage points for noninferiority.

Results

The trial included 1528 patients who underwent PCI with QCA guidance (763; mean [SD] age, 64.1 [9.9] years; 574 males [75.2%]) or IVUS guidance (765; mean [SD] age, 64.6 [9.5] years; 622 males [81.3%]). The post-PCI mean (SD) minimum lumen diameter was similar between the QCA- and IVUS-guided PCI groups (2.57 [0.55] vs 2.60 [0.58] mm, P = .26). Target lesion failure at 12 months occurred in 29 of 763 patients (3.81%) in the QCA-guided PCI group and 29 of 765 patients (3.80%) in the IVUS-guided PCI group (absolute risk difference, 0.01 percentage points [95% CI, -1.91 to 1.93 percentage points]; hazard ratio, 1.00 [95% CI, 0.60-1.68]; P = .99). There was no difference in the rates of stent edge dissection (1.2% vs 0.7%, P = .25), coronary perforation (0.2% vs 0.4%, P = .41), or stent thrombosis (0.53% vs 0.66%, P = .74) between the QCA- and IVUS-guided PCI groups. The risk of the primary end point was consistent regardless of subgroup, with no significant interaction.

Conclusions and Relevance

Findings of this randomized clinical trial indicate that QCA and IVUS guidance during PCI showed similar rates of target lesion failure at 12 months. However, due to the lower-than-expected rates of target lesion failure in this trial, the findings should be interpreted with caution.

Trial Registration

ClinicalTrials.gov Identifier: NCT02978456.

Experimental validation and clinical feasibility of 3D reconstruction of coronary artery bifurcation stents using intravascular ultrasound

The structural morphology of coronary stents and the local hemodynamic environment following stent deployment in coronary arteries are crucial determinants of procedural success and subsequent clinical outcomes. High-resolution intracoronary imaging has the potential to facilitate geometrically accurate three-dimensional (3D) reconstruction of coronary stents. This work presents an innovative algorithm for the 3D reconstruction of coronary artery stents, leveraging intravascular ultrasound (IVUS) and angiography. The accuracy and reproducibility of our method were tested in stented patient-specific silicone models, with micro-computed tomography serving as a reference standard. We also evaluated the clinical feasibility and ability to perform computational fluid dynamics (CFD) studies in a clinically stented coronary bifurcation. Our experimental and clinical studies demonstrated that our proposed algorithm could reproduce the complex 3D stent configuration with a high degree of precision and reproducibility. Moreover, the algorithm was proved clinically feasible in cases with stents deployed in a diseased coronary artery bifurcation, enabling CFD studies to assess the hemodynamic environment. In combination with patient-specific CFD studies, our method can be applied to stenting optimization, training in stenting techniques, and advancements in stent research and development.

Optical Coherence Tomography Measures Predicting Fractional Flow Reserve: The OMEF Study

Background

Optical coherence tomography (OCT) allows to carefully characterize coronary plaque morphology and lumen dimensions. We sought to evaluate the value of OCT in predicting fractional flow reserve (FFR).

Methods

We performed a multicenter, international, pooled analysis of individual patient-level data from published studies assessing FFR and OCT on the same vessel. Data from stable or unstable patients who underwent both FFR and OCT of the same coronary artery were collected through a dedicated database. Predefined OCT parameters were minimum lumen area (MLA), percentage area stenosis (%AS), and presence of thrombus or plaque rupture. Primary end point was FFR ≤0.80. Secondary outcome was the incidence of major adverse cardiac events in patients not undergoing revascularization based on negative FFR (>0.80).

Results

A total of 502 coronary lesions in 489 patients were included. A significant correlation was observed between OCT-MLA and FFR values (R = 0.525; P < .001), and between OCT-%AS and FFR values (R = -0.482; P < .001). In Receiver operating characteristic analysis, MLA <2.0 mm2 showed a good discriminative power to predict an FFR ≤0.80 (AUC, 0.80), whereas %AS >73% showed a moderate discriminative power (AUC, 0.73). When considering proximal coronary segments, the best OCT cutoff values predicting an FFR ≤0.80 were MLA <3.1 mm2 (AUC, 0.82), and %AS >61% (AUC, 0.84). In patients with a negative FFR not revascularized, the combination of lower MLA and higher %AS had a trend toward worse outcome (which was statistically significant in the analysis restricted to proximal vessels).

Conclusions

OCT lumen measures (MLA, %AS) may predict FFR, and different cutoffs are needed for proximal vessels.

The role of optical coherence tomography in guiding percutaneous coronary interventions: is left main the final challenge?

Left main (LM) coronary artery disease is a high-risk lesion subset, with important prognostic implications for the patients. Recent advances in the field of interventional cardiology have narrowed the gap between surgical and percutaneous approach of this complex lesion setting. However, the rate of repeat revascularization remains higher in the case of percutaneous coronary intervention (PCI) on long-term follow-up. As such, the need for better stent optimization strategies has led to the development of intravascular imaging techniques, represented mainly by intravascular ultrasound (IVUS) and optical coherence tomography (OCT). These techniques are both able to provide excellent pre- and post-PCI guidance. While IVUS is an established modality in optimizing LM PCI, and is recommended by international revascularization guidelines, data and experience on the use of OCT are still limited. This review paper deeply analyzes the current role of OCT imaging in the setting of LM disease, particularly focusing on its utility in assessing plaque morphology and distribution, vessel dimensions and proper stent sizing, analyzing mechanisms of stent failure such as malapposition and underexpansion, guiding bifurcation stenting, as well as offering a direct comparison with IVUS in this critical clinical scenario, based on the most recent available data.

Cardiac Optical Coherence Tomography: History, Current Status, and Perspective

For more than 2 decades since the first imaging procedure was performed in a living patient, intravascular optical coherence tomography (OCT), with its unprecedented image resolution, has made significant contributions to cardiovascular medicine in the realms of vascular biology research and percutaneous coronary intervention. OCT has contributed to a better understanding of vascular biology by providing insights into the pathobiology of atherosclerosis, including plaque phenotypes and the underlying mechanisms of acute coronary syndromes such as plaque erosion, neoatherosclerosis, stent thrombosis, and myocardial infarction with nonobstructive coronary arteries. Moreover, OCT has been used as an adjunctive imaging tool to angiography for the guidance of percutaneous coronary intervention procedures to optimize outcomes. However, broader application of OCT has faced challenges, including subjective interpretation of the images and insufficient clinical outcome data. Future developments including artificial intelligence-assisted interpretation, multimodality catheters, and micro-OCT, as well as large prospective outcome studies could broaden the impact of OCT on cardiovascular medicine.

Role of intravascular ultrasound and optical coherence tomography in intracoronary imaging for coronary artery disease: a systematic review

Coronary angiography has long been the standard for coronary imaging, but it has limitations in assessing vessel wall anatomy and guiding percutaneous coronary intervention (PCI). Intracoronary imaging techniques like intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can overcome these limitations. IVUS uses ultrasound and OCT uses near-infrared light to visualize coronary pathology in unique ways due to differences in temporal and spatial resolution. These techniques have evolved to offer clinical utility in plaque characterization and vessel assessment during PCI. Meta-analyses and adjusted observational studies suggest that both IVUS and OCT-guided PCI correlate with reduced cardiovascular risks compared to angiographic guidance alone. While IVUS demonstrates consistent clinical outcome benefits, OCT evidence is less robust. IVUS has progressed from early motion detection to high-resolution systems, with smaller compatible catheters. OCT utilizes near infrared light to achieve unparalleled resolutions, but requires temporary blood clearance for optimal imaging. Enhanced visualization and guidance make IVUS and OCT well-suited for higher risk PCI in patients with diabetes and chronic kidney disease by allowing detailed visualization of complex lesions and ensuring optimal stent deployment and positioning in PCI for patients with type 2 diabetes and chronic kidney disease, improving outcomes. IVUS and recent advancements in zero- and low-contrast OCT techniques can reduce nephrotoxic contrast exposure, thus helping to minimize PCI complications in these high-risk patient groups. IVUS and OCT provide valuable insights into coronary pathophysiology and guide interventions precisely compared to angiography alone. Both have comparable clinical outcomes, emphasizing the need for tailored imaging choices based on clinical scenarios. Continued refinement and integration of intravascular imaging will likely play a pivotal role in optimizing coronary interventions and outcomes. This systematic review aims to delve into the nuances of IVUS and OCT, highlighting their strengths and limitations as PCI adjuncts.

Guiding Intervention for Complex Coronary Lesions by Optical Coherence Tomography or Intravascular Ultrasound

BACKGROUND

Optical coherence tomography (OCT) and intravascular ultrasound (IVUS) have shown comparable outcomes in guiding percutaneous coronary intervention (PCI). However, their comparative effectiveness in complex coronary artery lesions remains unclear.

OBJECTIVES

This study compared the effectiveness and safety of OCT-guided vs IVUS-guided PCI for complex coronary artery lesions.

METHODS

This was a prespecified, main subgroup analysis of complex coronary artery lesions in the OCTIVUS (Optical Coherence Tomography Versus Intravascular Ultrasound Guided Percutaneous Coronary Intervention) trial, which included unprotected left main disease, bifurcation disease, an aorto-ostial lesion, a chronic total occlusion, a severely calcified lesion, an in-stent restenotic lesion, a diffuse long lesion, or multivessel PCI. The primary endpoint was a composite of death from cardiac causes, target vessel-related myocardial infarction, or ischemia-driven target vessel revascularization.

RESULTS

In 2,008 randomized patients, 1,475 (73.5%) underwent imaging-guided PCI for complex coronary artery lesions; 719 (48.7%) received OCT-guided and 756 (51.3%) IVUS-guided PCI. At a median follow-up of 2.0 years, primary endpoint event had occurred in 47 patients (6.5%) in the OCT-guided group and in 56 patients (7.4%) in the IVUS-guided group (HR: 0.87; 95% CI: 0.59-1.29; P = 0.50). These findings were consistent in adjusted analyses. The incidence of contrast-induced nephropathy was similar between the 2 groups (1.9% vs 1.5%; P = 0.46). The incidence of major procedural complications was lower in the OCT-guided group than in the IVUS-guided group (1.7% vs 3.4%; P = 0.03).

CONCLUSIONS

Among patients with complex coronary artery lesions, OCT-guided PCI showed a similar risk of primary composite event of death from cardiac causes, target vessel-related myocardial infarction, or target vessel revascularization as compared with IVUS-guided PCI. (Optical Coherence Tomography Versus Intravascular Ultrasound Guided Percutaneous Coronary Intervention [OCTIVUS]; NCT03394079).

Hybrid interpenetrating network of polyester coronary stent with tunable biodegradation and mechanical properties

Poly(l-lactide) (PLLA) is an important candidate raw material of the next-generation biodegradable stent for percutaneous coronary intervention, yet how to make a polyester stent with sufficient mechanical strength and relatively fast biodegradation gets to be a dilemma. Herein, we put forward a hybrid interpenetrating network (H-IPN) strategy to resolve this dilemma. As such, we synthesize a multi-functional biodegradable macromer of star-like poly(d,l-lactide-co-ɛ-caprolactone) with six acrylate end groups, and photoinitiate it, after mixing with linear PLLA homopolymer, to trigger the free radical polymerization. The resultant crosslinked polymer blend is different from the classic semi-interpenetrating network, and partial chemical crosslinking occurs between the linear polymer and the macromer network. Combined with the tube blow molding and the postprocessing laser cutting, we fabricate a semi-crosslinked-polyester biodegradable coronary stent composed of H-IPN, which includes a physical network of polyester spherulites and a chemical crosslinking network of copolyester macromers and a part of homopolymers. Compared with the currently main-stream PLLA stent in research, this H-IPN stent realizes a higher and more appropriate biodegradation rate while maintaining sufficient radial strength. A series of polymer chemistry, polymer physics, polymer processing, and in vitro and in vivo biological assessments of medical devices have been made to examine the H-IPN material. The interventional implanting of the H-IPN stent into aorta abdominalis of rabbits and the follow-ups to 12 months have confirmed the safety and effectiveness.

Clinical impact of OCT-derived suboptimal stent implantation parameters and definitions

AIMS

Despite growing evidence supporting the clinical utility of optical coherence tomography (OCT) guidance during percutaneous coronary interventions (PCIs), there is no common agreement as to the optimal stent implantation parameters that enhance clinical outcome.

METHODS AND RESULTS

We retrospectively examined the predictive accuracy of suboptimal stent implantation definitions proposed from the CLI-OPCI II, ILUMIEN-IV OPTIMAL PCI, and FORZA studies for the long-term risk of device-oriented cardiovascular events (DoCE) in the population of large all-comers CLI-OPCI project. A total of 1020 patients undergoing OCT-guided drug-eluting stent implantation in the CLI-OPCI registry with a median follow-up of 809 (quartiles 414-1376) days constituted the study population. According to CLI-OPCI II, ILUMIEN-IV OPTIMAL PCI, and FORZA criteria, the incidence of suboptimal stent implantation was 31.8%, 58.1%, and 57.8%, respectively. By multivariable Cox analysis, suboptimal stent implantation criteria from the CLI-OPCI II [hazard ratio 2.75 (95% confidence interval 1.88-4.02), P < 0.001] and ILUMIEN-IV OPTIMAL PCI [1.79 (1.18-2.71), P = 0.006] studies, but not FORZA trial [1.11 (0.75-1.63), P = 0.597], were predictive of DoCE. At long-term follow-up, stent edge disease with minimum lumen area <4.5 mm2 [8.17 (5.32-12.53), P < 0.001], stent edge dissection [2.38 (1.33-4.27), P = 0.004], and minimum stent area <4.5 mm2 [1.68 (1.13-2.51), P = 0.011] were the main OCT predictors of DoCE.

CONCLUSION

The clinical utility of OCT-guided PCI might depend on the metrics adopted to define suboptimal stent implantation. Uncovered disease at the stent border, stent edge dissection, and minimum stent area <4.5 mm2 were the strongest OCT associates of stent failure.

Definitions and Standardized Endpoints for Treatment of Coronary Bifurcations

The Bifurcation Academic Research Consortium (Bif-ARC) project originated from the need to overcome the paucity of standardization and comparability between studies involving bifurcation coronary lesions. This document is the result of a collaborative effort between academic research organizations and the most renowned interventional cardiology societies focused on bifurcation lesions in Europe, the United States, and Asia. This consensus provides standardized definitions for bifurcation lesions; the criteria to judge the side branch relevance; the procedural, mechanistic, and clinical endpoints for every type of bifurcation study; and the follow-up methods. Considering the complexity of bifurcation lesions and their evaluation, detailed instructions and technical aspects for site and core laboratory analysis of bifurcation lesions are also reported. The recommendations included within this consensus will facilitate pooled analyses and the effective comparison of data in the future, improving the clinical relevance of trials in bifurcation lesions, and the quality of care in this subset of patients.

Clinical quantitative coronary artery stenosis and coronary atherosclerosis imaging: a Consensus Statement from the Quantitative Cardiovascular Imaging Study Group

The detection and characterization of coronary artery stenosis and atherosclerosis using imaging tools are key for clinical decision-making in patients with known or suspected coronary artery disease. In this regard, imaging-based quantification can be improved by choosing the most appropriate imaging modality for diagnosis, treatment and procedural planning. In this Consensus Statement, we provide clinical consensus recommendations on the optimal use of different imaging techniques in various patient populations and describe the advances in imaging technology. Clinical consensus recommendations on the appropriateness of each imaging technique for direct coronary artery visualization were derived through a three-step, real-time Delphi process that took place before, during and after the Second International Quantitative Cardiovascular Imaging Meeting in September 2022. According to the Delphi survey answers, CT is the method of choice to rule out obstructive stenosis in patients with an intermediate pre-test probability of coronary artery disease and enables quantitative assessment of coronary plaque with respect to dimensions, composition, location and related risk of future cardiovascular events, whereas MRI facilitates the visualization of coronary plaque and can be used in experienced centres as a radiation-free, second-line option for non-invasive coronary angiography. PET has the greatest potential for quantifying inflammation in coronary plaque but SPECT currently has a limited role in clinical coronary artery stenosis and atherosclerosis imaging. Invasive coronary angiography is the reference standard for stenosis assessment but cannot characterize coronary plaques. Finally, intravascular ultrasonography and optical coherence tomography are the most important invasive imaging modalities for the identification of plaques at high risk of rupture. The recommendations made in this Consensus Statement will help clinicians to choose the most appropriate imaging modality on the basis of the specific clinical scenario, individual patient characteristics and the availability of each imaging modality.

Automatic lumen and anatomical layers segmentation in IVOCT images using meta learning

Automated analysis of the vessel structure in intravascular optical coherence tomography (IVOCT) images is critical to assess the health status of vessels and monitor coronary artery disease progression. However, deep learning-based methods usually require well-annotated large datasets, which are difficult to obtain in the field of medical image analysis. Hence, an automatic layers segmentation method based on meta-learning was proposed, which can simultaneously extract the surfaces of the lumen, intima, media, and adventitia using a handful of annotated samples. Specifically, we leverage a bi-level gradient strategy to train a meta-learner for capturing the shared meta-knowledge among different anatomical layers and quickly adapting to unknown anatomical layers. Then, a Claw-type network and a contrast consistency loss were designed to better learn the meta-knowledge according to the characteristic of annotation of the lumen and anatomical layers. Experimental results on the two cardiovascular IVOCT datasets show that the proposed method achieved state-of-art performance.

Comparison of definitions of coronary artery reference sizes and effects on stent selection and evaluation of stent expansion

Accurate determination of coronary reference size is essential for optimal stent selection and evaluation of stent expansion during percutaneous coronary intervention (PCI). Several approaches for reference size estimation have been published with no universal agreement. The aim of this study was to investigate if potential differences in coronary reference size estimation lead to differences in stent and balloon selection and in detection of stent under expansion. Definitions for coronary reference size estimation, stent size selection, and stent expansion were identified in 17 randomized controlled trials. The identified methods were applied in a population of 32 clinical cases. Reference size estimates ranged up to 1.35mm, and indicated nominal stent size ranged up to 1.0 mm in the same case depending on method. Mean relative stent expansion ranged from 54±12% to mean 100±29% depending on the applied reference method. Choice of method for reference size estimation using intravascular imaging may influence stent selection and greatly affects evaluation of post-PCI stent expansion.

Accuracy of IVUS-Based Machine Learning Segmentation Assessment of Coronary Artery Dimensions and Balloon Sizing

Background

Accurate intravascular ultrasound (IVUS) measurements are important in IVUS-guided percutaneous coronary intervention optimization by choosing the appropriate device size and confirming stent expansion.

Objectives

The purpose of this study was to assess the accuracy of machine learning (ML) automatic segmentation of coronary artery vessel and lumen dimensions and balloon sizing.

Methods

Using expert analysis as the gold standard, ML segmentation of 60 MHz IVUS images was developed using 8,076 IVUS cross-sectional images from 234 patients, which were randomly split into training (83%) and validation (17%) data sets. The performance of ML segmentation was then evaluated using an independent test data set (437 images from 92 patients). The endpoints were the agreement rate between ML vs experts' measurements for appropriate balloon size selection, and lumen and acute stent areas. Appropriate balloon size was determined by rounding down from the mean vessel diameter or rounding up from the mean lumen diameter to the next balloon size. The difference of lumen area ≥0.5 mm2 was considered as clinically significant.

Results

ML model segmentation correlated well with experts' segmentation for training data set with a correlation coefficient of 0.992 and 0.993 for lumen and vessel areas, respectively. The agreement rate in lumen and acute stent areas was 85.5% and 97.0%, respectively. The agreement rate for appropriate balloon size selection was 70.6% by vessel diameter only and 92.4% by adding lumen diameter.

Conclusions

ML model IVUS segmentation measurements were well-correlated with those of experts and selected an appropriate balloon size in more than 90% of images.

Utilization of intravascular imaging in elective non chronic total occlusion percutaneous intervention and chronic total occlusion percutaneous intervention: Trends in utilization and impact on in-hospital mortality

OBJECTIVES

The objectives of this retrospective study include outcomes associated with and without intravascular imaging in cases of elective single vessel (SV) CTO PCI and in non-CTO PCI.

METHOD

We explored the NIS database from October 1, 2015 to December 31, 2018 to identify 317,090 adult admissions with elective SV PCI. Admissions with STEMI and NSTEMI were excluded to identify elective cases only. Using the ICD 10 diagnosis code for CTO, we identified 33,345 admissions that underwent SV CTO PCI. We classified the remaining cases as SV non-CTO PCI.

RESULTS

Intravascular imaging was utilized in 2930 (8.8%) cases in CTO PCI group and 23,710 (8.3%) cases in non-CTO PCI groups. The utilization of intravascular imaging (IVUS/OCT) significantly increased in elective SV CTO PCI, 6.4%-11.2%, p-trend<0.001 and non-CTO PCI group, 7.3%-9.0%, p-trend<0.001. There was no significance difference in mortality with and without intravascular imaging (combined IVUS/OCT vs no IVUS/OCT: 1.5% vs 1.3%, p = 0.195) in the CTO PCI group. But, in non-CTO PCI admissions, there was a significantly lower in-hospital mortality when intravascular imaging was used (0.7% vs 0.8%, p = 0.003). The cost of hospitalization was significantly higher when intravascular imaging was used in elective single vessel CTO PCI admissions, combined IVUS/OCT vs no IVUS/OCT: $27,427 vs $21,452, p < 0.001 and non-CTO PCI admissions, combined IVUS/OCT vs no IVUS/OCT: $23,620 vs $20,272, p < 0.001.

CONCLUSIONS

In conclusion, despite the cost, intravascular imaging use decrease mortality in non-CTO PCI groups but there is no difference in mortality in CTO PCI groups.

3D reconstruction of coronary artery bifurcations from intravascular ultrasound and angiography

Coronary bifurcation lesions represent a challenging anatomical subset, and the understanding of their 3D anatomy and plaque composition appears to play a key role in devising the optimal stenting strategy. This study proposes a new approach for the 3D reconstruction of coronary bifurcations and plaque materials by combining intravascular ultrasound (IVUS) and angiography. Three patient-specific silicone bifurcation models were 3D reconstructed and compared to micro-computed tomography (µCT) as the gold standard to test the accuracy and reproducibility of the proposed methodology. The clinical feasibility of the method was investigated in three diseased patient-specific bifurcations of varying anatomical complexity. The IVUS-based 3D reconstructed bifurcation models showed high agreement with the µCT reference models, with r2 values ranging from 0.88 to 0.99. The methodology successfully 3D reconstructed all the patient bifurcations, including plaque materials, in less than 60 min. Our proposed method is a simple, time-efficient, and user-friendly tool for accurate 3D reconstruction of coronary artery bifurcations. It can provide valuable information about bifurcation anatomy and plaque burden in the clinical setting, assisting in bifurcation stent planning and education.

Serial changes of the side-branch ostial area after single crossover stenting with kissing-balloon inflation

PURPOSE

We aimed to investigate the serial change of the side-branch ostial area (SBOA) depended on the wire-position before Kissing-balloon inflation (KBI) in the single-stent strategy for bifurcation lesions separately in the left main coronary artery (LMCA) and in non-LMCA.

METHODS

Patients who underwent a single-stent KBI for a bifurcation lesion and had OCT images at the timing of the rewiring, at the post-procedure, and at the 9-month follow-up were extracted from the 3D-OCT Bifurcation Registry, which is a multicenter-prospective registry of patients with a percutaneous coronary intervention for a bifurcation lesion under OCT guidance. The SBOA was measured by dedicated software, and the rewiring position at the side-branch ostium after crossover stenting was assessed by three-dimensional-optical coherence tomography (3D-OCT). The optimal rewiring was defined as link-free-type and distal rewiring. The relationship between the optimal rewiring and the serial change of the SBOA was investigated separately in LMCA and non-LMCA cases.

RESULTS

We examined 75 bifurcation lesions (LMCA, n = 35; non-LMCA, n = 40). The serial changes of the SBOA with the optimal rewiring were not significantly different regardless of LMCA and non-LMCA (LMCA:3.96 to 3.73 mm2, p = 0.38; non-LMCA:2.16 to 2.21 mm2, p = 0.98), whereas the serial changes of the SBOA with the sub-optimal rewiring were significantly reduced (LMCA:6.75 to 5.54 mm2, p = 0.013; non-LMCA:2.28 mm2 to 2.09 mm2, p = 0.024). There was no significant difference in clinical events between the optimal and sub-optimal rewiring group regardless of the LMCA and non-LMCA.

CONCLUSION

The side-branch ostial area dilated with the optimal rewiring position in a bifurcation lesion treated with single crossover stenting and kissing-balloon inflation was preserved regardless of whether the bifurcation was in the LMCA or a non-LMCA.

IVUS-guided versus OCT-guided PCI among patients presenting with acute coronary syndrome

BACKGROUND

Intravascular imaging modalities such as intravascular ultrasound (IVUS) and, more recently, optical coherence tomography (OCT) improved the visualization of coronary anatomy and plaque pathology. We aimed to compare the procedural and short-term outcomes between IVUS-guided and OCT-guided percutaneous coronary interventions (PCIs) in patients with acute coronary syndrome (ACS).

METHODS

In the present retrospective study, we reviewed the data of 50 patients who had IVUS-guided PCI and 50 patients who had OCT-guided PCI for ACS between January 2020 and June 2021. Intravascular imaging was done before and after stenting. Both groups were compared in terms of minimal luminal area (MLA), stent dimensions, final minimal stent area (MSA) and stent expansion as well as negative angiographic outcomes. Patients were followed for six months to record major adverse cardiac events (MACE).

RESULTS

The patients' mean age was 57 ± 13 years with male predominance (78%). The radiation time and dose were significantly higher among IVUS group. Pre-stenting MLA was significantly higher in IVUS group (2.63 mm vs. 2.22 mm in OCT, P = 0.013). Stent expansion was significantly higher among OCT group (97% vs. 93% in IVUS group, P = 0.001) with no significant difference between both groups regarding MSA [mm²] (8.88 ± 2.87 in IVUS vs. 8.1 ± 2.76 in OCT, P = 0.169). No significant difference between both groups was noted regarding contrast volume, edge dissection, tissue prolapse, and no reflow. The rates of six-month MACE were significantly higher in the IVUS group.

CONCLUSIONS

OCT-guided PCI in ACS is safe and is associated with similar MSA to that of IVUS-guided PCI. Future randomized trials are needed to confirm these findings.

Optical Coherence Tomography-Guided Percutaneous Coronary Intervention: Evidence and Clinical Trials

Intracoronary imaging is beneficial to optimize stent implantation and reduce the risk of stent-related complications. Optical coherence tomography (OCT) is an intravascular imaging modality that allows for detailed microstructural evaluation during the percutaneous coronary intervention (PCI). Recently, several large-scale registries, randomized trials, and meta-analyses have shown the superiority of OCT to angiography and noninferiority to IVUS with respect to both acute procedural results and mid-term clinical outcomes. This article summarizes the data supporting the application of OCT-guided PCI to several specific situations, introduces important evidence, and discusses the ongoing controversies and limitations of the current evidence base in the field of OCT-guided PCI.

Identification of High-Risk Coronary Lesions by 3-Vessel Optical Coherence Tomography

BACKGROUND

Optical coherence tomography (OCT) may provide a method for detecting histologically defined high-risk plaques in vivo.

OBJECTIVES

The authors aimed to investigate the prognostic value of OCT for identifying patients and lesions that are at risk for adverse cardiac events.

METHODS

Between January 2017 and May 2019, OCT of all the 3 main epicardial arteries was performed in 883 patients with acute myocardial infarction (MI) who were referred for primary percutaneous coronary intervention. The primary endpoint was the composite of cardiac death, nonculprit lesion-related nonfatal MI, and unplanned coronary revascularization. Patients were followed for up to 4 years (median 3.3 years).

RESULTS

The 4-year cumulative rate of the primary endpoint was 7.2%. In patient-level analysis, thin-cap fibroatheroma (TCFA) (adjusted HR: 3.05; 95% CI: 1.67-5.57) and minimal lumen area (MLA) <3.5 mm² (adjusted HR: 3.71; 95% CI: 1.22-11.34) were independent predictors of the primary endpoint. In lesion-level analysis, nonculprit lesions responsible for subsequent events were not angiographically severe at baseline (mean diameter stenosis 43.8% ± 13.4%). TCFA (adjusted HR: 8.15; 95% CI: 3.67-18.07) and MLA <3.5 mm² (adjusted HR: 4.33; 95% CI: 1.81-10.38) were predictive of events arising from each specific lesion. TCFAs with an MLA <3.5 mm² carried a higher risk and were sufficient for identifying patients at risk for the composite of cardiac death and nonculprit lesion-related nonfatal MI.

CONCLUSIONS

OCT imaging of angiographically nonobstructive territories in patients with acute MI can aid in identifying patients and lesions at increased risk for adverse cardiac events.

Intravascular imaging modalities in coronary intervention: Insights from 3D-printed phantom coronary models

INTRODUCTION AND OBJECTIVES

Several studies comparing optical coherence tomography (OCT) and intravascular ultrasound (IVUS) have revealed that OCT consistently provides smaller area and diameter measurements. However, comparative assessment in clinical practice is difficult. Three-dimensional (3D) printing offers a unique opportunity to assess intravascular imaging modalities. We aim to compare intravascular imaging modalities using a 3D-printed coronary artery in a realistic simulator and to assess whether OCT underestimates intravascular dimensions, exploring potential corrections.

METHODS

A standard realistic left main anatomy with an ostial left anterior descending artery lesion was replicated using 3D printing. After provisional stenting and optimization, IVI was obtained. Modalities included 20 MHz digital IVUS, 60 MHz rotational IVUS (HD-IVUS) and OCT. We assessed luminal area and diameters at standard locations.

RESULTS

Considering all coregistered measurements, OCT significantly underestimated area, minimal diameter and maximal diameter measurements in comparison to IVUS and HD-IVUS (p<0.001). No significant differences were found between IVUS and HD-IVUS. A significant systematic dimensional error was found in OCT auto-calibration by comparing known reference diameter of guiding catheter (1.8 mm) to measured mean diameter (1.68 mm±0.04 mm). By applying a correction factor based on the reference guiding catheter area to OCT, the luminal areas and diameters became not significantly different compared to IVUS and HD-IVUS.

CONCLUSION

Our findings suggest that automatic spectral calibration method for OCT is inaccurate, with a systematic underestimation of luminal dimensions. When guiding catheter correction is applied the performance of OCT is significantly improved. These results may be clinically relevant and need to be validated.

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

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

Optical coherence tomography and coronary revascularization: from indication to procedural optimization

Angiography alone is the most commonly used imaging modality for guidance of percutaneous coronary interventions. Angiography is limited, however, by several factors, including that it only portrays a low resolution, two-dimensional outline of the lumen and does not inform on plaque composition and functional stenosis severity. Optical coherence tomography (OCT) is an intracoronary imaging technique that has superior spatial resolution compared to all other imaging modalities. High-resolution imaging of the vascular wall enables precise measurement of vessel wall and luminal dimensions, more accurately informing about the anatomic severity of epicardial stenoses, and also provides input for computational models to assess functional severity. The very high-resolution images also permit plaque characterization that may be informative for prognostication. Moreover, periprocedural imaging provides valuable information to guide lesion preparation, stent implantation and to evaluate acute stent complications for which iterative treatment might reduce the occurrence of major adverse stent events. As such, OCT represent a potential future all-in-one tool that provides the data necessary to establish the indications, procedural planning and optimization, and final evaluation of percutaneous coronary revascularization.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Impact of the adjunctive use criteria for intravascular ultrasound-guided percutaneous coronary intervention and clinical outcomes

The impact of the adherence to the adjunctive use criteria (AUC) for intravascular ultrasound (IVUS) guided percutaneous coronary intervention (PCI) and clinical outcomes in low IVUS volume countries are limited. The current study compared the procedural success and complication rates between used and not used IVUS catheter in the patients who were met (C +) and were not met (C-) the AUC for IVUS-guided PCI. From June 2018 through June 2019, a total of 21,066 patients were included in the Thai PCI registry. Among the study population, 15,966 patients (75.8%) have met the IVUS-AUC. The IVUS-guided PCI rates were 14.5% and 11.3% in the C + and C - groups, respectively. After adjusting for covariables by propensity model, IVUS-guided PCI was identified as an independent predictor of the procedural success rate regardless of whether the AUC were met with the relative risk [RR (95% confidence interval (CI)] of 1.033(1.026-1.040) and 1.012(1.002-1.021) in C + and C- groups, respectively. IVUS-guided PCI increased the procedural complication risks in both groups but were not significant with corresponding RRs of 1.171(0.915-1.426) and 1.693(0.959-2.426). Procedural success was achieved with IVUS-guided PCI regardless of whether the AUC were met. IVUS-guided PCI did not lead to an increase in procedural complications.

Human Coronary Plaque Optical Coherence Tomography Image Repairing, Multilayer Segmentation and Impact on Plaque Stress/Strain Calculations

Coronary vessel layer structure may have a considerable impact on plaque stress/strain calculations. Most current plaque models use single-layer vessel structures due to the lack of available multilayer segmentation techniques. In this paper, an automatic multilayer segmentation and repair method was developed to segment coronary optical coherence tomography (OCT) images to obtain multilayer vessel geometries for biomechanical model construction. Intravascular OCT data were acquired from six patients (one male; mean age: 70.0) using a protocol approved by the local institutional review board with informed consent obtained. A total of 436 OCT slices were selected in this study. Manually segmented data were used as the gold standard for method development and validation. The edge detection method and cubic spline surface fitting were applied to detect and repair the internal elastic membrane (IEM), external elastic membrane (EEM) and adventitia-periadventitia interface (ADV). The mean errors of automatic contours compared to manually segmented contours were 1.40%, 4.34% and 6.97%, respectively. The single-layer mean plaque stress value from lumen was 117.91 kPa, 10.79% lower than that from three-layer models (132.33 kPa). On the adventitia, the single-layer mean plaque stress value was 50.46 kPa, 156.28% higher than that from three-layer models (19.74 kPa). The proposed segmentation technique may have wide applications in vulnerable plaque research.

Network Meta-analysis of Trials Comparing Intravascular Ultrasound, Optical Coherence Tomography, and Angiography-Guided Technique for Drug-Eluting Stent Implantation

Background

The current advances in coronary imaging with the introduction of intravascular ultrasound (IVUS), and more recently, optical coherence tomography (OCT) have overcome the limitations of coronary angiography.

Objective

This study aimed to conduct a comprehensive network meta-analysis of randomized clinical trials to report clinical outcomes among patients undergoing drug-eluting stent (DES) implantation either by IVUS- or OCT-guided technique or angiography alone.

Methods

PubMed/MEDLINE and EMBASE databases were searched systematically for all relevant published randomized clinical trials from the inception of the respective database to October 15th, 2021. The outcomes of interest assessed in this meta-analysis were major adverse cardiac events, myocardial infarction, target vessel revascularization, all-cause mortality, and cardiovascular mortality. All the endpoints were expressed as odds ratio (OR) with 95% CI. The network diagrams were computed using the OR as an effective measure. All statistical analyses were carried out in R statistical software version 4.0.3.

Results

A total of 14 randomized clinical trials were included in our meta-analysis. In patient undergoing DES implantation, angiography alone was associated with higher odds of major adverse cardiac events (OR, 1.62; 95% CI, 1.17-2.24), target vessel revascularization (OR, 1.60; 95% CI, 1.21-2.13) and cardiovascular mortality (OR, 1.97; 95% CI, 1.25-3.11). However, OCT demonstrated similar odds of major adverse cardiac events, cardiovascular mortality, and target vessel revascularization compared with IVUS. The odds of myocardial infarction and all-cause mortality were similar among all the 3 groups.

Conclusions

Although angiography alone was associated with worse outcomes than IVUS in a patient undergoing DES implantation, no difference in outcome was noted between patients undergoing DES implantation with OCT compared with IVUS. Advanced intracoronary imaging use should be encouraged to prevent excess mortality and morbidity.

Optical coherence tomography versus angiography and intravascular ultrasound to guide coronary stent implantation: A systematic review and meta-analysis

BACKGROUND

Optical coherence tomography (OCT) is an adjunct to angiography-guided coronary stent placement. However, in the absence of dedicated, appropriately powered randomized controlled trials, the impact of OCT on clinical outcomes is unclear.

OBJECTIVE

To conduct a systematic review and meta-analysis of all available studies comparing OCT-guided versus angiography-guided and intravascular ultrasound (IVUS)-guided coronary stent implantation.

METHODS

MEDLINE and Cochrane Central were queried from their inception through July 2022 for all studies that sought to compare OCT-guided percutaneous coronary intervention (PCI) to angiography-guided and IVUS-guided PCI. The primary endpoint was minimal stent area (MSA) compared between modalities. Clinical endpoints of interest were all-cause and cardiovascular mortality, major adverse cardiovascular events (MACE), myocardial infarction (MI), target lesion revascularization (TLR), target vessel revascularization (TVR), and stent thrombosis (ST). Risk ratios (RRs) and mean differences (MDs) with their corresponding 95% confidence intervals (CIs) were pooled using a random-effects model.

RESULTS

Thirteen studies (8 randomized control trials and 5 observational studies) enrolling 6312 participants were included. OCT was associated with a strong trend toward increased MSA compared to angiography (MD = 0.36, p = 0.06). OCT-guided PCI was also associated with a reduction in the incidence of all-cause mortality [RR = 0.59, 95% CI (0.35, 0.97), p = 0.04] and cardiovascular mortality [RR = 0.41, 95% CI (0.21, 0.80), p = 0.009] compared with angiography-guided PCI. Point estimates favored OCT relative to angiography in MACE [RR = 0.75, 95% CI (0.47, 1.20), p = 0.22] and MI [RR = 0.75, 95% CI (0.53, 1.07), p = 0.12]. No differences were detected in ST [RR = 0.71, 95% CI (0.21, 2.44), p = 0.58], TLR [RR = 0.71, 95% CI (0.17, 3.05), p = 0.65], or TVR rates [RR = 0.89, 95% CI (0.46, 1.73), p = 0.73]. Compared with IVUS guidance, OCT guidance was associated with a nonsignificant reduction in the MSA (MD = -0.16, p = 0.27). The rates of all-cause and cardiovascular mortality, MACE, MI, TLR, TVR, or ST were similar between OCT-guided and IVUS-guided PCI.

CONCLUSIONS

OCT-guided PCI was associated with reduced all-cause and cardiovascular mortality compared to angiography-guided PCI. These results should be considered hypothesis generating as the mechanisms for the improved outcomes were unclear as no differences were detected in the rates of TLR, TVR, or ST. OCT- and IVUS-guided PCI resulted in similar post-PCI outcomes.

Intravascular Imaging for Percutaneous Coronary Intervention Guidance and Optimization: The Evidence for Improved Patient Outcomes

As of this writing, there have been approximately 24 randomized controlled trial publications, 32 meta-analyses, and 85 registries comparing intravascular ultrasound (IVUS) or optical coherence tomography (OCT) versus angiography-guided drug-eluting stent implantation (or IVUS versus OCT guidance). Although in specific clinical scenarios IVUS or OCT may be preferred, in most drug-eluting stent implantation procedures, either intravascular ultrasound or OCT can be used safely, efficiently, effectively, and interchangeably and will improve patient outcomes compared with stent implantation procedures performed just with angiography guidance.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Optical coherence tomography in coronary atherosclerosis assessment and intervention

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

Effect of Stenting Strategy on the Outcome in Patients with Non-Left Main Bifurcation Lesions

Previous studies have not compared outcomes between different percutaneous coronary intervention (PCI) strategies and lesion locations in non-left main (LM) bifurcation lesions. We enrolled 2044 patients from a multicenter registry with an LAD bifurcation lesion (n = 1551) or non-LAD bifurcation lesion (n = 493). The primary outcome was target lesion failure (TLF), a composite of cardiac death, myocardial infarction, and target lesion revascularization (TLR). During a median follow-up period of 38 months, non-LAD bifurcation lesions treated with the two-stent strategy, compared with the one-stent strategy, were associated with more frequent TLF (20.7% vs. 6.3%, p < 0.01), TLR (16.7% vs. 4.7%, p < 0.01), and target vessel revascularization (TVR; 18.2% vs. 6.3%, p < 0.01). There was no significant difference in outcome among LAD bifurcation lesions treated with different PCI strategies. The two-stent strategy was associated with a higher risk of TLF (adjusted HR 4.34, CI 1.93−9.76, p < 0.01), TLR (adjusted HR 4.30, CI 1.64−11.27, p < 0.01), and TVR (adjusted HR 5.07, CI 1.69−9.74, p < 0.01) in the non-LAD bifurcation lesions. The planned one-stent strategy is preferable to the two-stent strategy for the treatment of non-LAD bifurcation lesions.

Intravascular imaging in coronary stent restenosis: Prevention, characterization, and management

Despite the introduction of drug-eluting stents to combat the neointimal hyperplasia that occurred after BMS implantation, in-stent restenosis is still encountered in a significant number of patients, particularly as increasingly complex lesions are tackled by percutaneous coronary intervention. Many biological and mechanical factors interplay to produce restenosis, some of which are avoidable. Intravascular imaging provided unique insights into various forms of stent-related mechanical issues that contribute to this phenomenon. From a practical perspective, intravascular imaging can therefore help to optimize the stenting procedure to avert these issues. Moreover, once the problem of restenosis eventuates, imaging can guide the management by tackling the underlying identified mechanism. Finally, it can be used to evaluate the re-intervention results. Nevertheless, with the emergence of different treatment options, more evidence is needed to define patient/lesion-specific characteristics that may help to tailor treatment selection in a way that improves clinical outcomes.

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

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

Procedure-Related Differences and Clinical Outcomes in Patients Treated with Percutaneous Coronary Intervention Assisted by Optical Coherence Tomography between New and Earlier Generation Software (Ultreon™ 1.0 Software vs. AptiVue™ Software)

(1) Introduction: Optical coherence tomography (OCT) intravascular imaging facilitates percutaneous coronary intervention (PCI). Software for OCT is being constantly improved, including the latest version Ultreon™ 1.0 Software (U) (Abbott Vascular, Santa Clara, CA, USA). In the current analysis, we aim to compare processing results, procedural indices as well as clinical outcomes in patients treated via PCI. This was conducted using earlier generation OCT imaging software versions (non-U) and the newest available one on the market (U). (2) Methods: The study comprised 95 subsequent and not selected patients (55 processed with U and 40 non-U). The non-U processings were transferred for evaluation by U software, while the comparison of OCT parameters, selected clinical and procedural indices was performed between groups. We further assessed clinical outcomes during the follow-up period, i.e., major adverse cardiovascular events (MACE) and predictors of stent expansion. (3) Results: We did not detect any differences in general features between either of the assessed groups at baseline. Non-U software was more often used for bare-metal stenting (p = 0.004), while PCIs in the U group demanded a greater number of stents (p = 0.03). The distal reference of external elastic lamina (EEL) diameter was greater in the non-U group (p = 0.02) with no concurrent differences in minimal (p = 0.27) and maximal (p = 0.31) stent diameter. It was also observed that MACE was more frequently observed in the non-U group (p = 0.01). Neither univariable (estimate: 0.407, 95%CI: (−3.182) − 3.998, p = 0.82) nor multivariable (estimate: 2.29, 95%CI: (−4.207) − 8.788, p = 0.5) analyses demonstrated a relationship between the type of software and stent expansion. (4) Conclusions: Improvement in the software for image acquisition and processing of OCT is not related to stent expansion. The EEL diameter is preferably used to select the distal stent diameter in newer software.

Definitions and Standardized Endpoints for Treatment of Coronary Bifurcations

The Bifurcation Academic Research Consortium (Bif-ARC) project originated from the need to overcome the paucity of standardization and comparability between studies involving bifurcation coronary lesions. This document is the result of a collaborative effort between academic research organizations and the most renowned interventional cardiology societies focused on bifurcation lesions in Europe, the United States, and Asia. This consensus provides standardized definitions for bifurcation lesions; the criteria to judge the side branch relevance; the procedural, mechanistic, and clinical endpoints for every type of bifurcation study; and the follow-up methods. Considering the complexity of bifurcation lesions and their evaluation, detailed instructions and technical aspects for site and core laboratory analysis of bifurcation lesions are also reported. The recommendations included within this consensus will facilitate pooled analyses and the effective comparison of data in the future, improving the clinical relevance of trials in bifurcation lesions, and the quality of care in this subset of patients.