Angiography Alone Versus Angiography Plus Optical Coherence Tomography to Guide Percutaneous Coronary Intervention

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.

Intracoronary imaging guidance of percutaneous coronary interventions: how and when to apply validated metrics to improve the outcome

Percutaneous coronary intervention (PCI) is still burdened by a substantial number of complications despite constant technological advances, including the advent of intracoronary imaging (ICI) techniques. ICI modalities have been instrumental for the understanding the mechanism of PCI failure. Thanks to the ability to detail the pre-intervention coronary anatomy and identify the features indicative of sub-optimal stent deployment, ICI techniques can be utilised to improve coronary interventions in different clinical scenarios. More recently large randomized clinical trials on ICI guidance confirmed the clinical effectiveness of this approach especially in complex high-risk interventions.

Comparison of angiography-guided vs. intra-vascular imaging-guiding percutaneous coronary intervention of acute myocardial infarction: a real world clinical practice

Background

The role of routine intravascular imaging in percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) remains unclear. This study evaluated the clinical outcomes of PCI guided by different imaging modalities in AMI patients.

Materials and methods

Data from AMI patients who had undergone PCI between 2012 and 2022 were analyzed. The mean follow-up was 12.9 ± 1.73 months. The imaging modality-either intravascular ultrasound (IVUS), optical coherence tomography (OCT), or angiography alone-was selected at the operator's discretion. The primary endpoint was major adverse cardiac events (MACEs), including cardiovascular (CV) death, myocardial infarction (MI), target vessel revascularization.

Results

Of the 1,304 PCIs performed, 47.5% (n = 620) were guided by angiography alone, 37.0% (n = 483) by IVUS, and 15.4% (n = 201) by OCT. PCI guided by intravascular imaging modalities was associated with lower 1-year rates of MI (1.3%, P = 0.001) and MACE (5.2%, P = 0.036). OCT-guided PCI was linked to lower rates of 1-year CV death (IVUS vs. OCT: 6.2% vs. 1.5%, P = 0.016) and MACE (IVUS vs. OCT: 6.4% vs. 2.5%, P = 0.032). Intravascular imaging modalities and diabetes were identified as predictors of better and worse 1-year MACE outcomes, respectively.

Conclusion

PCI guided by intravascular imaging modalities resulted in improved 1-year clinical outcomes compared to angiography-guided PCI alone in AMI patients. OCT-guided PCI was associated with lower 1-year MACE rates compared to IVUS-guided PCI. Therefore, intravascular imaging should be recommended for PCI in AMI, with OCT being particularly considered when appropriate.

Five-year follow-up of OCT-guided percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction

BACKGROUND

Compared with intravascular ultrasound guidance, there is limited evidence for optical coherence tomography (OCT) guidance during primary percutaneous coronary intervention (pPCI) in ST-segment elevation myocardial infarction (STEMI) patients.

AIMS

We investigated the role of OCT in guiding a reperfusion strategy and improving the long-term prognosis of STEMI patients.

METHODS

All patients who were diagnosed with STEMI and who underwent pPCI between January 2017 and December 2020 were enrolled and divided into OCT-guided versus angiography-guided cohorts. They had routine follow-up for up to 5 years or until the time of the last known contact. All-cause death and cardiovascular death were designated as the primary and secondary endpoints, respectively.

RESULTS

A total of 3,897 patients were enrolled: 2,696 (69.2%) with OCT guidance and 1,201 (30.8%) with angiographic guidance. Patients in the OCT-guided cohort were less often treated with stenting during pPCI (62.6% vs 80.2%; p<0.001). The 5-year cumulative rates of all-cause mortality and cardiovascular mortality in the OCT-guided cohort were 10.4% and 8.0%, respectively, significantly lower than in the angiography-guided cohort (19.0% and 14.1%; both log-rank p<0.001). All 4 multivariate models showed that OCT guidance could significantly reduce 5-year all-cause mortality (hazard ratio [HR] in model 4: 0.689, 95% confidence interval [CI]: 0.551-0.862) and cardiovascular mortality (HR in model 4: 0.692, 95% CI: 0.536-0.895). After propensity score matching, the benefits of OCT guidance were consistent in terms of all-cause mortality (HR: 0.707, 95% CI: 0.548-0.913) and cardiovascular mortality (HR: 0.709, 95% CI: 0.526-0.955).

CONCLUSIONS

Compared with angiography alone, OCT guidance may change reperfusion strategies and lead to better long-term survival in STEMI patients undergoing pPCI. Findings in the current observational study should be further corroborated in randomised trials.

Development of machine learning models for fractional flow reserve prediction in angiographically intermediate coronary lesions

BACKGROUND

Fractional flow reserve (FFR) represents the gold standard in guiding the decision to proceed or not with coronary revascularization of angiographically intermediate coronary lesion (AICL). Optical coherence tomography (OCT) allows to carefully characterize coronary plaque morphology and lumen dimensions.

OBJECTIVES

We sought to develop machine learning (ML) models based on clinical, angiographic and OCT variables for predicting FFR.

METHODS

Data from a multicenter, international, pooled analysis of individual patient's level data from published studies assessing FFR and OCT on the same target AICL were collected through a dedicated database to train (n = 351) and validate (n = 151) six two-class supervised ML models employing 25 clinical, angiographic and OCT variables.

RESULTS

A total of 502 coronary lesions in 489 patients were included. The AUC of the six ML models ranged from 0.71 to 0.78, whereas the measured F1 score was from 0.70 to 0.75. The ML algorithms showed moderate sensitivity (range: 0.68-0.77) and specificity (range: 0.59-0.69) in detecting patients with a positive or negative FFR. In the sensitivity analysis, using 0.75 as FFR cut-off, we found a higher AUC (0.78-0.86) and a similar F1 score (range: 0.63-0.76). Specifically, the six ML models showed a higher specificity (0.71-0.84), with a similar sensitivity (0.58-0.80) with respect to 0.80 cut-off.

CONCLUSIONS

ML algorithms derived from clinical, angiographic, and OCT parameters can identify patients with a positive or negative FFR.

Application of optical coherence tomography in cardiovascular diseases: bibliometric and meta-analysis

Significance

Since the advent of Optical Coherence Tomography (OCT) two decades ago, there has been substantial advancement in our understanding of intravascular biology. Identifying culprit lesion pathology through OCT could precipitate a paradigm shift in the treatment of patients with Acute Coronary Syndrome. Given the technical prowess of OCT in the realm of cardiology, bibliometric analysis can reveal trends and research focal points in the application of OCT for cardiovascular diseases. Concurrently, meta-analyses provide a more comprehensive evidentiary base, supporting the clinical efficacy of OCT-guided Percutaneous Coronary Intervention (PCI).

Design

This study employs a dual approach of Bibliometric and Meta-analysis.

Methods

Relevant literature from 2003 to 2023 was extracted from the Web of Science Core Collection (WoSCC) and analyzed using VOSviewer, CiteSpace, and R for publication patterns, countries, institutions, authors, and research hotspots. The study compares OCT-guided and coronary angiography-guided PCI in treating adult coronary artery disease through randomized controlled trials (RCTs) and observational studies. The study has been reported in the line with PRISMA and AMSTAR Guidelines.

Results

Adhering to inclusion and exclusion criteria, 310 publications were incorporated, demonstrating a continual rise in annual output. Chinese researchers contributed the most studies, while American research wielded greater influence. Analysis of trends indicated that research on OCT and angiography-guided PCI has become a focal topic in recent cohort studies and RCTs. In 11 RCTs (n = 5,277), OCT-guided PCI was not significantly associated with a reduction in the risk of Major Adverse Cardiac Events (MACE) (Odds ratio 0.84, 95% CI 0.65-1.10), cardiac death (0.61, 0.36-1.02), all-cause death (0.7, 0.49-1.02), myocardial infarction (MI) (0.88, 0.69-1.13), target lesion revascularization (TLR) (0.94, 0.7-1.27), target vessel revascularization (TVR) (1.04, 0.76-1.43), or stent thrombosis (0.72, 0.38-1.38). However, in 7 observational studies (n = 4,514), OCT-guided PCI was associated with a reduced risk of MACE (0.66, 0.48-0.91) and TLR (0.39, 0.22-0.68).

Conclusion

Our comprehensive review of OCT in cardiovascular disease literature from 2004 to 2023, encompassing country and institutional origins, authors, and publishing journals, suggests that OCT-guided PCI does not demonstrate significant clinical benefits in RCTs. Nevertheless, pooled results from observational studies indicate a reduction in MACE and TLR.

Patient-specific in silico 3D coronary model in cardiac catheterisation laboratories

Coronary artery disease is caused by the buildup of atherosclerotic plaque in the coronary arteries, affecting the blood supply to the heart, one of the leading causes of death around the world. X-ray coronary angiography is the most common procedure for diagnosing coronary artery disease, which uses contrast material and x-rays to observe vascular lesions. With this type of procedure, blood flow in coronary arteries is viewed in real-time, making it possible to detect stenoses precisely and control percutaneous coronary interventions and stent insertions. Angiograms of coronary arteries are used to plan the necessary revascularisation procedures based on the calculation of occlusions and the affected segments. However, their interpretation in cardiac catheterisation laboratories presently relies on sequentially evaluating multiple 2D image projections, which limits measuring lesion severity, identifying the true shape of vessels, and analysing quantitative data. In silico modelling, which involves computational simulations of patient-specific data, can revolutionise interventional cardiology by providing valuable insights and optimising treatment methods. This paper explores the challenges and future directions associated with applying patient-specific in silico models in catheterisation laboratories. We discuss the implications of the lack of patient-specific in silico models and how their absence hinders the ability to accurately predict and assess the behaviour of individual patients during interventional procedures. Then, we introduce the different components of a typical patient-specific in silico model and explore the potential future directions to bridge this gap and promote the development and utilisation of patient-specific in silico models in the catheterisation laboratories.

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.

High-frequency optical coherence tomography for endovascular management of cerebral aneurysms

Endovascular management of intracranial aneurysms has become the mainstay of treatment in recent years; however, retreatment rates remain as high as 1 in 5. High-frequency optical coherence tomography (HF-OCT) is an emerging imaging modality for the assessment, treatment and follow-up of cerebral aneurysms. EMBASE and SCOPUS databases were searched for studies relating to the management of intracranial aneurysm with OCT. A combination of keywords were used including 'cerebral aneurysm', 'intracranial aneurysm', 'high-frequency optical coherence tomography', 'optical coherence tomography', and 'optical frequency domain imaging'. There were 23 papers included in this review. For the assessment of intracranial aneurysm, OCT was able to accurately assess aneurysm morphology as well as detailed analysis of arterial wall layers. During IA treatment, OCT was used to assess and troubleshoot stent placement to optimise successful isolation from the circulation. In the follow-up period, endothelial growth patterns were visualised by OCT imaging. OCT shows promise for the treatment of IAs at all stages of management. Due to the novel development of HF-OCT, there is limited longitudinal data in human studies. Further research in this area is required with a focus specifically on long-term treatment outcomes in humans.

Optical coherence tomography (OCT) - versus angiography-guided strategy for percutaneous coronary intervention: a meta-analysis of randomized trials

BACKGROUND

Optical coherence tomography (OCT) guidance in percutaneous coronary intervention (PCI) has been shown to improve procedural outcomes. However, evidence supporting its superiority over angiography-guided PCI in terms of clinical outcomes is still emerging and limited. This study aimed to compare the efficacy and safety of OCT-guided PCI versus angiography-guided PCI in patients with coronary artery disease (CAD).

METHODS

A systematic search of electronic databases was conducted to identify randomized control trials (RCTs) comparing the clinical outcomes of OCT-guided and angiography-guided PCI in patients with CAD. Clinical endpoints including all-cause mortality, myocardial infarction (MI), target lesion revascularization (TLR), stent thrombosis and major adverse cardiac events (MACE) were assessed.

RESULTS

Eleven RCTs, comprising 2,699 patients in the OCT-guided group and 2,968 patients in the angiography-guided group met inclusion criteria. OCT-guided PCI was associated with significantly lower rates of cardiovascular death(RR 0.56; 95%CI: 0.32-0.98; p = 0.04; I2 = 0%), stent thrombosis(RR 0.56; 95%CI: 0.33-0.95; p = 0.03; I2 = 0%), and MACE (RR 0.79; 95%CI: 0.66-0.95; p = 0.01; I2 = 5%). The incidence of all-cause death (RR 0.71; 95%CI: 0.49-1.02; p = 0.06; I2 = 0%), myocardial infarction (RR 0.86; 95%CI: 0.67-1.10; p = 0.22; I2 = 0%) and TLR (RR 0.98; 95%CI: 0.73-1.33; p = 0.91; I2 = 0%) was non-significantly lower in the OCT-guided group.

CONCLUSIONS

Among patients undergoing PCI, OCT-guided PCI was associated with lower incidences of cardiovascular death, stent thrombosis and MACE compared to angiography-guided PCI.

TRIAL REGISTRATION

PROSPERO registration number: CRD42023484342.

Three-Year Clinical Impact of Murray Law-Based Quantitative Flow Ratio and OCT- or FFR-Guidance in Angiographically Intermediate Coronary Lesions

BACKGROUND

The FORZA trial (FFR or OCT Guidance to Revascularize Intermediate Coronary Stenosis Using Angioplasty) prospectively compared the use of fractional flow reserve (FFR) or optical coherence tomography (OCT) for treatment decisions and percutaneous coronary intervention (PCI) optimization in patients with angiographically intermediate coronary lesions. Murray law-based quantitative-flow-ratio (μQFR) is a novel noninvasive method for the computation of FFR. In the present study, we evaluated the clinical impact of μQFR, FFR, or OCT guidance in FORZA trial lesions at 3-year follow-up.

METHODS

μQFR was assessed at baseline and, in the case of a decision to intervene, after (FFR- or OCT-guided) PCI. The baseline μQFR was considered the final μQFR for deferred lesions, and post-PCI μQFR value was taken as final for stented lesions. The primary end point was target vessel failure ([TVF]; cardiac death, target-vessel-related myocardial infarction, and target-vessel-revascularization) at a 3-year follow-up.

RESULTS

A total of 419 vessels (199 OCT-guided and 220 FFR-guided) were included in the FORZA trial. μQFR was evaluated in 256 deferred lesions and 159 treated lesions (98 OCT-guided PCI and 61 FFR-guided PCI). In treated lesions, post-PCI μQFR was higher in OCT-group compared with FFR-group (median, 0.93 versus 0.91; P=0.023), and the post-PCI μQFR improvement was greater in FFR-group (0.14 versus 0.08; P<0.0001). At 3-year follow-up, OCT- and FFR-guided treatment decisions resulted in comparable TVF rate (6.7% versus 7.9%; P=0.617). Final μQFR was the only predictor of TVF. μQFR ≤0.89 was associated with 3× increase in TVF (11.6% versus 3.7%; P=0.004). PCI was a predictor of higher final μQFR (odds ratio, 0.22 [95% CI, 0.14-0.34]; P<0.001).

CONCLUSIONS

In vessels with angiographically intermediate coronary lesions, OCT-guided PCI resulted in comparable clinical outcomes as FFR-guided PCI. μQFR estimated at the end of diagnostic or interventional procedure predicted 3-year TVF.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01824030.

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

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

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.

Clinical outcomes of optical coherence tomography versus conventional angiography guided percutaneous coronary intervention: A meta-analysis

BACKGROUND

Performing optical coherence tomography (OCT) as a guide for percutaneous coronary intervention (PCI) compared to conventional coronary angiography has been the subject of the recent cohorts and randomized trials. However, clear evidence demonstrating its superiority is still controversial.

METHODS

We performed a thorough search in digital databases to find the relevant observational studies and randomized trials comparing OCT and angiography in patients undergoing PCI. A random-effects meta-analysis was undertaken comparing clinical outcomes to generate an odds ratio (OR) with a corresponding 95% confidence interval (CI). Subgroup analyzes were performed based on study design, underlying cardiac condition, and complexity of cases.

RESULTS

A total of 21 studies (10 RCTs and 11 observational studies) with 11,163 participants (5319: OCT and 5844: angiography group) were included for quantitative synthesis. Performing OCT was associated with lower odds of all-cause (OR (95% CI) = 0.56 (0.48; 0.67)) and cardiac mortality (OR (95% CI) = 0.47 (0.35; 0.63)), major adverse cardiovascular events (OR (95% CI) = 0.60 (0.48; 0.76)), myocardial infarction (OR (95% CI) = 0.79 (0.64; 0.97)), and stent thrombosis (OR (95% CI) = 0.61 (0.39; 0.96)) compared to the angiography group. Other clinical outcomes were similar between the studied groups. The outperformance of OCT was more evident in observational studies and the ones with PCI on complex lesions.

CONCLUSION

Performing OCT prior to PCI is associated with better clinical outcomes compared to angiography alone based on contemporary evidence. Future well-designed randomized trials are needed to confirm the findings of this meta-analysis.

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.

Interventional cardiology in cancer patients: A position paper from the Portuguese Cardiovascular Intervention Association and the Portuguese Cardio-Oncology Study Group of the Portuguese Society of Cardiology

The field of Cardio-Oncology has grown significantly, especially during the last decade. While awareness of cardiotoxicity due to cancer disease and/or therapies has greatly increased, much of the attention has focused on myocardial systolic disfunction and heart failure. However, coronary and structural heart disease are also a common issue in cancer patients and encompass the full spectrum of cardiotoxicity. While invasive percutaneous or surgical intervention, either is often needed or considered in cancer patients, limited evidence or guidelines are available for dealing with coronary or structural heart disease. The Society for Cardiovascular Angiography and Interventions consensus document published in 2016 is the most comprehensive document regarding this particular issue, but relevant evidence has emerged since, which render some of its considerations outdated. In addition to that, the recent 2022 ESC Guidelines on Cardio-Oncology only briefly discuss this topic. As a result, the Portuguese Association of Cardiovascular Intervention and the Cardio-Oncology Study Group of the Portuguese Society of Cardiology have partnered to produce a position paper to address the issue of cardiac intervention in cancer patients, focusing on percutaneous techniques. A brief review of available evidence is provided, followed by practical considerations. These are based both on the literature as well as accumulated experience with these types of patients, as the authors are either interventional cardiologists, cardiologists with experience in the field of Cardio-Oncology, or both.

Enhanced Stent Imaging System Guided Percutaneous Coronary Intervention Is Linked to Optimize Stent Placement

Stent under-expansion is a predictor of restenosis and stent thrombosis. It remains uncertain whether enhanced stent imaging (ESI) (CLEARstent) guidance can improve stent under-expansion. Our aim was to assess the effect of using ESI on stent under-expansion, after percutaneous coronary intervention (PCI) in a single center, cross-sectional observational study. Participants attending our cardiology clinic with stable angina or acute coronary syndrome, from March to September 2020 were recruited. A total of 164 patients who underwent post-PCI ESI (CLEARstent) were compared with 77 age- and sex-matched control patients. Post-procedural minimal lumen diameter (MLD) was calculated. The patients in the ESI-guided PCI group, had a median age of 61 (54-69 IQR 25-75) years and 76.8% (n = 126) were males. The patients in ESI-guided PCI group had a greater minimal lumen diameter compared with the X-ray guided PCI group (βeta coefficient:2.88 (95% CI:2.58-2.99) vs βeta coefficient 2.55 (95% CI 2.34-2.63), P < .001). Our finding supports the use of the ESI system to optimize stent placement as expressed by the MLD.

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

BACKGROUND

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Impact of IVUS and OCT on physician decision-making during post-PCI optimization

BACKGROUND

Intravascular imaging (IVI) has been available as a complementary diagnostic tool in addition to coronary angiography for more than two decades. Prior studies have suggested that IVI influences physician decision making in up to 27 % of cases during post-percutaneous coronary intervention (PCI) optimization. However, no studies have compared the two intracoronary imaging modalities (intravascular ultrasound [IVUS] vs. optical coherence tomography [OCT]) in shaping physician decisions post-PCI.

METHODS

We retrospectively analyzed IVI studies performed during PCI at a tertiary care center. IVUS and OCT cases performed by a single operator with expertise in both imaging studies were selected. The primary endpoint was the physician reaction rate during post-PCI optimization comparing IVUS vs. OCT.

RESULTS

A total of 142 patients underwent IVUS evaluation, and 146 underwent OCT evaluation, post-PCI. The primary endpoint did not differ between IVUS-guided vs OCT-guided PCI optimization (35.2 % vs. 31.5 %, p = 0.505). The predominant cause of abnormalities deemed unsatisfactory by the implanting physician warranting further intervention were stent under-expansion (26.1 % vs. 19.2 %, p = 0.163), followed by malapposition (2.1 % vs. 6.2 %, p = 0.085), and dissection (3.5 % vs 4.1 %, p = 0.794). Overall, IVI using either IVUS or OCT influenced the physician decision in 33.3 % of cases.

CONCLUSION

In this first study comparing IVUS- and OCT-guided PCI to assess their impact on physician decision making during post-PCI optimization, the primary endpoint of physician reaction rate was similar for IVUS vs. OCT. The use of post-PCI IVI changed physician management in one third of cases.

Impact of real-time optical coherence tomography and angiographic coregistration on the percutaneous coronary intervention strategy

Background

The use of optical coherence tomography (OCT) with angiographic coregistration (ACR) during percutaneous coronary intervention (PCI) for procedural decision-making is evolving; however, large-scale data in real-world practice are lacking.

Aims

Our study aims to evaluate the real-time impact of OCT-ACR on clinician decision-making during PCI.

Methods

Patients with angiographic diameter stenosis >70% in at least one native coronary artery were enrolled in the study. The pre- and post-PCI procedural strategies were prospectively assessed after angiography, OCT, and ACR.

Results

A total of 500 patients were enrolled in the study between November 2018 and March 2020. Among these, data related to 472 patients with 483 lesions were considered for analysis. Preprocedural OCT resulted in a change in PCI strategy in 80% of lesions: lesion preparation (25%), stent length (53%), stent diameter (36%), and device landing zone (61%). ACR additionally impacted the treatment strategy in 34% of lesions. Postprocedural OCT demonstrated underexpansion (15%), malapposition (14%), and tissue/thrombus prolapse (7%), thereby requiring further interventions in 30% of lesions. No further change in strategy was observed with subsequent postprocedural ACR. Angiographic and procedural success was achieved in 100% of patients, and the overall incidence of major adverse cardiovascular events at 1 year was 0.85%.

Conclusions

The outcomes reflect the real-time impact of OCT-ACR on the overall procedural strategy in patients undergoing PCI. ACR had a significant impact on the treatment strategy and was associated with better clinical outcomes at 1 year after index PCI. OCT-ACR has become a practical tool for improving outcomes in patients with complex lesions.

Intracoronary Imaging Versus Coronary Angiography Guidance for Implantation of Second and Third Generation Drug Eluting Stents in a Systematic Review and Meta-Analysis of Randomized Controlled Trials

Intracoronary imaging (ICI) facilitates stent implant by characterizing the lesion calcification, providing accurate vessel dimensions, and optimizing the stent results. We sought to investigate the outcomes of routine ICI versus coronary angiography (CA) to guide percutaneous coronary intervention (PCI) with second- and third-generation drug-eluting stents. A systematic search of PubMed, Medline, and Cochrane databases was conducted from their inception to July 16, 2022 for randomized controlled trials comparing routine ICI with CA. The primary outcome was major adverse cardiovascular events. The secondary outcomes of interest were target lesion revascularization, target vessel revascularization, myocardial infarction, stent thrombosis, and cardiac and all-cause mortality. A random-effects model was used to calculate the pooled incidence and relative risk (RR) with 95% confidence intervals (CIs). A total of 9 randomized controlled trials with 5,879 patients (2,870 ICI-guided and 3,009 CA-guided PCI) met the inclusion criteria. The ICI and CA groups were similar in demographic characteristics and co-morbidity profiles. Compared with CA, patients in the routine ICI-guided PCI group had lower rates of major adverse cardiovascular events (RR 0.61, 95% CI 0.48 to 0.78, p <0.0001), target lesion revascularization (RR 0.60, 95% CI 0.43 to 0.83, p = 0.002), target vessel revascularization (RR 0.72, 95% CI 0.51 to 1.00, p = 0.05), and myocardial infarction (RR 0.48, 95% CI 0.25 to 0.95, p = 0.03). There were no significant differences in stent thrombosis or cardiac/all-cause mortality between the 2 strategies. In conclusion, routine ICI-guided PCI strategy, compared with CA guidance alone, is associated with improved clinical outcomes, largely driven by lower repeat revascularization.

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.

Fractional flow reserve use in coronary artery revascularization: A systematic review and meta-analysis

Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) is recommended in revascularization guidelines for intermediate lesions. However, recent studies comparing FFR-guided PCI with non-physiology-guided revascularization have reported conflicting results. PubMed and Embase were searched for studies comparing FFR-guided PCI with non-physiology-guided revascularization strategies (angiography-guided, intracoronary imaging-guided, coronary artery bypass grafting). Data were pooled by meta-analysis using random-effects model. 26 studies enrolling 78,897 patients were included. FFR-guided PCI as compared to non-physiology-guided coronary revascularization had lower risk of all-cause mortality (odds ratio [OR] 0.79 95% confidence interval [CI] 0.64-0.99, I² = 53%) and myocardial infarction (MI) (OR 0.74 95% CI 0.59-0.93, I² = 44.7%). However, no differences between groups were found in terms of major adverse cardiac events (MACEs) (OR 0.86 95% CI 0.72-1.03, I² = 72.3%) and repeat revascularization (OR 1 95% CI 0.82-1.20, I² = 43.2%). Among patients with coronary artery disease (CAD), FFR-guided PCI as compared to non-physiology-guided revascularization was associated with a lower risk of all-cause mortality and MI.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Optical Coherence Tomography-Guided Percutaneous Coronary Intervention: Practical Application

Optical coherence tomography (OCT) provides high-resolution imaging of coronary arteries and can be used to optimize percutaneous coronary intervention (PCI). Intracoronary OCT, however, has had limited adoption in clinical practice. Novelty and relative complexity of OCT interpretation compared with the more established intravascular ultrasound, lack of a standardized algorithm for PCI guidance, paucity of data from randomized trials, and lack of rebate for intravascular imaging have contributed to the modest practical adoption of OCT. We provide a practical step-by-step guide on how to use OCT in PCI, including device set-up, simplified image interpretation, and an algorithmic approach for PCI. optimization.

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.

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

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

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

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

Association Between Intracoronary Imaging During PCI and Clinical Outcomes in a Real-World US Medicare Population

Background

Use of intravascular ultrasound (IVUS) or optical coherence tomography (OCT) during percutaneous coronary intervention (PCI) is endorsed by society guidelines, but US data on real-world outcomes are lacking.

Methods

Medicare claims data were identified for inpatient PCIs performed October 2015 to March 2020, with IVUS/OCT captured by ICD-10-PCS codes. Three-way propensity score matching (angio vs IVUS vs OCT) on baseline and procedural characteristics was performed. Major adverse cardiovascular events (MACE), a composite of death, myocardial infarction (MI), or repeat revascularization, was evaluated through 3 years, with a 30-day blanking window after index PCI to exclude staged procedures.

Results

Of the 502,821 PCI procedures, 463,201 (92%) were guided by angiography alone, with IVUS or OCT used in 37,908 (7.5%) and 1712 (0.3%), respectively. After propensity matching, compared with angiography, the risk of major adverse cardiovascular event was similar for IVUS (hazard ratio [HR], 0.97; 95% CI, 0.91-1.03; P = .285) but lower for OCT (HR, 0.85; 95% CI, 0.77-0.94; P = .001). A similar trend was observed in clinically relevant subgroups. Compared with angiography alone, the risk of MI or repeat revascularization was lower with OCT (HR, 0.86; 95% CI, 0.76-0.97; P = .015), and the risk of MI alone was lower with IVUS (HR, 0.90; 95% CI, 0.82-0.99; P = .038).

Conclusions

In a real-world US cohort, IVUS and OCT were used infrequently during PCI. Compared with angiography alone, use of intracoronary imaging during index PCI was associated with lower rates of clinical events through 3 years.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Improved FAST algorithm for non-uniform rotational distortion correction in OCT endoscopic imaging

Optical Coherence Tomography (OCT) is widely used for endoscopic imaging in endoluminal organs because of its high imaging accuracy and resolution. However, OCT endoscopic imaging suffers from Non-Uniform Rotational Distortion (NURD), which can be caused by many factors, such as irregular motor rotation and changes in friction between the probe and the sheath. Correcting this distortion is essential to obtaining high-quality Optical Coherence Tomography Angiography (OCTA) images. There are two main approaches for correcting NURD: hardware-based methods and algorithm-based methods. Hardware-based methods can be costly, challenging to implement, and may not eliminate NURD. Algorithm-based methods, such as image registration, can be effective for correcting NURD but can also be prone to the problem of NURD propagation. To address this issue, we process frames by coarse and fine registration, respectively. The new reference frame is generated by filtering out the A-scan that may have the NURD problem by coarse registration. And the fine registration uses this frame to achieve the final NURD correction. In addition, we have improved the Features from Accelerated Segment Test (FAST) algorithm and put it into coarse and fine registration process. Four evaluation functions were used for the experimental results, including signal-to-noise ratio (SNR), peak signal-to-noise ratio (PSNR), mean squared error (MSE), and structural similarity index measure (SSIM). By comparing with Scale-invariant feature transform (SIFT), Speeded up robust features (SURF), Oriented FAST and Rotated BRIEF (ORB), intensity-based (Cross-correlation), and Optical Flow algorithms, our algorithm has a higher similarity between the corrected frames. Moreover, the noise in the OCTA data is better suppressed, and the vascular information is well preserved. Our image registration-based algorithm reduces the problem of NURD propagation between B-scan frames and improves the imaging quality of OCT endoscopic images.

Multi-Scale Reconstruction of Undersampled Spectral-Spatial OCT Data for Coronary Imaging Using Deep Learning

Coronary artery disease (CAD) is a cardiovascular condition with high morbidity and mortality. Intravascular optical coherence tomography (IVOCT) has been considered as an optimal imagining system for the diagnosis and treatment of CAD. Constrained by Nyquist theorem, dense sampling in IVOCT attains high resolving power to delineate cellular structures/features. There is a trade-off between high spatial resolution and fast scanning rate for coronary imaging. In this paper, we propose a viable spectral-spatial acquisition method that down-scales the sampling process in both spectral and spatial domain while maintaining high quality in image reconstruction. The down-scaling schedule boosts data acquisition speed without any hardware modifications. Additionally, we propose a unified multi-scale reconstruction framework, namely Multiscale-Spectral-Spatial-Magnification Network (MSSMN), to resolve highly down-scaled (compressed) OCT images with flexible magnification factors. We incorporate the proposed methods into Spectral Domain OCT (SD-OCT) imaging of human coronary samples with clinical features such as stent and calcified lesions. Our experimental results demonstrate that spectral-spatial down-scaled data can be better reconstructed than data that are down-scaled solely in either spectral or spatial domain. Moreover, we observe better reconstruction performance using MSSMN than using existing reconstruction methods. Our acquisition method and multi-scale reconstruction framework, in combination, may allow faster SD-OCT inspection with high resolution during coronary intervention.

OCT utilization: Summary statistics from the LightLab clinical initiative

OBJECTIVES

The study describes the evolution of optical coherence tomography (OCT) adoption and performance during percutaneous coronary intervention (PCI) following implementation of a standardized LightLab (LL) workflow.

BACKGROUND

The purpose of the LL Clinical Initiative was to evaluate the impact of a standardized workflow on physician efficiency, decision making, and image quality.

METHODS

The LL Clinical Initiative is a multicenter, prospective, observational clinical program. Data were collected from 48 physicians at 17 U.S. centers from 01/21/19 to 06/08/21. The study included 401 OCT-guided PCIs during the baseline phase and 1898 during the LL workflow phases. The baseline phase consisted of physicians utilizing OCT at their discretion. After completing the baseline phase, the workflow progressed through multiple phases culminating in the expansion phase, which focused on addressing greater procedural complexity. The LL workflow utilized OCT to assess plaque Morphology, lesion Length, and vessel Diameter before PCI, and optimized results by treating Medial edge dissection, stent mal-Apposition, and stent under-eXpansion (MLD MAX). High-level summary statistics were generated to elucidate trends.

RESULTS

After program implementation, there was a rise in the number of PCIs where the LL workflow was utilized compared to the baseline phase (68% during the expansion phase vs. 41% at baseline; p for trend <0.0001). Adoption of the LL workflow was associated with progressively greater procedural and lesion complexity when OCT was performed pre- and post-PCI (87% vs. 52%, p < 0.0001; 55% vs. 37%, p < 0.0001, respectively). In addition, the quality of OCT imaging obtained improved after LL workflow introduction, with over 95% of pre- and post-PCI pullback quality considered usable during the expansion phase. Finally, there was a reduction in time spent on OCT interpretation, both pre-PCI (4.6 min vs. 7.5 min, p < 0.0001) and post-PCI (2.9 min vs. 5.3 min, p < 0.0001).

CONCLUSIONS

After completion of the standardized OCT-guided workflow, there was greater uptake of OCT imaging, incorporation in more complex procedures, procedural efficiency, and image quality.

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.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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

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

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.

Clinical outcomes of suboptimal stent deployment as assessed by optical coherence tomography: long-term results of the CLI-OPCI registry

BACKGROUND

Intraprocedural optical coherence tomography (OCT) is a valuable tool for guidance of percutaneous coronary intervention, but long-term follow-up data are lacking.

AIMS

The aim of this study was to address the long-term (7.5 years) clinical impact of quantitative OCT metrics of suboptimal stent implantation.

METHODS

This retrospective study includes 391 patients with long-term follow-up (mean 2,737 days; interquartile range 1,301-3,143 days) from the multicentre Centro per la Lotta contro l'Infarto - Optimisation of Percutaneous Coronary Intervention (CLI-OPCI) registry. OCT-assessed suboptimal stent deployment required the presence of at least one of the following pre-defined OCT findings: in-stent MLA <4.5 mm2, proximal or distal reference lumen narrowing with lumen area <4.5 mm2, significant proximal or distal edge dissection width ≥200 μm.

RESULTS

One hundred and two patients (26.1%) with 138 stented lesions (27.7%) experienced a device-oriented cardiovascular event (DOCE). In-stent MLA <4.5 mm2 (38.1% vs 19.8%, p<0.001), in-stent lumen expansion <70% (29.5% vs 20.3%, p=0.032), proximal reference lumen narrowing <4.5 mm2 (6.5% vs 1.4%, p=0.004), and distal reference lumen narrowing <4.5 mm2 (12.9% vs 3.6%, p=0.001) were significantly more common in the DOCE vs non-DOCE group. OCT-assessed suboptimal stent deployment was an independent predictor of long-term DOCE (HR 2.17, p<0.001), together with bare metal stent implantation (HR 1.73, p=0.003) and prior revascularisation (HR 1.53, p=0.017).

CONCLUSIONS

The presence of OCT-assessed suboptimal criteria for stent implantation was related to a worse clinical outcome at very long-term follow-up. This information further supports an OCT-guided strategy of stent deployment.

Optical Coherence Tomography: An Eye Into the Coronary Artery

Optical coherence tomography (OCT) is slowly but surely gaining a foothold in the hands of interventional cardiologists. Intraluminal and transmural contents of the coronary arteries are no longer elusive to the cardiologist's probing eye. Although the graduation of an interventionalist in imaging techniques right from naked eye angiographies to ultrasound-based coronary sonographies to the modern light-based OCT has been slow, with the increasing regularity of complex coronary cases in practice, such a transition is inevitable. Although intravascular ultrasound (IVUS) due to its robust clinical data has been the preferred imaging modality in recent years, OCT provides a distinct upgrade over it in many imaging and procedural aspects. Better image resolution, accurate estimation of the calcified lesion, and better evaluation of acute and chronic stent failure are the distinct advantages of OCT over IVUS. Despite the obvious imaging advantages of OCT, its clinical impact remains subdued. However, upcoming newer trials and data have been encouraging for expanding the use of OCT to wider indications in clinical utility. During percutaneous coronary intervention (PCI), OCT provides the detailed information (dissection, tissue prolapse, thrombi, and incomplete stent apposition) required for optimal stent deployment, which is the key to successfully reducing the major adverse cardiovascular event (MACE) and stent-related morbidities. The increasing use of OCT in complex bifurcation stenting involving the left main (LM) is being studied. Also, the traditional pitfalls of OCT, such as additional contrast load for image acquisition and stenting involving the ostial and proximal LM, have also been overcome recently. In this review, we discuss the interpretation of OCT images and its clinical impact on the outcome of procedures along with current barriers to its use and newer paradigms in which OCT is starting to become a promising tool for the interventionalist and what can be expected for the immediate future in the imaging world.