Understanding the economic impact of intravascular ultrasound (IVUS)

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.

Intravascular Imaging-Guided Versus Coronary Angiography-Guided Complex PCI: A Meta-analysis of Randomized Controlled Trials

INTRODUCTION

Trials evaluating the role of intravascular imaging in percutaneous coronary intervention (PCI) for complex coronary artery disease have yielded mixed results. This study aimed to compare the outcomes of intravascular imaging specifically intravascular ultrasound (IVUS) with those from conventional coronary angiography in complex PCI.

METHODS

Comprehensive electronic search of MEDLINE, EMBASE, and Cochrane databases was performed until March 2023 for randomized clinical trials (RCTs) comparing intravascular imaging with coronary angiography in patients undergoing complex PCI. Complex PCI was defined per each study, and included PCI for American College of Cardiology/American Heart Association (ACC/AHA) type B2/C lesions, unprotected left main coronary artery disease, or multivessel stenting. The primary study outcome was major adverse clinical events (MACE).

RESULTS

The meta-analysis included 10 RCTs with a total of 6615 patients (3576 in the intravascular imaging group and 3039 in the coronary angiography group). The weighted mean-follow up was 28.9 months. Compared with coronary angiography, intravascular imaging reduced MACE (8% vs. 13.3%; relative risk [RR] 0.63; 95% confidence interval [CI] 0.54-0.73), cardiac death (RR 0.47; 95% CI 0.31-0.73), definite/probable stent thrombosis (RR 0.48; 95% CI 0.24-0.97), target vessel revascularization (RR 0.62; 95% CI 0.46-0.83), and target lesion revascularization (RR 0.61; 95% CI 0.47-0.79). There was no difference between both groups in all-cause death (RR 0.79; 95% CI 0.53-1.18) and myocardial infarction (RR 0.80; 95% CI 0.61-1.04).

CONCLUSION

In patients undergoing complex PCI, intravascular imaging-specifically IVUS-reduced MACE by decreasing the incidence of cardiac death, stent thrombosis, and target vessel and target lesion revascularization.

The mid-term effect of intravascular ultrasound on endovascular interventions for lower extremity peripheral arterial disease: A systematic review and meta-analysis

OBJECTIVE

Intravascular ultrasound (IVUS) is an important adjunctive tool for patients with lower extremity peripheral arterial disease (PAD) undergoing endovascular therapy (EVT). The evidence regarding the advantages of IVUS use is evolving, and recent studies have reported conflicting results. We aimed to perform a meta-analysis to evaluate the efficacy of IVUS during angiography-guided EVT for patients with PAD.

METHODS

MEDLINE and EMBASE were searched through April 2023 to identify studies that investigated the outcomes of IVUS with angiography-guided EVT vs angiography-alone-guided EVT. The primary outcome was restenosis/occlusion rate; secondary outcomes were target lesion revascularization, major amputation, and mortality.

RESULTS

One randomized controlled trial and 14 observational studies, largely of moderate quality, were included, yielding a total of 708,808 patients with 709,189 lesions that were treated with IVUS-guided EVT (n = 101,405) vs angiography-alone (n = 607,784). Compared with angiography alone, IVUS-guided EVT was associated with a non-significant trend towards decreased restenosis/occlusion (relative risk [RR], 0.74; 95% confidence interval [CI], 0.54-1.00; I2 = 60%). Although the risk of target lesion revascularization and mortality were comparable (RR, 0.85; 95% CI, 0.65-1.10; I2 = 70%; RR, 1.01; 95% CI, 0.79-1.28; I2 = 43%, respectively), the use of IVUS was also associated with significantly lower risk of major amputation (RR, 0.74; 95% CI, 0.67-0.82; I2 = 47%). Subgroup analysis focusing on femoropopliteal disease demonstrated significantly higher patency (RR, 0.72; 95% CI, 0.52-0.98; I2 = 73%). However, superiority with major amputation was not observed.

CONCLUSIONS

IVUS-guided EVT for PAD may possibly be associated with a lower major amputation rate compared with angiography alone-guided EVT, although the difference in patency remained an insignificant trend in favor of IVUS-guided EVT. Adjunctive use of IVUS during EVT may be beneficial, and further prospective studies are warranted to delineate this relationship and the applicability of this technology in routine practice.

Cost-Effectiveness of Intravascular Imaging-Guided Complex PCI: Prespecified Analysis of RENOVATE-COMPLEX-PCI Trial

BACKGROUND

Although clinical benefits of intravascular imaging-guided percutaneous coronary intervention (PCI) in patients with complex coronary artery lesions have been observed in previous trials, the cost-effectiveness of this strategy is uncertain.

METHODS

RENOVATE-COMPLEX-PCI (Randomized Controlled Trial of Intravascular Imaging Guidance vs Angiography-Guidance on Clinical Outcomes After Complex Percutaneous Coronary Intervention) was conducted in Korea between May 2018 and May 2021. This prespecified cost-effectiveness substudy was conducted using Markov model that simulated 3 states: (1) post-PCI, (2) spontaneous myocardial infarction, and (3) death. A simulated cohort was derived from the intention-to-treat population, and input parameters were extracted from either the trial data or previous publications. Cost-effectiveness was evaluated using time horizon of 3 years (within trial) and lifetime. The primary outcome was incremental cost-effectiveness ratio (ICER), an indicator of incremental cost on additional quality-adjusted life years (QALYs) gained, in intravascular imaging-guided PCI compared with angiography-guided PCI. The current analysis was performed using the Korean health care sector perspective with reporting the results in US dollar (1200 Korean Won, ₩=1 dollar, $). Willingness to pay threshold was $35 000 per QALY gained.

RESULTS

A total of 1639 patients were included in the trial. During 3-year follow-up, medical costs ($8661 versus $7236; incremental cost, $1426) and QALY (2.34 versus 2.31; incremental QALY, 0.025) were both higher in intravascular imaging-guided PCI than angiography-guided PCI, resulting incremental cost-effectiveness ratio of $57 040 per QALY gained within trial data. Conversely, lifetime simulation showed total cumulative medical cost was reversed between the 2 groups ($40 455 versus $49 519; incremental cost, -$9063) with consistently higher QALY (8.24 versus 7.89; incremental QALY, 0.910) in intravascular imaging-guided PCI than angiography-guided PCI, resulting in a dominant incremental cost-effectiveness ratio. Consistently, 70% of probabilistic iterations showed cost-effectiveness of intravascular imaging-guided PCI in probabilistic sensitivity analysis.

CONCLUSIONS

The current cost-effectiveness analysis suggests that imaging-guided PCI is more cost-effective than angiography-guided PCI by reducing medical cost and increasing quality-of-life in complex coronary artery lesions in long-term follow-up.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03381872.

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.

CVIT 2023 clinical expert consensus document on intravascular ultrasound

Intravascular ultrasound (IVUS) provides precise anatomic information in coronary arteries including quantitative measurements and morphological assessment. To standardize the IVUS analysis in the current era, this updated expert consensus document summarizes the methods of measurements and assessment of IVUS images and the clinical evidence of IVUS use in percutaneous coronary intervention.

Intracoronary imaging in PCI for acute coronary syndrome: Insights from British Cardiovascular Intervention Society registry

BACKGROUND

While previous studies have demonstrated the superiority of ICI-guided PCI over an angiography-based approach, there are limited data on all-comer ACS patients. This study aimed to identify the characteristics and in-hospital outcomes of patients undergoing intracoronary imaging (ICI) guided percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS).

METHODS

All patient undergoing PCI for ACS in England and Wales between 2006 and 2019 were retrospectively analyzed and stratified according to ICI utilization. The outcomes assessed were in-hospital all-cause mortality and major adverse cardiovascular and cerebrovascular events (MACCE) using multivariable logistic regression models.

RESULTS

598,921 patients underwent PCI for ACS, of which 41,716 (7.0 %) had ICI which was predominantly driven by IVUS use (5.6 %). ICI use steadily increased from 1.4 % in 2006 to 13.5 % in 2019. Adjusted odds of mortality (OR 0.69, 95%CI 0.58-0.83) and MACCE (OR 0.77, 95%CI 0.73-0.83) were significantly lower in the ICI group. The association between ICI and improved outcomes varied according to vessel treated with both left main stem (LMS) and LMS/left anterior descending (LAD) PCI associated with significantly lower odds of mortality (OR 0.34, 95%CI 0.27-0.44, OR 0.51 95%CI 0.45-0.56) and MACCE (OR 0.44 95%CI 0.35-0.54, OR 0.67 95%CI 0.62-0.72) respectively.

CONCLUSIONS

Although ICI use has steadily increased, less than one in seven patients underwent ICI-guided PCI. The association between ICI use and improved in-hospital outcomes was mainly observed in PCI procedures involving LMS and LAD.

Intravascular imaging during percutaneous coronary intervention: temporal trends and clinical outcomes in the USA

AIMS

Prior trials have demonstrated that intravascular imaging (IVI)-guided percutaneous coronary intervention (PCI) results in less frequent target lesion revascularization and major adverse cardiovascular events (MACEs) compared with standard angiographic guidance. The uptake and associated outcomes of IVI-guided PCI in contemporary clinical practice in the USA remain unclear. Accordingly, temporal trends and comparative outcomes of IVI-guided PCI relative to PCI with angiographic guidance alone were examined in a broad, unselected population of Medicare beneficiaries.

METHODS AND RESULTS

Retrospective cohort study of Medicare beneficiary data from 1 January 2013, through 31 December 2019 to evaluate temporal trends and comparative outcomes of IVI-guided PCI as compared with PCI with angiography guidance alone in both the inpatient and outpatient settings. The primary outcomes were 1 year mortality and MACE, defined as the composite of death, myocardial infarction (MI), repeat PCI, or coronary artery bypass graft surgery. Secondary outcomes were MI or repeat PCI at 1 year. Multivariable Cox regression was used to estimate the adjusted association between IVI guidance and outcomes. Falsification endpoints (hospitalized pneumonia and hip fracture) were used to assess for potential unmeasured confounding. The study population included 1 189 470 patients undergoing PCI (38.0% female, 89.8% White, 65.1% with MI). Overall, IVI was used in 10.5% of the PCIs, increasing from 9.5% in 2013% to 15.4% in 2019. Operator IVI use was variable, with the median operator use of IVI 3.92% (interquartile range 0.36%-12.82%). IVI use during PCI was associated with lower adjusted rates of 1 year mortality [adjusted hazard ratio (aHR) 0.96, 95% confidence interval (CI) 0.94-0.98], MI (aHR 0.97, 95% CI 0.95-0.99), repeat PCI (aHR 0.74, 95% CI 0.73-0.75), and MACE (aHR 0.85, 95% CI 0.84-0.86). There was no association with the falsification endpoint of hospitalized pneumonia (aHR 1.02, 95% CI 0.99-1.04) or hip fracture (aHR 1.02, 95% CI 0.94-1.10).

CONCLUSION

Among Medicare beneficiaries undergoing PCI, use of IVI has increased over the previous decade but remains relatively infrequent. IVI-guided PCI was associated with lower risk-adjusted mortality, acute MI, repeat PCI, and MACE.

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.

Outcomes of Intravascular Ultrasound-Guided Percutaneous Coronary Intervention in Non-ST-Elevation Myocardial Infarction-Propensity Matched Regression Analysis

Intravascular ultrasound (IVUS) guided percutaneous coronary intervention (PCI) is indicated in complex interventions. There is a paucity of evidence for outcomes with large studies on using IVUS during PCI in non-ST-elevation myocardial infarction (NSTEMI). Our objective was to compare the in-hospital outcome of IVUS-guided with that of nonguided PCI among NSTEMI hospitalizations. The National Inpatient Sample (2016 to 2019) was queried to identify all hospitalizations with a principal diagnosis of NSTEMI. In our study, we compared outcomes of PCI with and without IVUS guidance using a multivariate logistic regression model after propensity score matching, with the primary outcome being in-hospital mortality. A total of 671,280 NSTEMI-related hospitalizations were identified, of whom 48,285 (7.2%) underwent IVUS-guided PCI compared with 622,995 (92.8%) who underwent non-IVUS PCI. After adjusted analysis on matched pairs, we found that IVUS-guided PCI had a lower risk of in-hospital mortality than that of non-IVUS PCI (adjusted odds ratio [aOR] 0.736, confidence interval (CI) 0.578 to 0.937, p = 0.013). However, there was a higher use of mechanical circulatory support in the IVUS-guided PCI (aOR 2.138, CI 1.84 to 2.47, p <0.001) than in non-IVUS PCI. The odds of cardiogenic shock (aOR 1.11, CI 0.93 to 1.32, p = 0.233) and procedural complications (aOR 0.794, CI 0.549 to 1.14, p = 0.22) were similar between the cohorts. Hence, we conclude that patients with NSTEMIs who underwent IVUS-guided PCI had less risk of in-hospital mortality and a greater requirement of mechanical circulatory support than did those who underwent non-IVUS PCI, with no difference in procedural complications. Large prospective trials are essential to validate these findings.

Role of Intravascular Ultrasound in Pulmonary Embolism Patients Undergoing Mechanical Thrombectomy: A Systematic Review

BACKGROUND

Traditionally, mechanical thrombectomy performed for pulmonary embolism (PE) necessitates the utilization of iodinated contrast. Intravascular ultrasound (IVUS) has been used as a diagnostic and therapeutic modality in the management of acute high and intermediate-risk PE. Recently, with the shortage of contrast supplies and the considerable incidence of contrast-induced acute kidney injury (CI-AKI), other safer and more feasible IVUS methods have become desirable. The purpose of this systematic review was to evaluate the importance of IVUS in patients with PE undergoing thrombectomy.

METHODS

Medline/PubMed, Embase, Scopus, and Google Scholar were searched for review studies, case reports, and case series. Clinical characteristics, outcomes and the usage of IVUS-guided mechanical thrombectomy during the treatment of acute high and intermediate-risk PE were examined in a descriptive analysis.

RESULTS

In this systematic review, we included one prospective study, two case series, and two case reports from July 2019 to May 2023. A total of 39 patients were evaluated; most were female (53.8%). The main presenting symptoms were dyspnea and chest pain (79.5%); three patients (7.9%) presented with syncope, one with shock and one with cardiac arrest. Biomarkers (troponin and BNP) were elevated in 94.6% of patients. Most patients (87.2%) had intermediate-risk PE, and 12.8% had high-risk PE. All patients presented with right-heart strain (RV/LV ratio ≥ 0.9, n = 39). Most patients (56.4%) had bilateral PE. Mechanical thrombectomy was performed using IVUS without contrast utilization in 39.4% of the patients. After the initial learning curve, contrast usage decreased gradually over time. There was a significant decrease in the composite mean arterial pressure immediately following IVUS-guided thrombectomy from 35.1 ± 7.2 to 25.2 ± 8.3 mmHg (p < 0.001). Post-procedure, there was no reported (0%) CI-AKI, no all-cause mortality, no major bleeding, or other adverse events. There was a significant improvement in symptoms and RV function at the mean follow-up.

CONCLUSIONS

New evidence suggests that IVUS-guided mechanical thrombectomy is safe, with visualization of the thrombus for optimal intervention, and reduces contrast exposure.

Intravascular Ultrasound Guidance During Peripheral Vascular Interventions: Long-term Clinical Outcomes and Costs From the Japanese Perspective

PURPOSE

The value of intravascular ultrasound (IVUS) guidance during peripheral vascular revascularization procedures is incompletely understood. Moreover, data on long-term clinical outcomes and costs are limited. The objective of this study was to compare outcomes and costs between IVUS and contrast angiography alone in patients undergoing peripheral revascularization procedures in Japan.

MATERIALS AND METHODS

This retrospective comparative analysis was performed using the Japanese Medical Data Vision insurance claims database. All patients undergoing revascularization for peripheral artery disease (PAD) between April 2009 and July 2019 were included. Patients were followed until July 2020, death, or a subsequent revascularization procedure for PAD. Two patient groups were compared: one undergoing IVUS imaging or the other contrast angiography alone. The primary end point was major adverse cardiac and limb events, including all-cause-mortality, endovascular thrombolysis, subsequent revascularization procedures for PAD, stroke, acute myocardial infarction, and major amputations. Total health care costs were documented over the follow-up and compared between groups, using a bootstrap method.

RESULTS

The study included 3956 patients in the IVUS group and 5889 in the angiography alone group. Intravascular ultrasound was significantly associated with reduced risk of a subsequent revascularization procedure (adjusted hazard ratio: 0.25 [0.22-0.28]) and major adverse cardiac and limb events (0.69 [0.65-0.73]). The total costs were significantly lower in the IVUS group, with a mean cost saving over follow-up of $18 173 [$7 695-$28 595] per patient.

CONCLUSION

The use of IVUS during peripheral revascularization provides superior long-term clinical outcomes at lower costs compared with contrast angiography alone, warranting wider adoption and fewer barriers to IVUS reimbursement for patients with PAD undergoing routine revascularization.

CLINICAL IMPACT

Intravascular ultrasound (IVUS) guidance during peripheral vascular revascularization has been introduced to improve the precision of the procedure. However, questions over the benefit of IVUS in terms of long-term clinical outcome and over cost have limited its use in everyday clinical practice. This study, performed in a Japanese health insurance claims database, demonstrates that use of IVUS provides a superior clinical outcome over the long term at a lower cost compared to angiography alone. These findings should encourage clinicians to use IVUS in routine peripheral vascular revascularization procedures and encourage providers to reduce barriers to use.

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 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.

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.

Survivals of Angiography-Guided Percutaneous Coronary Intervention and Proportion of Intracoronary Imaging at Population Level: The Imaging Paradox

Background

There is a significant disparity between randomized controlled trials and observational studies with respect to any mortality benefit with intracoronary imaging during the percutaneous coronary intervention (PCI). This raises a suspicion that the imaging paradox, in which some operators may become over reliant on imaging and less proficient with angiography-guided PCI, might exist.

Method

This was a retrospective cohort study from 14 hospitals under the Hospital Authority of Hong Kong between January 1, 2010 and December 31, 2017. Participants were patients who underwent first-ever PCI. The association between mortality risks of patients undergoing angiography-guided PCI and three tertiles (low, medium, and high) of the proportion of PCI done under intracoronary imaging guidance at a population level (background imaging rate), were evaluated after confounder adjustment by multivariable logistic regression.

Results

In an adjusted analysis of 11,816 patients undergoing angiography-guided PCI, the risks of all-cause mortality for those were higher in the high-tertile group compared with the low-tertile group (OR, 1.45, 95% CI, 1.10–1.92, P = 0.008), the risks of cardiovascular mortality were higher in the high-tertile group compared with the low-tertile group (OR, 1.51, 95% CI, 1.08–2.13, P = 0.017). The results were consistent with multiple sensitivity analyses. Threshold analysis suggested that the mortality risks of angiography-guided PCI were increased when the proportion of imaging-guided PCI exceeded approximately 50%.

Conclusions

The risks of the all-cause mortality and cardiovascular mortality were higher for patients undergoing angiography-guided PCI in practices with a higher background imaging rate.

Vulnerable Plaque in Patients with Acute Coronary Syndrome: Identification, Importance, and Management

MI is a leading cause of morbidity and mortality worldwide. Coronary artery thrombosis is the final pathologic feature of the most cases of acute MI primarily caused by atherosclerotic coronary artery disease. The concept of vulnerable plaque has evolved over the years but originated from early pioneering work unveiling the crucial role of plaque rupture and subsequent coronary thrombosis as the dominant cause of MI. Along with systemic cardiovascular risk factors, developments of intravascular and non-invasive imaging modalities have allowed us to identify coronary plaques thought to be at high risk for rupture. However, morphological features alone may only be one of many factors which promote plaque progression. The current vulnerable-plaque-oriented approaches to accomplish personalized risk assessment and treatment have significant room for improvement. In this review, the authors discuss recent advances in the understanding of vulnerable plaque and its management strategy from pathology and clinical perspectives.

Clinical expert consensus document on intravascular ultrasound from the Japanese Association of Cardiovascular Intervention and Therapeutics (2021)

Intravascular ultrasound (IVUS) provides precise anatomic information in coronary arteries including quantitative measurements and morphological assessment. To standardize the IVUS analysis in the current era, this updated expert consensus document summarizes the methods of measurements and assessment of IVUS images and the clinical evidence of IVUS use in percutaneous coronary intervention.

A Vision Of Percutaneous Coronary Revascularisation In 2021: How to take advantage of intra-coronary imaging to perform more effective PCI

The use of intracoronary imaging with intravascular ultrasound (IVUS) or optical coherence tomography (OCT) can define vessel architecture and has an established role in guidance and optimisation of percutaneous coronary intervention. Additionally intracoronary imaging has an emerging role in diagnosis, afforded by the ability to depict vessel wall characteristics not seen on angiography alone. Use of intracoronary imaging is recommended by international consensus guidelines from the European Society of Cardiology and two recent expert consensus position statements from the European Association of Percutaneous Coronary Interventions (EAPCI). However, uptake in contemporary practice in the United Kingdom appears to lag behind these recommendations. Imaging is particularly advantageous in complex coronary lesions (such as left main stem coronary artery, bifurcation, or heavily calcified lesions) and in complex patients (acute presentations, atypical presentations, and renal dysfunction). Stent detail to the level of individual struts can be appreciated with intracoronary imaging, which facilitates appropriate stent selection and optimisation of the final stent result. We highlight specific subgroups that benefit from an imaging guided approach to percutaneous coronary intervention. We review the evidence and the role of intracoronary imaging and highlight specific subgroups that show particular benefit from imaging guided percutaneous coronary intervention.

Intravascular Ultrasound Versus Angiography-Guided Drug-Eluting Stent Implantation: A Health Economic Analysis

BACKGROUND

There is increasing evidence that use of intravascular ultrasound (IVUS) guidance during percutaneous coronary intervention (PCI) is associated with improved clinical outcomes compared with angiography guidance alone. However, concern regarding the cost-effectiveness of IVUS has limited use of this technology worldwide. In this study, we aimed to evaluate the cost-effectiveness of IVUS-guided PCI compared with angiography-guided PCI in patients undergoing drug-eluting stent implantation.

METHODS

A decision-analytic Markov model was constructed to compare the cost-effectiveness of IVUS to angiography guidance from the Australian healthcare system perspective. Procedure-related morbidity and mortality were estimated from the literature. Costs were obtained from Australian sources. The population of interest was all-comers undergoing PCI with drug-eluting stent. Outcomes of interest included costs, life-expectancy, and quality-adjusted life years (QALYs) for both treatment groups.

RESULTS

In the base case, IVUS guidance was cost-effective compared with angiography guidance alone. With 5% annual discounting, IVUS was associated with increased lifetime costs of Australian dollars (AUD) $823 (USD $597) per person and benefits of 0.04 life years and 0.05 QALYs compared with angiography, yielding an incremental cost-effectiveness ratio of AUD $17 539 (USD $12 730) per QALY gained. Results were robust to sensitivity analyses, with IVUS being cost-effective in 99% of 10 000 Monte Carlo iterations assuming a willingness-to-pay threshold of AUD $50 000 per QALY gained. In a worst-case scenario analysis, IVUS remained the cost-effective option, with an ICER of AUD $36 651 (USD $26 601) per QALY gained. Exploratory subgroup analysis revealed that cost-effectiveness may be greatest among patients with left main and complex coronary lesions.

CONCLUSIONS

Use of IVUS guidance during PCI is likely to be cost-effective compared with angiography guidance alone among patients undergoing drug-eluting stent implantation.

The role of intravascular ultrasound in percutaneous coronary intervention of complex coronary lesions

Intravascular ultrasound (IVUS) is a catheter-based coronary imaging technique. It utilises the emission & subsequent detection of reflected high frequency (30-60 MHz) sound waves to create high resolution, cross-sectional images of the coronary artery. IVUS has been the cornerstone of intracoronary imaging for more than two decades. When compared to the invasive coronary angiogram which studies only the silhouette of the contrast-filled artery lumen, IVUS also crucially images the vessel wall. Because of this capability, IVUS has greatly facilitated understanding of the coronary atherosclerosis process. Such insights from IVUS reveal how commonly and extensively plain angiography underestimates the true extent of coronary plaque, the characteristics of plaques prone to rupture and cause acute coronary syndromes (lipid rich, thin cap atheroma), and a realisation of the widespread occurrence of vessel remodelling in response to atherosclerosis. Similarly, IVUS has historically provided salutary mechanistic insights that have guided many of the incremental advances in the techniques of percutaneous coronary intervention (PCI). Examples include mechanisms of in-stent restenosis, and the importance of high-pressure post-dilatation of stents to ensure adequate stent apposition and thereby reduce the occurrence of stent thrombosis. IVUS also greatly facilitates the choice of correct diameter and length of stent to implant. Overall, a compelling body of evidence indicates that use of intravascular ultrasound in PCI helps to achieve optimal technical results and to mitigate the risk of adverse cardiac events. In this review, the role of intravascular ultrasound as an adjunct to PCI in complex coronary lesions is explored. The complex coronary situations discussed are the left main stem, ostial stenoses, bifurcation stenoses, thrombotic lesions, the chronically occluded coronary artery, and calcified coronary artery disease. By thorough review of the available evidence, we establish that the advantages of IVUS guidance are particularly evident in each of these complex CAD subsets. In particular, some consider the use of IVUS to be almost mandatory in left main PCI. A comparison with other intracoronary imaging techniques is also explored.

Procedural Characteristics and Outcomes of Patients Undergoing Percutaneous Coronary Intervention During Normal Work Hours Versus Non-work Hours

Percutaneous coronary intervention (PCI) performed during non-work hours is believed to have inferior outcomes because of operator fatigue, differences in baseline patient characteristics, and fewer on-call catheterization laboratory staff. We aimed to analyze a cohort of patients who underwent PCI (all comers) at our tertiary-care center between January 1, 2006, and December 31, 2018, and compare procedural and in-hospital outcomes between 2 groups defined by whether PCI was performed during normal work hours (7:00 A.M. to 7:00 PM) versus non-work hours (7:01 P.M. to 6:59 A.M. weekdays; all hours weekends and holidays). Finally, we examined temporal changes throughout the 24-hour weekday. Primary outcomes were unadjusted in-hospital adverse outcomes (composite death, recurrent myocardial infarction, emergent coronary artery bypass grafting, and target lesion revascularization). We identified 21,848 patients who underwent PCI at our institution. The proportions of ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) were higher during non-work hours. Overall, unadjusted in-hospital adverse outcomes were higher during non-work hours than during normal work hours (8.80% vs 2.00%; p <0.001). These findings were consistent based on the patient's clinical presentation (STEMI, NSTEMI, unstable angina, and stable angina). Despite confounding variables in the patients' presentations preventing definite causal attribution, our analysis demonstrates that in-hospital adverse outcomes were higher for those patients who underwent PCI (all comers) who had their procedures during non-work hours than during normal work hours.

When to use intravascular ultrasound or optical coherence tomography during percutaneous coronary intervention?

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are intravascular imaging technologies widely used in the cardiac catheterization laboratory. The impact of these modalities for optimizing the acute and longer-term clinical impact following percutaneous coronary intervention (PCI) is supported by a wealth of clinical evidence. Intravascular imaging provides unique information for enhanced lesion preparation, optimal stent sizing, recognizing post PCI complications, and the etiology of stent failure. This review compares and contrasts the key aspects of these imaging modalities during PCI.

Advances in IVUS/OCT and Future Clinical Perspective of Novel Hybrid Catheter System in Coronary Imaging

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have been developed and improved as both diagnostic and guidance tools for interventional procedures over the past three decades. IVUS has a resolution of 100 μm with a high tissue penetration and capability of assessing the entire structure of a coronary artery including the external elastic membrane, whereas OCT has a higher resolution of 10–20 μm to assess endoluminal structures with a limited tissue penetration compared to IVUS. Recently, two companies, CONAVI and TERUMO, integrated IVUS and OCT into a single catheter system. With their inherent strength and limitations, the combined IVUS and OCT probes are complementary and work synergistically to enable a comprehensive depiction of coronary artery. In this review, we summarize the performance of the two intracoronary imaging modalities—IVUS and OCT—and discuss the expected potential of the novel hybrid IVUS–OCT catheter system in the clinical field.

Contemporary practices using intravascular imaging guidance with IVUS or OCT to optimize percutaneous coronary intervention

Introduction: Angiography is routinely used to perform percutaneous coronary intervention (PCI). However, angiography has many limitations that prevent accurate assessment of coronary lesions. The development and evolution of intravascular imaging have offset the limitations of angiography. Overwhelming evidence supports intravascular imaging guidance to optimize PCI results and studies have shown that it is associated with better outcomes. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are the most commonly used modalities and both have far greater spatial resolution compared with angiography. There are advantages and disadvantages to both IVUS and OCT, and the optimal modality will depend on patient factors and indications.Areas covered: This review will summarize clinical evidence and current practices in the use of intravascular imaging in PCI. Literature review from year 2000-2019 was completed via PubMed search using keywords.Expert commentary: Intravascular imaging is an essential tool in PCI that has outcome implications, but it is still underutilized. Proper image acquisition, accurate interpretation, and correct decision-making are needed for patients to benefit from imaging-guided PCI. Training and education are essential in successful utilization of imaging technology. High-definition IVUS is likely to gain favor as there is improved image resolution without the use of contrast.

Intravascular Ultrasound Imaging-Guided Versus Coronary Angiography-Guided Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis

Background

Intravascular ultrasound (IVUS) guidance during percutaneous coronary intervention (PCI) offers tomographic images of the coronary vessels, allowing optimization of stent implantation at the time of PCI. However, the long‐term beneficial effect of IVUS over PCI guided by coronary angiography (CA) alone remains under question. We sought to investigate the outcomes of IVUS‐guided compared with CA‐guided PCI.

Methods and Results

We performed a comprehensive search of PubMed, Medline, and Cochrane Central Register, looking for randomized controlled trials and observational studies that compared PCI outcomes of IVUS with CA. Data were aggregated for the primary outcome measure using the random‐effects model as pooled risk ratio (RR). The primary outcomes were the rate of cardiovascular death, need for target lesion revascularization, occurrence of myocardial infarction, and rate of stent thrombosis. A total of 19 studies met the inclusion criteria, comprising 27 610 patients divided into IVUS (n=11 513) and CA (n=16 097). Compared with standard CA‐guided PCI, we found that the risks of cardiovascular death (RR, 0.63; 95% CI, 0.54–0.73), myocardial infarction (RR, 0.71; 95% CI, 0.58–0.86), target lesion revascularization (RR, 0.81; 95% CI, 0.70–0.94), and stent thrombosis (RR, 0.57; 95% CI, 0.41–0.79) were all significantly lower using IVUS guidance.

Conclusions

Compared with standard CA‐guided PCI, the use of IVUS imaging guidance to optimize stent implantation is associated with a reduced risk of cardiovascular death and major adverse events, such as myocardial infarction, target lesion revascularization, and stent thrombosis.

Fifteen years of coronary intravascular ultrasound in percutaneous coronary intervention in Portugal

INTRODUCTION

Coronary intravascular ultrasound (IVUS) is increasingly important in catheterization laboratories due to its positive prognostic impact. This study aims to characterize the use of IVUS in percutaneous coronary intervention (PCI) in Portugal.

METHODS

A retrospective observational study was performed based on the Portuguese Registry on Interventional Cardiology of the Portuguese Society of Cardiology. The clinical and angiographic profiles of patients who underwent PCI between 2002 and 2016, the percentage of IVUS use, and the coronary arteries assessed were characterized.

RESULTS

A total of 118 706 PCIs were included, in which IVUS was used in 2266 (1.9%). Over time, use of IVUS changed from none in 2002 to generally increasing use from 2003 (0.1%) to 2016 (2.4%). The age of patients in whom coronary IVUS was used was similar to that of patients in whom IVUS was not used, but in the former group there were fewer male patients, and a higher prevalence of cardiovascular risk factors (hypertension, hypercholesterolemia and diabetes), previous myocardial infarction, previous PCI, multivessel coronary disease, C-type or bifurcated coronary lesions, and in-stent restenosis. IVUS was used in 54.8% of elective PCIs and in 19.15% of PCIs of the left main coronary artery.

CONCLUSION

Coronary IVUS has been increasingly used in Portugal since 2003. It is used preferentially in elective PCIs, and in patients with higher cardiovascular risk, with more complex coronary lesions and lesions of the left main coronary artery.

Clinical utility of intravascular ultrasonography-guided therapy in a small-vessel coronary lesion associated with Type 2 diabetes mellitus

Objective:

It is unknown whether the intravascular ultrasound (IVUS) guidance for percutaneous coronary intervention (PCI) should be routinely used in small-vessel coronary lesions in patients affected by Type 2 diabetes mellitus (T2DM). This study aimed to assess the clinical significance of the IVUS-guided PCI treatment for small-vessel coronary lesions in T2DM.

Methods:

This was a prospective interventional trial. A total of 228 patients affected by T2DM with stable angina and a positive stress test in the presence of coronary arteriography (CAG) involving small vessels [online measurement reference vessel diameter ≤3.0 mm by means of quantitative coronary angiography (QCA)] were recruited and divided into two groups: an IVUS-guided group (n=120) and a CAG-guided group (n=108). Follow-up PCIs were performed via CAG or IVUS criteria, respectively. Between-group comparisons were made for the number of stents implanted, length, diameter, and high-pressure balloons used post-dilatation. Major adverse cardiac events (MACEs) defined as cardiac death, nonfatal myocardial infarction, and target lesion revascularization (TLR) were the primary endpoint. The value of late lumen loss and proportion of in-stent restenosis (ISR) were the secondary endpoint, all of which were also evaluated during the follow-up period.

Results:

There was an increased lesion length observed using the IVUS measurement when compared with QCA measurements in the IVUS-guided group (p≤0.001). The number of implanted stents, diameter, length, percentage of high-pressure balloons used during post-dilatation, value of late lumen loss, and proportion of ISR decreased in the IVUS-guided group when compared with the CAG-guided group (p=0.002, p=0.001, p=0.003, p=0.004, p=0.007, p=0.001, respectively). After a 2-year follow-up, the Kaplan–Meier curves indicated that the incidence of MACEs was significantly lower in the IVUS-guided group (log-rank p=0.029), mainly because of the TLR reduction (log-rank p=0.037).

Conclusion:

The IVUS-guided PCI treatment improved the event-free survival in small-vessel coronary lesions in patients affected by T2DM.

IVUS-Guided Versus OCT-Guided Coronary Stent Implantation: A Critical Appraisal

Procedural guidance with intravascular ultrasound (IVUS) imaging improves the clinical outcomes of patients undergoing percutaneous coronary intervention (PCI) by: 1) informing the necessity for lesion preparation; 2) directing appropriate stent sizing to maximize the final stent area and minimize geographic miss; 3) selecting the optimal stent length to cover residual disease adjacent to the lesion, thus minimizing geographic miss; 4) guiding optimal stent expansion; 5) identifying acute complications (edge dissection, stent malapposition, tissue protrusion); and 6) clarifying the mechanism of late stent failure (stent thrombosis, neointimal hyperplasia, stent underexpansion or fracture, or neoatherosclerosis). Optical coherence tomography (OCT) provides similar information to IVUS (with some important differences), also potentially improving acute and long-term patient outcomes compared to angiography-guided PCI. The purpose of this review is to describe the similarities and differences between IVUS and OCT technologies, and to highlight the evidence supporting their utility to improve PCI outcomes.

Current use of intracoronary imaging in interventional practice - Results of a European Association of Percutaneous Cardiovascular Interventions (EAPCI) and Japanese Association of Cardiovascular Interventions and Therapeutics (CVIT) Clinical Practice Survey

AIMS

This study evaluated the views of the cardiology community on the clinical use of coronary intravascular imaging (IVI).

METHODS AND RESULTS

A web-based survey was distributed to 31,893 individuals, with 1,105 responses received (3.5% response rate); 1,010 of 1,097 respondents (92.1%) self-reported as interventional cardiologists, 754 (68.7%) with >10 years experience. Overall, 96.1% had personal experience with IVI (95.5% with intravascular ultrasound [IVUS], 69.8% with optical coherence tomography [OCT], and 7.9% with near-infrared spectroscopy); 34.7% of respondents were from Europe and 52.0% were from Asia (45.4% from Japan). The most commonly reported indications for IVI were optimization of stenting (88.5%), procedural/strategy guidance (79.6%), and guidance of left main interventions (77.0%). Most respondents reported perceived equipoise regarding choice between IVUS and OCT for guidance of coronary intervention. High cost (65.9%) and prolongation of the procedure (35.0%) were the most commonly reported factors limiting use. IVI was used more frequently (>15% of cases guided by IVI) in Japan than Europe (96.6% vs. 10.4%, respectively; P<0.001) and by operators with longer interventional experience.

CONCLUSIONS

In a sample of predominantly experienced interventional cardiologists, there was a high rate of personal experience with IVI in clinical practice. The most commonly identified indications for IVI were optimization of stenting, procedural/strategy guidance, and guidance of left main interventions. Variability in practice patterns is substantial according to geographic region and interventional experience.

Intravascular Ultrasound for Guidance and Optimization of Percutaneous Coronary Intervention

Percutaneous coronary intervention (PCI) remains the mainstay management of symptomatic obstructive stable coronary artery disease (despite optimal medical treatment) and acute coronary syndrome. Intravascular ultrasound (IVUS) has emerged as an adjunct to angiography, permitting better assessment of the coronary lesion and stent apposition. Data from multiple studies have demonstrated improved clinical and procedural outcomes with IVUS-guided PCI. This review discusses the use of IVUS, with emphasis on technique, parameters, and applications during coronary interventions. In addition, the clinical outcomes data are highlighted with IVUS compared with conventional angiography-guided PCI.