Clinical utility of intravascular imaging and physiology in coronary artery disease

Predictive value of plaque characteristics for identification of lesions causing ischemia

BACKGROUND

Functional assessment using fractional flow reserve (FFR) and anatomical assessment using optical coherence tomography (OCT) are used in clinical practice for patients with intermediate coronary stenosis. Moreover, coronary computed tomography angiography (CTA) is a common noninvasive imaging technique for evaluating suspected coronary artery disease before being referred for angiography. This study aimed to investigate the association between FFR and plaque characteristics assessed using coronary CTA and OCT for intermediate coronary stenosis.

METHODS

Based on a prospective multicenter registry, 159 patients having 339 coronary lesions with intermediate stenosis were included. All patients underwent coronary CTA before being referred for coronary angiography, and both FFR measurements and OCT examinations were performed during angiography. A stenotic lesion identified with FFR ≤0.80 was deemed diagnostic of an ischemia-causing lesion. The predictive value of plaque characteristics assessed using coronary CTA and OCT for identifying lesions causing ischemia was analyzed.

RESULTS

Stenosis severity and plaque characteristics on coronary CTA and OCT differed between lesions that caused ischemia and those that did not. In multivariate analysis, low attenuation plaque on coronary CTA (odds ratio [OR]=2.78; P=0.038), thrombus (OR=5.13; P=0.042), plaque rupture (OR=3.25; P=0.017), and intimal vasculature on OCT (OR=2.57; P=0.012) were independent predictors of ischemic lesions. Increasing the number of these plaque characteristics offered incremental improvement in predicting the lesions causing ischemia.

CONCLUSIONS

Comprehensive anatomical evaluation of coronary stenosis may provide additional supportive information for predicting the lesions causing ischemia.

Optical coherence tomography-guided versus angiography-guided percutaneous coronary intervention: A meta-analysis of randomized controlled trials

Background

Optical Coherence Tomography (OCT), a high-resolution imaging modality, guides stent implantation during percutaneous coronary intervention (PCI). However, OCT-guided PCI safety and efficacy data is limited.

Methods

MEDLINE, Embase, and Cochrane Central were searched for randomized controlled trials (RCTs) comparing OCT-guided PCI to Angiography-guided PCI from inception to August 2023. A random-effects model was used to pool risk ratios (RRs), mean differences (MDs), and 95% confidence intervals (CIs) for clinical endpoints.

Results

Our analysis included 5,139 patients from 11 studies. OCT-guided PCI resulted in a higher minimum stent area (MD = 0.35 [95 % CI, 0.21-0.49]; p < 0.00001), significantly reduced risk of cardiovascular mortality (RR = 0.56 [95 % CI, = 0.32-0.99]; p = 0.04), stent thrombosis (RR = 0.56 [95 % CI, 0.32-0.96]; p = 0.04), stent malapposition RR = 0.79 [95 % CI, 0.71-0.88]; p = < 0.0001) and major edge dissection (RR = 0.47 [95 % CI, 0.34-0.65]; p = <0.00001). However, no statistically significant difference was observed for all-cause mortality (RR = 0.71; p = 0.06), major adverse cardiovascular events (MACE) [RR = 0.80; p = 0.10], myocardial infarction (MI) [RR = 0.84; p = 0.16], target lesion revascularization (TLR) [RR = 0.94; p = 0.68], and target vessel revascularization (TVR) [RR = 0.91; p = 0.52].

Conclusion

OCT-guided PCI led to an increased MSA and decreased cardiovascular mortality, stent thrombosis, stent malapposition, and major edge dissection. The incidence of all-cause mortality, MACE, MI, TLR, and TVR remained comparable across the two groups.

Coronary artery wall contrast enhancement imaging impact on disease activity assessment in IgG4-RD: a direct marker of coronary involvement

BACKGROUND

Coronary artery wall contrast enhancement (CE) has been applied to non-invasive visualization of changes to the coronary artery wall in systemic lupus erythematosus (SLE). This study investigated the feasibility of quantifying CE to detect coronary involvement in IgG4-related disease (IgG4-RD), as well as the influence on disease activity assessment.

METHODS

A total of 93 subjects (31 IgG4-RD; 29 SLE; 33 controls) were recruited in the study. Coronary artery wall imaging was performed in a 3.0 T MRI scanner. Serological markers and IgG4-RD Responder Index (IgG4-RD-RI) scores were collected for correlation analysis.

RESULTS

Coronary wall CE was observed in 29 (94 %) IgG4-RD patients and 22 (76 %) SLE patients. Contrast-to-noise ratio (CNR) and total CE area were significantly higher in patient groups compared to controls (CNR: 6.1 ± 2.7 [IgG4-RD] v. 4.2 ± 2.3 [SLE] v. 1.9 ± 1.5 [control], P < 0.001; Total CE area: 3.0 [3.0-6.6] v. 1.7 [1.5-2.6] v. 0.3 [0.3-0.9], P < 0.001). In the IgG4-RD group, CNR and total CE area were correlated with the RI (CNR: r = 0.55, P = 0.002; total CE area: r = 0.39, P = 0.031). RI´ scored considering coronary involvement by CE, differed significantly from RI scored without consideration of CE (RI v. RI´: 15 ± 6 v. 16 ± 6, P < 0.001).

CONCLUSIONS

Visualization and quantification of CMR coronary CE by CNR and total CE area could be utilized to detect subclinical and clinical coronary wall involvement, which is prevalent in IgG4-RD. The potential inclusion of small and medium-sized vessel involvements in the assessment of disease activity in IgG4-RD is worthy of further investigation.

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.

Invasive coronary imaging of inflammation to further characterize high-risk lesions: what options do we have?

Coronary atherosclerosis remains a leading cause of morbidity and mortality worldwide. The underlying pathophysiology includes a complex interplay of endothelial dysfunction, lipid accumulation and inflammatory pathways. Multiple structural and inflammatory features of the atherosclerotic lesions have become targets to identify high-risk lesions. Various intracoronary imaging devices have been developed to assess the morphological, biocompositional and molecular profile of the intracoronary atheromata. These techniques guide interventional and therapeutical management and allow the identification and stratification of atherosclerotic lesions. We sought to provide an overview of the inflammatory pathobiology of atherosclerosis, distinct high-risk plaque features and the ability to visualize this process with contemporary intracoronary imaging techniques.

Unveiling the Heart of the Matter: Intravascular Ultrasound in Acute Myocardial Infarction

Intravascular ultrasound (IVUS) has become crucial in contemporary percutaneous coronary interventions (PCIs), offering detailed two-dimensional (2D) arterial wall visualization. Current guidelines consider it valuable for guiding coronary stent placement, especially in complex cases like the left main (LM) artery, allowing a comprehensive assessment of vessel characteristics and stent performance. There are some studies that highlight the potential impact of IVUS on acute myocardial infarction (AMI) management, notably improving outcomes. This case involves a 37-year-old man who experienced an AMI, necessitating the use of IVUS to ascertain the underlying cause of his acute coronary syndrome (ACS). This approach was essential for guiding appropriate treatment and ultimately led to successful stent implantation.

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.

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

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

Reproducibility of Femoropopliteal Artery Intravascular Ultrasound Imaging in Patients With Peripheral Artery Disease

Despite increased use of intravascular ultrasound (IVUS) during peripheral artery interventions, evidence for reproducibility of IVUS measurements and its relation to angiography is lacking. Forty cross-sectional IVUS images of the femoropopliteal artery from 20 randomly selected patients enrolled in the XLPAD (Excellence in Peripheral Artery Disease) registry who underwent peripheral artery interventions and met criteria based on IVUS consensus guidelines were independently assessed by 2 blinded readers. IVUS images from 6 patients (40 images) were selected for angiographic correlation and met criteria for identifiable landmarks (e.g., stent edge and bifurcation). Lumen cross-sectional area (CSA), external elastic membrane (EEM) CSA, luminal diameter, and reference vessel diameter were repeatedly measured. The Lumen CSA and EEM CSA intra-observer agreement by Spearman rank-order correlation (ρ) was >0.993, intraclass correlation coefficient was >0.997, and repeatability coefficient was <1.34. For the interobserver measurement of luminal CSA and EEM CSA, the ρ = 0.742 and 0.764; intraclass correlation coefficient = 0.888 and 0.885; and repeatability coefficient = 7.24 and 11.34, respectively. A Bland-Altman plot for lumen and EEM CSA showed good reproducibility. For angiographic comparison, the ρ for luminal diameter, luminal area, and vessel area were 0.419, 0.414, and 0.649, respectively. Femoropopliteal IVUS measurements showed strong intra-observer and interobserver agreement; IVUS and angiographic measurements did not demonstrate a similar strong agreement.

Intracoronary Imaging of Proximal Coronary Artery Lesions A Nationwide Lesion-Level Analysis From SCAAR

Background

Current evidence suggests that use of intracoronary imaging during percutaneous coronary intervention (PCI) of the left main coronary artery (LMCA) reduces mortality. However, there is a scarcity of data on the overall role of intracoronary imaging, particularly in other non-LMCA proximal coronary artery lesions. We aimed to investigate the association of use of intracoronary imaging on outcome in proximal lesions treated with PCI.

Methods

The Swedish Coronary Angiography and Angioplasty Registry was used to identify all proximal coronary artery lesions treated with stent implantation between June 11, 2013, and January 16, 2021. Proximal coronary artery lesions (LMCA, proximal left anterior descending artery, left circumflex artery, and right coronary artery) assessed by intracoronary imaging before and/or after stent implantation were matched to control lesions treated based on angiography alone using propensity score matching. The primary end point was target lesion revascularization with PCI, and secondary end points included all-cause mortality and definite stent thrombosis within 3 years.

Results

Among the 3623 matched pairs, intracoronary imaging was associated with significantly lower risk of target lesion revascularization, 3.7% vs 4.7%; hazard ratio (HR), 0.77; 95% CI, 0.61-0.97; P = .025, and all-cause mortality, 9.1% vs 12.8%; HR, 0.70; 95% CI, 0.61-0.81; P < .001, with no difference in definite stent thrombosis.

Conclusions

The use of intracoronary imaging in proximal coronary artery lesions is associated with lower rates of repeat revascularization and better survival. The results appear to be primarily driven by improved outcome of LMCA lesions. These results reinforce the role of intracoronary imaging in assessing and treating proximal coronary lesions.

Near-Infrared Spectroscopy-Guided Percutaneous Coronary Intervention: Practical Applications and Available Evidence

Intracoronary near-infrared spectroscopy (NIRS) has been extensively validated against the gold standard of histopathology to identify lipid-rich plaque. NIRS is currently in clinical use as a combined multimodality imaging catheter with intravascular ultrasonography. When used before PCI, NIRS has clinical utility in determining the mechanism underlying acute coronary syndromes and can be used to guide stent length selection and identify the risk of periprocedural myocardial infarction. When used after PCI, NIRS can identify vulnerable patients at increased risk of future patient-level cardiovascular events and can detect vulnerable plaques at increased risk of future site-specific coronary events.

Pre-stenting angiography-FFR based physiological map provides virtual intervention and predicts physiological and clinical outcomes

BACKGROUND

Angiography-derived fractional flow reserve (FFR) (angio-FFR) has been validated against FFR and could provide virtual pullback. However, whether a physiological map can be generated by angio-FFR and its clinical value remains unclear. We aimed to investigate the feasibility of physiological map created from angio-FFR pullback and its value in predicting physiological and clinical outcomes after stenting.

METHODS

An angio-FFR physiological map was generated by overlaying the virtual pullback onto coronary angiogram, to calculate physiological stenosis severity, length, and intensity (Δangio-FFR/mm). This map in combination with virtual stenting was used to predict the best-case post-percutaneous coronary intervention (PCI) angio-FFR (angio-FFR_predicted ) according to the stented segments, and this was compared with the actual achieved post-PCI angio-FFR (angio-FFR_achieved ). Additionally, prognostic value of predicted angio-FFR was investigated.

RESULTS

Three hundred twenty-nine vessels with paired analyzable pre- and post-PCI angio-FFR were included. Physiological map was created successfully in all vessels. After successful PCI, angio-FFR_predicted and angio-FFR_achieved were significantly correlated (r = 0.82, p < 0.001) with small difference (mean difference: -0.010 ± 0.035). In the virtual PCI only covering the segment with high angio-FFR intensity, the same physiological outcome can be achieved with shorter stent length (14.1 ± 8.9 vs. 34.5 ± 15.8 mm, p < 0.001). Suboptimal angio-FFR_predicted was associated with increased risk of 2-year vessel-oriented composite endpoint (adjusted hazard ratio: 3.71; 95% confidence interval: 1.50-9.17).

CONCLUSIONS

Angio-FFR pullback could provide a physiological map of the interrogated coronary vessels by integrating angio-FFR pullback and angiography. Before a PCI, the physiological map can predict the physiological and clinical outcomes after stenting.

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.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusions

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

Comparison of Six Different Percutaneous Coronary Intervention Guidance Modalities

Background: New randomized trials and modalities in guiding percutaneous coronary intervention (PCI) have become available. Objective: We aimed to compare the clinical outcomes of coronary angiography (CAG), intravascular ultrasound (IVUS), optical coherence tomography (OCT), fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and optical frequency domain imaging (OFDI)-guided PCI. Methods: A network meta-analysis was performed to compare different PCI guidance modalities. The clinical outcomes included major adverse cardiovascular events (MACE), all-cause death, myocardial infarction (MI), and target vessel/lesion revascularization (TVR/TLR). Odds ratio (OR) and corresponding 95% credible interval (CrI) were calculated. Results: Thirty-six randomized trials, including 19,042 patients, were included. In comparison with CAG, IVUS significantly reduced MACE (OR: 0.71; 95% CrI: 0.57 to 0.86) and TVR/TLR (OR: 0.53; 95% CrI: 0.43 to 0.66). MACE (OR: 1.44; 95% CrI: 1.02 to 2.08) and TVR/TLR (OR: 1.87; 95% CrI: 1.04 to 3.71) were significantly increased in the FFR group, compared with IVUS group. There were no significant differences in MACE or TVR/TLR among the left guidance modality comparisons. Differences in all-cause death or MI were not observed in any comparisons. Conclusions: IVUS could reduce MACE and TVR/TLR, compared with CAG or FFR. Therefore, IVUS may be the optimal modality in guiding PCI.

Definition of Optimal Optical Coherence Tomography-Based Stent Expansion Criteria: In-Stent Minimum Lumen Area Versus Residual Stent Underexpansion

BACKGROUND

The mismatch between in-stent minimum lumen area (sMLA) and reference vessel lumen area, defined as stent underexpansion (SU), could be an important determinant of stent failure. We tested the clinical predictive value of absolute sMLA in comparison to relative SU in the context of the CLI-OPCI (Centro Per La Lotta Contro L'Infarto-Optimisation of Percutaneous Coronary Intervention) project registry.

METHODS

We retrospectively analyzed end procedural optical coherence tomography findings in 1211 patients (1422 lesions) undergoing percutaneous coronary intervention, assessing the prevalence and magnitude of residual SU and exploring correlation with outcome in comparison with sMLA.

RESULTS

In our series, both sMLA and SU were related to vessel size and anatomic lesion complexity. When compared with patients without adverse event at follow-up, those experiencing device-oriented cardiovascular events (composite of cardiac death, target vessel myocardial infarction, target lesion revascularization, and stent thrombosis) showed a lower sMLA (5.6±2.1 versus 6.1±2.1 mm²; P=0.011) but a comparable degree of SU (11.6±14.1% versus 11.2±13.3%; P=0.734). The prespecified cutoff value of sMLA <4.5 mm², documented in 23.8% of cases, was confirmed as independent outcome predictor for device-oriented cardiovascular events (hazard ratio [HR], 2.05 [95% CI, 1.5-2.9]) including target lesion revascularization (HR, 2.43 [95% CI, 1.7-3.5]) and stent thrombosis (HR, 3.23 [95% CI, 1.7-6.3]). A residual SU of 10%, 20%, and 30% was observed in 38.0%, 18.2%, and 7.6% of cases, respectively. No grade of residual SU significantly increased the risk of stent failure, unless if an SU >20% was associated with an sMLA <4.5 mm² (HR, 3.11 [95% CI, 1.7-5.6]). Finally, an association between stent overexpansion (ie, >110%) and device-oriented cardiovascular events was also observed (HR, 1.60 [95% CI, 1.1-2.3]).

CONCLUSIONS

Final absolute sMLA and not relative SU was associated with an increased risk of stent failure. A variable grade of SU was common, but it resulted in being clinically relevant only when associated with an sMLA <4.5 mm².

Framework for lumen-based nonrigid tomographic coregistration of intravascular images

Purpose: Modern medical imaging enables clinicians to effectively diagnose, monitor, and treat diseases. However, clinical decision-making often relies on combined evaluation of either longitudinal or disparate image sets, necessitating coregistration of multiple acquisitions. Promising coregistration techniques have been proposed; however, available methods predominantly rely on time-consuming manual alignments or nontrivial feature extraction with limited clinical applicability. Addressing these issues, we present a fully automated, robust, nonrigid registration method, allowing for coregistering of multimodal tomographic vascular image datasets using luminal annotation as the sole alignment feature. Approach: Registration is carried out by the use of the registration metrics defined exclusively for lumens shapes. The framework is primarily broken down into two sequential parts: longitudinal and rotational registration. Both techniques are inherently nonrigid in nature to compensate for motion and acquisition artifacts in tomographic images. Results: Performance was evaluated across multimodal intravascular datasets, as well as in longitudinal cases assessing pre-/postinterventional coronary images. Low registration error in both datasets highlights method utility, with longitudinal registration errors-evaluated throughout the paired tomographic sequences-of 0.29 ± 0.14    mm ( < 2 longitudinal image frames) and 0.18 ± 0.16    mm ( < 1 frame) for multimodal and interventional datasets, respectively. Angular registration for the interventional dataset rendered errors of 7.7 ° ± 6.7 ° , and 29.1 ° ± 23.2 ° for the multimodal set. Conclusions: Satisfactory results across datasets, along with additional attributes such as the ability to avoid longitudinal over-fitting and correct nonlinear catheter rotation during nonrigid rotational registration, highlight the potential wide-ranging applicability of our presented coregistration method.

The Continuum of Invasive Techniques for the Assessment of Intermediate Coronary Lesions

Ischemic heart disease is one of the most important causes of mortality and morbidity worldwide. Revascularization of coronary stenosis inducing ischemia, either by percutaneous or surgical intervention, significantly reduces major adverse cardiovascular events and improves quality of life. However, in cases of intermediate lesions, classified by a diameter stenosis between 50 and 90% by European guidelines and 40–70% in American counterparts with no clear evidence of ischemia, the indication of revascularization and impact is determined using various methods that altogether comprehensively evaluate the lesions. This review will discuss the various techniques to assess intermediate stenoses, highlighting indications and advantages, but also drawbacks. Fractional flow rate (FFR) and instantaneous wave-free ratio (iFR) are the gold standard for the functional evaluation of intermediate lesions, but there are clinical circumstances in which these pressure-wire-derived indices are not accurate. Complementary invasive investigations, mainly intravascular ultrasound and/or optical coherence tomography, offer parameters that can be correlated with FFR/iFR and additional insights into the morphology of the plaque guiding the eventual percutaneous intervention in terms of length and size of stents, thus improving the outcomes of the procedure. The development of artificial intelligence and machine learning with advanced algorithms of prediction will offer multiple scenarios for treatment, allowing real-time selection of the best strategy for revascularization.

Computational Fractional Flow Reserve From Coronary Computed Tomography Angiography—Optical Coherence Tomography Fusion Images in Assessing Functionally Significant Coronary Stenosis

Background

Coronary computed tomography angiography (CTA) and optical coherence tomography (OCT) provide additional functional information beyond the anatomy by applying computational fluid dynamics (CFD). This study sought to evaluate a novel approach for estimating computational fractional flow reserve (FFR) from coronary CTA-OCT fusion images.

Methods

Among patients who underwent coronary CTA, 148 patients who underwent both pressure wire-based FFR measurement and OCT during angiography to evaluate intermediate stenosis in the left anterior descending artery were included from the prospective registry. Coronary CTA-OCT fusion images were created, and CFD was applied to estimate computational FFR. Based on pressure wire-based FFR as a reference, the diagnostic performance of Fusion-FFR was compared with that of CT-FFR and OCT-FFR.

Results

Fusion-FFR was strongly correlated with FFR (r = 0.836, P < 0.001). Correlation between FFR and Fusion-FFR was stronger than that between FFR and CT-FFR (r = 0.682, P < 0.001; z statistic, 5.42, P < 0.001) and between FFR and OCT-FFR (r = 0.705, P < 0.001; z statistic, 4.38, P < 0.001). Area under the receiver operating characteristics curve to assess functionally significant stenosis was higher for Fusion-FFR than for CT-FFR (0.90 vs. 0.83, P = 0.024) and OCT-FFR (0.90 vs. 0.83, P = 0.043). Fusion-FFR exhibited 84.5% accuracy, 84.6% sensitivity, 84.3% specificity, 80.9% positive predictive value, and 87.5% negative predictive value. Especially accuracy, specificity, and positive predictive value were superior for Fusion-FFR than for CT-FFR (73.0%, P = 0.007; 61.4%, P < 0.001; 64.0%, P < 0.001) and OCT-FFR (75.7%, P = 0.021; 73.5%, P = 0.020; 69.9%, P = 0.012).

Conclusion

CFD-based computational FFR from coronary CTA-OCT fusion images provided more accurate functional information than coronary CTA or OCT alone.

Clinical Trial Registration

[www.ClinicalTrials.gov], identifier [NCT03298282].

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.

Reproducibility between three-dimensional turbo spin-echo and two-dimensional dual inversion recovery turbo spin-echo for coronary vessel wall imaging in Kawasaki disease

Magnetic resonance vessel wall imaging is desirable for evaluating Kawasaki disease (KD)-associated coronary arterial lesions. To evaluate the reproducibility of three-dimensional turbo spin-echo (3D-TSE) and two-dimensional dual inversion-recovery turbo spin-echo (2D-DIR-TSE) for coronary vessel wall imaging in KD. Ten patients were prospectively enrolled. Coronary vessel wall imaging with axial-slice orientation 3D-TSE and 2D-DIR-TSE were acquired for cross-sectional images in aneurysmal and normal regions. Lumen area (LA), wall area (WA), and normalized wall index (NWI) of cross-sectional images were measured in both regions. Reproducibility between 3D-TSE and 2D-DIR-TSE was evaluated via intraclass correlation coefficients (ICCs) and Bland–Altman plots. 48 points (aneurysmal, 27; normal, 21) were evaluated. There were high ICCs between 3D-TSE and 2D-DIR-TSE in LA (0.95) and WA (0.95). In aneurysmal regions, 95% limits of agreement were LA, WA, and NWI of − 29.9 to 30.4 mm², − 18.8 to 15.0 mm², and − 0.22 to 0.20, respectively. In normal regions, the 95% limits of agreement were LA, WA, and NWI of − 4.44 to 4.38 mm², − 3.51 to 4.30 mm², and − 0.14 to 0.16, respectively. No fixed and proportional biases between 3D-TSE and 2D-DIR-TSE images in aneurysmal and normal regions were noted. 3D-TSE was reproducible with conventional 2D-DIR-TSE for coronary vessel wall assessment on KD.

Intravascular ultrasound-guided versus coronary angiography-guided percutaneous coronary intervention in patients with acute myocardial infarction: A systematic review and meta-analysis

BACKGROUND

Intravascular ultrasound (IVUS) can overcome the intrinsic limitations of coronary angiography for lesion assessment and stenting. IVUS improves outcomes of patients presenting with stable or complex coronary artery disease, but dedicated data on the impact of IVUS-guided percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) remains scarce.

METHODS

We systematically searched Embase, MEDLINE, Web of Science Core Collection, Cochrane Central Register of Controlled Trials and Google Scholar for studies that compared clinical outcomes for IVUS- versus angio-guided PCI in patients with AMI. The primary endpoint was all-cause mortality and the secondary endpoint major adverse cardiovascular events (MACE). Mantel-Haenszel random-effects model was used to calculate pooled risk ratios (RR) with 95% confidence intervals (CI).

RESULTS

Nine studies (8 observational, 1 RCT) with a total of 838.902 patients (796.953 angio-guided PCI, 41.949 IVUS-guided PCI) were included. In patients with AMI, IVUS-guided PCI was associated with a significantly lower risk of all-cause mortality (pooled RR: 0.70; 95% CI, 0.59-0.82; p < 0.01), MACE (pooled RR: 0.86; 95% CI, 0.74-0.99; p = 0.04) and target vessel revascularization (TVR) (pooled RR: 0.83; 95% CI, 0.73-0.95; p < 0.01). In the subset of patients presenting with ST-segment elevation, IVUS-guided PCI remained associated with a reduced risk for both all-cause mortality (pooled RR: 0.79; 95% CI, 0.66-0.95, p = 0.01) and MACE (pooled RR: 0.86; 95% CI, 0.74-0.99, p = 0.04).

CONCLUSIONS

This is the first systematic review and meta-analysis comparing IVUS- versus angio-guided PCI in patients with AMI, showing a beneficial effect of IVUS-guided PCI on all-cause mortality, MACE and TVR. Results of ongoing dedicated prospective studies are needed to confirm these findings.

Association of Neutrophil to Lymphocyte Ratio With Plaque Rupture in Acute Coronary Syndrome Patients With Only Intermediate Coronary Artery Lesions Assessed by Optical Coherence Tomography

Objectives

Plaque vulnerability and rupture rather than plaque size are the major cause of clinical events in patients with intermediate coronary lesions. Therefore, the present study was aimed to explore potential markers associated with plaque rupture in acute coronary syndrome (ACS) patients with intermediate coronary lesions.

Methods

A total of 82 ACS patients presenting with only intermediate coronary lesions (40–70% stenosis demonstrated by quantitative coronary angiography) and no severe stenosis in other main coronary arteries [median age 63 years, 53 male and 29 female] were enrolled. Plaque morphology were assessed by optical coherence tomography (OCT). Hematological indices were assayed by automated hematological analyzer.

Results

Plaque rupture was identified in 14 patients by OCT. Neutrophil to lymphocyte ratio (NLR) in patients with plaque rupture (n = 14) was significantly higher than that in patients with non-plaque rupture (n = 68) [3.85 (3.28, 4.77) vs. 2.13 (1.40, 2.81), p < 0.001]. Multivariate logistic regression analysis revealed that NLR was one of the independent risk factors for plaque rupture in intermediate coronary artery lesions (odds ratio 1.64, 95% confidence intervals 1.18–2.29, p = 0.003). ROC curve analysis found a cutoff point of NLR > 2.94 for plaque rupture with 93.8% sensitivity and 77.9% specificity.

Conclusion

NLR, an inflammatory biomarker, is closely associated with plaque rupture in intermediate coronary artery lesions. Monitoring NLR may be useful in risk stratification and management for intermediate coronary artery lesions.

Three Technologies That Will Guide Revascularization of Chronic Coronary Syndrome Patients into the 21st Century: A Review

Although medical therapy is the preferred first-line treatment for patients with chronic coronary syndrome (CCS), revascularization remains an important consideration. We present a review that identifies the three diagnostic technologies most important to guiding the decision to revascularize patients with CCS: (1) cardiac computed tomography, (2) intracoronary imaging, and (3) lesion-specific physiological guidance.

Molecular and Nonmolecular Imaging of Macrophages in Atherosclerosis

Atherosclerosis is a major cause of ischemic heart disease, and the increasing medical burden associated with atherosclerotic cardiovascular disease has become a major public health concern worldwide. Macrophages play an important role in all stages of the dynamic progress of atherosclerosis, from its initiation and lesion expansion increasing the vulnerability of plaques, to the formation of unstable plaques and clinical manifestations. Early imaging can identify patients at risk of coronary atherosclerotic disease and its complications, enabling preventive measures to be initiated. Recent advances in molecular imaging have involved the noninvasive and semi-quantitative targeted imaging of macrophages and their related molecules in vivo, which can detect atheroma earlier and more accurately than conventional imaging. Multimodal imaging integrates vascular structure, function, and molecular imaging technology to achieve multi-dimensional imaging, which can be used to comprehensively evaluate blood vessels and obtain clinical information based on anatomical structure and molecular level. At the same time, the rapid development of nonmolecular imaging technologies, such as intravascular imaging, which have the unique advantages of having intuitive accuracy and providing rich information to identify macrophage inflammation and inform targeted personalized treatment, has also been seen. In this review, we highlight recent methods and research hotspots in molecular and nonmolecular imaging of macrophages in atherosclerosis that have enormous potential for rapid clinical application.

Association between coronary artery calcium score and stent expansion in percutaneous coronary intervention

BACKGROUND

Measurement of the coronary artery calcification score using multidetector computed tomography (MDCT) is a useful noninvasive test for the diagnosis of coronary artery disease. However, whether pre-intervention assessment of the target vessel coronary artery calcification (TV-CAC) score is associated with stent expansion failure and future target lesion revascularization (TLR), remains unknown. This study aimed to determine the association between the TV-CAC score measured by MDCT and stent expansion rate in patients who underwent IVUS-guided PCI for stable angina.

METHODS

We conducted a retrospective observational study including 135 consecutive patients (186 target lesions) who underwent MDCT and were scheduled for the first PCI. The patients were divided into 2 groups based on the median value of the TV-CAC score. The primary outcome was the stent expansion rate measured by IVUS after stent implantation. The secondary outcome was TLR within 1 year.

RESULTS

Stent expansion rate was associated with the TV-CAC score (p < 0.001). According to the ROC curve analysis, the TV-CAC score had the largest area under the curve (AUC) for the stent expansion area of 0.90 (AUC = 0.893, p < 0.001). The TV-CAC score was a positive predictor for stent expansion rate of <90% (odds ratio: 7.54, p < 0.001). Mediation analysis showed that stent under-expansion was a mediator of the association between high TV-CAC and TLR.

CONCLUSIONS

Our study demonstrates that pre-intervention assessment of TV-CAC using MDCT is a predictor of stent expansion. The TV-CAC score might predict the complexity and help in the PCI operative strategy.

Multi-modality intravascular imaging for guiding coronary intervention and assessing coronary atheroma: the Novasight Hybrid IVUS-OCT system

Intravascular imaging has evolved alongside interventional cardiology as an adjunctive tool for assessing plaque pathology and for guiding and optimising percutaneous coronary intervention (PCI) in challenging lesions. The two modalities which have dominated the field are intravascular ultrasound (IVUS), which relies on sound waves and optical coherence tomography (OCT), relying on light waves. These approaches however have limited efficacy in assessing plaque morphology and vulnerability that are essential for guiding PCI in complex lesions and identifying patient at risk that will benefit from emerging therapies targeting plaque evolution. These limitations are complementary and, in this context, it has been recognised and demonstrated in multi-modality studies that the concurrent use of IVUS and OCT can help overcome these deficits enabling a more complete and accurate plaque assessment. The Conavi Novasight Hybrid IVUS-OCT catheter is the first commercially available device that is capable of invasive clinical coronary assessment with simultaneously acquired and co-registered IVUS and OCT imaging. It represents a significant evolution in the field and is expected to have broad application in clinical practice and research. In this review article we present the limitations of standalone intravascular imaging techniques, summarise the data supporting the value of multimodality imaging in clinical practice and research, describe the Novasight Hybrid IVUS-OCT system and highlight the potential utility of this technology in coronary intervention and in the study of atherosclerosis.

Outcomes of optical coherence tomography compared with intravascular ultrasound and with angiography to guide coronary stent implantation: one-year results from the ILUMIEN III: OPTIMIZE PCI trial

AIMS

In the ILUMIEN III trial, among 450 randomised patients with non-complex lesions undergoing percutaneous coronary intervention (PCI), optical coherence tomography (OCT) guidance led to greater stent expansion than angiography guidance, similar minimal stent area compared to both intravascular ultrasound (IVUS) guidance and angiography guidance, and lower rates of uncorrected dissection and malapposition than both IVUS guidance and angiography guidance. Whether these differences impact on clinical outcomes is unknown. The aim of the present study was to report the 12-month clinical follow-up data from the ILUMIEN III study.

METHODS AND RESULTS

OCT-guided PCI, using an external elastic lamina-based protocol, was compared to operator-directed IVUS-guided or angiography-guided PCI. Target lesion failure (TLF) and major adverse cardiovascular events (MACE) at 12 months were adjudicated by a blinded clinical events committee. There were no significant differences in the rates of TLF (2.0% OCT, 3.7% IVUS, 1.4% angiography), MACE (9.8% OCT, 9.1% IVUS, 7.9% angiography), or any of the individual components of these outcomes among the groups. No independent predictors of 12-month stent-related clinical events were identified from final OCT.

CONCLUSIONS

In this underpowered study, OCT-guided PCI of non-complex lesions did not show a statistical difference in clinical outcomes at 12 months compared with IVUS or angiography guidance. An appropriately powered trial, including only complex patients and lesions, is underway to substantiate the potential clinical benefit of OCT-guided PCI.

TRIAL REGISTRATION

NCT02471586.

The assessment of intermediate coronary lesions using intracoronary imaging

Intermediate coronary artery stenosis, defined as visual angiographic stenosis severity of between 30-70%, is present in up to one quarter of patients undergoing coronary angiography. Patients with this particular lesion subset represent a distinct clinical challenge, with operators often uncertain on the need for revascularization. Although international guidelines appropriately recommend physiological pressure-based assessment of these lesions utilizing either fractional flow reserve (FFR) or quantitative flow ratio (QFR), there are specific clinical scenarios and lesion subsets where the use of such indices may not be reliable. Intravascular imaging, mainly utilizing intravascular ultrasound (IVUS) and optical coherence tomography (OCT) represents an alternate and at times complementary diagnostic modality for the evaluation of intermediate coronary stenoses. Studies have attempted to validate these specific imaging measures with physiological markers of lesion-specific ischaemia with varied results. Intravascular imaging however also provides additional benefits that include portrayal of plaque morphology, guidance on stent implantation and sizing and may portend improved clinical outcomes. Looking forward, research in computational fluid dynamics now seeks to integrate both lesion-based physiology and anatomical assessment using intravascular imaging. This review will discuss the rationale and indications for the use of intravascular imaging assessment of intermediate lesions, while highlighting the current limitations and benefits to this approach.

Intravascular ultrasound to guide left main stem intervention: a NOBLE trial substudy

AIMS

We aimed to investigate the association between the use and findings of IVUS with clinical outcomes in the PCI arm of a randomised trial of LMS PCI.

METHODS AND RESULTS

The NOBLE trial randomised patients with LMS disease to treatment by PCI or CABG. Of 603 patients treated by PCI, 435 (72%) underwent post-PCI IVUS assessment, 224 of which were analysed in a core laboratory. At five years, the composite of MACCE was 18.9% if post-PCI IVUS was performed versus 25.0% if it was not performed (p=0.45, after adjustment). Overall repeat revascularisation was not reduced (10.6% vs 16.5%, p=0.11); however, LMS TLR was (5.1% vs 11.6%, p=0.01) if IVUS was used. For comparison of stent expansion, LMS MSA was split into tertiles. We found no significant difference in MACCE, death, myocardial infarction or stent thrombosis between tertiles. There was a significant difference between the lower and upper tertiles for repeat revascularisation (17.6% vs 5.2%, p=0.02) and LMS TLR (12.2% vs 0%, p=0.002).

CONCLUSIONS

Post-PCI IVUS assessment and adequate stent expansion are not associated with reduced MACCE; however, there is an association with reduced LMS TLR. The use of intracoronary imaging to prevent stent underexpansion in LMS PCI is likely to improve outcomes.

Associations of coronary plaque characteristics by integrated backscatter intravascular ultrasound with detectability of vessel external elastic lamina using optical frequency domain imaging in human coronary arteries: A sub-analysis of the MISTIC-1 trial

OBJECTIVES

We sought to examine associations between plaque characteristics by intravascular ultrasound (IVUS) and detectability of external elastic lamina (EEL) by optical frequency domain imaging (OFDI) in human coronary arteries.

BACKGROUND

It is often challenging to detect EEL which represents vessel size by light-based imaging modalities due to light intensity attenuation through atherosclerotic plaque.

METHODS

IVUS and OFDI prior to stent implantation were sequentially investigated per protocol. We identified corresponding cross-sections by minimum lumen area (MLA) or just distally to side branches as anatomical landmarks. Plaque characterization was determined by integrated backscatter IVUS analysis. We categorized detectable EEL arc by OFDI into four groups: 0≤ and <1 quadrant (group 1), 1≤ and <2 quadrants (group 2), 2≤ and <3 quadrants (group 3), or 3≤ and <4 quadrants (group 4).

RESULTS

We prospectively studied 103 vessels in 93 patients with stable coronary artery disease. Corresponding 711 cross-sections were analyzed. Cross-sections with detectable EEL arc <2 quadrants (group 1 or 2) were observed in 86.1% of MLA sites but only in 29.3% of non-MLA sites (p < .05). Percentage plaque area (%PA) appeared to be the strongest predictor to detect EEL arc <2 quadrants with the cut-off of 60.3% (AUC 0.90; sensitivity 79.8%, specificity 85.5%). Lipid pool and calcification remained statistically significant in predicting detectable EEL arc <2 quadrants after adjustment with %PA.

CONCLUSIONS

Presence of large plaque burden, lipid pool, and calcification significantly predicts the detectability of EEL by OFDI assessment. Locations with detectable EEL arc <2 quadrants should thus be avoided for optimal stent landing zone.

Intracoronary Optical Coherence Tomography 2018: Current Status and Future Directions

The advent of intravascular imaging has been a significant advancement in visualization of coronary arteries, particularly with optical coherence tomography (OCT) that allows for high-resolution imaging of intraluminal and transmural coronary structures. Accumulating data support a clinical role for OCT in a multitude of clinical scenarios, including assessing the natural history of atherosclerosis and modulating effects of therapies, mechanisms of acute coronary syndromes, mechanistic insights into the effects of novel interventional devices, and optimization of percutaneous coronary intervention. In this state-of-the-art review, we provide an overview of the published data on the clinical utility of OCT, highlighting the areas that need further investigation and the current barriers for further adoption of OCT in interventional cardiology practice.

In Vivo Near-Infrared Fluorescence Imaging of Atherosclerosis Using Local Delivery of Novel Targeted Molecular Probes

This study aimed to evaluate the feasibility and accuracy of a technique for atherosclerosis imaging using local delivery of relatively small quantities (0.04-0.4 mg/kg) of labeled-specific imaging tracers targeting ICAM-1 and unpolymerized type I collagen or negative controls in 13 rabbits with atheroma induced by balloon injury in the abdominal aorta and a 12-week high-cholesterol diet. Immediately after local infusion, in vivo intravascular ultrasonography (IVUS)-NIRF imaging was performed at different time-points over a 40-minute period. The in vivo peak NIRF signal was significantly higher in the molecular tracer-injected rabbits than in the control-injected animals (P < 0.05). Ex vivo peak NIRF signal was significantly higher in the ICAM-1 probe-injected rabbits than in controls (P = 0.04), but not in the collagen probe-injected group (P = 0.29). NIRF signal discrimination following dual-probe delivery was also shown to be feasible in a single animal and thus offers the possibility of combining several distinct biological imaging agents in future studies. This innovative imaging strategy using in vivo local delivery of low concentrations of labeled molecular tracers followed by IVUS-NIRF catheter-based imaging holds potential for detection of vulnerable human coronary artery plaques.

Imaging during percutaneous coronary intervention for optimizing outcomes

Angiography is the current gold standard for imaging during percutaneous coronary interventions but has significant limitations. Catheter-based intravascular imaging techniques such as intravascular ultrasound and the more recent optical coherence tomography have the potential to overcome these limitations and thus optimize clinical outcomes. In this update, we discussed the current applications of the available imaging techniques, existing evidence, continuing unmet needs, and potential areas for further research.

Safety and efficacy of frequency-domain optical coherence tomography in evaluating and treating intermediate coronary lesions

AIM

To establish whether frequency-domain optical coherence tomography (FD-OCT) is safe and effective in the evaluation and treatment of angiographically-intermediate coronary lesions (ICL)

METHODS

Sixty-four patients with 2-dimensional quantitative coronary angiography (2D-QCA) demonstrating ICL were included. OCT imaging was performed. According to predetermined OCT criteria, patients were assigned to either of 2 groups: OCT-guided percutaneous coronary intervention (PCI) or OCT-guided optimal medical therapy (OMT). The primary efficacy endpoint was to demonstrate the superiority and higher accuracy of FD-OCT compared to 2D-QCA in evaluating stenosis severity in patients with ICL. The primary safety endpoint was the incidence of 30-d major adverse cardiac events (MACE). Secondary endpoints included MACE at 12 mo and other clinical events.

RESULTS

Analysis of the primary efficacy endpoint demonstrates that 2D-QCA overestimates the stenosis severity of ICL in both the OCT-guided PCI and OMT groups, proving FD-OCT to be superior to and more precise than 2D-QCA in treating this subset of lesions. The primary safety endpoint was fully met with the incidence of 30-d MACE being nil in both the OCT-guided PCI and OCT-guided OMT groups. Incidences of secondary endpoints were found to be low in both arms, the only exception being the relatively high incidence of recurrent episodes of angina which was, however, very similar in the 2 groups.

CONCLUSION

FD-OCT is safe and effective in the evaluation and treatment of ICL. Larger studies are needed to firmly establish the efficacy and safety of FD-OCT in treating ICL across all coronary artery disease population subgroups.

Association Between TG-to-HDL-C Ratio and In-Stent Stenosis Under Optical Coherence Tomography Guidance

We determined the relevance between the TG-to-HDL-C ratio and stent restenosis. Ninety-nine patients with in-stent stenosis (ISR) who were admitted to An Zhen Hospital in Beijing between April 2014 and June 2017 were selected. At the same time, 122 patients with coronary stenosis <50% were selected. All patients were tested for TG, HDL-C, and TG/HDL-C ratio. Optical coherence tomography (OCT) can assess microscopic status in all ISR patients. The proportion of male and Diabetic patients were significantly higher for ISR. There were differences in the prevalence of cigarette smokers among the different tissue types, among which the layered tissue type accounted for the highest proportion. In logistic regression analysis the study showed that male, diabetes mellitus, and the TG/HDL-C ratio are risk factors for ISR. The ISR ROC was 0.725 based on the TG/HDL-C ratio diagnosis. It is related to the degree of coronary stenosis and effective in diagnosing in-stent stenosis in ISR.

Validation of a Novel System for Co-Registration of Coronary Angiographic and Intravascular Ultrasound Imaging

INTRODUCTION

Intravascular ultrasound (IVUS) is a useful adjunct to guide percutaneous coronary intervention (PCI). Correlating IVUS images with angiographic findings can be challenging. We evaluated the utility of a novel co-registration system for IVUS and coronary angiography.

METHODS AND RESULTS

A 3-D virtual catheter trajectory was constructed from separate angiographic imaging runs using bespoke software. Intravascular ultrasound images were obtained using a commercially available mechanical rotational transducer with motorized pullback. Co-registration of ultrasound and angiographic images was then performed retrospectively based on the length of pullback, the 3-D trajectory and the start position of the catheter. Validation was performed in a spherical phantom model and in vivo in the coronary circulation of patients undergoing coronary angiography and intravascular imaging for clinical purposes. 111 paired angiographic and IVUS runs were performed in 3 phantom models. The differences between the reference length and the length measured on the 3D reconstructed path was -0.01 ± 0.40 mm. Intra-observer variability was 0.4%. We enrolled 25 patients in 3 European hospitals and performed 35 co-registration attempts with an 86% success rate. 71 landmarks were selected by the first operator, 68 by the second. Differences between angiographic and IVUS landmarks were -0.22 ± 0.72 mm and 0.05 ± 1.01 mm, respectively. Inter-observer variability was 0.23 ± 0.63 mm.

CONCLUSION

We present a novel method for the co-registration of IVUS and coronary angiographic images. This system performed well in a phantom model and using images obtained from the human coronary circulation.

CLASSIFICATIONS

Innovation, intravascular ultrasound, other technique.

Percutaneous Left Main Coronary Intervention: A Review of Plaque Modification in Left Main Percutaneous Coronary Intervention

Left main coronary artery (LMCA) stenosis has long been recognized as a marker of increased morbidity and mortality. Current treatment algorithms for LMCA stenosis consider both percutaneous coronary intervention (PCI) with drug eluting stents (DES) and coronary bypass surgery, each with advantages based on individual patient characteristics. Since the LMCA is the largest artery in the coronary tree, plaque volume and calcification is greater than other coronary segments and often extends to the distal bifurcation segment. In LMCA bifurcation lesions, larger minimal stent area is strongly associated with better outcome in the DES era. Plaque modification strategies such as rotational, orbital, or laser atherectomy are effective mechanisms to reduce plaque volume and alter compliance, facilitating stent delivery and stent expansion. We present a case of a calcified, medina class 1,1,1 LMCA lesion where intravascular ultrasound (IVUS) and orbital atherectomy were employed for optimal results. In this context, we review the evidence of plaque modification devices and the rationale for their use in unprotected left main PCI.

Impact and trends of intravascular imaging in diagnostic coronary angiography and percutaneous coronary intervention in inpatients in the United States

BACKGROUND

Intravascular imaging with intravascular ultrasound (IVUS) and optical coherence tomography (OCT) is an important adjunct to invasive coronary angiography.

OBJECTIVES

The primary objective was to examine the frequency of intravascular coronary imaging, trends in imaging use, and outcomes of patients undergoing angiography and/or percutaneous coronary intervention (PCI) in the United States.

METHODS

Adult patients ≥18 years of age undergoing in-hospital cardiac catheterization from January 2004 to December 2014 were identified from the National Inpatient Sample (NIS). International Classification of Diseases, Ninth Revision (ICD-9) diagnosis and procedure codes were used to identify IVUS and OCT use during diagnostic angiography and PCI.

RESULTS

Among 3,211,872 hospitalizations with coronary angiography, intracoronary imaging was performed in 88,775 cases (4.8% of PCI and 1.0% of diagnostic procedures), with IVUS in 98.9% and OCT in 1.1% of cases. Among patients undergoing PCI, the rate of intravascular coronary imaging increased from 2.1% in 2004-2005 to 6.6% in 2013-2014 (P < 0.001 for trend). Use of intravascular coronary imaging was associated with lower in-hospital mortality in patients undergoing PCI (adjusted OR 0.77; 95% CI 0.71-0.83). There was marked variability in intravascular imaging by hospital, with 63% and 13% of facilities using intravascular imaging in <5% and >15% of PCIs, respectively.

CONCLUSIONS

In a large administrative database from the United States, intravascular imaging use was low, increased over time, and imaging was associated with reduced in-hospital mortality. Substantial variation in the frequency of intravascular imaging by hospital was observed. Additional investigation to determine clinical benefits of IVUS and OCT are warranted.

Intravascular ultrasound-guided drug-eluting stent implantation is associated with improved clinical outcomes in patients with unstable angina and complex coronary artery true bifurcation lesions

Stenting coronary artery bifurcation lesion is associated with suboptimal clinical results. Clinical improvement by intravascular ultrasound (IVUS) guided bifurcation stenting is controversial because small-side-branch (SB), low-risk patients and false bifurcations were included in previous studies that had no exact IVUS criteria for optimal stent expansion. We sought determine whether IVUS guidance is superior to angiography guidance for patients with true and complex bifurcation lesions. Between July 2006 and July 2012, 1465 patients with unstable angina and Medina 1,1,1 or 0,1,1 coronary bifurcation lesions were prospectively studied. 310 patients in the IVUS guidance (defined as stent symmetry index > 0.7, stent expansion index > 0.9, well apposition, and no Type B/C dissection) group were paired with 620 patients in the angiography group by propensity score-matching. The primary endpoint was the rate of composite major adverse cardiac events (MACE) (cardiac death, myocardial infarction (MI), or clinically-driven target vessel revascularization) at 1-year and at the end of study after indexed procedure. Use of IVUS guidance was mainly driven by stenting technique selection and identification of lesions' specificities. IVUS criteria for optimal stent expansion were achieved in 82.9% of patients which contribute to IVUS group data assessment and the rest did not meet optimal criteria. MACE occurred in 10.0% of patients at 1-year follow-up and 15.2% at the 7-year follow-up in the IVUS group, significantly different from 15.0% (p = 0.036) and 22.4% (p = 0.01) in the angiography group, respectively. Compared to angiography guidance, IVUS guidance also resulted in a lower 7-year cardiac death rate (6.5 versus 1.3%, p = 0.002) and MI (8.4 versus 2.3%, P < 0.001). Any revascularization was also statistically lower in the IVUS group through whole study period, compared to the angiography group. Lower MACE rates were observed in IVUS guidance group in a 7-year follow-up compared with angiography guidance alone.