Carina: A major determinant in the pathophysiology and treatment of coronary bifurcation lesions

Over the last decade, several in vivo and computational investigations have significantly advanced our understanding of the pathophysiology of coronary bifurcations, contributing to the enhancement of their percutaneous revascularization. The carina of the coronary bifurcations plays a substantial role in generating their main hemodynamic features, including distinctive flow patterns with secondary flows and specific shear stress patterns. These factors play a pivotal role in determining the susceptibility, development, and progression of atherosclerosis. The underlying pathophysiological mechanisms of atherosclerosis in coronary bifurcations are complex and multifactorial. Understanding these mechanisms is fundamental to comprehending lesions at the bifurcation level and informing future treatment strategies. This review aims to present the currently available data regarding the pathophysiological and prognostic role of the carina in coronary bifurcations, offering an interpretation of these findings from the perspective of interventional cardiologists, providing valuable insights for their clinical practice.

T and Small Protrusion (TAP) Technique in Bifurcations: Coronary Artery Disease in Acute Myocardial Infarction Patients after COVID-19 Pneumonia

Ischemic coronary artery disease in all its forms remains the main cause of death worldwide. Coronary artery bifurcation lesions are a challenge because of their complexity and possible complications. The goal of treating bifurcation lesions is the optimal revascularization of the main vessel without compromising the side branch. Although the study of bifurcation stenting aims to keep the side branch viable, the outcomes regarding major acute cardiovascular events and survivability are related to the optimal treatment of the main vessel. There are many trials that have tried to evaluate the best technique to use with respect to bifurcation lesions, and early studies support provisional stenting as the election treatment. More recent trials highlighted the superior outcomes of the double kissing crush technique used on unprotected distal left main bifurcation lesions. In patients with acute myocardial infarction, two-stent techniques were avoided because of the prolonged procedural time in unstable patients, with high risks of complications. We present the case of a 53-year-old woman with multiple cardiovascular risk factors (dyslipidemia, hypertension, active cancer, post-COVID-19 state) and acute antero-lateral myocardial infarction who underwent primary coronary intervention with the use of the TAP technique for stenting the bifurcation culprit coronary lesion (left anterior descendent artery and first diagonal artery).

The 17th expert consensus document of the European Bifurcation Club - techniques to preserve access to the side branch during stepwise provisional stenting

Provisional stenting has become the default technique for the treatment of most coronary bifurcation lesions. However, the side branch (SB) can become compromised after main vessel (MV) stenting and restoring SB patency can be difficult in challenging anatomies. Angiographic and intracoronary imaging criteria can predict the risk of side branch closure and may encourage use of side branch protection strategies. These protective approaches provide strategies to avoid SB closure or overcome compromise following MV stenting, minimising periprocedural injury. In this article, we analyse the strategies of SB preservation discussed and developed during the most recent European Bifurcation Club (EBC) meetings.

Impact of coronary bifurcation angle on the pathogenesis of atherosclerosis and clinical outcome of coronary bifurcation intervention-A scoping review

BACKGROUND

A coronary bifurcation stenting is still a challenging issue due to frequent restenosis and stent thrombosis even with drug-eluting stents. The bifurcation angle (BA) between a main vessel and a side branch is one of the crucial determinants of coronary flow and shear stress that affect the plaque distribution. Previous bench and clinical studies have evaluated the impact of the BA between the proximal main vessel and the side branch (Angle A) and the BA between the distal main vessel and the side branch (Angle B) on the clinical outcomes of bifurcation stenting. However, the impact has not yet been fully elucidated due to a lack of statistical power or different manner of the assessment of BA.

OBJECTIVES

To analyze the published studies on coronary artery BA, the modalities used for assessment, and the impact of BA on interventions and attempt to define the pre-procedural protocols.

DATA SOURCES

A scoping review was performed using the Joanna Briggs Institute Methodology. A total of 52 relevant references were selected from PubMed, Cochrane Library, and CINAHL databases and categorized into three topic areas.

RESULTS AND CONCLUSIONS

A wider Angle A is associated with the increased likelihood of carina shift and a wider Angle B, with that of side branch occlusion. A wider Angle B promotes stent malapposition and deformation in the side branch ostium and has been reported as an independent predictor of major adverse cardiac events after bifurcation stenting; however, improvement of the drug-eluting stent, refinement of the stenting technique, and accurate 3-dimensional assessment may attenuate the adverse clinical impact of a wider BA.

IMPLICATIONS OF KEY FINDINGS

Assessment of the BA is necessary to predict the effect of bifurcation intervention procedure on the stent configuration and coronary flow at the bifurcated vessels. This will help to optimize stent selection and the stenting technique.

Percutaneous coronary intervention of bifurcation lesions

Bifurcation coronary artery disease is common as the development of atherosclerosis is facilitated by altered endothelial shear stress. Multiple anatomical and physiological factors need to be considered when treating bifurcation lesions. To achieve optimal results, various stenting techniques have been developed, each with benefits and limitations. In this state-of-the-art review we describe technically important characteristics of bifurcation lesions and summarise the evidence supporting contemporary bifurcation techniques.

Fundamentals of percutaneous coronary bifurcation interventions

Coronary bifurcation lesions (CBLs) account for 15%-20% of all percutaneous coronary interventions. The complex nature of these lesions is responsible for poorer procedural, early and late outcomes. This complex lesion subset has received great attention in the interventional cardiac community, and multiple stenting techniques have been developed. Of these, the provisional stenting technique is most often the default strategy; however, the elective double stenting (EDS) technique is preferred in certain subsets of complex CBLs. The double kissing crush technique may be the preferred EDS technique because of its efficacy and safety in comparative trials; however, this technique consists of many steps and requires training. Many new methods have recently been added to the EDS techniques to provide better stent scaffolding and to reduce early and late adverse outcomes. Intravascular imaging is necessary to determine the interventional strategy and postinterventional results. This review discusses the basic concepts, contemporary percutaneous interventional technical approaches, new methods, and controversial treatment issues of CBLs.

Feasibility, reproducibility and characteristics of coronary bifurcation type assessment by three-dimensional optical coherence tomography

Aim

To investigate the characteristics of coronary artery bifurcation type (parallel or perpendicular type) using three-dimensional (3D) optical coherence tomography (OCT), and determine the feasibility, reproducibility, assessment time and correlation with bifurcation angles measured by 3D quantitative coronary angiography (QCA).

Methods and results

We evaluated 60 lesions at the coronary bifurcation that were treated by main vessel (MV) stenting with kissing balloon inflation (KBI) under OCT/optical frequency domain imaging (OFDI) guidance. Inter- and intra-observer agreement regarding the assessment of 3D bifurcation types were 0.88 and 0.94, respectively. The assessment times of 3D-OCT bifurcation type with OCT and OFDI were within about 30 seconds. 3D-OCT bifurcation types showed the greatest correlation with the distal bifurcation angle assessed by 3D-QCA among the three bifurcation angles (distal bifurcation angle, proximal bifurcation angle and main vessel angle), and the optimal cut-off distal bifurcation angle to predict a perpendicular type bifurcation, as determined by ROC analysis, was 51.0° (AUC 0.773, sensitivity 0.80, specificity 0.67). Based on this cut-off value for the distal bifurcation angle (51°), the diagnostic accuracy for perpendicular type bifurcation in cases with a BA ≥ 51° (n = 34) was 70.6% (24/34) and that of the parallel type bifurcation in cases of BA < 51° (n = 26) was 76.9% (20/26).

Conclusion

Performing 3D-OCT for assessment of coronary artery bifurcation type is feasible and simple, and can be done in a short time with high reproducibility.

Noncalcified plaque burden quantified from coronary computed tomography angiography improves prediction of side branch occlusion after main vessel stenting in bifurcation lesions: results from the CT-PRECISION registry

OBJECTIVES

To assess the incremental value of quantitative plaque features measured from computed tomography angiography (CTA) for predicting side branch (SB) occlusion in coronary bifurcation intervention.

METHODS

We included 340 patients with 377 bifurcation lesions in the post hoc analysis of the CT-PRECISION registry. Each bifurcation was divided into three segments: the proximal main vessel (MV), the distal MV, and the SB. Segments with evidence of coronary plaque were analyzed using semi-automated software allowing for quantitative analysis of coronary plaque morphology and stenosis. Coronary plaque measurements included calcified and noncalcified plaque volumes, and corresponding burdens (respective plaque volumes × 100%/vessel volume), remodeling index, and stenosis.

RESULTS

SB occlusion occurred in 28 of 377 bifurcation lesions (7.5%). The presence of visually identified plaque in the SB segment, but not in the proximal and distal MV segments, was the only qualitative parameter that predicted SB occlusion with an area under the curve (AUC) of 0.792. Among quantitative plaque parameters calculated for the SB segment, the addition of noncalcified plaque burden (AUC 0.840, p = 0.003) and low-density plaque burden (AUC 0.836, p = 0.012) yielded significant improvements in predicting SB occlusion. Using receiver operating characteristic curve analysis, optimal cut-offs for noncalcified plaque burden and low-density plaque burden were > 33.6% (86% sensitivity and 78% specificity) and > 0.9% (89% sensitivity and 73% specificity), respectively.

CONCLUSIONS

CTA-derived noncalcified plaque burden, when added to the visually identified SB plaque, significantly improves the prediction of SB occlusion in coronary bifurcation intervention.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03709836 registered on October 17, 2018.

[Hot issues in bifurcation lesions PCI in 2019]

Coronary bifurcations are involved in 15-20% of all percutaneous coronary interventions (PCI) and remain one of the most challenging lesions in interventional cardiology in terms of procedural success rate as well as long-term cardiac events. The optimal management of bifurcation lesions is still debated but involves careful assessment, planning and a sequential provisional approach. The preferential strategy for PCI of bifurcation lesions remains to use main vessel (MV) stenting with a proximal optimisation technique (POT) and provisional side branch (SB) stenting as a preferred approach. Final kissing balloon inflation is not recommended in all cases. In the minority of lesions where two stents are required, careful deployment and optimal expansion are essential to achieve a long-term result. Intracoronary imaging techniques (IVUS, OCT) and FFR are useful endovascular tools to achieve optimal results.

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.

Assessment of intracoronary stent location and extension in intravascular ultrasound sequences

PURPOSE

An intraluminal coronary stent is a metal scaffold deployed in a stenotic artery during percutaneous coronary intervention (PCI). In order to have an effective deployment, a stent should be optimally placed with regard to anatomical structures such as bifurcations and stenoses. Intravascular ultrasound (IVUS) is a catheter-based imaging technique generally used for PCI guiding and assessing the correct placement of the stent. A novel approach that automatically detects the boundaries and the position of the stent along the IVUS pullback is presented. Such a technique aims at optimizing the stent deployment.

METHODS

The method requires the identification of the stable frames of the sequence and the reliable detection of stent struts. Using these data, a measure of likelihood for a frame to contain a stent is computed. Then, a robust binary representation of the presence of the stent in the pullback is obtained applying an iterative and multiscale quantization of the signal to symbols using the Symbolic Aggregate approXimation algorithm.

RESULTS

The technique was extensively validated on a set of 103 IVUS of sequences of in vivo coronary arteries containing metallic and bioabsorbable stents acquired through an international multicentric collaboration across five clinical centers. The method was able to detect the stent position with an overall F-measure of 86.4%, a Jaccard index score of 75% and a mean distance of 2.5 mm from manually annotated stent boundaries, and in bioabsorbable stents with an overall F-measure of 88.6%, a Jaccard score of 77.7 and a mean distance of 1.5 mm from manually annotated stent boundaries. Additionally, a map indicating the distance between the lumen and the stent along the pullback is created in order to show the angular sectors of the sequence in which the malapposition is present.

CONCLUSIONS

Results obtained comparing the automatic results vs the manual annotation of two observers shows that the method approaches the interobserver variability. Similar performances are obtained on both metallic and bioabsorbable stents, showing the flexibility and robustness of the method.

Optical coherence tomography to guide percutaneous treatment of coronary bifurcation disease

INTRODUCTION

Cardiovascular disease remains the most common cause of death worldwide. Enormous progress in the technology and applicability of percutaneous techniques to treat obstructive coronary heart disease has been made, and the number of percutaneous coronary interventions (PCI) is increasing. Coronary bifurcations are involved in a substantial number of PCIs and despite recent advances, bifurcation PCI remains a challenge in terms of immediate success and long-term outcome. Angiography has a limited capacity for showing important features of the 3 dimensional coronary vessel anatomy, position of stent struts and exact wire positions and is therefore suboptimal for guiding bifurcation PCI. Intracoronary optical coherence tomography (OCT) provides high resolution and the information gained during PCI is unprecedented compared with angiography guidance and intravascular ultrasound. Areas covered: This review will provide an overview of the use of OCT to guide bifurcation-PCI. Expert commentary: OCT is a promising guide for bifurcation-PCI at each individual step: from planning the strategy (provisional versus two-stent strategy), to guidance during PCI, and finally checking the interventional result. Until dedicated randomized trails are complete, we recommend OCT guidance for interventions in complex coronary bifurcation disease and for imaging when unexpected procedural events occur.

Bifurcation lesions involved in the recanalization process of coronary chronic total occlusions: Incidence, treatment and clinical implications

BACKGROUND

The presence of a bifurcation (BL) in the context of a coronary chronic total occlusion (CTO) represents an additional difficulty. This study analyzes the incidence of BLs in CTO recanalization, the treatment, predictors of bifurcation technical success and their clinical impact.

METHODS AND RESULTS

BLs with a side branch (SB) ≥2.0mm located proximally, distally or within the occluded segment were observed in 130 (33%) of 391 CTO. Provisional stenting was the strategy more frequently used (94%). Bifurcation success (stenosis <30% in main vessel and TIMI flow III in both branches) was achieved in 105 patients (81%). In the remaining 25 (19%), the TIMI flow at the SB was <III. Predictors of bifurcation success were baseline SB wiring (OR 0.01, 95% CI: 0.001-0.09; p<0.01), the absence of dissection across the bifurcation (OR 0.10, 95% CI: 0.02-0.49; p<0.01) and non-true BLs (OR 0.16, 95% CI: 0.04-0.68; p<0.05). Regarding in-hospital results, patients with final TIMI flow <III at the SB had a higher incidence of periprocedural MI (32% vs 4.8%; p<0.01). Subsequently, the rate of MI was higher in patients with CTO-BLs than in those without BLs. At follow-up, there were no differences in the event rate between CTO-BLs and non CTO-BLs (7.7% vs 9.5%, p=ns) CONCLUSIONS: BLs in CTO is a frequent finding and could be approached as regular bifurcations. The primary success was low and this was associated with a higher incidence of periprocedural MI. Baseline SB wiring was a powerful predictor of technical success.

Plaque morphology predictors of side branch occlusion after provisional stenting in coronary bifurcation lesion: Results of optical coherence tomography bifurcation study (ORBID)

OBJECTIVES

The aim of this study was to identify the predictors of side branch (SB) ostial stenosis developed after provisional stenting of the main vessel (MV) using optical coherence tomography (OCT).

BACKGROUND

Provisional stenting remains the main approach to treatment of bifurcation lesions; however, it may result in the narrowing of SB ostium. There is little information about underlying plaque morphology of the MV lesion and its potential impact on the SB after provisional stenting.

METHODS

Patients with stable coronary disease with angiographic MV lesion not involving SB were included in a prospective single center study. The primary outcome was significant SB ostium stenosis (SBOS), defined as residual stenosis of >50% after MV stenting.

RESULTS

Thirty bifurcation lesions in 30 patients were analyzed in the study. Poststenting significant SBOS was observed in 30% of patients. The MV lesions with SBOS > 50% were characterized by a higher prevalence of lipid rich plaques (100 vs. 64%, p = 0.040) and spotty calcifications (60 vs. 0%, p = 0.005). Maximal lipid arcs were greater (257° vs. 132°, p = 0.001) and lipid volume index was higher (1380 vs. 574, p = 0.012) in the SBOS >50% group. Multivariate logistic regression analysis identified maximal lipid arc (odds ratio (OR): 1.014, p = 0.038) and the presence of lipid plaque contralateral to SB ostium (OR: 8.14, p = 0.046) before stenting as independent predictors of significant SBOS after PCI.

CONCLUSIONS

High lipid content of the MV lesion and a contralateral location of lipid in the bifurcation area may contribute to SBOS after provisional stenting. © 2016 Wiley Periodicals, Inc.

The story of plaque shift and carina shift

Side branch (SB) occlusion is one of the most serious complications of main vessel (MV) stenting. Although plaque shift has been considered the major mechanism of SB occlusion, recent studies have suggested carina shift to be the more important cause. Considering the recent pressure wire as well as intravascular ultrasonography studies, the relationship between carina shift and plaque shift in SB occlusion can be described as follows. The anatomical compromise of the SB after MV stenting is not as functionally significant as it appears, because it is mostly explained by carina shift, which is not the major cause of functional compromise. Superimposition of plaque shift over carina shift appears to be the mechanism of haemodynamically significant SB stenosis. Plaque is shifted mostly from the proximal MV, which explains why the plaque burden of the proximal MV is a significant risk factor of SB functional compromise or occlusion.

Diagnosis and Evaluation of Stent Thrombosis with Optical Coherence Tomography

Stent thrombosis (ST) is a rare complication of percutaneous coronary interventions (PCI), especially with drug-eluting stents. ST presents as acute myocardial infarction requiring emergent repeat PCI; optimal reperfusion occurs in two-thirds of patients. As a result, ST has been associated with a high mortality rate and a high rate of recurrent thrombosis. We discuss the use of optical coherence tomography (OCT) for the diagnosis and evaluation of ST. OCT-guided ST management seems a feasible, safe, and appropriate approach. Intracoronary assesses the efficacy of coronary thrombus removal procedures and detects the prevalent stent-related factor that caused ST.

Intracoronary optical coherence tomography: a review of clinical applications

Optical coherence tomography (OCT) is a light-based technology that provides very high spatial resolution images. OCT has been initially employed as a research tool to investigate plaque morphology and stent strut coverage. The introduction of frequency domain OCT allowing fast image acquisition during a prolonged contrast injection via the guiding catheter has made OCT applicable for guidance of coronary interventions. In this manuscript, the various applications of OCT are reviewed, from assessment of plaque vulnerability and severity to characteristics of unstable lesions and thrombus burden to stent optimization and evaluation of late results.

Characteristics of drug-eluting stent platforms potentially influencing bifurcated lesion provisional stenting procedure

AIMS

We aimed to review the technical characteristics of DES platforms which have been documented to influence bifurcation stenting procedures conducted according to the provisional approach.

METHODS AND RESULTS

DES platforms have remarkable technical differences (side cell diameter, shape, deformability, etc.). We reviewed the literature data and performed original virtual bench tests to highlight the characteristics of DES platforms which influence the following phases of bifurcation stenting conducted according to the provisional approach: stent implantation in the main vessel across side-branch take-off ("crossover" stenting), proximal optimisation technique, rewiring and kissing balloon inflation. Available data show that the response of different DES platforms to the various procedural steps of provisional stenting is different.

CONCLUSIONS

When treating bifurcated lesions according to the provisional stenting approach, the search for an ideal matching between individual bifurcated anatomy and DES selection should take into account an articulated series of technical parameters.

A novel method to assess coronary artery bifurcations by OCT: cut-plane analysis for side-branch ostial assessment from a main-vessel pullback

AIMS

In coronary bifurcations assessment, evaluation of side-branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch (MB) could speed up lesion evaluation and minimize contrast volume. Dedicated software that reconstructs the cross-sections perpendicular to the SB centreline could improve this assessment. We aimed to validate a new method for assessing the SB ostium from an OCT pullback performed in the MB.

METHODS AND RESULTS

Thirty-one sets of frequency-domain OCT pullbacks from 28 patients, both from the MB and the SB of a coronary artery bifurcation were analysed. Measurements of the SB ostium from the SB pullback were used as a reference. Measurements of the SB ostium from the MB pullback were then performed in a laboratory setting by (i) conventional analysis and (ii) cut-plane analysis, and the measurement error for each analysis was estimated. Correlations of SB ostium measurements acquired from the MB pullback in comparison with reference measurements acquired from the SB pullback were higher with cut-plane analysis compared with conventional analysis, albeit not reaching statistical significance (area: rcut-plane = 0.927 vs. rconventional = 0.870, P = 0.256; mean diameter: rcut-plane = 0.918 vs. rconventional = 0.788, P = 0.056; minimum diameter: rcut-plane = 0.841 vs. rconventional = 0.812, P = 0.734; maximum diameter: rcut-plane = 0.770 vs. rconventional = 0.635, P = 0.316). Cut-plane analysis was associated with lower absolute error than conventional analysis (area: 0.56 ± 0.45, vs. 1.50 ± 1.31 mm(2), P < 0.001; mean diameter: 0.18 ± 0.14 vs. 0.44 ± 0.30 mm, P < 0.001).

CONCLUSION

Measurements of SB ostium performed in a laboratory setting by cut-plane analysis of an OCT pullback of the main branch have high correlation with reference measurements performed in a SB OCT pullback and lower error compared with conventional analysis.

Nonangiographic assessment of coronary artery disease: a practical approach to optical coherence tomography and fractional flow reserve

In an era of increased scrutiny of the appropriateness and safety of revascularization, interventional cardiologists must evolve by adding key tools to their armamentarium. This review highlights the utility of optical coherence tomography and fractional flow reserve in the catheterization lab and provides a practical guide for using these technologies during coronary intervention in various lesion subsets. We propose that fractional flow reserve informs the decision to intervene and optical coherence tomography guides the optimization of the outcome.

Technical Aspects of Provisional Stenting in Percutaneous Treatment of Complex Bifurcation Lesions

Drug-eluting stent (DES) implantation using the 'provisional' approach is the gold standard for percutaneous treatment of patients with unselected bifurcated lesions. Nevertheless, many operators still consider the provisional approach unsuitable for coronary patients with complex bifurcation anatomies. Yet, the provisional approach may be so differently carried out that its procedural outcome is often unpredictable. Some technical refinements may help to anticipate or manage procedural difficulties, which may occur during the management of complex patients. We sought to overview the issues related with DES selection as well as some technical points, which may increase the effectiveness of provisional stenting. In particular, the DES characteristics influencing bifurcation interventions and the technical refinements, which may be considered during a provisional stenting procedure are discussed. Indeed, main vessel stent sizing, proximal optimisation, side branch protection modality, side branch rewiring, kissing balloon and side branch rescue techniques are all pivotal to increase the safety and efficacy of the provisional strategy especially in the setting of complex anatomies and patients.