Intravascular Ultrasound Classification of Plaque Distribution in Left Main Coronary Artery Bifurcations

State-of-the-art percutaneous coronary intervention for left main coronary artery disease in Japan

Percutaneous coronary intervention for left main coronary artery disease (LM-PCI) represents a high-risk yet life-saving procedure that has evolved significantly over the years. This review outlines the current state-of-the-art practices for LM-PCI in Japan in detail, emphasizing the integration of coronary physiology and intracoronary imaging alongside with evidence-based standardized technique using latest drug-eluting stents. These advancements enable precise lesion assessment, stent sizing, and optimal deployment, thereby enhancing procedural safety and efficacy. Despite discrepancies between current guidelines favoring coronary artery bypass grafting and real-world practice trends towards increased LM-PCI adoption, particularly in elderly populations with multiple comorbidities, careful patient selection and procedural planning are critical. Future perspectives include further refining LM-PCI through conducting randomized controlled trials integrating advanced techniques and addressing the issue of ostial left circumflex lesions and nationwide standardization of medical care for LM disease.

Is Coronary Physiology Assessment Valid in Special Circumstances?: Aortic Stenosis, Atrial Fibrillation, Left Ventricular Hypertrophy, and Other

Fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs) provide an important clinical tool to evaluate the hemodynamic significance of coronary lesions. However, these indices have major limitations. As these indices are meant to be surrogates of coronary flow, clinical scenarios such as aortic stenosis (with increased end-systolic and end-diastolic pressures) or atrial fibrillation (with significant beat-to-beat cardiac output variability) can have significant effect on the accuracy and reliability of these hemodynamic indices. Here, we provide a comprehensive evaluation of the pitfalls, limitations, and strengths of FFR and NHPRs in common clinical scenarios paired with coronary artery disease.

Optimal Minimal Stent Area and Impact of Stent Underexpansion in Left Main Up-Front 2-Stent Strategy

BACKGROUND

We previously reported the use of minimal stent area to predict angiographic in-stent restenosis after drug-eluting stent implantation for unprotected left main (LM) disease. We aimed to evaluate the optimal minimal stent area criteria for up-front LM 2-stenting based on long-term clinical outcomes.

METHODS

We identified 292 consecutive patients with LM bifurcation stenosis who were treated using the crush technique. The final minimal stent area was measured in the ostial left anterior descending artery (LAD), ostial left circumflex artery (LCX), and distal LM. The primary outcome was 5-year major adverse cardiac events, including all-cause death, myocardial infarction, and target lesion revascularization.

RESULTS

The minimal stent area cutoff values that best predicted the 5-year major adverse cardiac events were 11.8 mm2 for distal LM (area under the curve, 0.57; P=0.15), 8.3 mm2 for LAD ostium (area under the curve, 0.62; P=0.02), and 5.7 mm2 for LCX ostium (area under the curve, 0.64; P=0.01). Using these criteria, the risk of 5-year major adverse cardiac events was significantly associated with stent underexpansion in the LAD ostium (hazard ratio, 3.14; [95% CI, 1.23-8.06]; P=0.02) and LCX ostium (hazard ratio, 2.60 [95% CI, 1.11-6.07]; P=0.03) but not in the distal LM (hazard ratio, 0.81 [95% CI, 0.34-1.91]; P=0.63). Patients with stent underexpansion in both ostial LAD and LCX had a significantly higher rate of 5-year major adverse cardiac events than those with no or 1 underexpanded stent of either ostium (P<0.01).

CONCLUSIONS

Stent underexpansion in the LAD and LCX ostium was significantly associated with long-term outcomes in patients who underwent up-front 2-stenting for LM bifurcation stenosis.

Definitions and Standardized Endpoints for Treatment of Coronary Bifurcations

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

Long-Term Evaluation of Revascularization Strategies for Medina 0.1.0 Left Main Bifurcation Lesions: The LM-CROSSOVER Registry

The present study aimed to compare long-term outcomes of patients with Medina 0.1.0 left main (LM) bifurcation lesions treated by crossover stenting (COS) versus accurate ostial stenting (AOS). A total of 229 consecutive eligible patients with Medina 0.1.0 LM bifurcation lesions were enrolled and were stratified according to the stenting techniques. The primary end-point was major cardiovascular and cerebral events (MACCE), defined as the combination of all-cause death, target vessel related-myocardial infarction (MI), clinically driven target lesion revascularization (TLR), stroke, or stent thrombosis. COS and AOS were applied to 78 (34%) and 151 (66%) patients, respectively. During a mean of 40.6 ± 21.1 months of follow-up, the rate of MACCE (27.8 vs 12.8%; P=.007) was higher in patients treated with AOS than those treated with the COS technique, mainly driven by more frequent all-cause death (13.9 vs 3.8%, P = .013) and TLR (6.4 vs 15.9%; P = .029). In multivariable Cox regression analysis, AOS strategy was one of the independent predictors of MACCE (odds ratio: 2.166; 95% confidence interval, 1.080-4.340; P = .029). The current study suggests that COS was associated with a better long-term MACCE rate and lower all-cause mortality rate than AOS in patients with Medina 0.1.0 LM bifurcation disease.

Accelerated stenotic flow in the left anterior descending coronary artery explains the causes of impaired coronary flow reserve: an integrated transthoracic enhanced Doppler study

Background

Accelerated stenotic flow (AsF) in the entire left anterior descending coronary artery (LAD), assessed by transthoracic enhanced color Doppler (E-Doppler TTE), can reveal coronary stenosis (CS) and its severity, enabling a distinction between the microcirculatory and epicardial causes of coronary flow reserve (CFR) impairment.

Methods

Eighty-four consecutive patients with a CFR <2.0 (1.5 ± 0.4), as assessed by E-Doppler TTE, scheduled for coronary angiography (CA) and eventually intracoronary ultrasounds (IVUS), were studied. CFR was calculated by the ratio of peak diastolic flow velocities: during i.v. adenosine (140 mcg/Kg/m) over resting; AsF was calculated as the percentage increase of localized maximal velocity in relation to a reference velocity.

Results

CA showed ≥50% lumen diameter narrowing of the LAD (critical CS) in 68% of patients (57/84) vs. non-critical CS in 32% (27/84). Based on the established CA/IVUS criteria, the non-critical CS subgroup was further subdivided into 2 groups: subcritical/diffuse [16/27 pts (57%)] and no atherosclerosis [11/27 pts (43%)]. CFR was similar in the three groups: 1.4 ± 0.3 in critical CS, 1.5 ± 0.4 in subcritical/diffuse CS, and 1.6 ± 0.4 in no atherosclerosis (p = ns). Overall, at least one segment of accelerated stenotic flow in the LAD was found in 73 patients (87%), while in 11 (13%) it was not. The AsF was very predictive of coronary segmental narrowing in both angio subgroups of atherosclerosis but as expected with the usage of different cutoffs. On the basis of the ROC curve, the optimal cutoff was 109% and 16% AsF % increment to successfully distinguish critical from non-critical CS (area under the curve [AUC] = 0.99, p < 0.001) and diffuse/subcritical from no CS (AUC = 0.91%, p < 0.001). Sensitivity and specificity were 96% and 100% and 82% and 100%, respectively.

Conclusion

E-Doppler TTE is highly feasible and reliable in detecting the CS of any grade of severity, distinguishing epicardial athero from microvascular causes of a severe CFR reduction.

Percutaneous Treatment of Left Main Disease: A Review of Current Status

Percutaneous treatment of the left main coronary artery is one of the most challenging scenarios in interventional cardiology, due to the large portion of myocardium at risk the technical complexity of treating a complex bifurcation with large branches. Our aim is to provide un updated overview of the current indications for percutaneous treatment of the left main, the different techniques and the rationale underlying the choice for provisional versus upfront two-stent strategies, intravascular imaging and physiology guidance in the management of left main disease, and the role of mechanical support devices in complex high-risk PCI.

Bail-Out Techniques in Percutaneous Intervention for Ellis Grade III Coronary Perforation in Left Main Distal Bifurcation Lesions

The left main (LM) coronary artery stenosis is associated with high morbidity and mortality and has traditionally been treated with coronary artery bypass grafting. However, in recent years, advancements in device technology and adjunctive pharmacotherapy have led to the widespread use of percutaneous coronary intervention (PCI) as a treatment for unprotected LM lesions. Despite this, LM lesions are often complex, involving distal bifurcation and heavy calcification, which increases the risk of coronary perforation (CP) during PCI. In addition, the use of rotational or orbital atherectomy in severely calcified LM bifurcation lesions carries a higher risk of complications and in-hospital mortality than that in non-LM lesions. CP is a rare but potentially fatal complication of PCI, particularly in cases of Ellis grade III (CP-G3), with a high rate of cardiac tamponade and mortality. The management of CP-G3 in LM distal bifurcation lesions is challenging and requires specialized techniques. This article presents a flowchart of bail-out strategies for CP-G3 in LM distal bifurcation lesions and provides detailed procedures for each technique. Furthermore, we highlight the challenges and limitations of each technique, requiring careful management when CP-G3 occurs in LM distal bifurcation lesions.

Provisional Strategy for Left Main Stem Bifurcation Disease: A State-of-the-Art Review of Technique and Outcomes

Left main coronary artery (LMA) disease jeopardizes a large area of myocardium and increases the risk of major adverse cardiovascular events. LMCA disease is found in 5% to 7% of all diagnostic coronary angiographies, and more than 80% of the patients enrolled in recent large randomized controlled left main trials had distal left main bifurcation or trifurcation disease. Emerging clinical evidence from prospective all-comer registries and randomized trials has provided a solid basis for percutaneous coronary intervention as a treatment option in selected patients with unprotected LMCA disease; however, to date, no uniform recommendations as to optimal stenting strategy for LMCA bifurcation lesions exist. This review provides an overview of provisional stenting technique and escalation to 2-stent strategies in LMCA bifurcation lesions. Data from randomized controlled trials and registries are reviewed. Technical characteristics of optimal provisional LMCA stenting technique and angiographic and intravascular determinants of escalation are also summarized.

Management of failed stenting of the unprotected left main coronary artery

Percutaneous coronary intervention (PCI) is increasingly accepted as treatment for unprotected left main coronary artery (ULMCA) disease especially in those patients who are unsuitable for cardiac surgery. Treatment of any stent failure is associated with increased complexity and worse clinical outcomes when compared with de novo lesion revascularization. Intracoronary imaging has provided new insight into mechanisms of stent failure and treatment options have developed considerably over the last decade. There is paucity of evidence on the management strategy for stent failure in the specific setting of ULMCA. Treating any left main with PCI requires careful consideration and consequently treatment of failed stents in ULMCA is complex and provides unique challenges. Consequently, we provide an overview of ULMCA stent failure, proposing a tailored algorithm to guide best management and decision in daily clinical practice, with a special focus on intracoronary imaging characterization of causal mechanisms and specific technical and procedural considerations.

Intravascular Ultrasound-Guided Percutaneous Coronary Intervention: Practical Application

Why is intravascular ultrasounography (IVUS) highly encouraged for the practical guidance of percutaneous coronary intervention (PCI)? First reason is to understand the mechanism of revascularization. Even if stenoses look similar in angiography, the pathophysiology could be different in each lesion. Second reason is to anticipate possible complications in advance. With prediction and appropriate preparation, most complications can be avoided or managed calmly when they occur. Third reason is to optimize PCI results with interactive IVUS use during the procedure. All these are essential to maximize the results of revascularization while minimizing acute complications, ultimately leading to improved long-term clinical outcomes.

Percutaneous Coronary Intervention Versus Coronary Artery Bypass Grafting for Revascularization of Left Main Coronary Artery Disease

Owing to a large-jeopardized myocardium, left main coronary artery disease (LMCAD) represents the substantial high-risk anatomical subset of obstructive coronary artery disease. For several decades, coronary artery bypass grafting (CABG) has been the "gold standard" treatment for LMCAD. Along with advances in CABG, percutaneous coronary intervention (PCI) has also dramatically evolved over time in conjunction with advances in the stent or device technology, adjunct pharmacotherapy, accumulated experiences, and practice changes, establishing its position as a safe, reasonable treatment option for such a complex disease. Until recently, several randomized clinical trials, meta-analyses, and observational registries comparing PCI and CABG for LMCAD have shown comparable long-term survival with tradeoffs between early and late risk-benefit of each treatment. Despite this, there are still several unmet issues for revascularization strategy and management for LMCAD. This review article summarized updated knowledge on evolution and clinical evidence on the treatment of LMCAD, with a focus on the comparison of state-of-the-art PCI with CABG.

A large, prospective, multicentre study of left main PCI using a latest-generation zotarolimus-eluting stent: the ROLEX study

BACKGROUND

Data on left main (LM) percutaneous coronary interventions (PCI) have mostly been obtained in studies using drug-eluting stent (DES) platforms without dedicated large-vessel devices and with limited expansion capability.

AIMS

Our study aimed to investigate the safety and efficacy of LM PCI with the latest-generation Resolute Onyx DES.

METHODS

ROLEX (Revascularization Of LEft main with resolute onyX) is a prospective, multicentre study (ClinicalTrials.gov: NCT03316833) enrolling patients with unprotected LM coronary artery disease and a SYNTAX score <33 undergoing PCI with the Resolute Onyx zotarolimus-eluting coronary stent, that includes dedicated extra-large vessel platforms. The primary endpoint (EP) was target lesion failure (TLF): a composite of cardiac death, target vessel myocardial infarction (TVMI) and ischaemia-driven target lesion revascularisation (ID-TLR), at 1 year. All events were adjudicated by an independent clinical event committee. An independent core lab analysed all procedural angiograms.

RESULTS

A total of 450 patients (mean age 71.8 years, SYNTAX score 24.5±7.2, acute coronary syndrome in 53%) were enrolled in 26 centres. Of these, 77% of subjects underwent PCI with a single-stent and 23% with a 2-stent technique (8% double kissing [DK] crush, 6% culotte, 9% T/T and small protrusion [TAP] stenting). Intravascular imaging guidance was used in 45% (42% intravascular ultrasound [IVUS], 3% optical coherence tomography [OCT]). At 1 year, the primary EP incidence was 5.1% (cardiac death 2.7%, TVMI 2.7%, ID-TLR 2.0%). The definite/probable stent thrombosis rate was 1.1%. In a prespecified adjusted subanalysis, the primary EP incidence was significantly lower in patients undergoing IVUS/OCT-guided versus angio-guided PCI (2.0 vs 7.6%; hazard ratio [HR] 0.28, 95% confidence interval [CI]: 0.13-0.58; p<0.001).

CONCLUSIONS

In this large, multicentre, prospective registry, LM PCI with the Resolute Onyx DES showed good safety and efficacy at 1 year, particularly when guided by intracoronary imaging.

Is Coronary Physiology Assessment Valid in Special Circumstances?: Aortic Stenosis, Atrial Fibrillation, Left Ventricular Hypertrophy, and Other

Fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs) provide an important clinical tool to evaluate the hemodynamic significance of coronary lesions. However, these indices have major limitations. As these indices are meant to be surrogates of coronary flow, clinical scenarios such as aortic stenosis (with increased end-systolic and end-diastolic pressures) or atrial fibrillation (with significant beat-to-beat cardiac output variability) can have significant effect on the accuracy and reliability of these hemodynamic indices. Here, we provide a comprehensive evaluation of the pitfalls, limitations, and strengths of FFR and NHPRs in common clinical scenarios paired with coronary artery disease.

Current clinical use of intravascular ultrasound imaging to guide percutaneous coronary interventions (update)

There are 3 main reasons to promote the practical application of IVUS during PCI. First reason is to understand the mechanism of vessel dilatation. Even if angiographic stenoses are similar, their pathophysiologies are different. It is important to understand what can happen by dilating coronary artery with balloon/stent, and to develop a strategy to achieve the maximum effect. Second reason is to anticipate possible complications and to reduce them in advance. In that case, we can deal with it as calmly as possible. Third reason is to validate the PCI performed. This should lead to further improvements of the procedures, which in turn will lead to improved short- and long-term prognosis. Then, high-quality PCI could be possible. This review summarizes the standard usage of IVUS in routine clinical practice and the use of IVUS in specific situations, especially complex lesions.

Influence of Rigid-Elastic Artery Wall of Carotid and Coronary Stenosis on Hemodynamics

Cardiovascular system abnormalities can result in serious health complications. By using the fluid-structure interaction (FSI) procedure, a comprehensive realistic approach can be employed to accurately investigate blood flow coupled with arterial wall response. The hemodynamics was investigated in both the coronary and carotid arteries based on the arterial wall response. The hemodynamics was estimated based on the numerical simulation of a comprehensive three-dimensional non-Newtonian blood flow model in elastic and rigid arteries. For stenotic right coronary artery (RCA), it was found that the maximum value of wall shear stress (WSS) for the FSI case is higher than the rigid wall. On the other hand, for the stenotic carotid artery (CA), it was found that the maximum value of WSS for the FSI case is lower than the rigid wall. Moreover, at the peak systole of the cardiac cycle (0.38 s), the maximum percentage of arterial wall deformation was found to be 1.9%. On the other hand, for the stenotic carotid artery, the maximum percentage of arterial wall deformation was found to be 0.46%. A comparison between FSI results and those obtained by rigid wall arteries is carried out. Findings indicate slight differences in results for large-diameter arteries such as the carotid artery. Accordingly, the rigid wall assumption is plausible in flow modeling for relatively large diameters such as the carotid artery. Additionally, the FSI approach is essential in flow modeling in small diameters.

Drug-coated balloon in the treatment of coronary bifurcation lesions: A hope or hype?

When compared to non-bifurcation lesions, percutaneous coronary intervention in coronary bifurcation lesions is technically demanding and has historically been limited by lower procedural success rates and inferior clinical results. Following the development of drug-eluting stents, dramatically better results have been demonstrated. In most of the bifurcation lesions, the provisional technique of implanting a single stent in the main branch (MB) remains the default approach. However, some cases require more complex two-stent techniques which carry the risk of side branch (SB) restenosis. The concept of leaving no permanent implant behind is appealing because of the complexity of bifurcation anatomy with significant size mismatch between proximal and distal MB which may drive rates of in-stent restenosis and the potential impact of MB stenting affecting SB coronary flow dynamics. With the perspective of leaving lower metallic burden, a drug-coated balloon (DCB) has been utilized to treat bifurcations in both the MB and SB. The author gives an overview of the existing state of knowledge and prospects for the future for using DCB to treat bifurcation lesions.

Colocalization of Coronary Plaque with Wall Shear Stress in Myocardial Bridge Patients

PURPOSE

Patients with myocardial bridges (MBs) have a higher prevalence of atherosclerosis. Wall shear stress (WSS) has previously been correlated with plaque in coronary artery disease patients, but such correlations have not been investigated in symptomatic MB patients. The aim of this paper was to use a multi-scale computational fluid dynamics (CFD) framework to simulate hemodynamics in MB patient, and investigate the co-localization of WSS and plaque.

METHODS

We identified N = 10 patients from a previously reported cohort of 50 symptomatic MB patients, all of whom had plaque in the proximal vessel. Dynamic 3D models were reconstructed from coronary computed tomography angiography (CCTA), intravascular ultrasound (IVUS) and catheter angiograms. CFD simulations were performed to compute WSS proximal to, within and distal to the MB. Plaque was quantified from IVUS images in 2 mm segments and registered to CFD model. Plaque area was compared to absolute and patient-normalized WSS.

RESULTS

WSS was lower in the proximal segment compared to the bridge segment (6.1 ± 2.9 vs. 16.0 ± 7.1 dynes/cm², p value < 0.01). Plaque area and plaque burden measured from IVUS peaked at 1-3 cm proximal to the MB entrance, coinciding with the first diagonal branch. Normalized WSS showed a statistically significant moderate correlation with plaque area (r = 0.41, p < 0.01).

CONCLUSION

WSS may be obtained non-invasively in MB patients and provides a surrogate marker of plaque area. Using CFD, it may be possible to non-invasively assess the extent of plaque area, and identify patients who could benefit from frequent monitoring or medical management.

How to deal with vessel diameter mismatch in left main bifurcation stenting

Left main coronary artery percutaneous coronary intervention is particularly complex when stenting across the distal bifurcation is required in the presence of a diameter mismatch between the proximal main and distal branches. A suboptimal procedural result increases the risk of thrombosis and restenosis. Considering the paucity of data published on this topic, our objective was to provide technical solutions to deal with this complex anatomy. We described four cases showing the use of devices and techniques which allowed us to overcome a diameter discrepancy between adjacent coronary segments: (1) self-expanding nitinol stent; (2) stent platform with noteworthy expansion capacity; (3) the 'extended skirt' technique; (4) the 'trouser-leg' technique. In conclusion, the use of specific strategies and devices allows a safe and effective approach to be used to perform treatment that respects the coronary anatomy, and to optimize percutaneous coronary intervention results in complex scenarios.

Hemodynamic and Geometric Risk Factors for In-Stent Restenosis in Patients with Intracranial Atherosclerotic Stenosis

Methods

Severe ICAS patients managed with percutaneous transluminal angioplasty and stenting (PTAS) were included in the retrospective cohort study and were divided into two groups according to whether ISR occurred at follow-up (ISR group and no-ISR group). Computational fluid dynamics models were built based on digital subtraction angiography before and after PTAS to simulate blood flow and quantify hemodynamic parameters. The associations between vessel geometry, hemodynamics, and ISR in ICAS patients were investigated.

Results

Among 39 patients, ISR occurred in seven patients (17.95%) after a mean follow-up period of 6.69 ± 3.24 months. Stenting decreased vessel angulation (51.11° [40.07°-67.27°] vs. 15.97° [0.00°-36.16°], P = 0.000) and vessel tortuosity (0.09 [0.06-0.13] vs. 0.01 [0.00-0.03], P = 0.000). Meanwhile, the translational pressure ratio (PR) dramatically increased (0.07 [0.00-0.31] vs. 0.62 [0.41-0.82], P = 0.000) with the wall shear stress ratio decreased (13.93 [8.37-40.30] vs. 2.90 [1.69-4.48], P = 0.000). In the multivariate analysis, smaller Δ tortuosity (P = 0.038) was independently associated with the occurrence of ISR, and smaller post-PTAS translesional PR was also a predictive factor of marginal significance (P = 0.059).

Conclusion

PTAS decreased vessel angulation, vessel tortuosity, and translesional wall shear stress ratio while it increased translesional pressure ratio (PR) dramatically in ICAS patients. Smaller Δ tortuosity was found to be a risk factor for ISR, and smaller post-PTAS translesional PR was also a predictive factor of marginal significance, indicating that both geometric and hemodynamic parameters played important roles in the occurrence of ISR after PTAS.

Definitions and Standardized Endpoints for Treatment of Coronary Bifurcations

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

Physiologic and compositional coronary artery disease extension in patients with takotsubo syndrome assessed using artificial intelligence: an optical coherence tomography study

BACKGROUND

Takotsubo syndrome (TTS) is an acute and reversible ventricular motion abnormality without epicardial coronary obstruction. Optical flow ratio (OFR) is an approach to evaluate the coronary stenosis significance based on three-dimensional optical coherence tomography (3D-OCT). The aim of this study is to utilize OCT and an artificial intelligence plaque characterization model to show the prevalence and composition of atherosclerotic disease in coronary vessels of patients with TTS.

METHODS

This is a retrospective and observational study which enrolled patients with TTS who underwent coronary angiography and OCT examination. OCT images were analyzed for tissue characterization and OFR computation using a novel artificial intelligence algorithm.

RESULTS

A total of 37 patients and 49 vessels were studied. All patients were imaged in the left anterior descending coronary artery (LAD) and about two-thirds were also imaged in the left circumflex coronary artery (LCX). Most patients were women (n = 35), and apical was the most common takotsubo type. Tissue composition analysis yielded the following overall plaque types: fibrous (67.1%), lipid (15.5%), and calcium (3.77%). The mean OFR for LAD and LCX was 0.97 ± 0.04 and 0.98 ± 0.02, respectively.

CONCLUSION

Utilizing automatic plaque characterization on OCT images by artificial intelligence, we found that TTS patients have coronary artery disease (i.e. presence of lipid, calcified, or fibrous tissue). The advent of artificial intelligence methods may allow for large-scale studies of patients with TTS.

Percutaneous Coronary Intervention for Left Main Coronary Artery Disease: Present Status and Future Perspectives

For several decades, coronary artery bypass grafting has been regarded as the standard choice of revascularization for significant left main coronary artery (LMCA) disease. However, in conjunction with remarkable advancement of device technology and adjunctive pharmacology, percutaneous coronary intervention (PCI) offers a more expeditious approach with rapid recovery and is a safe and effective alternative in appropriately selected patients with LMCA disease. Several landmark randomized clinical trials showed that PCI with drug-eluting stents for LMCA disease is a safe option with similar long-term survival rates to coronary artery bypass grafting surgery, especially in those with low and intermediate anatomic risk. Although it is expected that the updated evidence from recent randomized clinical trials will determine the next guidelines for the foreseeable future, there are still unresolved and unmet issues of LMCA revascularization and PCI strategy. This paper provides a comprehensive review on the evolution and an update on the management of LMCA disease.

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.

Predictors of Left Main Coronary Artery Disease in the ISCHEMIA Trial

BACKGROUND

Detection of ≥50% diameter stenosis left main coronary artery disease (LMD) has prognostic and therapeutic implications. Noninvasive stress imaging or an exercise tolerance test (ETT) are the most common methods to detect obstructive coronary artery disease, though stress test markers of LMD remain ill-defined.

OBJECTIVES

The authors sought to identify markers of LMD as detected on coronary computed tomography angiography (CTA), using clinical and stress testing parameters.

METHODS

This was a post hoc analysis of ISCHEMIA (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches), including randomized and nonrandomized participants who had locally determined moderate or severe ischemia on nonimaging ETT, stress nuclear myocardial perfusion imaging, or stress echocardiography followed by CTA to exclude LMD. Stress tests were read by core laboratories. Prior coronary artery bypass grafting was an exclusion. In a stepped multivariate model, the authors identified predictors of LMD, first without and then with stress testing parameters.

RESULTS

Among 5,146 participants (mean age 63 years, 74% male), 414 (8%) had LMD. Predictors of LMD were older age (P < 0.001), male sex (P < 0.01), absence of prior myocardial infarction (P < 0.009), transient ischemic dilation of the left ventricle on stress echocardiography (P = 0.05), magnitude of ST-segment depression on ETT (P = 0.004), and peak metabolic equivalents achieved on ETT (P = 0.001). The models were weakly predictive of LMD (C-index 0.643 and 0.684).

CONCLUSIONS

In patients with moderate or severe ischemia, clinical and stress testing parameters were weakly predictive of LMD on CTA. For most patients with moderate or severe ischemia, anatomical imaging is needed to rule out LMD. (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches [ISCHEMIA]; NCT01471522).

A multi-center, international, randomized, 2-year, parallel-group study to assess the superiority of IVUS-guided PCI versus qualitative angio-guided PCI in unprotected left main coronary artery (ULMCA) disease: Study protocol for OPTIMAL trial

Background

Percutaneous coronary intervention (PCI) is used increasingly for revascularization of unprotected left main coronary artery (LMCA) disease. Observational studies and subgroup analyses from clinical trials, have suggested a possible benefit from the use of intravascular ultrasound (IVUS) guidance when performing unprotected LMCA PCI. However, the value of imaging with IVUS has never been proven in an appropriately powered randomized clinical trial. The OPtimizaTIon of Left MAin PCI With IntravascuLar Ultrasound (OPTIMAL) trial has been designed to establish whether IVUS-guided PCI optimization on LMCA is associated with superior clinical outcomes when compared with standard qualitative angiography-guided PCI.

Methods

The OPTIMAL trial is a randomized, multicenter, international study designed to enroll a total of 800 patients undergoing PCI for unprotected LMCA disease. Patients will be randomized in a 1:1 fashion to IVUS-guided PCI versus angiogram-guided PCI. In patients allocated to the angiogram-guided arm, use of IVUS is discouraged, unless there are safety concerns. In patients allocated to the IVUS guidance arm, pre-procedural IVUS assessment is highly recommended, whilst post-procedural IVUS assessment is mandatory to confirm appropriate stenting result and/or to guide stent result optimization, according to predefined criteria. Patients will be followed up to 2 years after the index procedure. The primary outcome measure is the Academic Research Consortium (ARC) patient-oriented composite endpoint (PoCE) which includes all-cause death, any stroke, any myocardial infarction and any repeat revascularization at 2 years follow-up.

Discussion

The OPTIMAL trial aims to provide definitive evidence about the clinical impact of IVUS-guidance during PCI to an unprotected LMCA. It is anticipated by the investigators, that an IVUS-guided strategy will be associated with less clinical events compared to a strategy guided by angiogram alone.

Trial registration

ClinicalTrials.gov: NCT04111770. Registered on October 1, 2019.

Towards a common pathway for the treatment of left main disease: contemporary evidence and future directions: Left main disease treatment

There is increasing evidence to support percutaneous treatment of left main (LM) disease. Due to its major clinical impact, any procedure in the left main should be meticulously planned and performed. In this review, we aim to integrate the available evidence into a common treatment pathway, starting with understanding the distinct anatomical features of the left main. A three-level decision-making process is presented. First, in instances of angiographic ambiguity, intravascular ultrasound and fractional flow reserve can be used to decide if revascularisation could be deferred. Second, if revascularisation is indicated, the risks and benefits of percutaneous versus surgical procedures should be evaluated. Third, if percutaneous coronary intervention (PCI) is chosen, the operator should decide between the provisional single-stent versus upfront two-stent strategies. Regardless of the PCI technique selected, it should be performed according to the recommendations of a stepwise procedure utilising proximal optimisation (POT) after each instance of crossover stenting and kissing balloon inflation (KBI) where necessary. In addition to the recognised quality markers such as POT and KBI, we discuss the clinical relevance of the operator's LM PCI experience and the intracoronary imaging guidance when treating patients with left main disease.

Numerical modelling of blood rheology and platelet activation through a stenosed left coronary artery bifurcation

Coronary bifurcations are prone to atherosclerotic plaque growth, experiencing regions of reduced wall shear stress (WSS) and increased platelet adhesion. This study compares effects across different rheological approaches on hemodynamics, combined with a shear stress exposure history model of platelets within a stenosed porcine bifurcation. Simulations used both single/multiphase blood models to determine which approach best predicts phenomena associated with atherosclerosis and atherothrombosis. A novel Lagrangian platelet tracking model was used to evaluate residence time and shear history of platelets indicating likely regions of thrombus formation. Results show a decrease in area of regions with pathologically low time-averaged WSS with the use of multiphase models, particularly in a stenotic bifurcation. Significant non-Newtonian effects were observed due to low-shear and varying hematocrit levels found on the outer walls of the bifurcation and distal to the stenosis. Platelet residence time increased 11% in the stenosed artery, with exposure times to low-shear sufficient for red blood cell aggregation (>1.5 s). increasing the risk of thrombosis. This shows stenotic artery hemodynamics are inherently non-Newtonian and multiphase, with variations in hematocrit (0.163-0.617) and elevated vorticity distal to stenosis (+15%) impairing the function of the endothelium via reduced time-averaged WSS regions, rheological properties and platelet activation/adhesion.

Feasibility and Outcomes of Left Main to Branch Vessel PCI with Novel Tapered Coronary Stent in a Tertiary Care Centre: A Real World Experience

OBJECTIVE

To assess the safety and efficacy of Novel tapered (BioMime™ Morph) sirolimus-eluting stent (SES) for left main PCI in a real-world scenario.

BACKGROUND

Currently no data is available on clinical usefulness of tapered ultrathin stents in left main PCI.

METHODS

This was a prospective, non-randomised, single centre study carried out between February 2018 and May 2020 at a tertiary cardiac care centre in southern India. The study included patients treated with BioMime Morph tapered stent for distal de novo LMB lesion or ostial LAD/LCX lesions with significant size disparity between reference segments based on the eligibility criteria. Primary endpoint of the study was the cumulative incidence of major adverse cardiovascular events (MACE) composed of cardiac death, myocardial infraction, and clinically driven target-lesion revascularisation at follow-up.

RESULTS

A total of 41 patients (average age of 54.83±9.81 years) were included in the study. Average SS-2 score was 23.17±5.42. Majority of the lesions (n=31; 75.61%) were of medina class (0.1.0). Provisional single stent strategy was adopted for treatment of LMB lesions. TIMI flow-3 was achieved in 40 patients (97.56%). Median clinical follow-up was 20 months (range 6-34 months) There was no periprocedural complication or MACE during follow-up.

Impact of lesion preparation strategies on outcomes of left main PCI: The EXCEL trial

OBJECTIVES

We examined outcomes according to lesion preparation strategy (LPS) in patients with left main coronary artery (LMCA) percutaneous coronary intervention (PCI) in the EXCEL trial.

BACKGROUND

The optimal LPS for LMCA PCI is unclear.

METHODS

We categorized LPS hierarchically (high to low) as: (a) rotational atherectomy (RA); (b) cutting or scoring balloon (CSB); (c) balloon angioplasty (BAL); and d) direct stenting (DIR). The primary endpoint was 3-year MACE; all-cause death, stroke, or myocardial infarction.

RESULTS

Among 938 patients undergoing LMCA PCI, RA was performed in 6.0%, CSB 9.5%, BAL 71.3%, and DIR 13.2%. In patients treated with DIR, BAL, CSB, and RA, respectively, there was a progressive increase in SYNTAX score, LMCA complex bifurcation, trifurcation or calcification, number of stents, and total stent length. Any procedural complication occurred in 10.4% of cases overall, with the lowest rate in the DIR (7.4%) and highest in the RA group (16.1%) (p_trend  = .22). There were no significant differences in the 3-year rates of MACE (from RA to DIR: 17.9%, 20.2%, 14.5%, 14.7%; p = .50) or ischemia-driven revascularization (from RA to DIR: 16.8%, 10.8%, 12.3%, 14.2%; p = .65). The adjusted 3-year rates of MACE did not differ according to LPS.

CONCLUSIONS

The comparable 3-year outcomes suggest that appropriate lesion preparation may be able to overcome the increased risks of complex LMCA lesion morphology.

Mechanically Rotating Intravascular Ultrasound (IVUS) Transducer: A Review

Intravascular ultrasound (IVUS) is a valuable imaging modality for the diagnosis of atherosclerosis. It provides useful clinical information, such as lumen size, vessel wall thickness, and plaque composition, by providing a cross-sectional vascular image. For several decades, IVUS has made remarkable progress in improving the accuracy of diagnosing cardiovascular disease that remains the leading cause of death globally. As the quality of IVUS images mainly depends on the performance of the IVUS transducer, various IVUS transducers have been developed. Therefore, in this review, recently developed mechanically rotating IVUS transducers, especially ones exploiting piezoelectric ceramics or single crystals, are discussed. In addition, this review addresses the history and technical challenges in the development of IVUS transducers and the prospects of next-generation IVUS transducers.

Correlation of Computational Instantaneous Wave-Free Ratio With Fractional Flow Reserve for Intermediate Multivessel Coronary Disease

This study computationally assesses the accuracy of an instantaneous wave-free ratio (iFR) threshold range compared to standard modalities such as fractional flow reserve (FFR) and coronary flow reserve (CFR) for multiple intermediate lesions near the left main (LM) coronary bifurcation. iFR is an adenosine-independent index encouraged for assessment of coronary artery disease (CAD), but different thresholds are debated. This becomes particularly challenging in cases of multivessel disease when sensitivity to downstream lesions is unclear. Idealized LM coronary arteries with 34 different intermediate stenoses were created and categorized (Medina) as single and multiple lesion groups. Computational fluid dynamics modeling was performed with physiologic boundary conditions using an open-source software (simvascular1) to solve the time-dependent Navier-Stokes equations. A strong linear relationship between iFR and FFR was observed among studied models, indicating computational iFR values of 0.92 and 0.93 are statistically equivalent to an FFR of 0.80 in single and multiple lesion groups, respectively. At the clinical FFR value (i.e., 0.8), a triple-lesion group had smaller CFR compared to the single and double lesion groups (e.g., triple = 3.077 versus single = 3.133 and double = 3.132). In general, the effect of additional intermediate downstream lesions (minimum lumen area > 3 mm2) was not statistically significant for iFR and CFR. A computational iFR of 0.92 best predicts an FFR of 0.80 and may be recommended as threshold criteria for computational assessment of LM stenosis following additional validation using patient-specific models.

Outcomes of Unprotected Left Main Percutaneous Coronary Intervention: A Single-Centre Experience

Introduction

When the baseline anatomical syntax score-I (SxSI) is more than or equal to 33, percutaneous coronary intervention (PCI) of unprotected left main (UPLM) is discouraged and considered as high-risk of adverse cardiac events. We designed this study to compare the outcomes of UPLM-PCI between the low to intermediate-syntax score (SxSI^low/^int.) group (defined as SxSI <33) and the high-syntax score (SxSI^high) group (defined as SxSI more than or equal 33) with a subanalysis to explore the predictive role of intravascular images (IVI).

Methods

The study is a retrospective observational analysis in a prospective cohort. The prospectively gathered data of consecutive patients, who were enrolled from January 2018 to December 2018, were analyzed at 1-year regarding the primary outcome of major adverse cardiovascular and cerebrovascular events (MACCE). An independent committee calculated the SxSI and reviewed all the events.

Results

Baseline data of 2144 patients were considered for analysis. 1245 underwent PCI and 32 (2.57%) had PCI of UPLM; of these, 24 (75%) were in SxSI^low/^int. group and 8 (25%) in SxSI^high group. The mean SxSI was 20.3 ± 6.5 and 37.1 ± 4.9 for SxSI^low/^int. and SxSI^high groups, respectively. Compared with patients in the SxSI^low/^int., patients in SxSI^high group had a greater syntax score-II (<0.0001), which reflects the expected 4-year mortality after PCI by combining the SxSI and clinical variables.Interestingly, despite the fact that the proportion of subjects who sustained MACCE was almost three times more among the SxSIhigh compared to their SxSIlow/int. counterparts [1 (12.5%) vs. 1 (4.2%), P = 0.444], this difference was not statistically significant.It was noted that a higher proportion of patients in whom intravascular imaging (IVI) was not used to guide PCI sustained MACCE compared with that in whom IVI was utilized (2 [50%] vs. [0%], P = 0.012). There is a strong, negative, statistically significant association between the use of IVI and the occurrence of MAACE (Phi=-0.681), which reflects that the use of imaging is associated with significantly lower probability of developing MACCE.

Conclusion

As demonstrated in this real-world cohort, PCI of UPLM provides excellent outcome at one year regardless of the initial anatomical syntax score. Furthermore, it appears that IVI utilization during the index PCI procedure of UPLM is a potent and independent predictor of MACCE.

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

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

Asia Pacific consensus document on coronary bifurcation interventions

Coronary bifurcation intervention is common but complex. Progress in this field has been made in recent years with considerable contribution from the Asia Pacific (APAC) region. However, the standard of practice varies across the APAC region due to differences in culture, socioeconomic state and healthcare set-up. Practice may also differ from the rest of the world. Hence, a panel of experts was invited to discuss topics relevant to bifurcation intervention in order to make a concerted effort to achieve consensus that is applicable within the region and in line with available evidence.

Intravascular ultrasound guidance in the evaluation and treatment of left main coronary artery disease

Percutaneous coronary intervention (PCI) of left main coronary artery (LMCA) disease has become an acceptable revascularization strategy. Evaluating the extent and characteristics of obstructive disease of the LMCA by angiography is challenging and limited in its accuracy. In contrast, intravascular ultrasound (IVUS) provides accurate imaging of the coronary lumen as well as quantitative measurements and quantitative assessment of the vessel wall components. IVUS for LMCA PCI should be performed before, during, and after intervention; IVUS enhances every step in the procedure and is associated with a mortality advantage in comparison with angiographic guidance alone. In this review, we provide an update on LMCA PCI and the role of IVUS for lesion assessment and stent optimization. In addition, the latest clinical evidence of the benefits of IVUS-guided LMCA PCI as compared to angiography is reviewed.

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

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

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.

Fundamentals and role of intravascular ultrasound in percutaneous coronary intervention

Intravascular ultrasound (IVUS) is a catheter-based invasive imaging modality that has become an essential adjunctive tool to percutaneous coronary intervention (PCI) over the past 20 years. Clinical applications of IVUS in PCI include assessment of lesion severity, characterizing plaque morphology, optimization of acute stent results and clarification of mechanisms of stent failure. Numerous meta-analyses of large observational and randomized studies support the role of IVUS-guided PCI in reducing short and long-term adverse outcomes, including mortality and stent failure, particularly in patients receiving drug-eluting stents (DESs) and in complex lesion subsets. The current review provides a summary of the fundamental aspects and current clinical roles of IVUS in coronary intervention.

Left coronary artery calcification patterns after coronary bypass graft surgery: An in-vivo optical coherence tomography study

OBJECTIVES

We sought to evaluate the severity and patterns of calcifications in the left main coronary artery (LMCA) and proximal segments of left anterior descending coronary artery (LAD) and left circumflex artery (LCX) using optical coherence tomography (OCT) in patients with and without prior coronary artery bypass grafting (CABG).

BACKGROUND

CABG may accelerate upstream calcium development.

METHODS

OCT images (n = 76) of the LMCA bifurcation from either the LAD or LCX in 76 patients with at least one patent left coronary graft, on average 7.0 ± 5.6 years post-CABG, were compared with 148 OCT images in propensity-score-matched non-CABG controls.

RESULTS

Minimum lumen areas in the LMCA, LAD, and LCX in post-CABG patients were smaller than non-CABG controls. Maximum calcium arc and thickness as well as calcium length were greater in the LMCA and LCX, but not in the LAD in post-CABG patients versus non-CABG controls. Calcium located at the carina of a bifurcation, calcified nodules (CN), thin intimal calcium, and lobulated calcium were more prevalent in post-CABG patients. After adjusting for multiple covariates, prior CABG was an independent predictor of calcification at the carina of a bifurcation (odds ratio [OR] 5.77 [95% confidence interval, CI: 1.5-21.6]), thin intimal calcium (4.7 [1.5-14.4]), and the presence of a CN (15.60 [3.2-76.2]).

CONCLUSIONS

Prior CABG is associated with greater amount of calcium in the LMCA and the proximal LCX, as well as higher prevalence of atypical calcium patterns, including CN, thin or lobulated calcium, and calcifications located at the carina of a bifurcation, compared with non-CABG controls.

Efficacy of coronary imaging on bifurcation intervention

During the coronary bifurcation intervention procedure, imaging including intravascular ultrasound and optical coherence tomography is essential to provide precise anatomy of the lesion and morphological information. This consensus document between the Korean Bifurcation Club and the Japanese Bifurcation Club summarizes practical guidelines and current evidences on lesion assessment, device selection, procedural guidance, and the optimization of bifurcation intervention by the imaging.