Usefulness of coronary fractional flow reserve measurements in guiding clinical decisions in intermediate or equivocal left main coronary stenoses

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.

Left Main Disease

Traditionally, the treatment of left main coronary artery disease is recommended coronary artery bypass grafting because of its superior long-term outcomes compared with medical treatment and plain old balloon angioplasty. However, improvement of percutaneous coronary intervention technique and introduction of drug-eluting stent led to change of treatment strategy of left main coronary artery disease through cumulative data for revascularization that based on clinical evidence.

Physiological Approach for Coronary Artery Bifurcation Disease: Position Statement by Korean, Japanese, and European Bifurcation Clubs

Coronary artery bifurcation lesions are frequently encountered in cardiac catheterization laboratories and are associated with more complex procedures and worse clinical outcomes than nonbifurcation lesions. Therefore, anatomical and physiological assessment of bifurcation lesions before, during, and after percutaneous coronary intervention is of paramount clinical importance. Physiological assessment can help interventionalists appreciate the hemodynamic significance of coronary artery disease and guide ischemia-directed revascularization. However, it is important to understand that the physiological approach for bifurcation disease is more important than simply using physiological indexes for its assessment. This joint consensus document by the Korean, Japanese, and European bifurcation clubs presents the concept of a physiological approach for coronary bifurcation lesions, as well as current knowledge, practical tips, pitfalls, and future directions of applying physiological indexes in bifurcation percutaneous coronary intervention. This document aims to guide interventionalists in performing appropriate physiology-based assessments and treatment decisions for coronary bifurcation lesions.

Feasibility of coronary blood flow simulations using mid-fidelity numeric and geometric models

The fractional flow reserve index (FFR) is currently used as a gold standard to quantify coronary stenosis's functional relevance. Due to its highly invasive nature, the development of noninvasive surrogates based on simulations has drawn much attention in recent years, emphasizing efficient strategies that enable translational research. The focus of this work is twofold. First, to assess the feasibility of using a mid-fidelity numerical strategy (transversally enriched pipe element method, TEPEM), placed between low- and high-fidelity models, for the estimation of flow-related quantities, such as FFR and wall shear stress (WSS). Low-fidelity models, as zero- or one-dimensional models, are computationally inexpensive but in detriment of poorer spatially detailed predictions. On the other hand, high-fidelity models, such as classical three-dimensional numerical approximations, can provide detailed predictions but their transition to clinical application is prohibitive due to high computational costs. As a second goal, we quantify the impact of the length of lateral branches in the blood flow through the interrogated vessel of interest to further reduce the computational burden. Both studies are addressed considering a cohort of 17 coronary geometries. A total of 20 locations were selected to estimate the FFR index for a wide range of Coronary Flow Reserve (CFR) scenarios. Numerical results suggest that the mid-fidelity TEPEM model is a reliable approach for the efficient estimation of the FFR index and WSS, with an error in the order of [Formula: see text] and [Formula: see text], respectively, when compared to the high-fidelity prediction. Moreover, such mid-fidelity models require much less computational resources, in compliance with infrastructure frequently available in the clinic, by achieving a speedup between 30 and 60 times compared to a conventional finite element approach. Also, we show that shortening peripheral branches does not introduce considerable perturbations either in the flow patterns, in the wall shear stress, or the pressure drop. Comparing the different geometric models, the error in the estimation of FFR index and WSS is reduced to less than [Formula: see text] and [Formula: see text], respectively.

Interventional Strategies in Cancer-induced Cardiovascular Disease

PURPOSE OF REVIEW

To highlight the range of illnesses and procedures that the interventional onco-cardiologists face in their daily practice, along with the recent additions to anti-cancer therapies and their related cardiotoxicity.

RECENT FINDINGS

Immune checkpoint inhibitors (ICI) are not devoid of cardiotoxicity as thought earlier and lead to an increased incidence of myocarditis. Transcatheter valve replacement has been shown to be a safer alternative to surgical replacement in cancer patients. Interventional onco-cardiology is a novel field that addresses cardiovascular diseases in the setting of cancer. Traditionally excluding cancer patients from clinical trials has led to a dearth of information needed to tackle cardiac conditions like Takotsubo cardiomyopathy, malignant pericardial effusions, and radiation-induced vascular diseases encountered either exclusively or predominantly in this high-risk population. This review discusses the various treatment options available in the interventional armamentarium with a particular focus on ICI-myocarditis and transcatheter aortic valve replacement in cancer patients.

Correlation of Intravascular Ultrasound and Instantaneous Wave-Free Ratio in Patients With Intermediate Left Main Coronary Artery Disease

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Physiology-Based Revascularization of Left Main Coronary Artery Disease

It is of critical importance to correctly assess the significance of a left main lesion. Underestimation of significance beholds the risk of inappropriate deferral of revascularization, whereas overestimation may trigger major but unnecessary interventions. This article addresses the invasive physiological assessment of left main disease and its role in deciding upon revascularization. It mainly focuses on the available evidence for fractional flow reserve and instantaneous wave-free ratio, their interpretation, and limitations. We also discuss alternative invasive physiological indices and imaging, as well as the link between physiology, ischemia, and prognosis.

Cardiac Interventional Procedures in Cardio-Oncology Patients

Comorbidities specific to the cardio-oncology population contribute to the challenges in the interventional management of patients with cancer and cardiovascular disease (CVD). Patients with cancer have generally been excluded from cardiovascular randomized clinical trials. Endovascular procedures may represent a valid option in patients with cancer with a range of CVDs because of their minimally invasive nature. Patients with cancer are less likely to be treated according to societal guidelines because of perceived high risk. This article presents the specific challenges that interventional cardiologists face when caring for patients with cancer and the modern tools to optimize care.

Reliability of Instantaneous Wave-Free Ratio (iFR) for the Evaluation of Left Main Coronary Artery Lesions

The assessment of the left main coronary artery (LMCA) by coronary angiography has several limitations. The fractional flow reserve (FFR) is useful for the functional evaluation of LMCA stenoses. The instantaneous wave-free ratio (iFR), a resting index, was developed to simplify functional coronary assessment. However, its performance for LMCA stenoses has yet to be explored. The iFR was measured at rest, and the FFR was measured under maximal hyperemia. We calculated that a sample size of 90 lesions would have provided 90% power at a 5% significance level to detect an Area Under the Curve (AUC) < 0.7 for the iFR to identify FFR-positive stenoses. A total of 91 measurements were performed on angiographically intermediate LMCA stenoses at three centers. The comparison between the iFR and the FFR showed a significant correlation (r = 0.67, p < 0.001). At receiver operating characteristic (ROC) analysis, the iFR revealed a good diagnostic performance when compared to the FFR (AUC = 0.84; p < 0.001). A classification agreement between the iFR and the FFR was recorded in 81% of cases. The left ventricular ejection fraction (LVEF) was an independent predictor of the discrepancy between the FFR and iFR values (p = 0.040). The present study is the first demonstrating that the assessment of LMCA stenoses with the instantaneous wave-free ratio is a reliable adenosine-free alternative to classic fractional flow reserve. If confirmed in larger populations, these findings could be of relevance for real world daily practice.

Assessing the left main stem in the cardiac catheterization laboratory. What is "significant"? Function, imaging or both?

Revascularization of significant Left Main Stem (LMS) disease improves clinical outcomes. This can be achieved through either Coronary Artery Bypass Grafting or Percutaneous coronary intervention. Defining a significant stenosis of the LMS can be challenging and debatable, as most data have been derived using angiographic assessment alone, with a threshold of 50% luminal stenosis used as a marker of functional significance. The use of adjunctive technologies like Intravascular Ultrasound and Fractional Flow Reserve has improved our ability to accurately assess the anatomical severity and physiological significance of coronary artery stenoses, much more so, than can be achieved through conventional angiography alone. An improved assessment of LMS disease through these adjunctive techniques offers procedural and clinical benefits. Rather than focus on the preferred methods of revascularisation, this article aims to highlight the common pitfalls and misconceptions in the assessment of LMS stenoses. We also propose a simple algorithm for the assessment of LMS disease to help guide revascularisation decisions.

Percutaneous Coronary Intervention of Left Main Disease

For nearly half a century, coronary artery bypass grafting has been the standard treatment for patients with obstructive left main coronary artery (LMCA) disease. However, there has been considerable evolution in the field of percutaneous coronary intervention, and especially, percutaneous coronary intervention for LMCA disease has been rapidly expanded with adoption of drug-eluting stents. Some, but not all randomized trials, have shown that percutaneous coronary intervention with drug-eluting stents might be a suitable alternative for selected patients with LMCA disease instead of bypass surgery. However, none of previous trials involving early-generation drug-eluting stents was sufficiently powered and comparative trials using contemporary drug-eluting stents were limited. Recently, primary results of 2 new trials of EXCEL (Evaluation of XIENCE Everolimus Eluting Stent Versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization) and NOBLE (Nordic-Baltic-British Left Main Revascularization Study) were reported. However, these trials showed conflicting results, which might pose uncertainty on the optimal revascularization strategy for LMCA disease. In this article, with the incorporation of a key review on evolution of LMCA treatment, we summarize the similarity or disparity of the EXCEL and NOBLE trials, focus on how they relate to previous trials in the field, and finally speculate on how the treatment strategy may be changed or recommended for LMCA treatment.

Left main coronary artery stenosis: severity evaluation and implications for management

INTRODUCTION

The significant stenosis of the left main coronary artery is associated with poor outcomes and is considered a strong indication for revascularization. However, deciding whether the stenosis is significant can sometimes be challenging, especially when the degree of stenosis is intermediate, and can necessitate additional tests and imaging modalities. Areas covered: We did a literature search using keywords like 'left main', 'imaging', 'intravascular ultrasound', 'fractional flow reserve', 'computed tomographic angiography' and 'magnetic resonance imaging'. The most commonly used methods for better characterizing intermediate left main coronary stenoses are intravascular ultrasound and fractional flow reserve, while optical coherence tomography is the newer technique that provides better images, but for which not as much data is available. The noninvasive techniques are coronary computed tomographic angiography and, to a lesser degree, coronary magnetic resonance imaging. Expert commentary: Accurately determining the severity of left main coronary stenosis can mean the difference between a major intervention and conservative therapy. The reviewed newer imaging modalities give us greater confidence that patients with left main stenosis are assigned to the right treatment modality.

The effects of graded changes in oxygen and carbon dioxide tension on coronary blood velocity independent of myocardial energy demand

In humans, coronary blood flow is tightly regulated by microvessels within the myocardium to match myocardial energy demand. However, evidence regarding inherent sensitivity of the microvessels to changes in arterial partial pressure of carbon dioxide and oxygen is conflicting because of the accompanied changes in myocardial energy requirements. This study aimed to investigate the changes in coronary blood velocity while manipulating partial pressures of end-tidal CO2 (Petco2) and O2 (Peto2). It was hypothesized that an increase in Petco2 (hypercapnia) or decrease in Peto2 (hypoxia) would result in a significant increase in mean blood velocity in the left anterior descending artery (LADVmean) due to an increase in both blood gases and energy demand associated with the concomitant cardiovascular response. Cardiac energy demand was assessed through noninvasive measurement of the total left ventricular mechanical energy. Healthy subjects (n = 13) underwent a euoxic CO2 test (Petco2 = -8, -4, 0, +4, and +8 mmHg from baseline) and an isocapnic hypoxia test (Peto2 = 64, 52, and 45 mmHg). LADVmean was assessed using transthoracic Doppler echocardiography. Hypercapnia evoked a 34.6 ± 8.5% (mean ± SE; P < 0.01) increase in mean LADVmean, whereas hypoxia increased LADVmean by 51.4 ± 8.8% (P < 0.05). Multiple stepwise regressions revealed that both mechanical energy and changes in arterial blood gases are important contributors to the observed changes in LADVmean (P < 0.01). In summary, regulation of the coronary vasculature in humans is mediated by metabolic changes within the heart and an inherent sensitivity to arterial blood gases.

Practical based approach to left main bifurcation stenting

Despite the recent developments that have been made in the field of percutaneous left main (LM) intervention, the treatment of distal LM bifurcation remains challenging. The provisional one-stent approach for LM bifurcation has shown more favorable outcomes than the two-stent technique, making the former the preferred strategy in most types of LM bifurcation stenosis. However, elective two-stent techniques, none of which has been proven superior to the others, are still used in patients with severely diseased large side branches to avoid acute hemodynamic compromise. Selecting the proper bifurcation treatment strategy using meticulous intravascular ultrasound evaluation for side branch ostium is crucial for reducing the risk of side branch occlusion and for improving patient outcomes. In addition, unnecessary complex intervention can be avoided by measuring fractional flow reserve in angiographically isolated side branches. Most importantly, good long-term clinical outcomes are more related to the successful procedure itself than to the type of stenting technique, emphasizing the greater importance of optimizing the chosen technique than the choice of method.

New Invasive Assessment Measures of Coronary Artery Disease Severity

Ischemic heart disease is the leading cause of mortality worldwide. The assessment and treatment of patients with ischemic heart disease have advanced greatly over the past decade. Particular attention has been given recently to the recognition of lesions that cause ischemia or that are prone to plaque rupture. New invasive measures of coronary artery disease have been developed, including fractional flow reserve, intravascular ultrasound, optical coherence tomography, and most recently, near-infrared spectroscopy. These technologies have helped to guide the assessment of hemodynamically significant lesions and have shown particular promise in guiding percutaneous coronary interventions. However, mortality and the rate of revascularization have shown mixed results to date. This review seeks to investigate the use and potential benefit of these technologies, with particular attention to clinical end points.

Fractional Flow Reserve for the Evaluation of Tandem and Bifurcation Lesions, Left Main, and Acute Coronary Syndromes

Fractional flow reserve (FFR) is a well-established invasive tool to assess the physiologic significance of a coronary stenosis. Several randomized trials proved the safety of deferring revascularization based on FFR in subjects with stable coronary artery disease with single or multivessel disease. Subjects with tandem or bifurcations lesions, left main disease, and acute coronary syndromes were not included in these trials. Unique hemodynamic changes occur in each of these situations, making the measurement and interpretation of FFR challenging. This article reviews the technical aspects of assessing FFR and literature supporting FFR-guided revascularization in each of these situations.

Update on percutaneous intervention for left main coronary artery stenosis

Percutaneous coronary intervention (PCI) using drug-eluting stents (DES) is currently considered as a viable alternative to coronary artery bypass graft surgery (CABG) for selected patients with left main coronary artery disease. The updated results of the landmark randomized trials comparing CABG versus PCI demonstrated comparable 5-year outcomes and are in line with the current guidelines that designate PCI as a reasonable treatment in this disease subset. Given that the completed randomized trials did not include contemporary DESs, the upcoming results of the ongoing trials evaluating the performance of new-generation DES compared with CABG (such as the EXCEL trial), may further help to clarify the current role and future recommendations of PCI for left main coronary artery disease. Apart from the recent stent technology, further improvements in outcomes after PCI may be possible when it is used with an integrated approach that combines functional concepts for decision-making, adjunctive imaging support and optimal pharmacotherapies.

Value of FFR in clinical practice

Fractional flow reserve is an important tool in the cardiac catheterization lab to assess the physiological significance of coronary lesions. This article discusses the basic concepts about FFR and its utility in clinical decision making.

Left main coronary artery disease: importance, diagnosis, assessment, and management

Left main coronary disease is seen in 4%-6% of patients undergoing coronary angiography for an ischemic evaluation and is a potentially fatal condition if not promptly identified and treated. Recent studies have increased our understanding of the complexity of left main coronary artery disease. This lesion subset offers numerous challenges in diagnosis and management. Fractional flow reserve and intravascular ultrasound are important adjuncts to angiography to determine the significance of ambiguous lesions of the left main coronary artery. Surgery is associated with much better outcomes than medical therapy and is considered by many to be the standard of care in patients who are surgical candidates. Recent studies comparing surgery with percutaneous coronary intervention (PCI) have defined subgroups with lesser extent of disease burden that may do just as well with PCI. Challenges remain in the management of bifurcation disease, and the interventional community anxiously awaits the results of the large-scale randomized trials comparing PCI with surgery.

Outcomes associated with fractional flow-guided revascularization: a meta-analysis

BACKGROUND

Deferral of revascularization for abnormal but nonischemic lesions is usually recommended; however, the long-term outcome of this approach is not well known.

HYPOTHESIS

Deferral of nonischemic lesions will be associated with a low frequency of adverse events.

METHODS

A PubMed search of the MEDLINE database identified studies that reported clinical outcomes among patients who had fractional flow reserve-guided revascularization. We further categorized studies into 2 subgroups: left main and non-left main coronary artery lesions. Baseline demographics and clinical outcome data were extracted by 3 independent reviewers. Fixed and random effects summary risk ratios were constructed using Mantel-Haenszel and DerSimonian-Laird models, respectively. The primary outcome was the composite of death, myocardial infarction, and revascularization.

RESULTS

From 741 potential studies, 17 were included in the meta-analysis (n = 2975 participants), 8 in the left main subgroup (n = 595) and 9 studies (n = 2380) in non-left main subgroup. In the left main subgroup, the incidence of the composite outcome was 15.3% in the no-ischemia/deferral group vs 14.3% in the ischemia/revascularization group (risk ratio [RR] = 1.13, 95% confidence interval [CI]: 0.76-1.68, P = 0.54, I(2) = 3.7%). In the non-left main subgroup, the incidence of the composite outcome was 9.2% in the no-ischemia/deferral group vs 18.8% in the ischemia/revascularization group (RR = 0.42, 95% CI: 0.34-0.52, P < 0.0001, I(2) = 20.7%).

CONCLUSIONS

Patients with left main coronary disease had a relatively high incidence of adverse cardiovascular events, which was similar in both the deferral and revascularization groups. In patients with non-left main disease, ischemia was associated with worse outcomes despite revascularization.

Outcomes of coronary stenoses deferred revascularization for borderline versus nonborderline fractional flow reserve values

Current evidence supports deferral of revascularization for lesions with fractional flow reserve (FFR) values >0.80. The natural history after deferral of revascularization of lesions with borderline FFR values is unknown. This study evaluated the outcomes of patients after deferred revascularization of coronary stenoses based on a borderline FFR value. We retrospectively studied 720 patients with 881 intermediate-severity coronary stenoses who underwent FFR assessment from October 2002 to July 2010 and were deferred revascularization. Patients were divided into gray zone (0.75 to 0.80), borderline (0.81 to 0.85), and nonborderline (>0.85) FFR groups. Any subsequent percutaneous coronary intervention or coronary artery bypass grafting of a deferred stenosis during follow-up was classified as a deferred lesion intervention (DLI). Patient and/or lesion characteristics and clinical outcomes were compared between the FFR groups using univariate and propensity score-adjusted inverse probability of weighting Cox proportional hazards analyses. During a mean follow-up of 4.5 ± 2.1 years, 157 deferred lesions (18%) underwent DLI by percutaneous coronary intervention (n = 117) or coronary artery bypass grafting (n = 40). No statistically significant differences were observed in clinical outcomes between the gray zone and borderline FFR groups. Lesions with a borderline FFR were associated with a significantly higher risk of DLI compared with lesions with nonborderline FFR values (hazard ratio 1.63, 95% confidence interval 1.14 to 2.33, p = 0.007). Lesions deferred revascularization because of a borderline FFR (0.81 to 0.85) were associated with a higher risk of DLI compared with lesions with a nonborderline FFR (>0.85). Further study is needed to determine the optimal management of coronary stenoses with a borderline FFR value.

Fractional flow reserve or optical coherence tomography guidance to revascularize intermediate coronary stenosis using angioplasty (FORZA) trial: study protocol for a randomized controlled trial

BACKGROUND

The management of patients with angiographically intermediate coronary lesions is a major clinical issue. Fractional flow reserve provides validated functional insights while optical coherence tomography provides high resolution anatomic imaging. Both techniques may be applied to guide management in case of angiographically intermediate coronary lesions. Moreover, these techniques may be used to optimize the result of percutaneous coronary intervention. We aim to compare the clinical and economic impact of fractional flow reserve versus optical coherence tomography guidance in patients with angiographically intermediate coronary lesions.

METHODS/DESIGN

Patients with at least one angiographically intermediate coronary lesion will be randomized (ratio 1:1) to fractional flow reserve or optical coherence tomography guidance. In the fractional flow reserve arm, percutaneous coronary intervention will be performed if fractional flow reserve value is ≤0.80, and will be conducted with the aim of achieving a post-percutaneous coronary intervention fractional flow reserve target value of ≥0.90. In the optical coherence tomography arm, percutaneous coronary intervention will be performed if percentage of area stenosis (AS%) is ≥75% or 50 to 75% with minimal lumen area <2.5 mm2, or if a major plaque ulceration is detected. In case of percutaneous coronary intervention, optical coherence tomography will guide the procedure in order to minimize under-expansion, malapposition, and edge dissections.Cost load and clinical outcome will be prospectively assessed at one and thirteen months. The assessed clinical outcome measures will be: major cardiovascular events and occurrence of significant angina defined as a Seattle Angina Questionnaire score <90 in the angina frequency scale.

DISCUSSION

The FORZA trial will provide useful guidance for the management of patients with coronary artery disease by prospectively assessing the use of two techniques representing the gold standard for functional and anatomical definition of coronary plaques.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01824030.

Fractional flow reserve: an updated review

Revascularization of ischemia-producing coronary lesions is widely used in the management of coronary artery disease. However, some coronary lesions appear significant on the conventional angiogram when they are truly non-flow limiting. For this reason, it is becoming increasingly important to determine the coronary physiology. Fractional flow reserve (FFR) has emerged as a useful tool to determine the lesions that require revascularization. Measurement of FFR during invasive coronary angiography now has a class IA indication from the European Society of Cardiology for identifying hemodynamically significant coronary lesions when noninvasive evidence of myocardial ischemia is unavailable. Current data on FFR can be broadly classified into studies that compare the diagnostic accuracy of FFR measurement compared with other noninvasive modalities and studies that test treatment strategies of patients with intermediate coronary stenoses using a threshold value for FFR and that have clinical outcomes as endpoints. In this review, we will discuss the concept of FFR, current evidence supporting its usage, and future perspectives.

Invasive and non-invasive fractional flow reserve index in validation of hemodynamic severity of intracoronary lesions

This review discusses visual and functional evaluation of the hemodynamic significance of the degree of stenosis in coronary angiography, with respect to the indications for revascularization. The concept of the coronary flow reserve is defined, and the theoretical assumptions of the invasive measurement of the fractional flow reserve (FFR) are presented. In the following part, the publication describes the basic steps of numerical stimulations in terms of computational fluid dynamics (CFD) in calculating the fractional flow reserve based on computed tomography (CT) coronary angiography (FFRCT). The numerical FFRCT estimation in correlation with invasive measurements, as well as benefits deriving from FFRCT in the diagnosis of coronary artery disease, is presented in the example of the multicentre prospective DISCOVER-FLOW trial and the DeFACTO project. The CDF method enables to obtain hemodynamic significance of stenosis solely from the coronary anatomy vizualized by CT angiography. The calculation of FFRCT increases the diagnostic reliability of coronary flow reserve estimations. It contributes to the improvement in patients' qualification for contrast coronarography. If the accuracy of FFRCT is confirmed in clinical practice, and the time required for computational processing is shortened, it may turn out that the algorithms of coronary heart disease diagnosis will be verified and it will be to a greater extent based on the CT results.

Percutaneous revascularization of left main: role of imaging, techniques, and adjunct pharmacology

Refinement of interventional techniques, adjunctive pharmacological therapy, and the introduction of drug-eluting stents have fostered new interest for the percutaneous treatment of unprotected left main coronary artery (ULMCA) stenosis. Several observational registries, some randomized trials and several meta-analyses have consistently shown no difference in mortality and myocardial infarction between percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) surgery in patients with ULMCA stenosis, but a higher rate of target vessel revascularization in patients treated with PCI. As a consequence, PCI of ULMCA stenosis has been upgraded to class IIa or IIb indication in the current European or American practice guidelines. However, several critical issues should be properly addressed when pursuing a percutaneous strategy for the treatment of ULMCA stenosis, such as the use of IVUS for procedural guidance, assessment of disease location, optimal technique for distal ULMCA stenosis, risk of stent thrombosis, optimal duration of dual antiplatelet therapy, and the most appropriate strategy for post-procedure follow up. Multidisciplinary team approach remains essential to provide a balanced information to the patient and to offer the beast treatment option.

Intravascular ultrasound-derived predictors for fractional flow reserve in intermediate left main disease

OBJECTIVES

The aim of this study was to determine the best intravascular ultrasound (IVUS) criteria for predicting physiological significance of left main (LM) stenosis with fractional flow reserve (FFR) as the standard.

BACKGROUND

For identifying significant LM disease, optimal cutoff of minimal lumen area (MLA) and its accuracy remain debatable.

METHODS

We identified 55 patients (31 stable and 24 unstable angina) with an isolated LM lesion of 30% to 80% angiographic diameter stenosis who underwent IVUS and invasive physiological assessment before intervention.

RESULTS

The FFR at maximum hyperemia significantly correlated with IVUS-measured MLA within the LM (r = 0.623, p < 0.001), plaque burden (r = -0.548, p < 0.001), angiographic diameter stenosis (r = -0.449, p = 0.002), and angiographic length of the lesion (r = -0.292, p = 0.046). The FFR was significantly lower in 18 lesions with plaque rupture than 37 lesions without plaque rupture (0.76 ± 0.09 vs. 0.82 ± 0.09, p = 0.018). The independent determinants of FFR as a continuous variable were MLA (beta = 0.598, p < 0.001) and plaque rupture (beta = -0.255, p = 0.038). Furthermore, the MLA within the LM was the only independent determinant for FFR <0.80 (adjusted odds ratio: 0.312, p < 0.001) and for FFR <0.75 (adjusted odds ratio: 0.196, p = 0.001). The IVUS MLA value within the LM that best predicted FFR <0.80 was <4.8 mm(2) (89% sensitivity, 83% specificity). In addition, the cutoff value of plaque burden to predict FFR <0.80 was ≥72% (73% sensitivity, 79% specificity). The best cutoff values of the MLA and plaque burden for predicting FFR <0.75 were <4.1 mm(2) (95% sensitivity, 83% specificity) and ≥76% (79% sensitivity, 80% specificity), respectively.

CONCLUSIONS

In isolated LM disease, an IVUS-derived MLA <4.8 mm(2) is a useful criterion for predicting FFR <0.80.

Myocardial fractional flow reserve. Its role in guiding PCI in stable coronary artery disease

Revascularization of coronary artery lesions should be based on objective evidence of ischemia, as recommended by the guidelines of the European Society of Cardiology. However, even in the case of stable coronary artery disease and elective percutaneous coronary intervention (PCI), pre-procedural noninvasive stress test results are available in a minority of patients only. It is common practice for physicians to make decisions on revascularization in the catheterization laboratory after a cursory review of the angiogram, despite the well-recognized inaccuracy of such an approach. Myocardial fractional flow reserve (FFR) measured by a coronary pressure wire is a specific index of the functional significance of a coronary lesion, with superior diagnostic accuracy for the detection of ischemia than any noninvasive stress test. FFR trials on patients with single and multivessel disease, such as the DEFER and FAME studies, have demonstrated that the clinical benefit of PCI with respect to patient outcome is greatest when revascularization is limited to lesions inducing ischemia, whereas lesions not inducing ischemia should be treated medically.

New era of left main coronary artery treatment strategy

For several decades of medical history, coronary-artery bypass grafting (CABG) has been regarded as the best treatment option for patients with unprotected left main coronary artery (LMCA) disease, considering lesion priority and its clinical consequences. Over the time, with remarkable advancements in techniques of percutaneous coronary intervention (PCI), supporting devices, and adjunctive pharmacologic therapy, PCI with DES implantation has appeared to be new and alternative option for optimal revascularization therapy for these patients. The available cumulative evidence suggests that the safety outcomes such as mortality or composite of death, myocardial infarction and stroke are similar among PCI and CABG for patients with LMCA disease, the only difference was the rate of repeat revascularization. Current evidence and ongoing large clinical trials may encourage interventional cardiologists to choose PCI with stenting as an alternative revascularization strategy for unprotected LMCA disease in future. Finally, this evidence will change the current clinical practice and the guideline of optimal revascularization strategy for unprotected LMCA disease.

Coronary physiology in the cath lab: beyond the basics

The adoption of invasive coronary physiologic lesion assessment before percutaneous coronary intervention has become routine in many catheterization laboratories. In the last decade, numerous studies have demonstrated favorable outcomes for revascularization decisions based on in-lab coronary physiology in many patients. The use of coronary physiology in the laboratory has been identified as a class IIa recommendation for patients in whom the clinical presentation and supporting data are too inconclusive to make an objective decision regarding treatment. This article reviews pertinent concepts and studies of the more complex applications of translesional pressure measurements for optimal patient outcomes.

Differential effect of biventricular and right ventricular DDD pacing on coronary flow reserve in patients with ischemic cardiomyopathy

CRT and Coronary Flow Reserve.

BACKGROUND

Cardiac resynchronization therapy (CRT) has become a mainstay in heart failure management. There are also indications that upgrading of existing pacemakers to CRT systems may be of benefit. The aim of this study was to assess the effect of biventricular (BiV), compared with right ventricular (RV), pacing, on coronary flow reserve (CFR), in patients with ischemic cardiomyopathy.

METHODS AND RESULTS

From our database of heart failure patients implanted with BiV pacemakers, 20 patients (10 responders and 10 non-responders to CRT) were randomly selected. Left anterior descending artery coronary flow reserve was measured invasively, under BiV and RV pacing, using intracoronary adenosine to induce hyperemia. In all the 20 patients, there was a significant difference in the pairwise comparison between CFR recorded during BiV and RV pacing (mean difference 0.15, 95% confidence interval 0.07-0.23, P = 0.001). When comparing responders to non-responders, there was a significant difference as to the effect of BiV, compared with RV, pacing on CFR: mean difference (BiV minus RV CFR) was 0.26 ± 0.06 (95% confidence interval 0.13-0.39; P = 0.002), while in non-responders the difference was 0.04 ± 0.03 (95% confidence interval -0.02 to 0.10; P = 0.168).

CONCLUSION

BiV pacing is overall associated to higher CFR, compared with RV DDD pacing. This difference is almost exclusively attributable to the beneficial effect of CRT on coronary flow reserve in CRT-responders. This effect may contribute to the beneficial action of resynchronization in the failing heart and can be viewed in the context of reports of the usefulness of upgrading RV pacemakers to CRT systems.