Revascularization Decisions in Patients With Stable Angina and Intermediate Lesions

Illusion of revascularization: does anyone achieve optimal revascularization during percutaneous coronary intervention?

This Perspective article is a form of 'pastiche', inspired by the 1993 review by Lincoff and Topol entitled 'Illusion of reperfusion', and explores how their concept continues to apply to percutaneous revascularization in patients with coronary artery disease and ischaemia. Just as Lincoff and Topol argued that reperfusion of acute myocardial infarction was facing unresolved obstacles that hampered clinical success in 1993, we propose that challenging issues are similarly jeopardizing the potential benefits of stent-based angioplasty today. By analysing the appropriateness and efficacy of percutaneous coronary intervention (PCI), we emphasize the limitations of relying solely on visual angiographic guidance, which frequently leads to inappropriate stenting and overtreatment in up to one-third of patients and the associated increased risk of periprocedural myocardial infarction. The lack of optimal revascularization observed in half of patients undergoing PCI confers risks such as suboptimal physiology after PCI, residual angina and long-term stent-related events, leaving an estimated 76% of patients with an 'illusion of revascularization'. These outcomes highlight the need to refine our diagnostic tools by integrating physiological assessments with targeted intracoronary imaging and emerging strategies, such as co-registration systems and angiography-based computational methods enhanced by artificial intelligence, to achieve optimal revascularization outcomes.

Advancements and future perspectives in coronary angiography-derived fractional flow reserve

Angiography-derived fractional flow reserve (FFR) has emerged as a non-invasive technique to assess the functional significance of coronary artery stenoses. The clinical applications of angiography-derived FFR span a wide range of scenarios, including assessing intermediate coronary lesions and guiding revascularization decisions. This review paper aims to provide an overview of angiography-derived FFR, including its principles, clinical applications, and evidence supporting its accuracy and utility. Lastly, the review discusses future directions and ongoing research in the field, including the integration of angiography-derived FFR into routine clinical practice.

Biomechanical factors and atherosclerosis localization: insights and clinical applications

Although the entire vascular bed is constantly exposed to the same risk factors, atherosclerosis manifests a distinct intra-individual pattern in localization and progression within the arterial vascular bed. Despite shared risk factors, the development of atherosclerotic plaques is influenced by physical principles, anatomic variations, metabolic functions, and genetic pathways. Biomechanical factors, particularly wall shear stress (WSS), play a crucial role in atherosclerosis and both low and high WSS are associated with plaque progression and heightened vulnerability. Low and oscillatory WSS contribute to plaque growth and arterial remodeling, while high WSS promotes vulnerable changes in obstructive coronary plaques. Axial plaque stress and plaque structural stress are proposed as biomechanical indicators of plaque vulnerability, representing hemodynamic stress on stenotic lesions and localized stress within growing plaques, respectively. Advancements in imaging and computational fluid dynamics techniques enable a comprehensive analysis of morphological and hemodynamic properties of atherosclerotic lesions and their role in plaque localization, evolution, and vulnerability. Understanding the impact of mechanical forces on blood vessels holds the potential for developing shear-regulated drugs, improving diagnostics, and informing clinical decision-making in coronary atherosclerosis management. Additionally, Computation Fluid Dynamic (CFD) finds clinical applications in comprehending stent-vessel dynamics, complexities of coronary bifurcations, and guiding assessments of coronary lesion severity. This review underscores the clinical significance of an integrated approach, concentrating on systemic, hemodynamic, and biomechanical factors in atherosclerosis and plaque vulnerability among patients with coronary artery disease.

Impact of minimal lumen segmentation uncertainty on patient-specific coronary simulations: A look at FFRCT

We examined the effect of minimal lumen segmentation uncertainty on Fractional Flow Reserve obtained from Coronary Computed Tomography AngiographyFFR CT . A total of 14 patient-specific coronary models with different stenosis locations and degrees of severity were enrolled in this study. The optimal segmented coronary lumens were disturbed using intra± 6 % and inter-operator± 15 % variations on the segmentation threshold.FFR CT was evaluated in each case by 3D-OD CFD simulations. The findings suggest that the sensitivity ofFFR CT to this type of uncertainty increases distally and with the stenosis severity. Cases with moderate or severe distal coronary lesions should undergo either exact and thorough segmentation operations or invasive FFR measurements, particularly if theFFR CT is close to the cutoff (0.80). Therefore, we conclude that it is crucial to consider the lesion's location and degree of severity when evaluatingFFR CT results.

Operator decision-making in angiography-only guided revascularization for lesions not indicated for FFR: a QFR-based functional assessment in chronic coronary syndrome

Background

Discordance between coronary angiographic findings and invasive functional significance is well-established. Yet, the prevalence of this mismatch in an era increasingly utilizing invasive functional assessments, such as fractional flow reserve (FFR), remains unclear. This study examines the extent of such discrepancies in current clinical practice.

Methods

This single-center prospective registry included consecutive patients with chronic coronary syndrome (CCS) who underwent elective coronary angiography, with or without revascularization. Coronary angiograms deemed not requiring FFR due to clear anatomical distinctions, either anatomically severe indicating a need for revascularization or mild suggesting no need for intervention, were selected for evaluation. These were then subjected to post-hoc analysis by three independent operators who were blinded to the definitive treatment strategies. Importantly, the post-hoc analysis was conducted in two distinct phases: firstly, a re-evaluation of coronary stenosis, and secondly, a separate functional assessment, each carried out independently. Coronary stenosis severity was assessed visually, while functional relevance was determined by quantitative flow ratio (QFR), calculated using a computational fluid dynamics algorithm applied to angiographic images. Analysis focused on discrepancies between QFR-based functional indications and revascularization strategies actually performed.

Results

In 191 patients, 488 vessels were analyzed. Average diameter stenosis (DS) was 37 ± 34%, and QFR was 0.87 ± 0.15, demonstrating a moderate correlation (r = -0.84; 95% CI: -0.86 to -0.81, p < 0.01). Agreement with QFR at conventional anatomical cutoffs was 88% for 50% DS and 91% for 70% DS. Mismatches between revascularization decisions and QFR indications occurred in 10% of cases. Discrepancies were more frequent in the left anterior descending artery (14%) compared to the left circumflex (6%) and the right coronary artery (9%; p = 0.07).

Conclusion

In a cardiac-center where FFR utilization is high, discordance between coronary angiography and functional significance persists, even when operators are confident in their decisions not to use functional interrogation. This gap, most evident in the left anterior descending artery, highlights the potential need for integrated angiography-based functional assessments to refine revascularization decisions in CCS.

Standardized angiographic projections allow evaluation of coronary artery side branches with quantitative flow ratio (QFR)

Quantitative flow ratio (QFR) is a novel, software-based noninvasive method for the quantitative evaluation of coronary physiology. QFR results correlate with invasive FFR measurements in the three main epicardial coronary arteries. However, QFR data for the evaluation of coronary side branches (SB) are scarce. The evaluation of QFR-performance of SB was retrospective and prospective. Eighty-seven patients with suspected chronic coronary syndrome, who received angiography using routine core lab projections, were retrospectively analyzed. On the second part 37 patients, who received angiography using recommended standardized coronary angiography projections, were prospectively analyzed. Quantitative analysis was performed for SB with a maximum lumen diameter proximal of ≥2 mm based on quantitative coronary angiography (QCA) by two certified experts with the software QAngio XA 3D 3.2. Using routine projections, QFR computation in 55 % of the SB were obtained (123 out of 224). Using standardized projections, 85 % of SB were computed by QFR (64 out of 75; p < 0.001 vs routine projections). The fluoroscopy time for recommended projections was not significantly different as opposed to routine projections (3.75 ± 2.2 vs. 4.58 ± 3.00 min, p = 2.6986). Using the standardized projections was associated with a higher amount of contrast medium (53.44 ± 24.23 vs. 87.95 ± 43.73 ml, p < 0.01), longer overall procedure time (23.23 ± 16.35 vs. 36.14 ± 17.21 min, p < 0.01) and a higher dose area product (1152.28 ± 576.70 vs. 2540.68 ± 1774.07 cGycm2, p < 0.01). Our study shows that the blood flow of the vast majority of coronary SB can be determined non-invasively by QFR in addition to the main epicardial coronary arteries when standardized projections are used.

Non-invasive fractional flow reserve estimation using deep learning on intermediate left anterior descending coronary artery lesion angiography images

This study aimed to design an end-to-end deep learning model for estimating the value of fractional flow reserve (FFR) using angiography images to classify left anterior descending (LAD) branch angiography images with average stenosis between 50 and 70% into two categories: FFR > 80 and FFR ≤ 80. In this study 3625 images were extracted from 41 patients' angiography films. Nine pre-trained convolutional neural networks (CNN), including DenseNet121, InceptionResNetV2, VGG16, VGG19, ResNet50V2, Xception, MobileNetV3Large, DenseNet201, and DenseNet169, were used to extract the features of images. DenseNet169 indicated higher performance compared to other networks. AUC, Accuracy, Sensitivity, Specificity, Precision, and F1-score of the proposed DenseNet169 network were 0.81, 0.81, 0.86, 0.75, 0.82, and 0.84, respectively. The deep learning-based method proposed in this study can non-invasively and consistently estimate FFR from angiographic images, offering significant clinical potential for diagnosing and treating coronary artery disease by combining anatomical and physiological parameters.

Prognostic role of discordance between quantitative flow ratio and visual estimation in revascularization guidance

Aims

Revascularization guided by functional severity has presented improved outcomes compared with visual angiographic guidance. Quantitative flow ratio (QFR) is a reliable angiography-based method for functional assessment. We sought to investigate the prognostic value of discordance between QFR and visual estimation in coronary revascularization guidance.

Methods and results

We performed offline QFR analysis on all-comers undergoing coronary angiography. Vessels with calculated QFR were divided into four groups based on the decision to perform or defer percutaneous coronary intervention (PCI) and on the QFR result, i.e.: Group A (PCI-, QFR > 0.8); Group B (PCI+, QFR ≤ 0.8); Group C (PCI+, QFR > 0.8); Group D (PCI-, QFR ≤ 0.8). Patients with at least one vessel falling within the disagreement groups formed the discordance group, whereas the remaining patients formed the concordance group. The primary endpoint was the composite endpoint of cardiovascular death, myocardial infarction, and ischaemia-driven revascularization. Overall, 546 patients were included in the study. Discordance between QFR and visual estimation was found in 26.2% of patients. After a median follow-up period of 2.5 years, the discordance group had a significantly higher rate of the composite outcome (hazard ratio: 3.34, 95% confidence interval 1.99-5.60, P < 0.001). Both disagreement vessel Groups C and D were associated with increased cardiovascular risk compared with agreement Groups A and B.

Conclusion

Discordance between QFR and visual estimation in revascularization guidance was associated with a worse long-term prognosis. Our results highlight the importance of proper patient selection for intervention and the need to avoid improper stent implantations when not dictated by a comprehensive functional assessment.

Validation of Quantitative Flow Ratio-Derived Virtual Angioplasty with Post-Angioplasty Fractional Flow Reserve-The QIMERA-I Study

Background: Quantitative flow ratio (QFR) virtual angioplasty with pre-PCI residual QFR showed better results compared with an angiographic approach to assess post-PCI functional results. However, correlation with pre-PCI residual QFR and post-PCI fractional flow reserve (FFR) is lacking. Methods: A multicenter prospective study including consecutive patients with angiographically 50-90% coronary lesions and positive QFR results. All patients were evaluated with QFR, hyperemic and non-hyperemic pressure ratios (NHPR) before and after the index PCI. Pre-PCI residual QFR (virtual angioplasty) was calculated and compared with post-PCI fractional flow reserve (FFR), QFR and NHPR. Results: A total of 84 patients with 92 treated coronary lesions were included, with a mean age of 65.5 ± 10.9 years and 59% of single vessel lesions being the left anterior descending artery in 69%. The mean vessel diameter was 2.82 ± 0.41 mm. Procedural success was achieved in all cases, with a mean number of implanted stents of 1.17 ± 0.46. The baseline QFR value was 0.69 ± 0.12 and baseline FFR and NHPR were 0.73 ± 0.08 and 0.82 ± 0.11, respectively. Mean post-PCI FFR increased to 0.87 ± 0.05 whereas residual QFR had been estimated as 0.95 ± 0.05, showing poor correlation with post-PCI FFR (0.163; 95% CI:0.078-0.386) and low diagnostic accuracy (30.9%, 95% CI:20-43%). Conclusions: In this analysis, the results of QFR-based virtual angioplasty did not seem to accurately correlate with post-PCI FFR.

Unveiling the Prognostic Power of Coronary Physiological Progression

Coronary atherosclerosis, a progressive disease, has long been the focus of clinical investigations aimed at understanding its natural evolution and response to medical therapies. While traditional imaging modalities, such as intravascular ultrasound (IVUS) and coronary computed tomography angiography (CTA), have shed light on plaque characteristics and vulnerability to rupture leading to clinical events, the clinical implications of coronary physiological techniques associated with increased risk of clinical events remain underexplored. The incremental prognostic value of 3V-quantitative flow ratio (QFR) advocates for its integration into routine clinical evaluations as a non-invasive tool for risk stratification in coronary artery disease patients.

Long-term prognostic value of quantitative-flow-ratio-concordant revascularization in stable coronary artery disease

OBJECTIVES

Confirming the prognostic value of global QFR and evaluating the long-term prognosis of QFR-concordant therapy in stable coronary artery disease.

BACKGROUND

Wire-based functional evaluation of coronary disease is linked to patient's prognosis. Quantitative Flow Ratio (QFR) is a newer index of computational physiology, linked to clinical outcomes and prognosis at 1 year follow-up. Long-term prognosis of QFR-concordant revascularization in stable coronary artery disease is however unknown hitherto.

METHODS

Consecutive patients with stable coronary disease undergoing coronary angiography were included. Centralized and blinded QFR analysis of three coronary territories was performed. Three vessel QFR (3vQFR) was defined as the sum of the basal QFR of each coronary territory. QFR-concordant revascularization was met if all significant lesions (QFR ≤ 0.80) were revascularized and all non-significant lesions (QFR > 0.80) were not; otherwise, the case was defined as QFR-discordant revascularization. Patient-oriented composite end-point (POCE) of cardiac death, myocardial infarction and unscheduled revascularization was the primary endpoint.

RESULTS

A total of 803 patients from six high-volume centers were included. Canadian Cardiovascular Society (CCS) class II angina was the most frequent (48.9%) clinical presentation. Median of follow-up was 68.8 months. 3vQFR was an independent predictor of POCE (HR 1.79 CI95% 1.01-3.18), with 2.75 as optimal cut-off value, irrespective of the therapy received. QFR-discordant revascularization (QFR+/Revascularization- or QFR-/Revascularization+) was an independent predictor of POCE in multivariate analysis (HR 1.65, CI 95% 1.03-2.64).

CONCLUSION

Global burden of epicardial coronary atherosclerosis, as evaluated by 3vQFR, as well as QFR-discordant therapy are independent predictors of adverse clinical outcome at long-term follow-up in stable coronary artery disease.

Moving toward Precision Medicine in Acute Coronary Syndromes: A Multimodal Assessment of Non-Culprit Lesions

Patients with acute coronary syndrome and multivessel disease experience several recurrent adverse events that lead to poor outcomes. Given the complexity of treating these patients, and the extremely high risk of long-term adverse events, the assessment of non-culprit lesions becomes crucial. Recently, two trials have shown a possible clinical benefit into treat non-culprit lesions using a fraction flow reserve (FFR)-guided approach, compared to culprit-lesion-only PCI. However, the most recent FLOW Evaluation to Guide Revascularization in Multivessel ST-elevation Myocardial Infarction (FLOWER-MI) trial did not show a benefit of the use of FFR-guided PCI compared to an angiography-guided approach. Otherwise, intracoronary imaging using optical coherence tomography (OCT), intravascular ultrasound (IVUS), or near-infrared spectroscopy (NIRS) could provide both quantitative and qualitative assessments of non-culprit lesions. Different studies have shown how the characterization of coronary lesions with intracoronary imaging could lead to clinical benefits in these peculiar group of patients. Moreover, non-invasive evaluations of NCLs have begun to take ground in this context, but more insights through adequately powered and designed studies are needed. The aim of this review is to outline the available techniques, both invasive and non-invasive, for the assessment of multivessel disease in patients with STEMI, and to provide a systematic guidance on the assessment and approach to these patients.

Intravascular Imaging versus Physiological Assessment versus Biomechanics-Which Is a Better Guide for Coronary Revascularization

Today, coronary artery disease (CAD) continues to be a prominent cause of death worldwide. A reliable assessment of coronary stenosis represents a prerequisite for the appropriate management of CAD. Nevertheless, there are still major challenges pertaining to some limitations of current imaging and functional diagnostic modalities. The present review summarizes the current data on invasive functional and intracoronary imaging assessment using optical coherence tomography (OCT), and intravascular ultrasound (IVUS). Amongst the functional parameters-on top of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR)-we point to novel angiography-based measures such as quantitative flow ratio (QFR), vessel fractional flow reserve (vFFR), angiography-derived fractional flow reserve (FFRangio), and computed tomography-derived flow fractional reserve (FFR-CT), as well as hybrid approaches focusing on optical flow ratio (OFR), computational fluid dynamics and attempts to quantify the forces exaggerated by blood on the coronary plaque and vessel wall.

Myocardial infarction with nonobstructive coronary arteries: from pathophysiology to therapeutic strategies

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a heterogeneous group of clinical entities characterized by clinical evidence of acute myocardial infarction (AMI) with normal or near-normal coronary arteries on coronary angiography (stenosis < 50%) and without an over the alternative diagnosis for the acute presentation. Its prevalence ranges from 6% to 11% among all patients with AMI, with a predominance of young, nonwhite females with fewer traditional risks than those with an obstructive coronary artery disease (MI-CAD). MINOCA can be due to either epicardial causes such as rupture or fissuring of unstable nonobstructive atherosclerotic plaque, coronary artery spasm, spontaneous coronary dissection and cardioembolism in-situ or microvascular causes. Besides, also type-2 AMI due to supply-demand mismatch and Takotsubo syndrome must be considered as a possible MINOCA cause. Because of the complex etiology and a limited amount of evidence, there is still some confusion around the management and treatment of these patients. Therefore, the key focus of this condition is to identify the underlying individual mechanisms to achieve patient-specific treatments. Clinical history, electrocardiogram, echocardiography, and coronary angiography represent the first-level diagnostic investigations, but coronary imaging with intravascular ultrasound and optical coherent tomography, coronary physiology testing, and cardiac magnetic resonance imaging offer additional information to understand the underlying cause of MINOCA. Although the prognosis is slightly better compared with MI-CAD patients, MINOCA is not always benign and depends on the etiopathology. This review analyzes all possible pathophysiological mechanisms that could lead to MINOCA and provides the most specific and appropriate therapeutic approach in each scenario.

Impact of Functional vs Anatomic Complete Revascularization in Coronary Artery Bypass Grafting

BACKGROUND

This study was conducted to evaluate the impact of functional and anatomic complete revascularization on long-term clinical outcomes after coronary artery bypass grafting (CABG).

METHODS

Of 2034 patients who underwent primary isolated CABG between 2006 and 2017, 1162 patients who underwent off-pump CABG for 3-vessel disease and for whom data on functional and anatomic completeness of revascularization were available on the basis of preoperative myocardial single photon emission computed tomography and early postoperative graft angiography were enrolled. The median follow-up duration was 82.4 months (interquartile range, 50.8-122.4 months). Univariate and multivariate analyses were performed to evaluate the impact of the functional and anatomic completeness of revascularization on long-term survival.

RESULTS

Of 1162 patients, anatomic complete revascularization was achieved in 1014 patients (87.3%), whereas functional complete revascularization was achieved in 1077 patients (92.7%). Early mortality occurred in 7 patients. Late death occurred in 322 of 1155 early survivors. The 5- and 10-year overall survival rates were 84.3% and 66.7%, respectively. Univariate analyses demonstrated that functional completeness of revascularization was a statistically significant risk factor (P = .038), whereas anatomic completeness was not (P = .859). The multivariate analysis showed that functional completeness of revascularization (hazard ratio, 1.54; 95% CI, 1.08-2.22; P = .019) and age, underweight status, diabetes mellitus, chronic kidney disease, chronic obstructive pulmonary disease, and left ventricular dysfunction were significant factors associated with long-term survival.

CONCLUSIONS

Functional rather than anatomic completeness of revascularization has a significant impact on the long-term survival in patients who undergo CABG.

Coronary Physiologic Assessment Based on Angiography and Intracoronary Imaging

Intracoronary physiology testing has evolved as a promising diagnostic approach in the management of patients with coronary artery disease. The value of hyperemic translesional pressure ratios to estimate the functional relevance of coronary stenoses is supported by a wealth of outcomes data. The continuing drive to further simplify this approach led to the development of non-hyperemic pressure-based indices. Recent attention has focused on estimating functional significance without invasively measuring coronary pressure through the measurement of virtual indices derived from the coronary angiogram. By offering a routine assessment of the physiology of all the major epicardial coronary vessels, angiogram-derived physiology has the potential to modify current practice by facilitating more accurate patient-level, vessel-level, and even lesion-level decision making. This article reviews the current state of angiogram-derived physiology and speculates on its potential impact on clinical practice, in continuation to the previously published article on coronary physiology in this journal.

Validity and Diagnostic Performance of Computing Fractional Flow Reserve From 2-Dimensional Coronary Angiography Images

BACKGROUND

Measurement of fractional flow reserve (FFR) is the gold standard for determining the physiologic significance of coronary artery stenosis, but newer software programs can calculate the FFR from 2-dimensional angiography images.

METHODS

A retrospective analysis was conducted using the records of patients with intermediate coronary stenoses who had undergone adenosine FFR (aFFR). To calculate the computed FFR, a software program used simulated coronary blood flow using computational geometry constructed using at least 2 patient-specific angiographic images. Two cardiologists reviewed the angiograms and determined the computational FFR independently. Intraobserver variability was measured using κ analysis and the intraclass correlation coefficient. The correlation coefficient and Bland-Altman plots were used to assess the agreement between the calculated FFR and the aFFR.

RESULTS

A total of 146 patients were included, with 95 men and 51 women, with a mean (SD) age of 61.1 (9.5) y. The mean (SD) aFFR was 0.847 (0.072), and 41 patients (27.0%) had an aFFR of 0.80 or less. There was a strong intraobserver correlation between the computational FFRs (r = 0.808; P < .001; κ = 0.806; P < .001). There was also a strong correlation between aFFR and computational FFR (r = 0.820; P < .001) and good agreement on the Bland-Altman plot. The computational FFR had a high sensitivity (95.1%) and specificity (90.1%) for detecting an aFFR of 0.80 or less.

CONCLUSION

A novel software program provides a feasible method of calculating FFR from coronary angiography images without resorting to pharmacologically induced hyperemia.

Assessment of fractional flow reserve in intermediate coronary stenosis using optical coherence tomography-based machine learning

Objectives

This study aimed to evaluate and compare the diagnostic accuracy of machine learning (ML)- fractional flow reserve (FFR) based on optical coherence tomography (OCT) with wire-based FFR irrespective of the coronary territory.

Background

ML techniques for assessing hemodynamics features including FFR in coronary artery disease have been developed based on various imaging modalities. However, there is no study using OCT-based ML models for all coronary artery territories.

Methods

OCT and FFR data were obtained for 356 individual coronary lesions in 130 patients. The training and testing groups were divided in a ratio of 4:1. The ML-FFR was derived for the testing group and compared with the wire-based FFR in terms of the diagnosis of ischemia (FFR ≤ 0.80).

Results

The mean age of the subjects was 62.6 years. The numbers of the left anterior descending, left circumflex, and right coronary arteries were 130 (36.5%), 110 (30.9%), and 116 (32.6%), respectively. Using seven major features, the ML-FFR showed strong correlation (r = 0.8782, P < 0.001) with the wire-based FFR. The ML-FFR predicted wire-based FFR ≤ 0.80 in the test set with sensitivity of 98.3%, specificity of 61.5%, and overall accuracy of 91.7% (area under the curve: 0.948). External validation showed good correlation (r = 0.7884, P < 0.001) and accuracy of 83.2% (area under the curve: 0.912).

Conclusion

OCT-based ML-FFR showed good diagnostic performance in predicting FFR irrespective of the coronary territory. Because the study was a small-size study, the results should be warranted the performance in further large-scale research.

Impact of epicardial adipose tissue volume on hemodynamically significant coronary artery disease in Chinese patients with known or suspected coronary artery disease

Background

Epicardial adipose tissue (EAT) is directly related to coronary artery disease (CAD), but little is known about its role in hemodynamically significant CAD. Therefore, our goal is to explore the impact of EAT volume on hemodynamically significant CAD.

Methods

Patients who underwent coronary computed tomography angiography (CCTA) and received coronary angiography within 30 days were retrospectively included. Measurements of EAT volume and coronary artery calcium score (CACs) were performed on a semi-automatic software based on CCTA images, while quantitative flow ratio (QFR) was automatically calculated by the AngioPlus system according to coronary angiographic images.

Results

This study included 277 patients, 112 of whom had hemodynamically significant CAD and showed higher EAT volume. In multivariate analysis, EAT volume was independently and positively correlated with hemodynamically significant CAD [per standard deviation (SD) cm³; odds ratio (OR), 2.78; 95% confidence interval (CI), 1.86-4.15; P < 0.001], but negatively associated with QFR_min (per SD cm³; β coefficient, -0.068; 95% CI, -0.109 to -0.027; P = 0.001) after adjustment for traditional risk factors and CACs. Receiver operating characteristics curve analysis demonstrated a significant improvement in predictive value for hemodynamically significant CAD with the addition of EAT volume to obstructive CAD alone (area under the curve, 0.950 vs. 0.891; P < 0.001).

Conclusion

In this study, we found that EAT volume correlated substantially and positively with the existence and severity of hemodynamically significant CAD in Chinese patients with known or suspected CAD, which was independent of traditional risk factors and CACs. In combination with obstructive CAD, EAT volume significantly improved diagnostic performance for hemodynamically significant CAD, suggesting that EAT could be a reliable noninvasive indicator of hemodynamically significant CAD.

Comparison between the diagnostic performance of vessel fractional flow reserve and nonhyperemic pressure ratio for functionally significant coronary stenosis severity as assessed by fractional flow reserve

BACKGROUND

Fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs) have been widely used to assess the functional severity of coronary stenosis. However, their measurement requires using a pressure wire, making their use in all patients difficult. The recently developed vessel fractional flow reserve (vFFR), derived from three-dimensional quantitative coronary angiography, is expected to serve as a surrogate for pressure wire assessment.

METHODS

This retrospective study was conducted on patients with intermediate coronary stenosis who underwent FFR and NHPR measurements. The vFFR and NHPR values were compared for diagnosing coronary stenosis as defined by an FFR of ≤0.80, and the number of patients not requiring wire-based assessment was estimated.

RESULTS

In a total of 90 lesions from 74 patients (median [SD] age 75 [12] years; men 80%), the median FFR was 0.78 (0.72-0.84), and 57% of these lesions (N = 51) exhibited an FFR of ≤0.80. vFFR provided high discrimination for coronary stenosis (area under the curve 0.80, 95% confidence interval 0.70-0.90), which was comparable to that of NHPRs (p = 0.42). High diagnostic accuracy was consistently observed across a variety of clinical presentations (i.e., old age, diabetes, target coronary artery, and left ventricular hypertrophy) (p_interaction  > 0.05). In total, 55 lesions (61%) demonstrated positive or negative likelihood of coronary stenosis when vFFR was <0.73 (specificity 90%) or >0.87 (sensitivity 88%), respectively.

CONCLUSION

vFFR demonstrated excellent diagnostic performance for detecting functionally significant coronary stenosis as evaluated by FFR. vFFR may be used as a surrogate for pressure wire assessment.

Coronary physiology in the catheterisation laboratory: an A to Z practical guide

Coronary revascularisation, either percutaneous or surgical, aims to improve coronary flow and relieve myocardial ischaemia. The decision-making process in patients with coronary artery disease (CAD) remains largely based on invasive coronary angiography (ICA), even though until recently ICA could not assess the functional significance of coronary artery stenoses. Invasive wire-based approaches for physiological evaluations were developed to properly assess the ischaemic relevance of epicardial CAD. Fractional flow reserve (FFR) and later, instantaneous wave-free ratio (iFR), were shown to improve clinical outcomes in several patient subsets when used for coronary revascularisation guidance or deferral and for procedural optimisation of percutaneous coronary intervention (PCI) results. Despite accumulating evidence and positive guideline recommendations, the adoption of invasive physiology has remained quite low, mainly due to technical and economic issues as well as to operator-resistance to change. Coronary image-based computational physiology has been recently developed, with promising results in terms of accuracy and a reduction in computational time, costs, radiation exposure and risks for the patient. Lastly, the integration of intracoronary imaging and physiology allows for individualised PCI treatment, aiming at complete relief of ischaemia through optimised morpho-functional immediate procedural results. Instead of a conventional state-of-the-art review, this A to Z dictionary attempts to provide a practical guide for the application of coronary physiology in the catheterisation laboratory, exploring several methods, their pitfalls, and useful tips and tricks.

Improved Functional Assessment of Ischemic Severity Using 3D Printed Models

Objective

To develop a novel in vitro method for evaluating coronary artery ischemia using a combination of non-invasive coronary CT angiograms (CCTA) and 3D printing (FFR_3D).

Methods

Twenty eight patients with varying degrees of coronary artery disease who underwent non-invasive CCTA scans and invasive fractional flow reserve (FFR) of their epicardial coronary arteries were included in this study. Coronary arteries were segmented and reconstructed from CCTA scans using Mimics (Materialize). The segmented models were then 3D printed using a Carbon M1 3D printer with urethane methacrylate (UMA) family of rigid resins. Physiological coronary circulation was modeled in vitro as flow-dependent stenosis resistance in series with variable downstream resistance. A range of physiological flow rates (Q) were applied using a peristaltic steady flow pump and titrated with a flow sensor. The pressure drop (ΔP) and the pressure ratio (P_d/P_a) were assessed for patient-specific aortic pressure (P_a) and differing flow rates (Q) to evaluate FFR_3D using the 3D printed model.

Results

There was a good positive correlation (r = 0.87, p < 0.0001) between FFR_3D and invasive FFR. Bland-Altman analysis revealed a good concordance between the FFR_3D and invasive FFR values with a mean bias of 0.02 (limits of agreement: −0.14 to 0.18; p = 0.2).

Conclusions

3D printed patient-specific models can be used in a non-invasive in vitro environment to quantify coronary artery ischemia with good correlation and concordance to that of invasive FFR.

FFR pressure wire comparative study: piezoresistive versus optical sensor

BACKGROUND

This study aimed to assess the reliability of pressure derived fractional flow reserve (FFR) measurement and the handling performance of the OptoWire Deux with an optical pressure sensor relative to both the PressureWire X and the Verrata Pressure wire with piezoresistive pressure sensors.

METHODS

This single centre study included 80 patients between October 2016 and May 2017 undergoing a diagnostic coronary angiography. The reliability of FFR measurement measured with the OptoWire Deux relative to the PressureWire X and Verrata Pressure wire was assessed by the presence of drift. Drift was defined as a Pd/Pa measurement different from 1.00 ± 0.02 when pulled back after a FFR measurement at the location of the initial equalisation. Handling characteristics for all pressure wires were assessed qualitatively with respect to the PressureWire Aeris.

RESULTS

Ninety-eight measurements in 78 patients were performed; two patients were excluded because the lesion could not be crossed. Very stable and reliable FFR measurements with the optical sensors were registered, relative to the piezoresistive pressure sensors. Drift was found in 11%, 37%, and 33% of the measurements for OptoWire Deux, PressureWire X, and Verrata Pressure wire respectively. The handling performance of the OptoWire Deux was better rated for steerability and torqueability in relation to the standard FFR wire. The handling of the PressureWire X was rated equally good whereas the handling of the Verrata pressure wire was rated inferior in relation to the standard FFR wire.

CONCLUSIONS

In patients undergoing FFR measurement, the OptoWire Deux has a stable and reliable pressure hence FFR measurement with fewer drift events and has good handling characteristics.

Myocardial Infarction With Non-obstructive Coronary Arteries: Risk Factors and Associated Comorbidities

Myocardial infarction with non-obstructive coronary arteries (MINOCA), despite a lower burden of coronary atherosclerosis, has a non-negligible prognostic impact. The label of MINOCA includes an array of different aetiologies and pathologic conditions, thus the identification of the underlying disease is crucial to patient management. Myocardial infarction with obstructive coronary artery disease and MINOCA share only some risk factors and comorbid conditions. While traditional cardiovascular risk factors have a lower prevalence in MINOCA patients, atypical ones—e.g., anxiety, depression, and autoimmune diseases—are much more frequent in this population. Other conditions—e.g., pregnancy, cancer, and anti-cancer therapy—can predispose to or even induce MINOCA through various mechanisms. The evidence of such risk factors for MINOCA is still scarce and contradicting, as no randomised controlled trials exist in this field. In our work, we performed a review of registries, clinical studies, and case reports of MINOCA, in order to summarise the available data and analyse its possibile pathogenic mechanisms.

Vessel fractional flow reserve (vFFR) for the assessment of stenosis severity: the FAST II study

BACKGROUND

Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) is superior to angiography-guided PCI. The clinical uptake of FFR has been limited, however, by the need to advance a wire in the coronary artery, the additional time required and the need for hyperaemic agents which can cause patient discomfort. FFR derived from routine coronary angiography eliminates these issues.

AIMS

The aim of this study was to assess the diagnostic performance and accuracy of three-dimensional quantitative coronary angiography (3D-QCA)-based vessel FFR (vFFR) compared to pressure wire-based FFR (≤0.80).

METHODS

The FAST II (Fast Assessment of STenosis severity) study was a prospective observational multicentre study designed to evaluate the diagnostic accuracy of vFFR compared to the reference standard (pressure wire-based FFR ≤0.80). A total of 334 patients from six centres were enrolled. Both site-determined and blinded independent core lab vFFR measurements were compared to FFR.

RESULTS

The core lab vFFR was 0.83±0.09 and pressure wire-based FFR 0.83±0.08. A good correlation was found between core lab vFFR and pressure wire-based FFR (R=0.74; p<0.001; mean bias 0.0029±0.0642). vFFR had an excellent diagnostic accuracy in identifying lesions with an invasive wire-based FFR ≤0.80 (area under the curve [AUC] 0.93; 95% confidence interval [CI]: 0.90-0.96; p<0.001). Positive predictive value, negative predictive value, diagnostic accuracy, sensitivity and specificity of vFFR were 90%, 90%, 90%, 81% and 95%, respectively.

CONCLUSIONS

3D-QCA-based vFFR has excellent diagnostic performance to detect FFR ≤0.80. The study was registered on clinicaltrials.gov under identifier NCT03791320.

The prognostic value of angiography-based vessel fractional flow reserve after percutaneous coronary intervention: The FAST Outcome study

BACKGROUND

Vessel Fractional Flow Reserve (vFFR) as assessed by three-dimensional quantitative coronary angiography has high correlation with pressure wire-based fractional flow reserve in both a pre- and post-PCI setting. The present study aims to assess the prognostic value of post-PCI vFFR on the incidence of target vessel failure (TVF), a composite endpoint of cardiac death, target vessel myocardial infarction and target vessel revascularization (TVR) at 5-year follow up.

METHODS

Post-PCI vFFR was calculated after routine PCI in a total of 748 patients (832 vessels) with available orthogonal angiographic projections of the stented segment.

RESULTS

Median age was 65 (IQR 55-74) years, 18.2% were diabetic, and 29.1% presented with stable angina. Median post-PCI vFFR was 0.91 (IQR 0.86-0.95). Vessels were categorized into tertiles based on post-PCI vFFR: low (vFFR <0.88), middle (vFFR 0.88-0.93), and upper (vFFR ≥0.94). Vessels in the lower and middle tertile were more often LADs and had smaller stent diameters (p-value <0.001). Vessels in the lower and middle tertile had a higher risk of TVF as compared to vessels in the upper tertile (24.6% and 21.5% vs. 17.1%; adjusted HR 1.84 (95%CI 1.15-2.95), p = 0.011, and 1.58 (95%CI 1.02-2.45), p = 0.040) at 5-years follow-up. Additionally, vessels in the lower tertile had higher rates of TVR as compared to vessels in the higher tertile (12.6% vs. 6.5%, adjusted HR 1.93 (95%CI 1.06-3.53), p-value = 0.033).

CONCLUSION

Lower post-PCI vFFR values are associated with a significantly increased risk of TVF and TVR at 5-years follow-up.

Three-dimensional QCA-based vessel fractional flow reserve (vFFR) in Heart Team decision-making: a multicentre, retrospective, cohort study

OBJECTIVES

To evaluate the feasibility of three-vessel three-dimensional (3D) quantitative coronary angiography (QCA)-based fractional flow reserve (FFR) computation in patients discussed within the Heart Team in whom the treatment decision was based on angiography alone, and to evaluate the concordance between 3D QCA-based vessel FFR (vFFR)-confirmed functional lesion significance and revascularisation strategy as proposed by the Heart Team.

DESIGN

Retrospective, cohort.

SETTING

3D QCA-based FFR indices have not yet been evaluated in the context of Heart Team decision-making; consecutive patients from six institutions were screened for eligibility and three-vessel vFFR was computed by blinded analysts.

PARTICIPANTS

Consecutive patients with chronic coronary syndrome or unstable angina referred for Heart Team consultation. Exclusion criteria involved: presentation with acute myocardial infarction (MI), significant valve disease, left ventricle ejection fraction <30%, inadequate quality of angiogram precluding vFFR computation in all three epicardial coronary arteries (ie, absence of a minimum of two angiographic projections with views of at least 30° apart, substantial foreshortening/overlap of the vessel, poor contrast medium injection, ostial lesions, chronic total occlusions).

PRIMARY AND SECONDARY OUTCOME MEASURES

Discordance between vFFR-confirmed lesion significance and revascularisation was assessed as the primary outcome measure. Rates of major adverse cardiac events (MACE) defined as cardiac death, MI and clinically driven revascularisation were reported.

RESULTS

Of a total of 1003 patients were screened for eligibility, 416 patients (age 65.6±10.6, 71.2% male, 53% stable angina) were included. The most important reason for screening failure was insufficient quality of the angiogram (43%). Discordance between vFFR confirmed lesion significance and revascularisation was found in 124/416 patients (29.8%) corresponding to 149 vessels (46/149 vessels (30.9%) were reclassified as significant and 103/149 vessels (69.1%) as non-significant by vFFR). Over a median of 962 days, the cumulative incidence of MACE was 29.7% versus 18.5% in discordant versus concordant patients (p=0.031).

CONCLUSIONS

vFFR computation is feasible in around 40% of the patients referred for Heart Team discussion, a limitation that is mostly based on insufficient quality of the angiogram. Three vessel vFFR screening indicated discordance between vFFR confirmed lesion significance and revascularisation in 29.8% of the patients.

Angiography-derived physiology guidance vs usual care in an All-comers PCI population treated with the healing-targeted supreme stent and Ticagrelor monotherapy: PIONEER IV trial design

BACKGROUND

Current ESC guidelines recommend the use of intra-coronary pressure guidewires for functional assessment of intermediate-grade coronary stenoses. Angiography-derived quantitative flow ratio (QFR) is a novel method of assessing these stenoses, and guiding percutaneous coronary intervention (PCI).

METHODS/DESIGN

The PIONEER IV trial is a prospective, all-comers, multi-center trial, which will randomize 2,540 patients in a 1:1 ratio to PCI guided by angiography-derived physiology or usual care, with unrestricted use in both arms of the Healing-Targeted Supreme sirolimus-eluting stent (HT Supreme). The stent's fast, biologically healthy, and robust endothelial coverage allows for short dual-antiplatelet therapy (DAPT); hence the antiplatelet regimen of choice is 1-month DAPT, followed by ticagrelor monotherapy. In the angiography-derived physiology guided arm, lesions will be functionally assessed using on-line QFR, with stenting indicated in lesions with a QFR ≤0.80. Post-stenting, QFR will be repeated in the stented vessel(s), with post-dilatation or additional stenting recommended if the QFR<0.91 distal to the stent, or if the delta QFR (across the stent) is >0.05. Usual care PCI is performed according to standard clinical practice. The primary endpoint is a non-inferiority comparison of the patient-oriented composite endpoint (POCE) of all-cause death, any stroke, any myocardial infarction, or any clinically, and physiologically driven revascularization with a non-inferiority risk-difference margin of 3.2%, at 1-year post-procedure. Clinical follow-up will be up to 3 years.

SUMMARY

The PIONEER IV trial aims to demonstrate non-inferiority of QFR-guided PCI to usual care PCI with respect to POCE at 1-year in patients treated with HT Supreme stents and ticagrelor monotherapy.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov UNIQUE IDENTIFIER: NCT04923191 CLASSIFICATIONS: Interventional Cardiology.

The Role of Coronary Physiology in Contemporary Percutaneous Coronary Interventions

Invasive assessment of coronary physiology has radically changed the paradigm of myocardial revascularization in patients with coronary artery disease. Despite the prognostic improvement associated with ischemia-driven revascularization strategy, functional assessment of angiographic intermediate epicardial stenosis remains largely underused in clinical practice. Multiple tools have been developed or are under development in order to reduce the invasiveness, cost, and extra procedural time associated with the invasive assessment of coronary physiology. Besides epicardial stenosis, a growing body of evidence highlights the role of coronary microcirculation in regulating coronary flow with consequent pathophysiological and clinical and prognostic implications. Adequate assessment of coronary microcirculation function and integrity has then become another component of the decision-making algorithm for optimal diagnosis and treatment of coronary syndromes. This review aims at providing a comprehensive description of tools and techniques currently available in the catheterization laboratory to obtain a thorough and complete functional assessment of the entire coronary tree (both for the epicardial and microvascular compartments).

Angiographic quantitative flow ratio-guided coronary intervention (FAVOR III China): a multicentre, randomised, sham-controlled trial

BACKGROUND

Compared with visual angiographic assessment, pressure wire-based physiological measurement more accurately identifies flow-limiting lesions in patients with coronary artery disease. Nonetheless, angiography remains the most widely used method to guide percutaneous coronary intervention (PCI). In FAVOR III China, we aimed to establish whether clinical outcomes might be improved by lesion selection for PCI using the quantitative flow ratio (QFR), a novel angiography-based approach to estimate the fractional flow reserve.

METHODS

FAVOR III China is a multicentre, blinded, randomised, sham-controlled trial done at 26 hospitals in China. Patients aged 18 years or older, with stable or unstable angina pectoris or patients who had a myocardial infarction at least 72 h before screening, who had at least one lesion with a diameter stenosis of 50-90% in a coronary artery with a reference vessel of at least 2·5 mm diameter by visual assessment were eligible. Patients were randomly assigned to a QFR-guided strategy (PCI performed only if QFR ≤0·80) or an angiography-guided strategy (PCI based on standard visual angiographic assessment). Participants and clinical assessors were masked to treatment allocation. The primary endpoint was the 1-year rate of major adverse cardiac events, a composite of death from any cause, myocardial infarction, or ischaemia-driven revascularisation. The primary analysis was done in the intention-to-treat population. The trial was registered with ClinicalTrials.gov (NCT03656848).

FINDINGS

Between Dec 25, 2018, and Jan 19, 2020, 3847 patients were enrolled. After exclusion of 22 patients who elected not to undergo PCI or who were withdrawn by their physicians, 3825 participants were included in the intention-to-treat population (1913 in the QFR-guided group and 1912 in the angiography-guided group). The mean age was 62·7 years (SD 10·1), 2699 (70·6%) were men and 1126 (29·4%) were women, 1295 (33·9%) had diabetes, and 2428 (63·5%) presented with an acute coronary syndrome. The 1-year primary endpoint occurred in 110 (Kaplan-Meier estimated rate 5·8%) participants in the QFR-guided group and in 167 (8·8%) participants in the angiography-guided group (difference, -3·0% [95% CI -4·7 to -1·4]; hazard ratio 0·65 [95% CI 0·51 to 0·83]; p=0·0004), driven by fewer myocardial infarctions and ischaemia-driven revascularisations in the QFR-guided group than in the angiography-guided group.

INTERPRETATION

In FAVOR III China, among patients undergoing PCI, a QFR-guided strategy of lesion selection improved 1-year clinical outcomes compared with standard angiography guidance.

FUNDING

Beijing Municipal Science and Technology Commission, Chinese Academy of Medical Sciences, and the National Clinical Research Centre for Cardiovascular Diseases, Fuwai Hospital.

Adoption and patterns of use of invasive physiological assessment of coronary artery disease in a large cohort of 40821 real-world procedures over a 12-year period

INTRODUCTION AND OBJECTIVES

Use of invasive physiological assessment in patients with coronary artery disease varies widely and is perceived to be low. We aimed to examine adoption rates as well as patterns and determinants of use in an unselected population undergoing invasive coronary angiography over a long time frame.

METHODS

We retrospectively determined the per-procedure prevalence of physiological assessment in 40821 coronary cases performed between 2007 and 2018 in two large-volume centers. Adoption was examined according to procedure type and patient- and operator-related variables. Its association with relevant scientific landmarks, such as the release of clinical trial results and practice guidelines, was also assessed.

RESULTS

Overall adoption was low, ranging from 0.6% in patients undergoing invasive coronary angiography due to underlying valve disease, to 6% in the setting of stable coronary artery disease (CAD); it was 3.1% in patients sustaining an acute coronary syndrome. Of scientific landmarks, FAME 1, the long-term results of FAME 2 and the 2014 European myocardial revascularization guidelines were associated with changes in practice. Publication of instantaneous wave-free ratio (iFR) trials had no influence on adoption rates, except for a higher proportion of iFR use. In 42.9% of stable CAD patients undergoing percutaneous coronary intervention there was no objective non-invasive evidence of ischemia, nor was physiological assessment performed. Younger operator age (4.5% vs. 4.0% vs. 0.9% for ages <40, 40-55 and >55 years, respectively; p<0.001) and later time of procedure during the day (2.9% between 6 and 8 p.m. vs. 4.4% at other times) were independent correlates of use of invasive physiology.

CONCLUSIONS

Our study confirms the low use of invasive physiology in routine practice. The availability of resting indices did not increase adoption. Strategies are warranted to promote guideline implementation and to improve patient care and clinical outcomes.

Sex differences in assessing stenosis severity between physician visual assessment and quantitative coronary angiography

BACKGROUND

Physician visual assessment (PVA) in invasive coronary angiography (ICA) is the current clinical method to determine stenosis severity and guide percutaneous coronary intervention. This study sought to evaluate the effect of sex differences in assessing coronary stenosis severity between PVA and quantitative coronary angiography (QCA).

METHODS

209 patients with coronary artery disease (288 coronary lesions) underwent ICA and fractional flow reserve (FFR). ICA image processing including PVA and QCA was used to quantify diameter stenosis (DS). The difference of DS (ΔDS) between PVA and QCA was defined as DS_PVA-DS_QCA. DS ≥50% was considered anatomically obstructive. FFR ≤0.8 was defined as myocardial ischemia.

RESULTS

Mean ± SD age was 63 ± 9 years. There were no significant differences in DS_PVA (61.1 ± 16.3% vs 60.1 ± 18.9%) and DS_QCA (53.1 ± 12.1% vs 55.4 ± 14.3%) between females and males. However, ΔDS between PVA and QCA was higher in females (8.0 ± 10.9%) than in males (4.7 ± 10.9%) (P = 0.03). Thirty-four of 72 vessels (47.2%) in female patients and 75 of 216 vessels (34.7%) in male patients were classified differently by at least one grade using PVA compared to QCA assessment. DS_PVA and DS_QCA were negatively correlated with FFR in females (r_PVA = -0.397, r_QCA = -0.448) with an even stronger negative correlation in males (r_PVA = -0.607, r_QCA = -0.607). ROC analysis demonstrated that DS_QCA had better discrimination capability for myocardial ischemia (FFR ≤ 0.80) than DS_PVA in both sexes (P < 0.05).

CONCLUSIONS

A systematic bias was found in PVA (QCA reference) for overestimating severity of coronary artery disease in females compared to males.

Myocardial infarction with non-obstructive coronary artery disease

As a result of the increased use of coronary angiography in acute myocardial infarction in the last two decades, myocardial infarction with non-obstructive coronary arteries (MINOCA) has received growing attention in everyday clinical practice. At the same time, research interest in MINOCA has increased significantly. MINOCA is a heterogeneous disease entity seen in 5-10% of all patients with myocardial infarction, especially in women. Clinically, MINOCA may be difficult to distinguish from other non-ischaemic conditions that can cause similar symptoms and myocardial injury. There is still some confusion around the diagnosis, investigation and management of patients with MINOCA. The present review summarises the current knowledge of MINOCA regarding epidemiology, pathophysiology, investigation, and treatment, with a special focus on imaging modalities. In addition, remaining important knowledge gaps are highlighted.

Identification of Flow-Limiting Coronary Stenosis With PCS: A New Cost-Effective Index Derived From the Product of Corrected TIMI Frame Count and Percent Diameter Stenosis

Background: Identifying functional coronary stenosis with simple and cost-effective methods during invasive coronary angiography is still challenging. Corrected TIMI frame count (CTFC) is considered to be the frame count velocity of coronary blood flow. We aimed to propose a simple and cost-effective index based on CTFC and percent diameter stenosis (DS) to identify flow-limiting coronary stenosis. For this, a new index was put forward as the product of CTFC and DS (PCS). PCS can be regarded as the loss of coronary blood flow due to diameter stenosis.

Methods: DS, CTFC, PCS, and Fractional flow reserve (FFR) of 111 vessels in 84 patients with suspected coronary heart disease were measured. FFR ≤0.80 was defined as flow-limiting. Models involving CTFC, DS, and PCS were developed. Logistic regression was performed to evaluate the values on diagnosing flow-limiting stenosis.

Results: Vessels with flow-limiting coronary stenosis exhibited higher CTFC values than those without (28.56 vs. 21.64). The performance including the AUC (0.887), sensitivity (87.8%), and Youden index (0.678) for detecting flow-limiting stenosis was improved by adding the CTFC to the DS, while PCS had the largest positive predictive value (PPV) and diagnostic accuracy (DA) being 72.0 and 82.9%, respectively. For vessels with ≥50% lesions, PCS still had the best DA (80.9%), specificity (85.9%), and PPV (72.9%). At the same stenosis severity level, the AUC, Youden index and, DA of PCS were higher than those of CTFC.

Conclusions: PCS is simple and accurate to identify flow-limiting coronary stenosis, especially at vessels with moderate to severe stenosis.

Head to head comparison of quantitative flow ratio using 4-French and 6-French catheters versus fractional flow reserve

OBJECTIVES

To validate QFR using 4-F diagnostic catheters compared to using 6-F guiding catheters, with conventional guidewire-based FFR as the reference standard, using independent core laboratory analysis.

BACKGROUND

Quantitative Flow Ratio (QFR) allows Fractional Flow Reserve (FFR) calculation based on the coronary angiogram, using 5- or 6-French (F) catheters. However, the use of 4-F diagnostic catheters to perform coronary angiography is currently routine in some centers.

METHODS

We included all consecutive patients with stable coronary artery disease and indicated for physiological assessment. QFR was performed using a 4-F diagnostic catheter, then QFR was performed using a 6-F guiding catheter while conventional FFR was measured using a pressure guidewire. Angiograms were sent to two separate core laboratories.

RESULTS

One hundred lesions in 67 consecutive patients with QFR performed using 4-F and 6-F catheters, and with conventional FFR, were included. Pearson's correlation coefficient was for QFR 4-F vs. FFR 0.91 [0.87-0.94], for QFR 6-F vs. FFR 0.90 [0.86-0.94], and for QFR 4-F vs. QFR 6-F 0.93 [0.90-0.95]. Receiver-operator characteristic curves (ROC) comparing the ability to predict an FFR value above or below 0.80 with QFR 4-F and 6-F were generated. The area under the ROC curve (AUC) vs. FFR was 0.972 [0.95-0.99] for QFR 4-F and 0.970 [0.94-0.99] for QFR 6-F.

CONCLUSIONS

Our study demonstrated the feasibility of performing QFR analysis from angiograms obtained by 4-F catheters, and showed a good correlation with QFR performed using 6-F catheters as well as with conventional FFR performed using a pressure guidewire.

Adoption and patterns of use of invasive physiological assessment of coronary artery disease in a large cohort of 40821 real-world procedures over a 12-year period

INTRODUCTION AND OBJECTIVES

Use of invasive physiological assessment in patients with coronary artery disease varies widely and is perceived to be low. We aimed to examine adoption rates as well as patterns and determinants of use in an unselected population undergoing invasive coronary angiography over a long time frame.

METHODS

We retrospectively determined the per-procedure prevalence of physiological assessment in 40821 coronary cases performed between 2007 and 2018 in two large-volume centers. Adoption was examined according to procedure type and patient- and operator-related variables. Its association with relevant scientific landmarks, such as the release of clinical trial results and practice guidelines, was also assessed.

RESULTS

Overall adoption was low, ranging from 0.6% in patients undergoing invasive coronary angiography due to underlying valve disease, to 6% in the setting of stable coronary artery disease (CAD); it was 3.1% in patients sustaining an acute coronary syndrome. Of scientific landmarks, FAME 1, the long-term results of FAME 2 and the 2014 European myocardial revascularization guidelines were associated with changes in practice. Publication of instantaneous wave-free ratio (iFR) trials had no influence on adoption rates, except for a higher proportion of iFR use. In 42.9% of stable CAD patients undergoing percutaneous coronary intervention there was no objective non-invasive evidence of ischemia, nor was physiological assessment performed. Younger operator age (4.5% vs. 4.0% vs. 0.9% for ages <40, 40-55 and >55 years, respectively; p<0.001) and later time of procedure during the day (2.9% between 6 and 8 p.m. vs. 4.4% at other times) were independent correlates of use of invasive physiology.

CONCLUSIONS

Our study confirms the low use of invasive physiology in routine practice. The availability of resting indices did not increase adoption. Strategies are warranted to promote guideline implementation and to improve patient care and clinical outcomes.

Functionally Complete Coronary Revascularisation in Patients Presenting with ST-elevation MI and Multivessel Coronary Artery Disease

Up to half of patients undergoing primary percutaneous coronary intervention of a culprit stenosis in the context of the ST-elevation MI may present with multivessel disease. The presence of non-culprit stenoses have been shown to affect the outcomes of these patients, and the results of the more recent randomised trials highlight the importance of complete coronary revascularisation. In this paper, the authors review the main trials published on the topic and discuss tools for the assessment of non-culprit stenoses, while considering the right time for carrying out a complete coronary revascularisation.

The relationship between coronary stenosis morphology and fractional flow reserve: a computational fluid dynamics modelling study

Aims

International guidelines mandate the use of fractional flow reserve (FFR) and/or non-hyperaemic pressure ratios to assess the physiological significance of moderate coronary artery lesions to guide revascularization decisions. However, they remain underused such that visual estimation of lesion severity continues to be the predominant decision-making tool. It would be pragmatic to have an improved understanding of the relationship between lesion morphology and haemodynamics. The aim of this study was to compute virtual FFR (vFFR) in idealized coronary artery geometries with a variety of stenosis and vessel characteristics.

Methods and results

Coronary artery geometries were modelled, based upon physiologically realistic branched arteries. Common stenosis characteristics were studied, including % narrowing, length, eccentricity, shape, number, position relative to branch, and distal (myocardial) resistance. Computational fluid dynamics modelling was used to calculate vFFRs using the VIRTUheart™ system. Percentage lesion severity had the greatest effect upon FFR. Any ≥80% diameter stenosis in two views (i.e. concentric) was physiologically significant (FFR ≤ 0.80), irrespective of length, shape, or vessel diameter. Almost all eccentric stenoses and all 50% concentric stenoses were physiologically non-significant, whilst 70% uniform concentric stenoses about 10 mm long straddled the ischaemic threshold (FFR 0.80). A low microvascular resistance (MVR) reduced FFR on average by 0.05, and a high MVR increased it by 0.03.

Conclusion

Using computational modelling, we have produced an analysis of vFFR that relates stenosis characteristics to haemodynamic significance. The strongest predictor of a positive vFFR was a concentric, ≥80% diameter stenosis. The importance of MVR was quantified. Other lesion characteristics have a limited impact.

Coronary physiologic assessment based on angiography and intracoronary imaging

Despite the current evidence supporting clinical benefits of fractional flow reserve (FFR), its uptake in the cardiac catheterization laboratory has been slow due to procedural cost and increased time with the need for maximum hyperemia. Recently, novel physiological indices derived from coronary angiography and intracoronary imaging have emerged to overcome issues with a wire-based FFR. Angiography-based FFR can be measured without vessel instrumentation and has shown excellent diagnostic performance using wire-based FFR as the reference standard. Thus, angiography-based FFR may facilitate coronary functional assessment before and after percutaneous coronary intervention (PCI). Angiography-based index of microcirculatory resistance (IMR) is another new computational index for assessing the coronary microcirculation. Although angiography-derived IMR remains in an early phase of development and requires further validation, its less-invasive nature may help broaden the adoption of microvascular functional assessment in various conditions such as myocardial infarction and cardiac allograft vasculopathy. Lastly, computational FFR based on intravascular ultrasound and optical coherence tomography allows detailed lesion assessment from both morphological and functional standpoints. Given a growing interest in physiology-guided PCI optimization strategies, intravascular imaging-based FFR may become the main assessment tool to confirm successful PCI.

Ten-year clinical outcomes in patients with intermediate coronary stenosis according to the combined culprit lesion

BACKGROUND

We assessed the long-term clinical outcomes of an intermediate lesion (IL) according to the presence of a combined culprit lesion (CCL).

HYPOTHESIS

Long-term clinical outcomes of IL may be affected by the presence of a CCL.

METHODS

Angiographic findings (n = 1096) and medical chart were reviewed. Patients with IL were divided into two groups: IL without CCL group (n = 383, 64.5%) and IL with CCL group (n = 211, 35.5%).

RESULTS

The major adverse cardiovascular events (MACE) in the IL with CCL group were significantly higher than those in the IL without CCL group (death: 12.3% vs. 7.0%, myocardial infarction: 3.3%vs. 0.5%, stroke: 6.6% vs. 2.6%, and revascularization [RVSC]: 25.1% vs. 7.6%) during a mean follow up period of 118.4 ± 5.5 months. IL related RVSC rate in the IL with CCL group was higher than that in the IL without CCL group (5.7% vs. 2.1%, p = 0.020). RVSC rate related to IL in total subjects was lower than that related to stented lesion (3.4% vs. 6.4%). The important predictors of total MACE in total subjects were the presence of CCL, IL percent diameter stenosis, hypertension, history of percutaneous coronary intervention, blood glucose and ejection fraction. The predictors of IL related RVSC were IL percent diameter stenosis and IL located in the right coronary artery.

CONCLUSION

10-year clinical outcomes of an IL (especially IL without CCL) were better than those of stented lesions. This study suggests that the IL can be safely followed up in sites that do not have ability to assess functional study.

Angiography-based estimation of coronary physiology: A frame is worth a thousand words

Cumulative evidence has shown that coronary revascularization should be guided by functional significance of coronary lesions. Fractional flow reserve (FFR) is the gold standard for assessment of hemodynamic significance of coronary stenosis and FFR-guided percutaneous coronary intervention has improved clinical outcomes in patients with coronary artery disease. However, limitations of FFR such as increased operational time and cost, requirement of pressure wire and adenosine and technical difficulties have led to significant underutilization of the method in clinical practice. In the last few years, several methods of FFR estimation based on coronary angiography images have emerged to overcome invasive FFR limitations. The common elements of the novel indices include a 3D anatomical reconstruction of coronary vessels by angiographic projections and various approaches to fluid dynamics computation. Angiography-derived FFR methods have shown high diagnostic accuracy compared to invasive FFR. Although there are promising results regarding their prognostic role, large randomized trials evaluating clinical outcomes are lacking. The aim of this review is to present currently available angiography-derived FFR indices and highlight their differences, advantages, disadvantages and potential clinical implications.

Fractional flow reserve in patients with reduced ejection fraction

AIMS

Fractional flow reserve (FFR) has never been investigated in patients with reduced ejection fraction and associated coronary artery disease (CAD). We evaluated the impact of FFR on the management strategies of these patients and related outcomes.

METHODS AND RESULTS

From 2002 to 2010, all consecutive patients with left ventricular ejection fraction (LVEF) ≤50% undergoing coronary angiography with ≥1 intermediate coronary stenosis [diameter stenosis (DS)% 50-70%] treated based on angiography (Angiography-guided group) or according to FFR (FFR-guided group) were screened for inclusion. In the FFR-guided group, 433 patients were matched with 866 contemporary patients of the Angiography-guided group. For outcome comparison, 617 control patients with LVEF >50% were included. After FFR, stenotic vessels per patient were significantly downgraded compared with the Angiography-guided group (1.43 ± 0.98 vs. 1.97 ± 0.84; P < 0.001). This was associated with lower revascularization rate (52% vs. 62%; P < 0.001) in the FFR-guided vs. the Angiography-guided group. All-cause death at 5 years of follow-up was significantly lower in the FFR-guided as compared with Angiography-guided group [22% vs. 31%. HR (95% CI) 0.64 (0.51-0.81); P < 0.001]. Similarly, rate of major adverse cardiovascular and cerebrovascular events (MACCE: composite of all-cause death, myocardial infarction, revascularization, and stroke) was significantly lower in the FFR-guided group [40% vs. 46% in the Angiography-guided group. HR (95% CI) 0.81 (0.67-0.97); P = 0.019]. Higher rates of death and MACCE were observed in patients with reduced LVEF compared with the control cohort.

CONCLUSIONS

In patients with reduced LVEF and CAD, FFR-guided revascularization was associated with lower rates of death and MACCE at 5 years as compared with the Angiography-guided strategy. This beneficial impact was observed in parallel with less coronary artery bypass grafting and more patients deferred to percutaneous coronary intervention or medical therapy.

Invasive coronary physiology assessment for patients with stable coronary disease

Visual assessment of coronary stenosis severity using conventional coronary angiography is associated with wide inter-operator variability and a weak relationship with hemodynamics. Invasive coronary physiology assessment using fractional flow reserve (FFR) has been shown to be safe and beneficial. Large multicenter randomized trials have demonstrated the superiority of FFR-guided percutaneous coronary intervention (PCI) in reducing the risk of major cardiac adverse events, number of stents used, and total cost in patients with multi-vessel coronary disease. FFR requires vasodilatory agents for the microvasculature to induce maximal hyperemia, which carry a slight risk, cost, and effort. Non-hyperemic pressure ratios (NHPR) provide a physiologic metric without vasodilator medications but with more limited clinical outcomes data. The transition from anatomy to physiology for CAD decision-making represents a cultural sea change in the cardiac catheterization laboratory that requires time and retooling.

Revascularization decisions in patients with chronic coronary syndromes: Results of the second International Survey on Interventional Strategy (ISIS-2)

BACKGROUND

In chronic coronary syndromes, guidelines mandate invasive functional guidance of revascularization whenever non-invasive proof of ischemia is missing. ISIS-2 survey aimed to evaluate how the adoption of guideline recommendation on ischemia-guided revascularization has evolved over the last 5-7 years.

METHODS

In ISIS-2 participants assessed five complete angiograms, presenting only intermediate stenoses without information on non-invasive pre-testing. Fractional flow reserve was known for each stenosis, but remained undisclosed. Participants could determine stenosis significance either by angiography or by requesting an adjunctive invasive diagnostic method (intravascular imaging or functional tests). Primary endpoint was the rate of requesting adjunctive functional assessment. Secondary endpoints were the rate of concordance between angiography-based decisions and know functional severity. ISIS-2 utilized the same web-based platform as ISIS-1 in 2013. (NCT04001452).

RESULTS

334 participants performed 2059 lesion evaluations: 1202 (59%) decisions were based solely on angiography without expressed need for further evaluation. These decisions were discordant with known functional significance in 39%, mainly with potential of overtreatment. Participants requested invasive functional assessment in 643 (31%) and intravascular imaging in 214 (10%) cases. Compared to ISIS-1 the rate of purely angiography-based decisions has decreased (59% vs 66%; p < 0.001), while invasive functional tests were more frequently requested (31% vs 25%; p < 0.001).

CONCLUSIONS

ISIS-2 suggests an evolving pattern in the intention to integrate invasive coronary physiology into the revascularization decisions. However, the disconnect between recommendations and current thinking is still dominant.

The new role of diagnostic angiography in coronary physiological assessment

The role of 'stand-alone' coronary angiography (CAG) in the management of patients with chronic coronary syndromes is the subject of debate, with arguments for its replacement with CT angiography on the one hand and its confinement to the interventional cardiac catheter laboratory on the other. Nevertheless, it remains the standard of care in most centres. Recently, computational methods have been developed in which the laws of fluid dynamics can be applied to angiographic images to yield 'virtual' (computed) measures of blood flow, such as fractional flow reserve. Together with the CAG itself, this technology can provide an 'all-in-one' anatomical and functional investigation, which is particularly useful in the case of borderline lesions. It can add to the diagnostic value of CAG by providing increased precision and reduce the need for further non-invasive and functional tests of ischaemia, at minimal cost. In this paper, we place this technology in context, with emphasis on its potential to become established in the diagnostic workup of patients with suspected coronary artery disease, particularly in the non-interventional setting. We discuss the derivation and reliability of angiographically derived fractional flow reserve (CAG-FFR) as well as its limitations and how CAG-FFR could be integrated within existing national guidance. The assessment of coronary physiology may no longer be the preserve of the interventional cardiologist.

Agreement of Angiography-Derived and Wire-Based Fractional Flow Reserves in Percutaneous Coronary Intervention

Background: Coronary angiography-derived fractional flow reserve (caFFR) measurements have shown good correlations and agreement with invasive wire-based fractional flow reserve (FFR) measurements. However, few studies have examined the diagnostic performance of caFFR measurements before and after percutaneous coronary intervention (PCI). This study sought to compare the diagnostic performance of caFFR measurements against wire-based FFR measurements in patients before and after PCI.

Methods: Patients who underwent FFR-guided PCI were eligible for the acquisition of caFFR measurements. Offline caFFR measurements were performed by blinded hospital operators in a core laboratory. The primary endpoint was the vessel-oriented composite endpoint (VOCE), defined as a composite of vessel-related cardiovascular death, vessel-related myocardial infarction, and target vessel revascularization.

Results: A total of 105 pre-PCI caFFR measurements and 65 post-PCI caFFR measurements were compared against available wire-based FFR measurements. A strong linear correlation was found between wire-based FFR and caFFR measurements (r = 0.77; p < 0.001) before PCI, and caFFR measurements also showed a high correlation (r = 0.82; p < 0.001) with wire-based FFR measurements after PCI. A total of 6 VOCEs were observed in 61 patients during follow-up. Post-PCI FFR values (≤0.82) in the target vessel was the strongest predictor of VOCE [hazard ratio (HR): 5.59; 95% confidence interval (CI): 1.12–27.96; p = 0.036). Similarly, patients with low post-PCI caFFR values (≤0.83) showed an 8-fold higher risk of VOCE than those with high post-PCI caFFR values (>0.83; HR: 8.83; 95% CI: 1.46–53.44; p = 0.017).

Conclusion: The study showed that the caFFR measurements were well-correlated and in agreement with invasive wire-based FFR measurements before and after PCI. Similar to wire-based FFR measurements, post-PCI caFFR measurements can be used to identify patients with a higher risk for adverse events associated with PCI.

Clinical application of computed tomography angiography and fractional flow reserve computed tomography in patients with coronary artery disease: A meta-analysis based on pre- and post-test probability

PURPOSE

To assess the diagnostic role of coronary computed tomography angiography (CCTA) and fractional flow reserve computed tomography (FFRCT) in confirming or excluding ischemic coronary artery disease (CAD) and to provide a rational use of CCTA and FFRCT in different pre-test probability (PTP) of CAD.

METHODS

We searched the electronic databases from the earliest relevant literature to July 2020 comparing FFRCT or CCTA with FFR. The bivariate random-effects models and Bayes' theorem were used to investigate the diagnostic performance of CCTA and FFRCT with the sensitivity, specificity, pre- and post-test probability.

RESULTS

Fifty-three articles with 4817 patients and 7026 vessels finally met our inclusion criteria. At the patient level, the sensitivity and specificity of CCTA were (0.94, 0.89-0.97), and (0.50, 0.43-0.58), respectively. For FFRCT, the sensitivity and specificity were (0.90, 0.87-0.93) and (0.81, 0.73-0.87). CCTA or FFRCT could increase the post-test probability to >85 % in patients with a PTP > 74.9 % or 54.5 %; CCTA or FFRCT could decrease the post-test probability to <15 % in patients with a pre-test probability <61.3 % or 59.3 %.

CONCLUSIONS

In patients with low to intermediate PTP, CCTA is suggested to exclude CAD, while the time-consuming calculation of FFRCT may be unnecessary. If CCTA detects significant or uncertain stenosis with intermediate to high PTP of CAD, further FFRCT is suggested. The advantages of FFRCT for guiding CAD treatment have sufficiently been demonstrated.

Behavioural determinants impacting the adoption rate of coronary physiology

BACKGROUND

Despite international revascularisation guidelines strongly recommending functional assessment of coronary artery stenosis using pressure-wire derived indices, the adoption rate of coronary physiology remains low.

METHODS

An online questionnaire was designed to evaluate behavioural determinants impacting the adoption rate of coronary physiology. Factor analysis was performed to combine multiple items of a common behavioural domain into one explanatory factor. Regression analysis was performed to evaluate the influence of resulting factors on the variance of the coronary physiology adoption rate. Additionally, the influence of experience, demographics and provider structures was assessed.

RESULTS

104 interventional cardiologists, from 21 countries, completed the questionnaire. Mean adoption rate of coronary physiology was 26.9%. Regression analysis revealed that factors ease-of-use (Coefficient = 0.58, p = 0.01), financial and/or time constraints (Coefficient = -0.22, p = 0.01) and knowledge about guideline recommendations (Coefficient = 0.21, p = 0.06) had the greatest influence on coronary physiology adoption rate variance (R² = 0.3, p < 0.001), with ease-of-use and guideline recommendations positively influencing greater uptake and constraints influencing lesser uptake of adoption of coronary physiology.

CONCLUSION

Ease-of-use, financial and/or time constraints, and knowledge about guideline recommendations were the most relevant behavioural factors impacting the adoption rate of coronary physiology. Ease-of-use was identified as the most influential factor, highlighting the importance of cardiac catheterisation laboratory teams being adequately trained to perform coronary physiology assessment seamlessly.

Association of Quantitative Flow Ratio with Lesion Severity and Its Ability to Discriminate Myocardial Ischemia

BACKGROUND AND OBJECTIVES

Quantitative flow ratio (QFR) is an angiography-based technique for functional assessment of coronary artery stenosis. This study investigated the response of QFR to different degree of stenosis severity and its ability to predict the positron emission tomography (PET)-defined myocardial ischemia.

METHODS

From 109 patients with 185 vessels who underwent both 13N-ammonia PET and invasive physiological measurement, we compared QFR, fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) for the responses to the different degree of anatomical (percent diameter stenosis [%DS]) and hemodynamic (relative flow reserve [RFR], coronary flow reserve, hyperemic stenosis resistance, and stress myocardial flow) stenosis severity and diagnostic performance against PET-derived parameters.

RESULTS

QFR, FFR, and iFR showed similar responses to both anatomic and hemodynamic stenosis severity. Regarding RFR, the diagnostic accuracy of QFR was lower than FFR (76.2% vs. 83.2%, p=0.021) and iFR (76.2% vs. 84.3%, p=0.031). For coronary flow capacity (CFC), QFR showed a lower accuracy than iFR (74.1% vs. 82%, p=0.031) and lower discriminant function than FFR (area under curve: 0.74 vs. 0.79, p=0.044). Discordance between QFR and FFR or iFR was shown in 14.6% of cases and was driven by the difference in %DS and heterogeneous distribution of PET-derived RFR and stress myocardial blood flow.

CONCLUSIONS

QFR demonstrated a similar response to different anatomic and hemodynamic stenosis severity as FFR or iFR. However, its diagnostic performance was inferior to FFR and iFR when PET-derived RFR and CFC were used as a reference.