Safety and feasibility evaluation of planning and execution of surgical revascularisation solely based on coronary CTA and FFRCT in patients with complex coronary artery disease: study protocol of the FASTTRACK CABG study

Favorable impact of FFRCT on myocardial revascularization outcomes: Results from an observational real-world registry

BACKGROUND

Coronary computed tomography angiography (CCTA)-derived fractional flow reserve (FFRCT) strategy significantly decreases unnecessary invasive coronary angiography and refines the appropriateness of revascularization decision. The present study aimed to evaluate how FFRCT guided - strategy impacts outcomes postrevascularization.

METHODS

We included patients with suspected obstructive coronary artery disease (OCAD in a registry from 2013 to 2021. FFRCT entered Heart-Team decision from 2017. Propensity score adjusted Cox - and logistic - regression analyzed FFRCT's impact on post- revascularization major adverse cardiovascular events (MACE) and myocardial injury (PMI).

RESULTS

Among 7541 patients, 1601 had suspected OCAD. 559 patients underwent revascularization: 69.0 % PCI, 29.7 % CABG and 1.2 % both. 252(45.1 %) patients underwent FFRCT. Over 4.4 ± 2.2 years, 137(24.5 %) patients experienced MACE. FFRCT was associated with a trend toward reduced MACE (HR 0.736, 95 % CI 0.513-1.055, p = 0.095) and significantly reduced all-cause mortality (HR 0.476, 95 % CI 0.230-0.985, p = 0.046). In the post-2017 cohort (413 patients, follow-up 3.7 ± 1.5 years), FFRCT significantly reduced MACE (HR 0.610, 95 % CI 0.390-0.954, P = 0.030) and all-cause mortality (HR 0.285, 95 % CI 0.104-0.779, P = 0.014). In CABG patients, FFRCT was associated with lower PMI incidence (5.3 % vs. 15.6 %, p = 0.044). Multivariable analysis revealed no significant association between FFRCT use and PMI.

CONCLUSIONS

Revascularization decision-making with FFRCT translates into better post-revascularization outcomes, primarily by reducing MACE through lower mortality. There was no clear impact on PMI. These findings suggests that FFRCT's value lies indeed in improving patient selection for revascularization, but warrants further confirmation in randomized clinical trials.

Cardiac computed tomography: Current practice, guidelines, applications, and prospects

Cardiac computed tomography (CT) has evolved significantly as a critical tool in diagnosing and managing cardiac diseases, greatly facilitated by technological advancements in multidetector systems, dose-reduction techniques, and sophisticated imaging algorithms. This article discusses the historical progression and technological evolution in cardiac CT (CCT), focusing on the impact of 64-multidetector row CT and dual-energy CT systems on improving spatial and temporal resolutions and reducing radiation exposure. It explores the role of these technologies in enhancing diagnostic accuracy, such as through detailed three-dimensional reconstructions and minimized imaging artifacts. Furthermore, it highlights the integration of machine learning to automate complex imaging analysis and photon-counting CT, which promises higher resolution and further dose reduction. Prospective studies and ongoing trials such as FASTTRACK coronary artery bypass grafting also underscore the potential of advanced CT technologies in refining procedural planning and execution. The continuous advancements in detector technology, computational techniques, and image reconstruction are poised to expand the applications and efficacy of CCT, cementing its role in modern cardiology.

The REVOLUTION project: planning and performing surgical revascularization based solely on coronary computed tomography angiography

Coronary computed tomography angiography (CCTA) is a non-invasive diagnostic tool that is increasingly being used as an alternative to invasive coronary angiography (ICA) in patients with suspected coronary artery disease (CAD), providing important information on the extent and severity of CAD. Furthermore, stress CT myocardial perfusion imaging (CT-MPI) and fractional flow reserve derived from CCTA (CT-FFR) have been recently introduced in clinical practice as new tools for evaluating the functional relevance of coronary stenoses. ICA has been the preferred diagnostic method to guide the decision-making process between coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI). Recently, two studies have investigated the feasibility of using CCTA rather than ICA to plan CABG. In patients with three-vessel disease and/or left main CAD, the SYNTAX III REVOLUTION trial concluded that clinical decision-making between CABG and PCI using CCTA had a high level of agreement with treatment decisions based on ICA. In the FASTTRACK study, CABG procedures were planned based on CCTA without knowledge of ICA. CABG guided by CCTA showed to be feasible with an acceptable safety profile in a selected population of complex CAD. These intriguing findings should be confirmed in a large randomized trial on the revascularization outcome by comparing patients who underwent a novel non-invasive vs. a traditional invasive roadmap.

Contemporary Functional Coronary Angiography: An Update

Functional coronary angiography (FCA) is a novel modality for assessing the physiology of coronary lesions, going beyond anatomical visualization by traditional coronary angiography. FCA incorporates indices like fractional flow reserve (FFR) and instantaneous wave-free ratio (IFR), which utilize pressure measurements across coronary stenoses to evaluate hemodynamic impacts and to guide revascularization strategies. In this review, we present traditional and evolving modalities and uses of FCA. We will also evaluate the existing evidence and discuss the applicability of FCA in various clinical scenarios. Finally, we provide insight into emerging evidence, current challenges, and future directions in FCA.

Patient-Specific Numerical Simulations of Coronary Artery Hemodynamics and Biomechanics: A Pathway to Clinical Use

PURPOSE

Numerical models that simulate the behaviors of the coronary arteries have been greatly improved by the addition of fluid-structure interaction (FSI) methods. Although computationally demanding, FSI models account for the movement of the arterial wall and more adequately describe the biomechanical conditions at and within the arterial wall. This offers greater physiological relevance over Computational Fluid Dynamics (CFD) models, which assume the walls do not move or deform. Numerical simulations of patient-specific cases have been greatly bolstered by the use of imaging modalities such as Computed Tomography Angiography (CTA), Magnetic Resonance Imaging (MRI), Optical Coherence Tomography (OCT), and Intravascular Ultrasound (IVUS) to reconstruct accurate 2D and 3D representations of artery geometries. The goal of this study was to conduct a comprehensive review on CFD and FSI models on coronary arteries, and evaluate their translational potential.

METHODS

This paper reviewed recent work on patient-specific numerical simulations of coronary arteries that describe the biomechanical conditions associated with atherosclerosis using CFD and FSI models. Imaging modality for geometry collection and clinical applications were also discussed.

RESULTS

Numerical models using CFD and FSI approaches are commonly used to study biomechanics within the vasculature. At high temporal and spatial resolution (compared to most cardiac imaging modalities), these numerical models can generate large amount of biomechanics data.

CONCLUSIONS

Physiologically relevant FSI models can more accurately describe atherosclerosis pathogenesis, and help to translate biomechanical assessment to clinical evaluation.

Cardiovascular care with digital twin technology in the era of generative artificial intelligence

Digital twins, which are in silico replications of an individual and its environment, have advanced clinical decision-making and prognostication in cardiovascular medicine. The technology enables personalized simulations of clinical scenarios, prediction of disease risk, and strategies for clinical trial augmentation. Current applications of cardiovascular digital twins have integrated multi-modal data into mechanistic and statistical models to build physiologically accurate cardiac replicas to enhance disease phenotyping, enrich diagnostic workflows, and optimize procedural planning. Digital twin technology is rapidly evolving in the setting of newly available data modalities and advances in generative artificial intelligence, enabling dynamic and comprehensive simulations unique to an individual. These twins fuse physiologic, environmental, and healthcare data into machine learning and generative models to build real-time patient predictions that can model interactions with the clinical environment to accelerate personalized patient care. This review summarizes digital twins in cardiovascular medicine and their potential future applications by incorporating new personalized data modalities. It examines the technical advances in deep learning and generative artificial intelligence that broaden the scope and predictive power of digital twins. Finally, it highlights the individual and societal challenges as well as ethical considerations that are essential to realizing the future vision of incorporating cardiology digital twins into personalized cardiovascular care.

Quantitative coronary computed tomography assessment for differentiating between total occlusions and severe stenoses

BACKGROUNDS

The impact of quantitative assessment to differentiate total occlusions (TOs) from severe stenoses on coronary computed tomography angiography (CCTA) remains unknown.

OBJECTIVE

This study investigated whether quantitative characteristics assessed on CCTA could help differentiate a TO from a severe stenosis on invasive coronary angiography (ICA).

METHODS

This study is a sub-analysis of the FASTTRACK CABG (NCT04142021) in which both CCTA and ICA were routinely performed. Quantitative analysis was performed with semi-automated CCTA plaque-analysis software. Blinded analysts compared TOs on CCTA, defined as a complete lack of contrast opacification within the coronary occlusion, with corresponding ICA.

RESULTS

Eighty-four TOs were seen on CCTA in 59 of the 114 patients enrolled in the trial. The concordance in diagnosing a TO between ICA and CCTA was 56.0% (n ​= ​47). Compared to severe stenoses, TOs had a significantly longer lesion length (25.1 ​± ​23.0 ​mm vs 9.4 ​± ​11.2 ​mm, P ​< ​0.001). The best cut-off value to differentiate a TO from severe stenosis was a lesion length of 5.5 ​mm (area under the curve 0.77, 95% CI: 0.66-0.87), with a 91.1% sensitivity and 61.1% specificity. Dense calcium percentage atheroma volume (PAV) was significantly higher in TOs compared to severe stenoses (18.7 ​± ​19.6% vs. 6.6 ​± ​13.0%, P ​< ​0.001), whilst the opposite was seen for fibro-fatty PAV (31.3 ​± ​14.2% vs. 19.5 ​± ​10.5%, P ​< ​0.001). On a multivariable logistic regression analysis, lesion length (>5.5 ​mm) was the only parameter associated with differentiating a TO from a severe stenosis.

CONCLUSION

In quantitative CCTA analysis, a lesion length >5.5 ​mm was the only independent predictor differentiating a TO from a severe stenosis.

NCT REGISTRATION NUMBER

NCT04142021.

Cardiac computed tomography-derived coronary artery volume to myocardial mass in patients with severe coronary artery disease

BACKGROUND

Coronary artery lumen volume (V) to myocardial mass (M) ratio (V/M) can show the mismatch between epicardial coronary arteries and the underlying myocardium.

METHODS

The V, M and V/M were obtained from the coronary computed tomography angiography (CCTA) of patients in the FAST-TRACK CABG study, the first-in-human trial of coronary artery bypass grafting (CABG) guided solely by CCTA and fractional flow reserve derived from CCTA (FFRCT) in patients with complex coronary artery disease (CAD). The correlations between V/M ratios and baseline characteristics were determined and compared with those from the ADVANCE registry, an unselected cohort of historical controls with chronic CAD.

RESULTS

The V/M ratio was obtained in 106 of the 114 pre-CABG CCTAs. Mean age was 65.6 years and 87% of them were male. The anatomical SYNTAX score from CCTA was significantly higher than the functional SYNTAX score derived using FFRCT [43.1 (15.2) vs 41.1 (16.5), p ​< ​0.001]. Mean V, M, and V/M were 2204 ​mm3, 137 ​g, and 16.5 ​mm3/g, respectively. There were weak negative correlations between V and anatomical and functional SYNTAX scores (Pearson's r ​= ​-0.26 and -0.34). V and V/M had a strong correlation (r ​= ​0.82). The V/M ratio in the current study was significantly lower than that in the ADVANCE registry (median 16.1 vs. 24.8 [1st quartile 20.1]).

CONCLUSION

Systematically smaller V/M ratios were found in this population with severe CAD requiring CABG compared to an unselected cohort with chronic CAD. The V/M ratio could provide additional non-invasive assessment of CAD especially when combined with FFRCT.

Clinical Updates in Coronary Artery Disease: A Comprehensive Review

Despite significant goals achieved in diagnosis and treatment in recent decades, coronary artery disease (CAD) remains a high mortality entity and continues to pose substantial challenges to healthcare systems globally. After the latest guidelines, novel data have emerged and have not been yet considered for routine practice. The scope of this review is to go beyond the guidelines, providing insights into the most recent clinical updates in CAD, focusing on non-invasive diagnostic techniques, risk stratification, medical management and interventional therapies in the acute and stable scenarios. Highlighting and synthesizing the latest developments in these areas, this review aims to contribute to the understanding and management of CAD helping healthcare providers worldwide.

Managing Iatrogenic Aortic Dissection: Insight From 3D Holographic Imaging and CT Computational Fluid Dynamic Simulations

Iatrogenic aortic dissection is a rare but life-threatening complication of coronary artery bypass surgery. We report a case with incidentally detected iatrogenic aortic dissection related to aorta cross-clamping that was successfully managed with watchful follow-up. The decision making was based on 3-dimensional holographic and fluid dynamic analysis guidance.

Coronary bypass surgery guided by computed tomography in a low-risk population

BACKGROUND AND AIMS

In patients with three-vessel disease and/or left main disease, selecting revascularization strategy based on coronary computed tomography angiography (CCTA) has a high level of virtual agreement with treatment decisions based on invasive coronary angiography (ICA).

METHODS

In this study, coronary artery bypass grafting (CABG) procedures were planned based on CCTA without knowledge of ICA. The CABG strategy was recommended by a central core laboratory assessing the anatomy and functionality of the coronary circulation. The primary feasibility endpoint was the percentage of operations performed without access to the ICA. The primary safety endpoint was graft patency on 30-day follow-up CCTA. Secondary endpoints included topographical adequacy of grafting, major adverse cardiac and cerebrovascular (MACCE), and major bleeding events at 30 days. The study was considered positive if the lower boundary of confidence intervals (CI) for feasibility was ≥75% (NCT04142021).

RESULTS

The study enrolled 114 patients with a mean (standard deviation) anatomical SYNTAX score and Society of Thoracic Surgery score of 43.6 (15.3) and 0.81 (0.63), respectively. Unblinding ICA was required in one case yielding a feasibility of 99.1% (95% CI 95.2%-100%). The concordance and agreement in revascularization planning between the ICA- and CCTA-Heart Teams was 82.9% with a moderate kappa of 0.58 (95% CI 0.50-0.66) and between the CCTA-Heart Team and actual treatment was 83.7% with a substantial kappa of 0.61 (95% CI 0.53-0.68). The 30-day follow-up CCTA in 102 patients (91.9%) showed an anastomosis patency rate of 92.6%, whilst MACCE was 7.2% and major bleeding 2.7%.

CONCLUSIONS

CABG guided by CCTA is feasible and has an acceptable safety profile in a selected population of complex coronary artery disease.

Predictors of percutaneous coronary intervention derived from CCTA in patients with chronic coronary syndrome

BACKGROUND

To identify anatomical and morphological plaque features predictors of PCI and create a multiparametric score to increase the predictive yield. Moreover, we assessed the incremental predictive value of FFRCT (Fractional Flow Reserve derived from CCTA) trans-lesion gradient (ΔFFRCT) when integrated into the score.

METHODS

Observational cohort study including patients undergoing CCTA for suspected coronary artery disease, with FFRCT available, referred to invasive coronary angiogram and assessment of fractional flow reserve. Plaque analysis was performed using validated semi-automated software. Logistic regression was performed to identify anatomical and morphological plaque features predictive of PCI. Optimal thresholds were defined by area under the receiver-operating characteristics curve (AUC) analysis. A scoring system was developed in a derivation cohort (70 ​% of the study population) and tested in a validation cohort (30 ​% of patients).

RESULTS

The overall study population included 340 patients (455 vessels), among which 238 patients (320 vessels) were included in the derivation cohort. At multivariate logistic regression analysis, absence of left main disease, diameter stenosis (DS), non-calcified plaque (NCP) volume, and percent atheroma volume (PAV) were independent predictors of PCI. Optimal thresholds were: DS ​≥ ​50 ​%, volume of NCP>113 ​mm3 and PAV>17 ​%. A weighted score (CT-PCI Score) ranging from 0 to 11 was obtained. The AUC of the score was 0.80 (95%CI 0.74-0.86). The integration of ΔFFRCT in the CT-PCI score led to a mild albeit not significant increase in the AUC (0.82, 95%CI 0.77-0.87, p ​= ​0.328).

CONCLUSIONS

Plaque anatomy and morphology derived from CCTA could aid in identifying patients amenable to PCI.

Cardiac Computed Tomography Angiography in the Evaluation of Coronary Artery Disease: An Interventional Perspective

Cardiac computed tomography angiography (CCTA) has become the gold standard for noninvasive anatomic assessment of the coronary arteries. With high positive predictive value and even higher negative predictive value, CCTA allows for rapid determination of the presence or absence of coronary plaque and triage of patients' need for further invasive evaluation and treatment. From an interventional cardiologist's perspective, CCTA (more so than stress testing) is helpful in determining the need for invasive therapy. In conjunction with functional assessments, the anatomic evaluation from CCTA mirrors the anatomical assessment of a coronary angiogram more than any other noninvasive assessment. This allows for catheter selection, percutaneous coronary intervention preplanning, as well as additional decision making before the patient has entered the catheterization laboratory. This manuscript explores some of the more recent developments in noninvasive coronary angiography and discusses the use and utility of CCTA from an interventional cardiologist's perspective.

Coronary computed tomography angiography-based SYNTAX score for comprehensive assessment of advanced coronary artery disease

BACKGROUND

Since the initial attempt to adapt the anatomical SYNTAX score (aSS) to coronary computed tomography angiography (CCTA), CCTA imaging technology has evolved, and is currently used as a "decision-maker" for revascularization strategy in complex coronary artery disease (CAD) and has rendered necessary some updating of the aSS to the CCTA modality.

OBJECTIVES

The aim is to provide updated definitions of the aSS derived from CCTA in patients with complex CAD undergoing CABG.

METHODS

The modifications of CCTA-aSS are the following; (i) updated definition and detection criteria of total occlusion (TO) in CCTA based on length assessment, (ii) inclusion of scoring points for serial bifurcations located in one single coronary segment. (iii) inclusion of weighing score points for lesions located distal to a TO, not visualized on conventional coronary angiography, but visible in CCTA, (iv) removal of thrombus and bridging collateral items from the weighing score, considering the limited diagnostic capability of CCTA in detecting these specific lesion characteristics.

RESULTS

the updated CCTA-aSS was tested in a first-in-man study using the sole guidance of CCTA for the planning and performance of bypass surgery in complex CAD (n ​= ​114). An interobserver analysis showed excellent reproducibility (ICC ​= ​0.96, 95 ​% confidence interval 0.94-0.97).

CONCLUSION

The updated CCTA-aSS was implemented in a cohort of patients with complex CAD undergoing CABG with the sole guidance of CCTA and FFRCT and the Inter-reproducibility of the analysis of the updated score was found excellent. The prognostic value of the modified CCTA-aSS will be examined in future studies.

CT-derived Fractional Flow Reserve: How, When, and Where to use this Novel Cardiac Imaging Tool

Fractional flow reserve computed tomography (FFRCT) is a novel imaging modality. It utilizes computational fluid dynamics analysis of coronary blood flow obtained from CCTA images to estimate the decrease in pressure across coronary stenosis during the maximum hyperemia. The FFRCT can serve as a valuable tool in the assessment of coronary artery disease (CAD). This non-invasive option can be used as an alternative to the invasive fractional Flow Reserve (FFR) evaluation, which is presently considered the gold standard for evaluating the physiological significance of coronary stenoses. It can help in several clinical situations, including Assessment of Acute and stable chest pain, virtual planning for coronary stenting, and treatment decision-making. Although FFRCT has demonstrated potential clinical applications as a non-invasive imaging technique, it is also crucial to acknowledge its limitations in clinical practice. As a result, it is imperative to meticulously evaluate the advantages and drawbacks of FFRCT individually and contemplate its application in combination with other diagnostic examinations and clinical data.

Revaiah P, Stanuch M, Skalski A, Onuma Y, Serruys PW. Feasibility and accuracy of real-time 3D-holographic graft length measurements

Aims

Mixed reality (MR) holograms can display high-definition images while preserving the user's situational awareness. New MR software can measure 3D objects with gestures and voice commands; however, these measurements have not been validated. We aimed to assess the feasibility and accuracy of using 3D holograms for measuring the length of coronary artery bypass grafts.

Methods and results

An independent core lab analyzed follow-up computer tomography coronary angiograms performed 30 days after coronary artery bypass grafting in 30 consecutive cases enrolled in the FASTTRACK CABG trial. Two analysts, blinded to clinical information, performed holographic reconstruction and measurements using the CarnaLife Holo software (Medapp, Krakow, Poland). Inter-observer agreement was assessed in the first 20 cases. Another analyst performed the validation measurements using the CardIQ W8 CT system (GE Healthcare, Milwaukee, Wisconsin). Seventy grafts (30 left internal mammary artery grafts, 31 saphenous vein grafts, and 9 right internal mammary artery grafts) were measured. Holographic measurements were feasible in 97.1% of grafts and took 3 minutes 36 s ± 50.74 s per case. There was an excellent inter-observer agreement [interclass correlation coefficient (ICC) 0.99 (0.97-0.99)]. There was no significant difference between the total graft length on hologram and CT [187.5 mm (157.7-211.4) vs. 183.1 mm (156.8-206.1), P = 0.50], respectively. Hologram and CT measurements are highly correlated (r = 0.97, P < 0.001) with an excellent agreement [ICC 0.98 (0.97-0.99)].

Conclusion

Real-time holographic measurements are feasible, quick, and accurate even for tortuous bypass grafts. This new methodology can empower clinicians to visualize and measure 3D images by themselves and may provide insights for procedural strategy.

Murray law-based quantitative flow ratio to assess left main bifurcation stenosis: selecting the angiographic projection matters

Murray law-based quantitative flow ratio (µQFR) assesses fractional flow reserve (FFR) in bifurcation lesions using a single angiographic view, enhancing the feasibility of analysis; however, accuracy may be compromised in suboptimal angiographic projections. FFRCT is a well-validated non-invasive method measuring FFR from coronary computed tomographic angiography (CCTA). We evaluated the feasibility of µQFR in left main (LM) bifurcations, the impact of the optimal/suboptimal fluoroscopic view with respect to CCTA, and its diagnostic concordance with FFRCT. In 300 patients with three-vessel disease, the values of FFRCT and µQFR were compared at distal LM, proximal left anterior descending artery (pLAD) and circumflex artery (pLCX). The optimal viewing angle of LM bifurcation was defined on CCTA by 3-dimensional coordinates and converted into a 2-dimensional fluoroscopic view. The best fluoroscopic projection was considered the closest angulation to the optimal viewing angle on CCTA. µQFR was successfully computed in 805 projections. In the best projections, µQFR sensitivity was 88.2% (95% CI 76.1-95.6) and 84.8% (71.1-93.7), and specificity was 96.8% (93.8-98.6) and 97.2% (94.4-98.9), in pLAD and pLCX, respectively, with regard to FFRCT. The AUC of µQFR for predicting FFRCT ≤ 0.80 tended to be improved using the best versus suboptimal projections (0.94 vs. 0.89 [p = 0.048] in pLAD; 0.94 vs. 0.88 [p = 0.075] in pLCX). Computation of µQFR in LM bifurcations using a single angiographic view showed high feasibility from post-hoc analysis of coronary angiograms obtained for clinical purposes. The fluoroscopic viewing angle influences the diagnostic performance of physiological assessment using a single angiographic view.

Artificial Intelligence, Computational Simulations, and Extended Reality in Cardiovascular Interventions

Artificial intelligence, computational simulations, and extended reality, among other 21st century computational technologies, are changing the health care system. To collectively highlight the most recent advances and benefits of artificial intelligence, computational simulations, and extended reality in cardiovascular therapies, we coined the abbreviation AISER. The review particularly focuses on the following applications of AISER: 1) preprocedural planning and clinical decision making; 2) virtual clinical trials, and cardiovascular device research, development, and regulatory approval; and 3) education and training of interventional health care professionals and medical technology innovators. We also discuss the obstacles and constraints associated with the application of AISER technologies, as well as the proposed solutions. Interventional health care professionals, computer scientists, biomedical engineers, experts in bioinformatics and visualization, the device industry, ethics committees, and regulatory agencies are expected to streamline the use of AISER technologies in cardiovascular interventions and medicine in general.

Merging virtual and physical experiences: extended realities in cardiovascular medicine

Technological advancement and the COVID-19 pandemic have brought virtual learning and working into our daily lives. Extended realities (XR), an umbrella term for all the immersive technologies that merge virtual and physical experiences, will undoubtedly be an indispensable part of future clinical practice. The intuitive and three-dimensional nature of XR has great potential to benefit healthcare providers and empower patients and physicians. In the past decade, the implementation of XR into cardiovascular medicine has flourished such that it is now integrated into medical training, patient education, pre-procedural planning, intra-procedural visualization, and post-procedural care. This review article discussed how XR could provide innovative care and complement traditional practice, as well as addressing its limitations and considering its future perspectives.

Science mapping analysis of computed tomography-derived fractional flow reverse: a bibliometric review from 2012 to 2022

Background

Computed tomography-derived fractional flow reserve (CT-FFR) is a non-invasive imagological examination used for diagnosing suspected coronary atherosclerotic heart disease, providing the morphological and functional value on a three-dimensional (3D) coronary artery model. This article aimed to collate the existing knowledge and predict this novel technology's future research hotspots.

Methods

To collect data, 1,712 articles were retrieved from the Web of Science Core Collection (WoSCC) database from 2012-2022. CiteSpace5.8.R3 was used to visually analyze the research status and predict future research hotspots.

Results

Firstly, the United States, China, and the Netherlands were identified as the countries having published the most articles about CT-FFR. Jonathan Leipsic's group ranked first for the highest number of published articles. Secondly, the visualized analysis indicated that the exploration of CT-FFR is multi-disciplinary and involves cardiology, radiology, engineering, and computer science. Thirdly, the hotspots in this field, which were inferred from the keyword distribution and clustering, included the following: "diagnostic performance", "accuracy", and the "prognostic value" of CT-FFR, and comparison of CT-FFR and other imaging methods sharing similarities. The research frontiers included technologies utilized to obtain more accurate CT-FFR values, such as artificial intelligence (AI) and deep learning.

Conclusions

As the first visualized bibliometric analysis on CT-FFR, this study captured the current accumulated information in this field and offer more insight and guidance for future research.

Treatment recommendation based on SYNTAX score 2020 derived from coronary computed tomography angiography and invasive coronary angiography

The diagnostic performance of the SYNTAX score 2020 (SS-2020) when calculated using CCTA remains unknown. This study aimed to compare treatment recommendations based on the SS-2020 derived from coronary computed tomography angiography (CCTA) versus invasive coronary angiography (ICA). This interim analysis included 57 of the planned 114 patients with de-novo three-vessel disease, with or without left main coronary artery disease, enrolled in the ongoing FASTTRACK CABG trial. The anatomical SYNTAX scores derived from ICA or CCTA were evaluated by two separate teams of blinded core-lab analysts. Treatment recommendations were based on a maximal individual absolute risk difference in all-cause mortality between percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) of 4.5% ([predicted PCI mortality] - [predicted CABG mortality]). The level of agreement was evaluated with Bland-Altman plots and Cohen's Kappa. The mean age was 66.2 ± 9.2 years and 89.5% of patients were male. Mean anatomical SYNTAX scores derived from ICA and CCTA were 35.1 ± 11.5 and 35.6 ± 11.4 (p = 0.751), respectively. The Bland-Altman analysis showed mean differences of - 0.26 and - 0.93, with standard deviation of 3.69 and 5.23, for 5- and 10-year all-cause mortality, respectively. The concordance in recommended treatment for 5- and 10-year mortalities were 84.2% (48/57 patients) and 80.7% (46/57 patients), with Cohen's κ coefficients of 0.672 and 0.551. There was moderate to substantial agreement between treatment recommendations based on the SS-2020 derived using CCTA and ICA, suggesting that CCTA could be used as an alternative to ICA when making decisions regarding the modality of revascularization.

The ability of computed tomography angiography to predict 5-year mortality in the SYNTAX III REVOLUTION trial

BACKGROUND

The feasibility of using coronary computed tomography angiography (CCTA) for long-term prediction of vital prognosis post-revascularization remains unknown.

OBJECTIVES

To compare the prognostic value of the SYNTAX score II 2020 (SS-2020) derived from invasive coronary angiography (ICA) or CCTA in patients with three-vessel disease and/or left main coronary artery disease undergoing percutaneous or surgical revascularization.

METHODS

In the SYNTAX III REVOLUTION trial, the probability of death at five years was retrospectively assessed by calculating the SS-2020 using ICA and CCTA. High- and low-risk patients for mortality were categorized according to the median percentages of predicted mortality based on both modalities. The discriminative abilities of the SS-2020 were assessed using Harrell's C statistic.

RESULTS

The vital status at five years of the 215 patients revascularized percutaneously (64 patients, 29.8%) or surgically (151 patients, 70.2%) was established through national registries. In patients undergoing revascularization, the SS-2020 was possibly helpful in discriminating vital prognosis at 5 years, with similar results seen with ICA and CCTA (C-index with ICA ​= ​0.75, intercept ​= ​-0.19, slope ​= ​0.92 and C-index with CCTA ​= ​0.75, intercept ​= ​-0.22, slope ​= ​0.99). In high- and low-risk patients, Kaplan-Meier estimates showed significant, and almost identical relative differences in observed mortality, irrespective of imaging modality (ICA: 93.8% vs 78.7%, log-lank P ​< ​0.001; CCTA: 93.7% vs 78.5%, log-lank P ​< ​0.001).

CONCLUSIONS

The predictive ability of the SS-2020 for five-year all-cause mortality derived from ICA and CCTA was comparable, and could helpfully discriminate vital prognosis in high- and low-risk patients.

The Role of Non-Invasive Multimodality Imaging in Chronic Coronary Syndrome: Anatomical and Functional Pathways

Coronary artery disease (CAD) is one of the major causes of mortality and morbidity worldwide, with a high socioeconomic impact. Currently, various guidelines and recommendations have been published about chronic coronary syndromes (CCS). According to the recent European Society of Cardiology guidelines on chronic coronary syndrome, a multimodal imaging approach is strongly recommended in the evaluation of patients with suspected CAD. Today, in the current practice, non-invasive imaging methods can assess coronary anatomy through coronary computed tomography angiography (CCTA) and/or inducible myocardial ischemia through functional stress testing (stress echocardiography, cardiac magnetic resonance imaging, single photon emission computed tomography-SPECT, or positron emission tomography-PET). However, recent trials (ISCHEMIA and REVIVED) have cast doubt on the previous conception of the management of patients with CCS, and nowadays it is essential to understand the limitations and strengths of each imaging method and, specifically, when to choose a functional approach focused on the ischemia versus a coronary anatomy-based one. Finally, the concept of a pathophysiology-driven treatment of these patients emerged as an important goal of multimodal imaging, integrating 'anatomical' and 'functional' information. The present review aims to provide an overview of non-invasive imaging modalities for the comprehensive management of CCS patients.

10 Years of SYNTAX: Closing an Era of Clinical Research After Identifying New Outcome Determinants

The SYNTAX trial randomized patients equally eligible for coronary artery bypass grafting or percutaneous coronary intervention using the Heart Team approach. The SYNTAXES study achieved a follow-up rate of 93.8% and reported the 10-year vital status. Factors associated with increased mortality at 10 years were pharmacologically treated diabetes mellitus, increased waist circumference, reduced left ventricular function, prior cerebrovascular and peripheral vascular disease, western Europe and North American descent, current smoking, chronic obstructive pulmonary disease, elevated C-reactive protein, anemia, and an increase in HbA1c. Procedural factors associated with higher 10 years mortality include periprocedural myocardial infarction, extensive stenting, small stents, ≥1 heavily calcified lesion, ≥1 bifurcation lesion, residual SYNTAX score >8, and staged percutaneous coronary intervention. Optimal medical therapy at 5 years, use of statins, on-pump coronary artery bypass grafting, multiple arterial grafts, and higher physical component score and mental component score were associated with lower mortality at 10 years. Numerous scores and prediction models were developed to help individualize risk assessment. Machine learning has emerged as a novel approach for developing risk models.

Discordance between Invasive and Non-Invasive Coronary Angiography: An In-Depth Functional and Anatomical Analysis

A 79-year-old male with chronic coronary syndrome with complex coronary artery disease was included in the first-in-man trial of surgical revascularization guided solely by coronary computed tomography angiography (CCTA) and fractional flow reserve derived from CCTA (FFRCT). In CCTA analysis, the patient had calcified three-vessel disease, with a global anatomical SYNTAX score of 27. In contrast, in the initial FFRCT, only the ramus intermediate stenosis was physiologically significant, with no other vessels having an FFRCT ≤ 0.80 (functional SYNTAX score of 2). Discordance between the results of the CCTA and FFRCT necessitated an in-depth analysis by using both invasive and non-invasive coronary angiography. Angiography-derived fractional flow reserve (FFR) confirmed that the stenosis in the proximal left anterior descending artery (LAD) was physiologically significant, while it remained functionally negative in the second assessment of FFRCT. Extensive calcification is the most plausible explanation for the underestimation of the stenosis of proximal LAD in CCTA-derived FFR technology.

Appropriateness of the modality of revascularization according to the SYNTAX Score II 2020 in the FASTTRACK CABG study: An interim report on patient selection

BACKGROUND

Personalized long term vital prognosis plays a key role in deciding between percutaneous coronary intervention (PCI) and CABG in patients with complex coronary artery disease. The FASTTRACK CABG trial enrolls patients with the sole guidance of coronary computed tomographic angiography (CCTA) and fractional flow reserve CCTA (FFR_CT). The feasibility/non-feasibility of this approach is determined by the surgeon request to have access to the invasive coronary angiography.

METHODS

This interim analysis, which was requested by the Data and Safety Monitoring Board (DSMB), compared the treatment decision of the "on site" Heart team to the recommended treatment as per the SYNTAX Score II 2020 (SS-2020), which was prospectively assessed by the central core laboratory in the first 57 consecutive patients (half of the planned population) enrolled in this First in Man study.

RESULTS

The average anatomical SYTAX Score is 35.6 ± 11.5. The SS-2020 predicted 5-year MACE and 10-year all-cause mortality are 14.7 % and 21.6 % following CABG, and 23.0 % and 30.4 % following PCI. Among the enrolled patients the SS-2020 predicts long-term PCI outcomes similar to CABG (absolute risk difference ≤0 % in favor of PCI) in only two patients whilst the remaining 55 patients had a predicted survival benefit with CABG.

CONCLUSIONS

According to the SS-2020, the first 57 patients recruited into the FASTTRACK CABG trial received the appropriate modality of revascularization and the DSMB allowed the investigators to complete the study.

Is it the Time to Move Towards Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve Guided Percutaneous Coronary Intervention? The Pros and Cons

Coronary artery disease is the leading cause of mortality worldwide. Diagnosis is conventionally performed by direct visualization of the arteries by invasive coronary angiography (ICA), which has inherent limitations and risks. Measurement of fractional flow reserve (FFR) has been suggested for a more accurate assessment of ischemia in the coronary artery with high accuracy for determining the severity and decision on the necessity of intervention. Nevertheless, invasive coronary angiography-derived fractional flow reserve (ICA-FFR) is currently used in less than one-third of clinical practices because of the invasive nature of ICA and the need for additional equipment and experience, as well as the cost and extra time needed for the procedure. Recent technical advances have moved towards non-invasive high-quality imaging modalities, such as magnetic resonance, single-photon emission computed tomography, and coronary computed tomography (CT) scan; however, none had a definitive modality to confirm hemodynamically significant coronary artery stenosis. Coronary computed tomography angiography (CCTA) can provide accurate anatomic and hemodynamic data about the coronary lesion, especially calculating fractional flow reserve derived from CCTA (CCTA-FFR). Although growing evidence has been published regarding CCTA-FFR results being comparable to ICA-FFR, CCTA-FFR has not yet replaced the invasive conventional angiography, pending additional studies to validate the advantages and disadvantages of each diagnostic method. Furthermore, it has to be identified whether revascularization of a stenotic lesion is plausible based on CCTA-FFR and if the therapeutic plan can be determined safely and accurately without confirmation from invasive methods. Therefore, in the present review, we will outline the pros and cons of using CCTA-FFR vs. ICA-FFR regarding diagnostic accuracy and treatment decision-making.

The prognostic value of CT-derived fractional flow reserve in coronary artery bypass graft: a retrospective multicenter study

OBJECTIVES

To investigate the predictive value of CT-derived fractional flow reserve (FFR_CT) in anastomosis occlusion after coronary artery bypass graft (CABG) surgery.

METHODS

Patients undergoing CABG with both pre- and post-operative coronary computed tomographic angiography (CCTA) were retrospectively included. Preoperative CCTA studies were used to evaluate anatomical and FFR_CT information of target vessels. A diameter stenosis (DS) ≥ 70% or left main > 50% was considered to be anatomically severe, while FFR_CT value ≤ 0.80 be functionally significant. The primary endpoint was anastomosis occlusion evaluated on post-operative CCTA during follow-up. Predictors of anastomosis occlusion were assessed by the multivariate binary logistic regression with generalized estimating equations.

RESULTS

A total of 270 anastomoses were identified in 88 enrolled patients. Forty-one anastomoses from 30 patients exhibited occlusion during a follow-up of 15.3 months after CABG. The occluded group had significantly increased prevalence of non-severe DS (58.5% vs. 40.2%; p = 0.023) and non-significant FFR_CT (48.8% vs. 10.0%; p < 0.001). Multivariable analysis indicated FFR_CT ≤ 0.80 (odds ratio [OR]: 0.10, 95% CI: 0.03-0.33; p < 0.001) and older age (OR: 0.92, 95% CI: 0.87-0.97; p = 0.001) were predictors for bypass patency during follow-up, while myocardial infarction history and anastomosis to a local lesion or bifurcation (all p value < 0.05) were predictors of occlusion. Adding FFR_CT into the model based on the clinical and anatomical predictors had an improved AUC of 0.848 (p = 0.005).

CONCLUSIONS

FFR_CT ≤ 0.80 was associated with a significant risk reduction of anastomosis occlusion after CABG. Preoperative judgment of the hemodynamic significance may improve the CABG surgery strategy and reduce graft failure.

KEY POINTS

• FFR_CT ≤ 0.80 was associated with a significant risk reduction of anastomosis occlusion after CABG. • The addition of FFR_CT into the integrated model including clinical (age and history of myocardial infarction) and anatomical CCTA indicators (local lesion and bifurcation) significantly improved the model performance with an AUC of 0.848 (p = 0.005). • Preoperative judgment of the hemodynamic significance may help improve the decision-making and surgery planning in patients indicated for CABG and significantly reduce graft failure, without an extra radiation exposure and risk of invasive procedure.

Pre-procedural planning of coronary revascularization by cardiac computed tomography: An expert consensus document of the Society of Cardiovascular Computed Tomography

Coronary CT angiography (CCTA) demonstrated high diagnostic accuracy for detecting coronary artery disease (CAD) and a key role in the management of patients with low-to-intermediate pretest likelihood of CAD. However, the clinical information provided by this noninvasive method is still regarded insufficient in patients with diffuse and complex CAD and for planning percutaneous coronary intervention (PCI) and surgical revascularization procedures. On the other hand, technology advancements have recently shown to improve CCTA diagnostic accuracy in patients with diffuse and calcific stenoses. Moreover, stress CT myocardial perfusion imaging (CT-MPI) and fractional flow reserve derived from CCTA (CT-FFR) have been introduced in clinical practice as new tools for evaluating the functional relevance of coronary stenoses, with the possibility to overcome the main CCTA drawback, i.e. anatomical assessment only. The potential value of CCTA to plan and guide interventional procedures lies in the wide range of information it can provide: a) detailed evaluation of plaque extension, volume and composition; b) prediction of procedural success of CTO PCI using scores derived from CCTA; c) identification of coronary lesions requiring additional techniques (e.g., atherectomy and lithotripsy) to improve stent implantation success by assessing calcium score and calcific plaque distribution; d) assessment of CCTA-derived Syntax Score and Syntax Score II, which allows to select the mode of revascularization (PCI or CABG) in patients with complex and multivessel CAD. The aim of this Consensus Document is to review and discuss the available data supporting the role of CCTA, CT-FFR and stress CT-MPI in the preprocedural and possibly intraprocedural planning and guidance of myocardial revascularization interventions.

Pre-procedural planning of coronary revascularization by cardiac computed tomography: An expert consensus document of the Society of Cardiovascular Computed Tomography

Coronary CT angiography (CCTA) demonstrated high diagnostic accuracy for detecting coronary artery disease (CAD) and a key role in the management of patients with low-to-intermediate pretest likelihood of CAD. However, the clinical information provided by this noninvasive method is still regarded insufficient in patients with diffuse and complex CAD and for planning percutaneous coronary intervention (PCI) and surgical revascularization procedures. On the other hand, technology advancements have recently shown to improve CCTA diagnostic accuracy in patients with diffuse and calcific stenoses. Moreover, stress CT myocardial perfusion imaging (CT-MPI) and fractional flow reserve derived from CCTA (CT-FFR) have been introduced in clinical practice as new tools for evaluating the functional relevance of coronary stenoses, with the possibility to overcome the main CCTA drawback, i.e. anatomical assessment only. The potential value of CCTA to plan and guide interventional procedures lies in the wide range of information it can provide: a) detailed evaluation of plaque extension, volume and composition; b) prediction of procedural success of CTO PCI using scores derived from CCTA; c) identification of coronary lesions requiring additional techniques (e.g., atherectomy and lithotripsy) to improve stent implantation success by assessing calcium score and calcific plaque distribution; d) assessment of CCTA-derived Syntax Score and Syntax Score II, which allows to select the mode of revascularization (PCI or CABG) in patients with complex and multivessel CAD. The aim of this Consensus Document is to review and discuss the available data supporting the role of CCTA, CT-FFR and stress CT-MPI in the preprocedural and possibly intraprocedural planning and guidance of myocardial revascularization interventions.

Computed tomography to replace invasive coronary angiography? The DISCHARGE trial

Ongoing advancements of coronary computed tomographic angiography (CTA) continue to challenge the role of invasive coronary angiography (ICA) as the gold standard for the evaluation of coronary artery disease (CAD). To investigate the comparative effectiveness of ICA when compared with CTA as an initial diagnostic imaging strategy the DISCHARGE Trial enrolled 3561 patients with stable chest pain and an intermediate pre-test probability of obstructive CAD. The study showed no difference between CTA and ICA in the incidence of the primary composite outcome of cardiovascular death, non-fatal myocardial infarction, or non-fatal stroke during 3.5 years of follow up. As with many trials that advance a field, this trial raises several additional questions of interest that will be discussed. Furthermore, recent studies focused on the discrepancies of CTA vs. ICA indicate that the status of CTA remains unchanged in its ability to rule out disease but at present cannot be considered a substitute for ICA when coronary lesions are documented. Thus, a change in clinical practice patterns likely requires evidence from clinical studies demonstrating equivalence of CT to ICA for guiding medical management. Developments, however, are swift, and CT technology is catching up on its invasive counterpart.

Successful coronary artery bypass grafting based solely on non-invasive coronary computed tomography angiography

An 81-year-old female presented with chronic coronary disease (Canadian Cardiovascular Society angina severity grading III). The patient underwent coronary computed tomography angiography (CCTA) that revealed three-vessel coronary artery disease (3VD). This case illustrates that in a patient with 3VD, planning and execution of coronary artery bypass grafting (CABG) were successfully performed based solely on CCTA combined with fractional flow reserve derived from computed tomography angiography (FFR_CT). Coronary artery bypass grafting (CABG) was planned and executed as follows: left internal mammary artery grafted to the left anterior descending artery (LAD), saphenous vein graft (SVG) to the right coronary artery (RCA), and SVG to the obtuse marginal artery (OM). Repeat imaging assessment with non-invasive CCTA and FFR_CT at 30-day follow-up confirmed the safety of this approach. The FFR_CT values of the RCA and LAD were normalized, whereas a borderline pressure drop was observed in the distal run-off of the OM (FFR_CT=0.79). Notably, this is the first case in which post-CABG FFR_CT assessment was performed. Post-CABG FFR_CT is an investigational novel non-invasive tool for assessing the functional improvement of the epicardial conductance vessels following surgical revascularization.

Coronary Computed Tomographic Angiography for Complete Assessment of Coronary Artery Disease: JACC State-of-the-Art Review

Coronary computed tomography angiography (CTA) has shown great technological improvements over the last 2 decades. High accuracy of CTA in detecting significant coronary stenosis has promoted CTA as a substitute for conventional invasive coronary angiography in patients with suspected coronary artery disease. In patients with coronary stenosis, CTA-derived physiological assessment is surrogate for intracoronary pressure and velocity wires, and renders possible decision-making about revascularization solely based on computed tomography. Computed tomography coronary anatomy with functionality assessment could potentially become a first line in diagnosis. Noninvasive imaging assessment of plaque burden and morphology is becoming a valuable substitute for intravascular imaging. Recently, wall shear stress and perivascular inflammation have been introduced. These assessments could support risk management for both primary and secondary cardiovascular prevention. Anatomy, functionality, and plaque composition by CTA tend to replace invasive assessment. Complete CTA assessment could provide a 1-stop-shop for diagnosis, risk management, and decision-making on treatment.

Percutaneous Coronary Revascularization: JACC Historical Breakthroughs in Perspective

Over the last 4 decades, percutaneous coronary intervention has evolved dramatically and is now an acceptable treatment option for patients with advanced coronary artery disease. However, trialists have struggled to establish the respective roles for percutaneous coronary intervention and coronary artery bypass graft surgery, especially in patients with multivessel disease and unprotected left-main stem coronary artery disease. Several pivotal trials and meta-analyses comparing these 2 revascularization strategies have enabled the relative merits of each technique to be established with regard to the type of ischemic syndrome, the coronary anatomy, and the patient's overall comorbidity. Precision medicine with individualized prognosis is emerging as an important method of selecting treatment. However, the never-ending advancement of technology, in conjunction with the emergence of novel pharmacological agents, will in the future continue to force us to reconsider the evolving question: "Which treatment strategy is better and for which patient?"

Diagnostic performance of computed tomography-based fraction flow reserve in identifying myocardial ischemia caused by coronary artery stenosis: A meta-analysis

BACKGROUND

As a new noninvasive diagnostic technique, computed tomography (CT)-based fraction flow reserve (FFR) has been used to identify hemodynamically significant coronary artery stenosis. This meta-analysis used invasive FFR as the standard to evaluate the diagnostic performance of FFRCT.

METHODS

We searched the PubMed, Cochrane library, and EMBASE for articles published between January 2009 and January 2021. The synthesized sensitivity and specificity of invasive FFR and FFRCT were analyzed at both the patient and vessel levels. We generated a summary receiver operating characteristic curve (SROC) and then calculated the area under the curve (AUC).

RESULTS

We included a total of 23 studies, including 2,178 patients and 3,029 vessels or lesions. Analysis at each patient level demonstrated a synthesized sensitivity of 88%, specificity of 79%, LR+ of 4.16, LR-of 0.15, and AUC of 0.89 for FFRCT. Analysis at the level of each vessel or lesion showed a synthesized sensitivity of 85%, specificity of 81%, LR+ of 4.44, LR-of 0.19, and AUC of 0.87 for FFRCT.

CONCLUSION

Our research reveals that FFRCT has high diagnostic performance in patients with coronary artery stenosis, regardless of whether it is at the patient level or the vessel level.