Assessment Of Coronary Lesions Research Articles

Association of polarimetric signatures with coronary plaque composition in patients with acute and chronic coronary syndrome: an intravascular polarization-sensitive optical coherence tomography study

Abstract Background Intravascular polarimetry with polarization-sensitive (PS-) optical coherence tomography (OCT) measures polarization properties, birefringence and depolarization, in parallel with structural features available with conventional OCT (Figure 1). Birefringence is elevated in collagen and collagen-synthesizing smooth muscle cells, which imparts mechanical integrity to fibrous caps. Depolarization is elevated in the presence of macrophages and lipid/necrotic core. Purpose This study aimed to investigate polarimetric signatures of coronary lesions in patients with acute coronary syndrome (ACS) and chronic coronary syndrome (CCS). Furthermore, we aimed to investigate diagnostic value for birefringence and depolarization of ACS culprit lesions discriminating from CCS target lesions. Methods This was the first-in-human study of intracoronary PS-OCT in Japan, consisting of 17 patients with ACS (n = 5) or CCS (n = 12) who underwent intravascular PS-OCT. ACS culprit lesions (ACS-lesions) and CCS target lesions (CCS-lesions) were included in the analysis, resulting in a total of 862 cross-sections. In the cross-sectional images, lumen segmentation and guidewire artifact were automatically segmented. The median value of birefringence and depolarization were automatically analyzed using depolarization cut-off value (cross-sectional level). Birefringence and depolarization of ACS- and CCS-lesions were compared by using a generalized estimating equation model. Receiver operating characteristic (ROC) analysis was used to investigate diagnostic performance of polarimetric signatures for the identification of ACS-lesions. Results Compared to CCS-lesions, ACS-lesions featured higher lipid-burden index and maximum lipid arc (both p < 0.05). Compared to the CCS-lesions, ACS-lesions exhibited significantly lower birefringence (p < 0.05) and higher depolarization (p < 0.05) (Figure 2). In the ROC analysis for differentiating ACS-lesions from CCS-lesions, area under the curves (AUC) for birefringence and depolarization were 0.712 and 0.672, respectively. In the multivariable ROC analysis in diagnosing ACS lesions, combination of birefringence with depolarization improved the AUC to 0.755 (p ＝ 0.025). Conclusions Intravascular PS-OCT provides quantitative compositional assessment of coronary lesions. Decreased birefringence and pronounced depolarization within the ACS-lesions indicate increased collagenolytic activity and the presence of macrophage infiltration, respectively. These results suggest that polarization properties may serve as quantitative imaging markers for assessing natural history of coronary atherosclerosis.

Accuracy of coronary computed tomography angiography-derived quantitative flow ratio for onsite assessment of coronary lesions.

Coronary computed tomography angiography (CCTA)-derived Murray law-based quantitative flow ratio (CT-μFR) is a novel non-invasive method for fast computation of fractional flow reserve (FFR) from CCTA images, yet its diagnostic performance remains to be prospectively validated. We aimed to evaluate the diagnostic performance of onsite CT-μFR in patients with coronary artery disease. This prospective, single-centre trial enrolled patients with ≥1 lesion with 30-90% diameter stenosis on CCTA and planned invasive coronary angiography (ICA) within 30 days. CT-μFR, ICA-derived μFR and FFR were evaluated separately in a blinded fashion. The primary endpoint was the diagnostic accuracy of CT-μFR in identifying patients with haemodynamically significant coronary stenosis defined by the invasive standard: FFR ≤0.80, or μFR ≤0.80 when FFR was not available. Between December 2020 and August 2023, 260 patients were consecutively enrolled. Paired comparison between CT-μFR and the invasive standard was obtained in 706 vessels from 260 patients. The patient-level accuracy of CT-μFR was 89.6% (95% confidence interval [CI]: 85.9-93.4%), which was significantly higher than the prespecified target of 72.0% (p<0.001). Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios for CT-μFR were 93.1%, 86.1%, 87.1%, 92.5%, 6.7, and 0.1, respectively. Out of the 231 vessels investigated by FFR, the accuracy of CT-μFR in vessels without extensive calcification was non-inferior to that of μFR (90.6% vs 88.9%; difference=1.8% [95% CI: -2.8 to 5.5%]; p for non-inferiority<0.001). The study met its prespecified primary endpoint of the diagnostic accuracy of CT-μFR in identifying patients with haemodynamically significant coronary stenosis. CT-μFR was non-inferior to ICA-derived μFR in vessels without extensive calcification. (ClinicalTrials.gov: NCT04665817).

Validation of angiography-derived Murray law-based quantitative flow reserve (μQFR) against pressure-derived instantaneous wave-free ratio for assessing coronary lesions, a single-center study in Egypt

BackgroundInstantaneous wave-free ratio (iwFR) is a well-validated method for functional evaluation of intermediate coronary lesions. A recently developed Murray law-based QFR (µQFR) allows wire-free FFR estimation using a high-quality single angiographic projection. We aim to determine the diagnostic accuracy of µQFR as compared to wire-based iwFR for physiological assessment of coronary lesions in a sample of Egyptian patients.ResultsOver a one-year period, patients who previously underwent iwFR assessment of an intermediate coronary stenosis (40–90%) were retrospectively included. μQFR analysis was then performed offline using a dedicated artificial intelligence (AI)-aided computation software. All the measurements were performed blinded to iwFR results, and the agreement between iwFR and μQFR values was tested. Forty-nine patients (mean age 57.9 ± 9 years, 72.9% males) were included. Mean value of iwFR and μQFR was 0.90 ± 0.075 and 0.79 ± 0.129, respectively. There was a significant moderate positive linear correlation between μQFR and iwFR (r = 0.47, p = 0.001; 95% CI 0.22–0.68) with moderate-to-substantial agreement between the two methods (Kappa 0.6). In assessing the diagnostic accuracy of μQFR, the receiver operating characteristic (ROC) curve yielded an area under the curve (AUC) of 0.84 (95% CI 0.717–0.962) for predicting functionally significant lesions defined as iwFR < 0.89. The sensitivity and specificity of μQFR < 0.8 for detecting physiological significance of coronary lesions were 89% and 74% with positive and negative predictive values of 70 and 91%, respectively.ConclusionµQFR has good diagnostic accuracy for predicting functionally significant coronary lesions with moderate correlation and agreement with the gold standard iwFR. Angiography-derived µQFR could be a promising tool for improving the utilization of physiology-guided revascularization.

Intracoronary Imaging for Changing Therapeutic Decisions in Patients with Multivascular Coronary Artery Disease.

Background and Objectives: Atherosclerotic disease is a major contributor to heart failure, stroke, and myocardial infarction, significantly lowering the quality of life and life expectancy and placing a significant burden on healthcare. Not all lesions deemed non-significant are benign, and conversely, not all significant lesions are causative of ischemia. Fractional flow reserve (FFR) provides a functional assessment of coronary lesions, while optical coherence tomography (OCT) offers detailed imaging of plaque morphology, aiding in therapeutic decision-making. The objective of this study was to evaluate the utility of OCT and FFR as adjunctive tools in the catheterization laboratory for guiding therapeutic decisions in patients with multivessel disease for non-culprit vessels. Specifically, we aimed to assess how OCT and FFR influence therapeutic decision-making in patients with multivessel coronary artery disease. Materials and Methods: A total of 36 patients with acute coronary syndrome (ACS) and multivessel disease were randomized 1:1 into two groups: one guided by FFR alone and the other by a combination of FFR and OCT. For the FFR group, revascularization decisions for non-culprit lesions were based solely on FFR measurements. If the FFR was >0.8, the procedure was concluded, and the patient received maximal medical treatment. If the FFR was ≤0.8, a stent was placed. For the FFR + OCT group, if the FFR was >0.8, the revascularization decision was based on OCT findings. If there were no vulnerable plaques (VP), the procedure was concluded, and the patient received maximal medical treatment. If OCT imaging indicated VP, then the patient underwent revascularization. If the FFR was ≤0.8, the patient underwent revascularization regardless of OCT findings. Results: OCT imaging altered the therapeutic decision in 11 cases where FFR measurements were above 0.8, but the lesions were characterized as VP. Analyzing the total change in the decision to stent, 4 cases in the FFR group and 15 cases in the FFR and OCT groups (4 based on FFR and 11 on OCT) revealed a statistically significant difference (p = 0.0006; Relative Risk = 0.2556; 95% CI: 0.1013 to 0.5603). When analyzing the change in the total decision both to stent and not to stent, we observed a statistically significant difference, with Group 1 having 7 cases and Group 2 having 15 cases (p = 0.0153; Relative Risk = 0.4050; 95% CI: 0.2004 to 0.7698. Conclusions: Based on the findings of this study, OCT significantly increases the percentage of stenting procedures by identifying vulnerable lesions. The use of intracoronary imaging facilitates the timely identification and treatment of these vulnerable lesions. This underscores the crucial role of OCT in enhancing the precision of coronary interventions by ensuring timely intervention for vulnerable lesions, thereby potentially improving patient outcomes.

Offline Assessment of the Quantitative Flow Ratio: Is it Useful in Clinical Practice?

Fractional flow reserve (FFR) has been established as the gold standard in the physiological assessment of coronary obstructions severity. However, the need to insert an intracoronary pressure guidewire is a factor that limits its use. Quantitative flow ratio (QFR) is a method that infers the value of FFR from 3-dimensional quantitative coronary angiography (3D-QCA), eliminating the use of a pressure wire and coronary hyperemia. The present study aims to evaluate the diagnostic accuracy of QFR and 3D-QCA in comparison with FFR for the identification of significant obstructive coronary lesions (FFR ≤.80) and the feasibility to assess QFR in a cohort of patients without dedicated angiographic acquisition. Consecutive patients with coronary angiography with moderate obstructive lesions that had previous FFR measurement were evaluated. Validation of QFR was assessed by the area under the curve (AUC) and other statistical tools, using FFR as the reference method. Seventy-five arteries from 69 patients were evaluated. The accuracy of the QFR to detect FFR ≤.80 was 84.0% (95% confidence interval, 75.6-92.4). The correlation and agreement between FFR and QFR were r=0.54 (P<.01) and mean difference was -0.02 ± 0.09 (P=.09), respectively. The AUC of QFR and 3D-QCA identifying stenosis >50% was 0.854 and 0.755, respectively (P=.09). QFR demonstrated good accuracy compared with FFR for the assessment of moderate obstructive coronary lesions in an unselected clinical practice population. However, many patients were excluded from the analysis and there was no statistical difference between the receiver operator characteristic curves of the QFR and percent diameter stenosis.

Evaluation of functional significance of intermediate coronary artery lesions noninvasively by tissue doppler echocardiography and single photon emission computed tomography versus invasively by IFR

Background: Myocardial perfusion imaging by single photon emission computed tomography (MPI–SPECT) is noninvasive test that can give an important information for the diagnosis of coronary artery disease (CAD), detect reversible ischemia, quantify defect sizes and help in clinical decisions of interventions as well as assessment of disease prognosis. Tissue Doppler imaging (TDI) emerged as a potential modality for assessing systolic and diastolic LV performance. Strain doppler echocardiography (SDE) is a new tool for measuring regional myocardial deformation excluding the effect of adjacent myocardial tissue. The development of Instantaneous wave-free Ratio (IFR) as a relatively new invasive method for physiological assessment of coronary lesions without the use of pharmacologic hyperemic agents is the golden standard test for assessment of intermediate coronary lesions and guiding the revascularization decision. Methods: This Cross-sectional study was done was conducted on 50 cases with intermediate coronary artery lesions admitted at the Cardiology departments in Benha University, Kobry Elkobba Military Hospital and Air Force Specialized Hospital. All groups were subjected to history and clinical examination, cardiac examination, 12 lead ECG, 2D echocardiography, routine laboratory investigations, coronary angiography with evaluation of intermediate lesion by IFR then TDI and SDE for evaluation the regional myocardial deformation of the segments supplied by the same coronary artery, after that 99mTc-sestamibi (MIBI) SPECT imaging was done to quantify defect size and finally correlation was done between results of IFR, TDI and SPECT to guide the revascularization decision. Results: Pearson’s correlation analysis showed that; Gated single-photon emission computed moderate and severe Ischemia, Sm-velocity, WMSI, DT, had a highly significant positive correlation with IFR value (p &lt; 0.001). E/A ratio, Mean E/e’ velocity ratio, FS, LVEF and LV GLS had a highly significant negative correlation with IFR value (p &lt; 0.001). Conclusions: Instantaneous wave-free Ratio (IFR) modality is a reliable measure to guide functional significance of the intermediate coronary artery lesions for decision making and guiding plan of management. But it is an expensive and invasive modality. On the other hand, SPECT and tissue doppler modalities showed high sensitivity and specificity in the same group of patients with less expensive, non-invasive and no contrast use advantages.

Invasive and Non-invasive Assessment of Non-culprit Coronary Lesions in Patients with ST-segment Elevation Myocardial Infarction.

The angiographic evidence of coronary multivessel disease (MVD) increases significantly the risk of recurrent ischemic events in patients with ST-segment elevation myocardial infarction (STEMI). Recent evidence suggests that a complete revascularization strategy should be considered the standard of care in these patients and performed for significant non-culprit lesions (NCLs) after careful assessment of the individual risk-benefit ratio. However, the optimal timing and the modality for the assessment of NCLs is not fully standardized. This brief review aims to summarise the management of MVD in patients with STEMI and to provide an overview of the principal techniques used to guide revascularisation in this high-risk clinical setting.

Virtual Hemodynamic Assessment of Coronary Lesions: The Advent of Functional Angiography and Coronary Imaging.

Search of the bibliographic database for articles published from 2011 to 2023 using the following search terms: invasive FFR and non-invasive FFR. Pooled analysis of the sensitivity and specificity, with the corresponding confidence intervals from 32% to 94%. In addition, the summary processing times were determined. In total, 24 studies published between 2011 and 2023 were included, with a total of 13,591 patients and 3345 vessels. The diagnostic accuracy of the invasive and non-invasive techniques at the per-patient level was 89% (95% CI, 85-92%) and 76% (95% CI, 61-80%), respectively, while on the per-vessel basis, it was 92% (95% CI, 82-88%) and 81% (95% CI, 75-87%), respectively. These opportunities providing hemodynamic information based on anatomy have given rise to a new era of functional angiography and coronary imaging. However, further validations are needed to overcome several scientific and computational challenges before these methods are applied in everyday clinical practice.

Artificial intelligence-based quantitative coronary angiography of major vessels using deep-learning

BackgroundQuantitative coronary angiography (QCA) offers objective and reproducible measures of coronary lesions. However, significant inter- and intra-observer variability and time-consuming processes hinder the practical application of on-site QCA in the current clinical setting. This study proposes a novel method for artificial intelligence-based QCA (AI-QCA) analysis of the major vessels and evaluates its performance. MethodsAI-QCA was developed using three deep-learning models trained on 7658 angiographic images from 3129 patients for the precise delineation of lumen boundaries. An automated quantification method, employing refined matching for accurate diameter calculation and iterative updates of diameter trend lines, was embedded in the AI-QCA. A separate dataset of 676 coronary angiography images from 370 patients was retrospectively analyzed to compare AI-QCA with manual QCA performed by expert analysts. A match was considered between manual and AI-QCA lesions when the minimum lumen diameter (MLD) location identified manually coincided with the location identified by AI-QCA. Matched lesions were evaluated in terms of diameter stenosis (DS), MLD, reference lumen diameter (RLD), and lesion length (LL). ResultsAI-QCA exhibited a sensitivity of 89% in lesion detection and strong correlations with manual QCA for DS, MLD, RLD, and LL. Among 995 matched lesions, most cases (892 cases, 80%) exhibited DS differences ≤10%. Multiple lesions of the major vessels were accurately identified and quantitatively analyzed without manual corrections. ConclusionAI-QCA demonstrates promise as an automated tool for analysis in coronary angiography, offering potential advantages for the quantitative assessment of coronary lesions and clinical decision-making.

Advanced CT measures of coronary artery disease with intermediate stenosis in patients with severe aortic valve stenosis

BackgroundCoronary artery disease (CAD) and severe aortic valve stenosis (AS) frequently coexist. While pre-transcatheter aortic valve replacement (TAVR) computed tomography angiography (CTA) allows to rule out obstructive CAD, interpreting hemodynamic significance of intermediate stenoses is challenging. This study investigates the incremental value of CT-derived fractional flow reserve (CT-FFR), quantitative coronary plaque characteristics (e.g., stenosis degree, plaque volume, and composition), and peri-coronary adipose tissue (PCAT) density to detect hemodynamically significant lesions among those with AS and CAD.Materials and methodsWe included patients with severe AS and intermediate coronary lesions (20–80% diameter stenosis) who underwent pre-TAVR CTA and invasive coronary angiogram (ICA) with resting full-cycle ratio (RFR) assessment between 08/16 and 04/22. CTA image analysis included assessment of CT-FFR, quantitative coronary plaque analysis, and PCAT density. Coronary lesions with RFR ≤ 0.89 indicated hemodynamic significance as reference standard.ResultsOverall, 87 patients (age 77.9 ± 7.4 years, 38% female) with 95 intermediate coronary artery lesions were included. CT-FFR showed good discriminatory capacity (area under receiver operator curve (AUC) = 0.89, 95% confidence interval (CI) 0.81–0.96, p < 0.001) to identify hemodynamically significant lesions, superior to anatomical assessment, plaque morphology, and PCAT density. Plaque composition and PCAT density did not differ between lesions with and without hemodynamic significance. Univariable and multivariable analyses revealed CT-FFR as the only predictor for functionally significant lesions (odds ratio 1.28 (95% CI 1.17–1.43), p < 0.001). Overall, CT-FFR ≤ 0.80 showed diagnostic accuracy, sensitivity, and specificity of 88.4% (95%CI 80.2–94.1), 78.5% (95%CI 63.2–89.7), and 96.2% (95%CI 87.0–99.5), respectively.ConclusionCT-FFR was superior to CT anatomical, plaque morphology, and PCAT assessment to detect functionally significant stenoses in patients with severe AS.Clinical relevance statementCT-derived fractional flow reserve in patients with severe aortic valve stenosis may be a useful tool for non-invasive hemodynamic assessment of intermediate coronary lesions, while CT anatomical, plaque morphology, and peri-coronary adipose tissue assessment have no incremental or additional benefit. These findings might help to reduce pre-transcatheter aortic valve replacement invasive coronary angiogram.Key Points• Interpreting the hemodynamic significance of intermediate coronary stenoses is challenging in pre-transcatheter aortic valve replacement CT.• CT-derived fractional flow reserve (CT-FFR) has a good discriminatory capacity in the identification of hemodynamically significant coronary lesions.• CT-derived anatomical, plaque morphology, and peri-coronary adipose tissue assessment did not improve the diagnostic capability of CT-FFR in the hemodynamic assessment of intermediate coronary stenoses.

The Management of Coronary Artery Disease in TAVR Patients.

About half of the transcatheter aortic valve replacement (TAVR) recipients exhibit some degree of coronary artery disease (CAD), and controversial results have been reported regarding the impact of the presence and severity of CAD on clinical outcomes post-TAVR. In addition to coronary angiography, promising data has been recently reported on the use of both cardiac computed tomography angiography and the functional invasive assessment of coronary lesions whether by FFR or iFR in the work-up pre-TAVR. Despite mitigated available data, percutaneous revascularization of significant coronary lesions has been the routine strategy in TAVR candidates with CAD. Additionally, scarce data exists on the incidence, characteristics and management of coronary events post-TAVR, and increasing interest exists on the potential coronary access challenges in patients requiring coronary angiography/intervention post-TAVR. This review provides an updated overview of the knowledge of CAD in TAVR recipients, focusing on its prevalence, clinical impact, pre- and post-procedural evaluation and management.

Contemporary Use of Coronary Physiology in Cardiology.

Coronary angiography has a limited ability to predict the functional significance of intermediate coronary lesions. Hence, physiological assessment of coronary lesions, via fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR), has been introduced to determine their functional significance. An accumulating body of evidence has consolidated the role of physiology-guided revascularization, particularly among patients with stable ischemic heart disease. The use of FFR or iFR to guide decision-making in patients with stable ischemic heart disease and intermediate coronary lesions received a class I recommendation from major societal guidelines. Nevertheless, the role of coronary physiology testing is less clear among certain patients' groups, including patients with serial coronary lesions, acute coronary syndromes, aortic stenosis, heart failure, as well as post-percutaneous coronary interventions. In this review, we aimed to discuss the utility and clinical evidence of coronary physiology (mainly FFR and iFR), with emphasis on those specific patient groups.

Real-world approach to comprehensive artificial intelligence-aided CT evaluation of coronary artery disease in 530 patients: A retrospective study

PurposeRecent guidelines provide broader support for the use of less invasive imaging modalities for the evaluation of patients with stable chest pain. Coronary CT angiography (CCTA) uses increasingly sophisticated techniques to improve evaluation of coronary lesions. The purpose of this study is to describe one center's experience implementing AI-assisted advanced imaging techniques to diagnose coronary artery disease. Materials & methodsRetrospective study of patients who had AI-assisted CCTA interpretation, including a subgroup who underwent fractional flow reserve CT (FFR-CT) and invasive coronary angiography. Descriptive statistics summarized baseline characteristics and univariate statistics compared findings between groups of patients with and without anatomically and hemodynamically significant lesions based on FFR-CT. For patients who underwent invasive coronary angiography, concordance between CCTA and angiography was evaluated. ResultsOf 532 included patients, AI-assisted CCTA identified statistically significant difference in calcification scores, plaque types and total plaque volume between lesions <50% and ≥50% stenosis. CCTA results were mostly concordant with invasive coronary angiography. Importantly, we identified a subset of patients with less than 50% anatomical stenosis that demonstrated physiologically significant stenosis on FFR-CT and invasive coronary angiography. ConclusionsAI-assisted CCTA and other advanced techniques are a tool to support high quality diagnostic assessment of coronary lesions in a clinical environment. Combined CCTA with FFRCT in mild to moderate coronary stenosis identifies patients with hemodynamically significant stenosis even when quantitative stenosis is <50%. Implementation of AI-assisted coronary CT angiography is feasible in a community hospital setting, but these technologies do not replace the need for expert review and clinical correlation.

Validation of a new model of non-invasive functional assessment of coronary lesions by computer tomography fractional flow reserve

Introduction and objectivesComputed tomography of coronary arteries (CTCA) is emerging as the gold standard in the initial evaluation of chest pain. The aim of this study is to calculate the diagnostic performance and clinical usefulness of numerical models of arterial channels flow to assess non-invasive coronary fractional flow reserve by computed tomography (FFRct) compared to assessment by invasive angiography (FFR). MethodsComputation of FFR from CTCA images was performed on 39 vessels in 32 patients who followed the usual clinical protocol including invasive coronary angiography and FFR following the usual clinical protocol. From the segmentation of the CTCA images, 3D geometry is obtained, and computational fluid dynamics techniques are applied to accurately reproduce the circulation of blood considering steady and unsteady circulatory conditions. Additional parameters as wall shear stress, stenosis resistance index and ΔFFRct were also calculated. ResultsThe results obtained show a good correlation between FFRct and invasive FFR, without obtaining false positives values. In addition, no differences were observed between the simulations considering steady conditions or those considering the transient. Additional parameters as wall shear stress, stenosis resistance, and ΔFFRct also showed a good correlation with the invasive values. ConclusionsThis new model for calculating the FFRct from non-invasive 3D medical images of coronary tree has shown good agreement with those obtained using invasive techniques. Parameters as wall shear stress, stenosis resistance and ΔFFRct provide useful information that could be helpful in medical decision-making in those situations with FFR values close to the cut-off zone.

Current status and future perspectives of fractional flow reserve derived from invasive coronary angiography.

Assessment of the functional significance of coronary artery stenosis using invasive measurement of fractional flow reserve (FFR) or non-hyperemic indices has been shown to be safe and effective in making clinical decisions on whether to perform percutaneous coronary intervention (PCI). Despite strong evidence from clinical trials, utilization of these techniques is still relatively low worldwide. This may be to some extent attributed to factors that are inherent to invasive measurements like prolongation of the procedure, side effects of drugs that induce hyperemia, additional steps that the operator should perform, the possibility to damage the vessel with the wire, and additional costs. During the last few years, there was a growing interest in the non-invasive assessment of coronary artery lesions, which may provide interventionalist with important physiological information regarding lesion severity and overcome some of the limitations. Several dedicated software solutions are available on the market that could provide an estimation of FFR using 3D reconstruction of the interrogated vessel derived from two separated angiographic projections taken during diagnostic coronary angiography. Furthermore, some of them use data about aortic pressure and frame count to more accurately calculate pressure drop (and FFR). The ideal non-invasive system should be integrated into the workflow of the cath lab and performed online (during the diagnostic procedure), thereby not prolonging procedural time significantly, and giving the operator additional information like vessel size, lesion length, and possible post-PCI FFR value. Following the development of these technologies, they were all evaluated in clinical trials where good correlation and agreement with invasive FFR (considered the gold standard) were demonstrated. Currently, only one trial (FAVOR III China) with clinical outcomes was completed and demonstrated that QFR-guided PCI may provide better results at 1-year follow-up as compared to the angiography-guided approach. We are awaiting the results of a few other trials with clinical outcomes that test the performance of these indices in guiding PCI against either FFR or angiography-based approach, in various clinical settings. Herein we will present an overview of the currently available data, a critical review of the major clinical trials, and further directions of development for the five most widely available non-invasive indices: QFR, vFFR, FFRangio, caFFR, and AccuFFRangio.

Predictors of discordance between fractional flow reserve (FFR) and diastolic pressure ratio (dPR) in intermediate coronary lesions

BackgroundRecently, non-hyperemic pressure ratios (NHPRs) have been validated as a reliable alternative to fractional flow reserve (FFR). However, a discordance between FFR and NHPRs is observed in 20–25% of cases. The aim of this study is to evaluate predictors of discordance between FFR and diastolic Pressure ratio (dPR). MethodsPREDICT is a retrospective, single center, investigator-initiated study including 813 patients (1092vessels) who underwent FFR assessment of intermediate coronary lesions (angiographic 30%-80% stenosis). dPR was calculated using individual pressure waveforms and dedicated software. Clinical, angiographic and hemodynamic variables were compared between patients with concordant and discordant FFR and dPR values. ResultsMedian age was 65 (IQR:59–73) years and 70% were male. Hemodynamically significant lesions, as defined by FFR ≤ 0.80, and dPR ≤ 0.89, were identified in 29.6% and 30.3% of cases, respectively. Overall, FFR and dPR values were discordant in 22.1% patients (17.4% of the vessels). Discordance was related to FFR+/dPR- and FFR-/dPR + in 11.8% and 10.3% of patients, respectively.In case of FFR-dPR discordance, a higher prevalence of left anterior descending arteries lesions was observed (70.5% vs. 53.1%, p < 0.001) and mean values of both FFR and dPR were significantly lower (FFR 0.81 ± 0.05 vs 0.85 ± 0.08, p < 0.001, and dPR 0.89 ± 0.04 vs 0.92 ± 0.08,p < 0.001) as compared to vessels with FFR and dPR concordance. Following multivariable adjustment, dPR delta (defined as the absolute difference between measured dPR to the cut-off value of 0.89) turned out to be the only independent predictor of discordance (OR = 0.74, 95% CI 0.68–0.79, p < 0.001). ConclusionOur study suggests that FFR-to-dPR discordance occurs in approximately one-fifth of patients. Absolute dPR delta appears to be the only independent predictor of discordance.

Diagnostic efficacy of the optical flow ratio in patients with coronary heart disease: A meta-analysis.

Coronary atherosclerotic heart disease (CAD) remains one of the most serious diseases threatening human health and life. PCI (Percutaneous Coronary Intervention) is the most common treatment for patients with CAD. A rigorous and comprehensive assessment of coronary artery lesions is now needed before PCI, however, there is no consensus on how best evaluate the combination of various intracavitary imaging techniques. By merging the benefits of physiological assessment and high-definition imaging, the optical flow ratio (OFR) has emerged as a novel technology with promising prospects for application. A systematic review of the literature was conducted. Studies that met the criteria of the meta-analysis were considered to assess OFR and FFR (fractional flow reserve). And the summary values of sensitivity and specificity of diagnostic tests and summary receiver operating curves (SROC) were calculated. A total of 5 studies were included. The sensitivity and specificity of OFR in the diagnosis of coronary artery lesions were 0.83 (95% CI: 0.75-0.88) and 0.94 (95% CI: 0.91-0.96), respectively; the positive likelihood ratio and the negative likelihood ratio were 14 (95% CI: 9.3, 21.3) and 0.18 (95% CI:0.13, 0.27), respectively. OFR showed good correlation and consistency with FFR. The new OFR technique achieve an encouraging diagnostic performance, which also showed good correlation and consistency with FFR.

Fractional Flow Reserve to Assess Coronary Artery Disease in Patients with Severe Aortic Stenosis Undergoing Transcatheter Aortic Valve Implantation: Long-Term Outcomes

BackgroundThe long-term outcomes of patients undergoing functional assessment of coronary lesions with fractional flow reserve (FFR) while awaiting transcatheter aortic valve implantation (TAVI) are unknown. Data on the safety of intracoronary adenosine use in this setting are scarce. The objectives of this study were to describe (1) the long-term outcomes based on the coronary artery disease (CAD) assessment strategy used and (2) the safety of intracoronary adenosine in patients with severe aortic stenosis (AS). Methods1023 patients with severe AS awaiting TAVI were included. Patients were classified according to their CAD assessment strategy: angiography guided or FFR guided. Patients were further subdivided according to the decision to proceed with percutaneous coronary intervention (PCI): angiography-guided PCI (375/1023), angiography-guided no-PCI (549/1023), FFR-guided PCI (50/1023), and FFR-guided no-PCI (49/1023). Patients were followed up for the occurrence of major adverse cardiac and cerebrovascular events (MACCEs). ResultsAt a mean follow-up of 33.7 months, we observed no significant differences in terms of major adverse cardiovascular and cerebrovascular events (MACCE) in the angiography-guided group (42.4%) compared with the FFR-guided group (37.4%) (p = 0.333). When comparing outcomes of the FFR-guided no-PCI group (32.7%) with the angiography-guided PCI group (46.4%), no significant difference was noted (p = 0.999). Following intracoronary adenosine, a single adverse event occurred. ConclusionsIn this population, intracoronary adenosine is safe and well tolerated. We found no significant benefit to an FFR-guided strategy compared with an angiography-guided strategy with respect to MACCEs. Although clinically compelling, avoiding the procedural risks of PCI by deferring the intervention in functionally insignificant lesions failed to show a statistically significant benefit.

Quantitative Flow Ratio for Assessment of Non-Culprit Coronary Artery Lesions During Percutaneous Coronary Intervention (PCI) in 79 Patients Diagnosed with ST-Elevation Myocardial Infarction (STEMI): A Study from a Single Center in Lithuania.

BACKGROUND Approximately half of the patients requiring percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) have additional stenotic coronary artery (CA) lesions in non-infarct-related arteries (non-IRA). This study from a single center in Lithuania aimed to evaluate the use of the quantitative flow ratio (QFR) in assessing non-IRA lesions during PCI in 79 patients diagnosed with STEMI. MATERIAL AND METHODS We prospectively included 105 vessels of 79 patients with worldwide STEMI criteria and ≥1 intermediate (35-75%) lesion in non-IRA between July 2020 and June 2021. For all included patients, QFR analyses were performed twice, during the index PCI (QFR 1) and during a staged procedure ≥3 months later (QFR 2). The QFR analyses were performed with the QAngio-XA 3D and £0.80 were used as cut-off values for PCI. The primary endpoint was a head-to-head numerical agreement between 2 measurements. RESULTS An excellent numerical agreement was found in all investigated lesions, r=0.931, p<0.001, left anterior descending (LAD) r=0.911, p<0.001, left circumflex (LCx) r=0.977, p<0.001, and right coronary artery (RCA) 0.946, p<0.001. Clinical treatment decision-making showed amazing agreement between the 1st and the 2nd QFR analyses, r=0.980, p<0.001. There was 1 disagreement between QFR 1 and QFR 2. CONCLUSIONS The findings from this support previous studies and showed that the QFR is a practical quantitative method to evaluate non-IRA lesions, which in this study included STEMI patients during PCI following occlusive CA stenosis.

Research progress on image-based calculation of coronary artery fractional flow reserve

Coronary artery fractional flow reserve (FFR) is a critical physiological indicator for assessment of impaired blood flow caused by coronary artery stenosis. The wire-based invasive measurement of blood flow pressure gradient across stenosis is the gold standard for clinical measurement of FFR. However, it has the risk of vascular injury and requires the use of vasodilators, increasing the time and overall cost of interventional examination. Coronary imaging is playing an important role in clinical diagnosis of stenotic lesions, evaluation of severity of lesions, and planning of therapies. In recent years, the computation of FFR based on the physiological information of blood flow obtained from routinely collected coronary image data has become a research focus in this field. This technique reduces the cost of physiological assessment of coronary lesions and the use of pressure wires. It is beneficial to strengthen the physiological guidance in interventional therapy. In order to better understand this emerging technique, this paper highlights its implementation principle and diagnostic performance, analyzes practical problems and current challenges in clinical applications, and discusses possible future development.