Fractional Flow Reserve Research Articles

Role of Coronary Physiology in the Modern Catheterisation Lab

Over the past two decades, invasive coronary physiology assessment has advanced significantly. Despite the proven prognostic significance provided by invasive physiological assessment of lesions by means of fractional flow reserve or adenosine-free non-hyperaemic pressure ratios, challenges in clinical practice hinder widespread adoption and limit additional value for optimising percutaneous coronary intervention decisions. Despite notable progress, uncertainties persist, emphasising the need for further research to establish a single numerical parameter in the diagnosis of a functionally significant disease, clarify the impact of longitudinal vessel analysis, and support the relevance of pressure indices in post-intervention optimisation.

Evaluation of functional significance of coronary arteries stenoses with estimation of fractional flow reserve based on computed tomography angiography data

Evaluation of functional significance of coronary arteries stenoses with estimation of fractional flow reserve based on computed tomography angiography data

Fractional flow reserve versus intravascular ultrasound during percutaneous intervention

Fractional flow reserve versus intravascular ultrasound during percutaneous intervention

Myocardial Bridging: In-Depth Review of Coronary Anomalies

Myocardial bridging (MB) is a congenital coronary anomaly where segment of the epicardial coronary artery traverses through the myocardium for a portion of its length. While traditionally regarded as a benign condition, there is a growing focus on specific subsets of MB associated with ischemic symptoms and requires treatment. Increasing attention is being given to specific subsets of MB associated with ischemic symptomatology. The emergence of modern functional and anatomical imaging techniques; coronary angiography, coronary computed tomography angiography (CCTA), instantaneous wave-free ratio (iFR), dan diastolic fractional flow reserve (dFFR), has improved our capacity to characterize symptoms associated with MB. In cases involving symptomatic patients, medical therapy often represents an effective treatment option. For individuals who do not respond satisfactorily to medical interventions, comprehensive multimodal assessment; percutaneous coronary intervention (PCI), coronary artery bypass graft (CABG), and myotomy should be considered.

Comparison of myocardial perfusion study and invasive hemodynamic measurement of the significance of non-infarct-related residual stenoses in ST elevation myocardial infarction patients.

Nearly 50% of ST elevation myocardial infarction (STEMI) patients have multivessel coronary artery disease. The optimal selection of non-culprit lesions for complete revascularization is a matter of current debate. Little is known about the predictive value of myocardial perfusion study (MPS) in this scenario. We enrolled 49 STEMI patients (61.5 ± 10.3 years) with at least one major non-culprit lesion (50-90%) other than left main coronary artery lesions. Overall 63 non-infarct- related artery (IRA) stenoses (65.2 ± 11.9%) were recommended for further evaluation using Fractional Flow Reserve (FFR) measurement as is standard in our institution. Prior to FFR, all patients were scheduled for non-invasive MPS using single-photon emission computed tomography (SPECT). Both FFR and MPS were performed 4-8 weeks after STEMI with MPS preceding FFR within no more than 48 hours. An FFR value of ≤0.80 was considered significant and guided the final revascularization strategy. The results of MPS were correlated to FFR as well as to the clinical and angiographic characteristics of both culprit and non-infarct-related lesions. Based on FFR, 30 out of 63 stenoses (47.6%) in 27 patients were considered hemodynamically significant (FFR 0.69 ± 0.08, range 0.51-0.79) compared to residual 33 stenoses considered negative (FFR 0.87 ± 0.04, range 0.81-0.96). The MPS revealed abnormal myocardium (23.6% average, range 5-56%) in 21 patients (42.8%). Among those patients, only 9 showed the evidence of ischemic myocardium (average 10.8%, range 4-18%) with low sensitivity of MPS in predicting positive FFR. Besides that, higher proportion of patients (71.4% vs. 42.9%, P=0.047) with overall lower FFR values (0.73 vs. 0.80, P=0.014, resp.) in non-IRAs as well as higher proportion of patients with more severely compromised flow in IRAs (P=0.048) during STEMI had MPS-detected abnormal myocardium. In STEMI patients with multivessel coronary artery disease, we observed rather weak correlation between MPS using SPECT and invasive hemodynamic measurement using FFR in ischemia detection.

Coronary microvascular dysfunction in patients with Takotsubo syndrome

BackgroundThe pathophysiology of Takotsubo syndrome (TTS) remains incompletely understood. While coronary microvascular dysfunction (CMD) is a potential pathophysiologic mechanism, evidence is limited. ObjectivesWe sought to evaluate CMD in patients with TTS. MethodsConsecutive patients diagnosed with TTS were included and underwent coronary angiography with invasive microvascular function evaluation, including fractional flow reserve, Coronary Flow Reserve (CFR), Index of Microcirculatory Resistance (IMR), and Resistive Reserve Ratio (RRR). Patients had an echocardiography evaluation during their index admission and at approximately 6 weeks. ResultsThirty patients were included (mean age 74 ±9, 90 % female). Twenty-five patients (83 %) had at least one abnormal coronary microvascular function parameter. Abnormal parameters included CFR<2.5 in 20 patients (67 %), IMR>25 in 18 patients (60 %), and RRR<3.5 in 25 (83 %). Longer time from symptoms to angiography correlated with a higher CFR (r = 0.51, P<0.01), and had an area under the receiver operating characteristic curve of 0.793 (95 % CI 0.60-0.98) for pathologic CFR. Patients with emotional trigger had a lower rate of pathologic IMR compared with non-emotional trigger (36 % vs 81 %, p = 0.01). Follow up echocardiography performed at a median of 1.5 months (IQR 1.15-6) showed an improvement in left ventricular ejection fraction for all patients (from mean of 40 % to 57 %). ConclusionCMD was present in most patients with TTS. The role of microvascular function in TTS may vary according to the clinical presentation and RRR may be more sensitive for the diagnosis of CMD in TTS.

Radiomics analysis of lesion-specific pericoronary adipose tissue to predict major adverse cardiovascular events in coronary artery disease

ObjectiveTo investigate the prognostic performance of radiomics analysis of lesion-specific pericoronary adipose tissue (PCAT) for major adverse cardiovascular events (MACE) with the guidance of CT derived fractional flow reserve (CT-FFR) in coronary artery disease (CAD).Materials and methodsThe study retrospectively analyzed 608 CAD patients who underwent coronary CT angiography. Lesion-specific PCAT was determined by the lowest CT-FFR value and 1691 radiomic features were extracted. MACE included cardiovascular death, nonfatal myocardial infarction, unplanned revascularization and hospitalization for unstable angina. Four models were generated, incorporating traditional risk factors (clinical model), radiomics score (Rad-score, radiomics model), traditional risk factors and Rad-score (clinical radiomics model) and all together (combined model). The model performances were evaluated and compared with Harrell concordance index (C-index), area under curve (AUC) of the receiver operator characteristic.ResultsLesion-specific Rad-score was associated with MACE (adjusted HR = 1.330, p = 0.009). The combined model yielded the highest C-index of 0.718, which was higher than clinical model (C-index = 0.639), radiomics model (C-index = 0.653) and clinical radiomics model (C-index = 0.698) (all p < 0.05). The clinical radiomics model had significant higher C-index than clinical model (p = 0.030). There were no significant differences in C-index between clinical or clinical radiomics model and radiomics model (p values were 0.796 and 0.147 respectively). The AUC increased from 0.674 for clinical model to 0.721 for radiomics model, 0.759 for clinical radiomics model and 0.773 for combined model.ConclusionRadiomics analysis of lesion-specific PCAT is useful in predicting MACE. Combination of lesion-specific Rad-score and CT-FFR shows incremental value over traditional risk factors.

Efficiency assessment of a two-stage diagnostic strategy combining CT angiography and fractional flow reserve derived from coronary CT angiography for the detection of myocardial ischemia: a simulation study

BackgroundThe importance of a diagnostic strategy combining coronary computed tomography angiography (CCTA) with fractional flow reserve derived from CCTA (FFRCT) for detecting myocardial ischemia is increasing. However, sensitivity and specificity alone may be insufficient to understand the efficiency characteristics of a diagnostic strategy combining CCTA and FFRCT (DSCCF). Our study aimed to evaluate the overall efficiency of DSCCF in detecting myocardial ischemia and compare it with other diagnostic strategies to determine whether evaluation by DSCCF is currently appropriate.ResultsThis simulation study included 1000 patients with stable chest pain and suspected myocardial ischemia. Using a decision tree analysis, assuming a diagnostic strategy of adding FFRCT to CCTA-positive patients, we calculated the following efficiency parameters of DSCCF: (1) true positive (TP), false positive (FP), net false negative (FN), and net true negative (TN) test results; (2) net sensitivity; (3) net specificity; (4) positive predictive value; (5) negative predictive value; (6) post-test probability; (7) diagnostic accuracy; (8) diagnostic odds ratio; and (9) number needed to diagnose. We also calculated the efficiency parameters of other diagnostic strategies and compared them with those of DSCCF. In the basic setting, regarding efficiency parameters (1), the number of TPs, FPs, net FNs, and net TNs were 254, 69, 46, and 631, respectively. Efficiency parameters (2)–(9) were 0.85 (95% confidence interval [CI], 0.80–0.89), 0.90 (95% CI 0.88–0.92), 0.79 (95% CI 0.74–0.83), 0.93 (95% CI 0.91–0.95), 0.07 (95% CI 0.05–0.09), 0.89 (95% CI 0.86–0.90), 50.50 (95% CI 33.83–75.37), and 1.34 (95% CI 1.24–1.48), respectively. Compared with other diagnostic strategies, DSCCF had good efficiency parameters. Moreover, the sensitivity analysis did not reveal any evidence to contradict the findings in the basic setting.ConclusionsThis study demonstrated the diagnostic ability characteristics of DSCCF by assessing various efficiency parameters. Compared with other diagnostic strategies, DSCCF had good efficiency. In terms of efficiency, evaluation using DSCCF for detecting myocardial ischemia appears to be appropriate.

Simulation of coronary fractional flow reserve and whole-cycle flow based on optical coherence tomography in individual patients with coronary artery disease

Computer simulations of coronary fractional flow reserve (FFR) based on coronary imaging have emerged as an attractive alternative to invasive measurements. However, most methods are proprietary and employ non-physiological assumptions. Our aims were to develop and validate a physiologically realistic open-source simulation model for coronary flow, and to use this model to predict FFR based on intracoronary optical coherence tomography (OCT) data in individual patients. We included patients undergoing elective coronary angiography with angiographic borderline coronary stenosis. Invasive measurements of coronary hyperemic pressure and absolute flow and OCT imaging were performed. A computer model of coronary flow incorporating pulsatile flow and the effect of left ventricular contraction was developed and calibrated, and patient-specific flow simulation was performed. Forty-eight coronary arteries from 41 patients were included in the analysis. Average FFR was 0.79 ± 0.14, and 50% had FFR ≤ 0.80. Correlation between simulated and measured FFR was high (r = 0.83, p < 0.001). Average difference between simulated FFR and observed FFR in individual patients was − 0.009 ± 0.076. Overall diagnostic accuracy for simulated FFR ≤ 0.80 in predicting observed FFR ≤ 0.80 was 0.88 (0.75–0.95) with sensitivity 0.79 (0.58–0.93) and specificity 0.96 (0.79–1.00). The positive predictive value was 0.95 (0.75–1.00) and the negative predictive value was 0.82 (0.63–0.94). In conclusion, realistic simulations of whole-cycle coronary flow can be produced based on intracoronary OCT data with a new, computationally simple simulation model. Simulated FFR had moderate numerical agreement with observed FFR and a good diagnostic accuracy for predicting hemodynamic significance of coronary stenoses.

Coronary computed tomographic angiography-derived anatomic and hemodynamic plaque characteristics in prediction of cardiovascular events.

This study investigated the association of anatomic and hemodynamic plaque characteristics based on deep learning coronary computed tomography angiography (CCTA) with high-risk plaques that caused subsequent major adverse cardiovascular events (MACE). A retrospective analysis was conducted on patients who underwent CCTA between 1month and 3years prior to the occurrence of a MACE. Deep learning and computational fluid dynamics algorithms based on CCTA were applied to extract adverse plaque characteristics (low-attenuation plaque, positive remodeling, napkin-ring sign, and spotty calcification), and hemodynamic parameters (fractional flow reserve derived by coronary computed tomographic angiography [FFRCT], change in FFRCT across the lesion [△FFRCT], wall shear stress [WSS], and axial plaque stress [APS]). Correlation analysis, logistic regression, and Cox proportional risk analysis were conducted to understand the relationship between these measures and the occurrence of MACE and assess the value of hemodynamic parameters in predicting the incidence of MACE events and their prognosis. Our study included 86 patients with a total of 134 vessels exhibiting plaque formation and 83 culprit vessels with a subsequent coronary event. Culprit vessels had percent diameter stenosis [%DS] (0.54 ± 0.16 vs. 0.62 ± 0.13, P = 0.003), larger non-calcified plaque volume (45.8 vs. 101.7, P < 0.001), larger low-attenuation plaque volume (3.6 vs. 14.5, P < 0.001), more lesions with ≥ 3 adverse plaque characteristics (APC) (4 vs.26, P = 0.002), and worse hemodynamic features of adverse plaque. FFRCT demonstrated better visualization of maximum achievable flow in the presence of coronary stenosis and better correlation with the stenosis severity, while maximum of wall shear stress (WSSmax) was highly correlated with low-attenuation plaques and APC. The inclusion of hemodynamic parameters improved the efficacy of the predictive model, and a high WSS suggested a higher probability of MACE. Hemodynamic parameters based on CCTA are significantly correlated with plaque morphology. Importantly, integrating CCTA-derived parameters can refine the predictive performance of MACE occurrence.

Cardiac troponin concentrations following exercise and the association with cardiovascular disease and outcomes: rationale and design of the prospective TREAT cohort study

Exercise can produce transient elevations of cardiac troponin (cTn) concentrations, which may resemble the cTn release profile of myocardial infarction. Consequently, clinical interpretation of postexercise cTn elevations (ie, values above...

The Role of Multimodality Imaging (CT & MR) as a Guide to the Management of Chronic Coronary Syndromes.

Chronic coronary syndrome (CCS) is one of the leading cardiovascular causes of morbidity, mortality, and use of medical resources. After the introduction by international guidelines of the same level of recommendation to non-invasive imaging techniques in CCS evaluation, a large debate arose about the dilemma of choosing anatomical (with coronary computed tomography angiography (CCTA)) or functional imaging (with stress echocardiography (SE), cardiovascular magnetic resonance (CMR), or nuclear imaging techniques) as a first diagnostic evaluation. The determinant role of the atherosclerotic burden in defining cardiovascular risk and prognosis more than myocardial inducible ischemia has progressively increased the use of a first anatomical evaluation with CCTA in a wide range of pre-test probability in CCS patients. Functional testing holds importance, both because the role of revascularization in symptomatic patients with proven ischemia is well defined and because functional imaging, particularly with stress cardiac magnetic resonance (s-CMR), gives further prognostic information regarding LV function, detection of myocardial viability, and tissue characterization. Emerging techniques such as stress computed tomography perfusion (s-CTP) and fractional flow reserve derived from CT (FFRCT), combining anatomical and functional evaluation, appear capable of addressing the need for a single non-invasive examination, especially in patients with high risk or previous revascularization. Furthermore, CCTA in peri-procedural planning is promising to acquire greater importance in the non-invasive planning and guiding of complex coronary revascularization procedures, both by defining the correct strategy of interventional procedure and by improving patient selection. This review explores the different roles of non-invasive imaging techniques in managing CCS patients, also providing insights into preoperative planning for percutaneous or surgical myocardial revascularization.

Late Outcomes of Patients in the Emergency Department With Acute Chest Pain Evaluated With Computed Tomography–Derived Fractional Flow Reserve

Computed tomography (CTA)-derived fractional flow reserve (FFRCT) guides the need for invasive coronary angiography (ICA). Late outcomes after FFRCT are reported in stable ischemic heart disease, but not in acute chest pain in the Emergency Department (ACP-ED). The objectives are to assess the risk of death, myocardial infarction (MI), revascularization, and ICA after FFRCT. From 2015-2018, 389 ACP-ED low-risk patients (negative biomarkers, no ECG ischemia) underwent CTA and FFRCT and were entered into a prospective institutional registry; patients were followed for 41 ± 10 months. CTA stenosis ≥ 50% was present in 81% of patients. Positive (FFRCT ≤0.80) and negative FFRCT were observed in 124 (32%) and 265 (68%) patients, respectively. ICA was performed in 108/124 (87%) patients with positive and 89/265 (34%) patients with negative FFRCT (p<0.00001). Revascularization was performed in 87/124 (70%) with positive FFRCT and in 22/265 (8%) with negative FFRCT (p<0.00001). Appropriateness of revascularization was established by blinded adjudication of ICA and invasive FFR using practice guidelines; revascularization was appropriate in 81/124 (65%) and 6/265 (2%) of FFRCT positive and negative patients, respectively (p<0.00001). At follow up, for positive versus negative FFRCT patients, the rates were 0.8% versus 0% for death (p=0.32) and 1.6% versus 0.4% for MI (p=0.24). In conclusion, low-risk ACP-ED patients undergoing CTA and FFRCT, the risk of late death (0.2%) and MI (0.7%) are low. Negative FFRCT is associated with excellent long-term prognosis, and positive FFRCT predicts obstructive disease requiring revascularization. FFRCT can safely triage ACP-ED patients, and reduce unnecessary ICA and revascularization.

An Overview of Computational Coronary Physiology Technologies Based on Medical Imaging and Artificial Intelligence.

This article reviews four new technologies for assessment of coronary hemodynamics based on medical imaging and artificial intelligence, including quantitative flow ratio (QFR), optical flow ratio (OFR), computational fractional flow reserve (CT-FFR) and artificial intelligence (AI)-based instantaneous wave-free ratio (iFR). These technologies use medical imaging such as coronary angiography, computed tomography angiography (CTA), and optical coherence tomography (OCT), to reconstruct three-dimensional vascular models through artificial intelligence algorithms, simulate and calculate hemodynamic parameters in the coronary arteries, and achieve non-invasive and rapid assessment of the functional significance of coronary stenosis. This article details the working principles, advantages such as non-invasiveness, efficiency, accuracy, limitations such as image dependency, and assumption restrictions, of each technology. It also compares and analyzes the image dependency, calculation accuracy, calculation speed, and operation simplicity, of the four technologies. The results show that these technologies are highly consistent with the traditional invasive wire method, and shows distinct advantages in terms of accuracy, reliability, convenience and cost-effectiveness, but there are also factors that affect accuracy. The results of this review demonstrates that AI-based iFR technology is currently one of the most promising technologies. The main challenges and directions for future development are also discussed. These technologies bring new ideas for the non-invasive assessment of coronary artery disease, and are expected to promote the technological progress in this field.

Additional prognostic impact of plaque characterization with on-site CT-derived fractional flow reserve in coronary CT angiography

BackgroundOn-site computed tomography-derived fractional flow reserve (CT-FFR) is a feasible method for examining lesion-specific ischemia, and plaque analysis of coronary CT angiography (CCTA) is useful for predicting future cardiac events. However, their utility and association on a per-vessel level remain unclear. MethodsWe analyzed vessels showing 50–90 % stenosis on CCTA where planned revascularization was not performed after CCTA within 90 days. Relevant features, including CT-FFR and the plaque burden [necrotic core to the total plaque volume (% necrotic core), and non-calcified plaque (NCP) to vessel volume (% NCP)] using a novel algorithm for analyzing plaque to predict vessel-oriented composite outcomes (VOCO), including cardiac death, non-fatal myocardial infarction, and unplanned vessel-related revascularization, were assessed. ResultsIn 256 patients (68.7 ± 9.4 years; 73.8 % male) with 354 vessels (10.5 % CT-FFR ≤ 0.80), VOCO occurred in 24 vessels (6.8 %) during a median follow-up of 3.6 years. Multivariable Cox analysis revealed CT-FFR ≤ 0.80 had the pronounced impact on VOCO, and moreover, higher % necrotic core and % NCP were independently associated with VOCO [adjusted hazard ratio 3.43 (95 % confidence interval 1.42–8.29) and 4.05 (1.19–13.71), respectively], especially for vessels with CT-FFR > 0.80. ConclusionsIn vessels without planned revascularization, per-vessel CT-FFR ≤ 0.80 was the notable predictor of future cardiac events. Additionally, necrotic core volume and NCP were identified as independent predictors along with CT-FFR.

Computing pulsatile blood flow of coronary artery under incomplete boundary conditions

BackgroundAccurate measurement of pulsatile blood flow in the coronary arteries enables coronary wave intensity analysis, which can serve as an indicator for assessing coronary artery physiology and myocardial viability. Computational fluid dynamics (CFD) methods integrating coronary angiography images and fractional flow reserve (FFR) offer a novel approach for computing mean coronary blood flow. However, previous methods neglect the inertial effect of blood flow, which may have great impact on pulsatile blood flow calculation. To improve the accuracy of pulsatile blood flow calculation, a novel CFD based method considering the inertia term is proposed. MethodsA flow resistance model based on Pressure-Flow vs.Time curves is proposed to model the resistance of the epicardial artery. The parameters of the flow resistance model can be fitted from the simulated pulsating flow rates and pressure drops of a specific mode. Then, pulsating blood flow can be calculated by combining the incomplete pressure boundary conditions under pulsating conditions which are easily obtained in clinic. Through simulation experiments, the effectiveness of the proposed method is validated in idealized and reconstructed 3D model of coronary artery. The impacts of key parameters for generating the simulated pulsating flow rates and pressure drops on the accuracy of pulsatile blood flow calculation are also investigated. ResultsFor the idealized model, the previously proposed Pressure-Flow model has a significant leading effect on the computed blood flow waveform in the moderate model, and this leading effect disappears with the increase of the degree of stenosis. The improved model proposed in this paper has no leading effect, the root mean square error (RMSE) of the proposed model is low (the left coronary mode:≤0.0160, the right coronary mode:≤0.0065) for all simulated models, and the RMSE decreases with an increase of stenosis. The RMSE is consistently small (≤0.0217) as the key parameters of the proposed method vary in a large range. It is verified in the reconstructed model that the proposed model significantly reduces the RMSE of patients with moderate stenosis (the Pressure-Flow model:≤0.0683, the Pressure-Flow vs.Time model:≤0.0297), and the obtained blood flow waveform has a higher coincidence with the simulated reference waveform. ConclusionsThis paper confirms that ignoring the effect of inertia term can significantly affect the accuracy of calculating pulsatile blood flow in moderate stenosis lesions, and the new method proposed in this paper can significantly improves the accuracy of calculating pulsatile blood flow in moderate stenosis lesions. The proposed method provides a convenient clinical method for obtaining pressure-synchronized blood flow, which is expected to facilitate the application of waveform analysis in the diagnosis of coronary artery disease.

The Usefulness of Intravascular Ultrasound and Optical Coherence Tomography in Patients Treated with Rotational Atherectomy: An Analysis Based on a Large National Registry.

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have been shown to improve the clinical outcomes of percutaneous coronary interventions (PCIs) in selected subsets of patients. The aim was to investigate whether the use of OCT or IVUS during a PCI with rotational atherectomy (RA-PCI) will increase the odds for successful revascularization, defined as thrombolysis in myocardial infarction (TIMI) 3 flow. Data were obtained from the national registry of PCIs (ORPKI) maintained by the Association of Cardiovascular Interventions (AISN) of the Polish Cardiac Society. The dataset includes PCIs spanning from January 2014 to December 2021. A total of 6522 RA-PCIs were analyzed, out of which 708 (10.9%) were guided by IVUS and 86 (1.3%) by OCT. The postprocedural TIMI 3 flow was achieved significantly more often in RA-PCIs guided by intravascular imaging (98.7% vs. 96.6%, p < 0.0001). Multivariable analysis revealed that using IVUS and OCT was independently associated with an increased chance of achieving postprocedural TIMI 3 flow by 67% (odds ratio (OR), 1.67; 95% confidence interval (CI): 1.40-1.99; p < 0.0001) and 66% (OR, 1.66; 95% CI: 1.09-2.54; p = 0.02), respectively. Other factors associated with successful revascularization were as follows: previous PCI (OR, 1.72; p < 0.0001) and coronary artery bypass grafting (OR, 1.09; p = 0.002), hypertension (OR, 1.14; p < 0.0001), fractional flow reserve assessment during angiogram (OR, 1.47; p < 0.0001), bifurcation PCI (OR, 3.06; p < 0.0001), and stent implantation (OR, 19.6, p < 0.0001). PCIs with rotational atherectomy guided by intravascular imaging modalities (IVUS or OCT) are associated with a higher procedural success rate compared to angio-guided procedures.

Use of coronary physiology to guide revascularization in clinical practice: results of the F(FR)2 registry

BackgroundDespite the recommendation of coronary physiology to guide revascularization in angiographically intermediate stenoses without established correlation to ischemia, its uptake in clinical practice is slow.AimsThis study aimed to analyze the use of coronary physiology in clinical practice.MethodsBased on a multicenter registry (Fractional Flow Reserve Fax Registry, F(FR)2, ClinicalTrials.gov identifier NCT03055910), clinical use, consequences, and complications of coronary physiology were systematically analyzed.ResultsF(FR)2 enrolled 2,000 patients with 3,378 intracoronary pressure measurements. Most measurements (96.8%) were performed in angiographically intermediate stenoses. Out of 3,238 lesions in which coronary physiology was used to guide revascularization, revascularization was deferred in 2,643 (78.2%) cases.Fractional flow reserve (FFR) was the most common pressure index used (87.6%), with hyperemia induced by an intracoronary bolus of adenosine in 2,556 lesions (86.4%) and intravenous adenosine used for 384 measurements (13.0%). The route of adenosine administration did not influence FFR results (change-in-estimate -3.1% for regression model predicting FFR from diameter stenosis). Agreement with the subsequent revascularization decision was 93.4% for intravenous and 95.0% for intracoronary adenosine (p = 0.261).Coronary artery occlusion caused by the pressure wire was reported in two cases (0.1%) and dissection in three cases (0.2%), which was fatal once (0.1%).ConclusionsIn clinical practice, intracoronary pressure measurements are mostly used to guide revascularization decisions in angiographically intermediate stenoses. Intracoronary and intravenous administration of adenosine seem equally suited. While the rate of serious complications of wire-based intracoronary pressure measurements in clinical practice seems to be low, it is not negligible.Graphical abstract

Impact of hyperaemic stenosis resistance on long-term outcomes of stable angina in the ILIAS Registry.

The hyperaemic stenosis resistance (HSR) index was introduced to provide a more comprehensive indicator of the haemodynamic severity of a coronary lesion. HSR combines both the pressure drop across a lesion and the flow through it. As such, HSR overcomes the limitations of the more traditional fractional flow reserve (FFR) or coronary flow reserve (CFR) indices. We aimed to identify the diagnostic and prognostic value of HSR and evaluate the clinical implications. Patients with chronic coronary syndromes (CCS) and obstructive coronary artery disease were selected from the multicentre ILIAS Registry. For this study, only patients with combined Doppler flow and pressure measurements were included. A total of 853 patients with 1,107 vessels were included. HSR more accurately identified the presence of inducible ischaemia compared to FFR and CFR (area under the curve 0.71 vs 0.66 and 0.62, respectively; p<0.005 for both). An abnormal HSR measurement was an independent and important predictor of target vessel failure at 5-year follow-up (hazard ratio 3.80, 95% confidence interval: 2.12-6.73; p<0.005). In vessels deferred from revascularisation, HSR seems to identify more accurately those vessels that may benefit from revascularisation rather than FFR and/or CFR. The present study affirms the theoretical advantages of the HSR index for the detection of ischaemia-Âinducing coronary lesions in a large CCS population. (Inclusive Invasive Physiological Assessment in Angina Syndromes Registry [ILIAS Registry], ClinicalTrials.gov: NCT04485234).

The Plaque Analysis Classifies the Coronary Artery Disease-Reporting and Data System (CAD-RADS) Stenosis and Plaque Burden Categories: Association of the Plaque Features, Fat Attenuation Index, Coronary Computed Tomography Fractional Flow Reserve, and the Combination of Stenosis and Calcification.

The coronary artery disease-reporting and data system (CAD-RADS) 2.0 is used to standardize the reporting of coronary computed tomography angiography (CCTA) results. Artificial intelligence software can quantify the plaque composition, fat attenuation index, and fractional flow reserve. To analyze plaque features of varying severity in patients with a combination of CAD-RADS stenosis and plaque burden categorization and establish a random forest classification model. The data of 100 patients treated between April 2021 and February 2022 were retrospectively collected. The most severe plaque observed in each patient was the target lesion. Patients were categorized into three groups according to CAD-RADS: CAD-RADS 1-2 + P0-2, CAD-RADS 3-4B + P0-2, and CAD-RADS 3-4B + P3-4. Differences and correlations between variables were assessed between groups. AUC, accuracy, precision, recall, and F1 score were used to evaluate the diagnostic performance. A total of 100 patients and 178 arteries were included. The differences of computed tomography fractional flow reserve (CT-FFR) (H = 23.921, p < 0.001),the volume of lipid component (H = 12.996, p = 0.002),the volume of fibro-lipid component (H = 8.692, p = 0.013),the proportion of lipid component volume (H = 22.038, p < 0.001),the proportion of fibro-lipid component volume (H = 11.731, p = 0.003),the proportion of calcification component volume (H = 11.049, p = 0.004), and plaque type (χ2 = 18.110, p = 0.001) was statistically significant. CT-FFR, volume and proportion of lipid and fibro-lipid components of plaques, the proportion of calcified components, and plaque type were valuable for CAD-RADS stenosis + plaque burden classification, especially CT-FFR, volume, and proportion of lipid and fibro-lipid components. The model built using the random forest was better than the clinical model (AUC: 0.874 vs. 0.647).