The Evolving Future of Instantaneous Wave-Free Ratio and Fractional Flow Reserve

Prognostic impact of quantitative flow ratio (QFR)-consistent complete revascularization in patients with myocardial infarction and multivessel coronary artery disease

BACKGROUND

Complete revascularization is associated with improved outcomes in patients with myocardial infarction and multivessel coronary artery disease. Quantitative flow ratio (QFR) represents an emerging angiography-based tool for functional lesion assessment. The present study investigated the prognostic impact of QFR-consistent complete revascularization in patients with myocardial infarction and multivessel disease.

METHODS

A total of 792 patients with myocardial infarction and multivessel disease were enrolled in the analysis. Post-hoc QFR analyses of 1,320 nonculprit vessels were performed by investigators blinded to clinical outcomes. The primary endpoint was a composite of all-cause death, nonculprit vessel related nonfatal myocardial infarction, and ischemia-driven revascularization at 2 years after index myocardial infarction. Patients were stratified into a QFR-consistent PCI group (n = 646) and a QFR-inconsistent PCI group (n = 146), based on whether the intervention was congruent with the QFR-determined functional significance of the nonculprit lesions.

RESULTS

The primary endpoint occurred in a total of 22 patients (3.4%) in the QFR-consistent PCI group and in 27 patients (18.5%) in the QFR-inconsistent group (HR 0.17, 95% CI 0.10-0.30, P < .001).The difference in the primary endpoint was driven by reduced rates of nonfatal myocardial infarction (2.0% vs. 15.1%; HR 0.13, 95% CI 0.06-0.25; P < .001) and ischemia-driven revascularization (1.2% vs. 5.5%; HR 0.21, 95% CI 0.08-0.57; P = .001) in the QFR-consistent PCI group.

CONCLUSIONS

Among patients with myocardial infarction and multivessel disease, a QFR-consistent complete revascularization was associated with a reduced risk of all-cause mortality, nonfatal myocardial infarction, and ischemia-driven revascularization. These findings underline the value of angiography-based functional lesion assessment for personalized revascularization strategies.

Noninvasive and fast method of calculation for instantaneous wave-free ratio based on haemodynamics and deep learning

BACKGROUND AND OBJECTIVES

Instantaneous wave-free ratio (iFR) is a new invasive indicator of myocardial ischaemia, and its diagnostic performance is as good as the "gold standard" of myocardial ischaemia diagnosis: fractional flow reserve (FFR). iFR can be approximated by iFRCT, which is calculated based on noninvasive coronary CT angiography (CTA) images and computational fluid dynamics (CFD). However, the existing methods for calculating iFRCT fail to accurately simulate the resting state of the coronary artery, resulting in low computational accuracy. Furthermore, the use of CFD technology limits its computational efficiency, making it difficult to meet clinical application needs. The role of coronary microcirculatory resistance compensation suggests that microcirculatory resistance can be adaptively reduced to compensate for increases in coronary stenotic resistance, thereby maintaining stable myocardial perfusion in the resting state. It is therefore necessary to consider this compensation mechanism to establish a high-fidelity microcirculation resistance model in the resting state in line with human physiology, and so to achieve accurate calculation of iFRCT.

METHODS

In this study we successfully collected clinical data, such as FFR, in 205 stenotic vessels from 186 patients with coronary heart disease. A neural network model was established to predict coronary artery stenosis resistance. Based on the compensation mechanism of coronary microcirculation resistance, an iterative solution algorithm for microcirculation resistance in the resting state was developed. Combining the two methods, a simplified single-branch model combining coronary stenosis and microcirculation resistance was established, and the noninvasive and rapid numerical calculation of iFRCT was performed.

RESULTS

The results showed that the mean squared error (MSE) between the pressure drop predicted by the neural network value for the coronary artery stenosis model and the ground truth in the test set was 0.053 %, and correlation analysis proved that there was a good correlation between them (r = 0.99, p < 0.001). With reference to clinical diagnosis of myocardial ischaemia (using FFR as the gold standard), the diagnostic accuracy of the iFRCT calculation model for the 205 cases was 88.29 % (r = 0.71, p < 0.001), and the total calculation time was < 8 s.

CONCLUSIONS

The results of this study demonstrate the utility of a simplified single-branch model in an iFRCT calculation method based on haemodynamics and deep learning, which is important for noninvasive and rapid diagnosis of myocardial ischaemia.

Correlation and consistency between resting full-cycle ratio and fractional flow reserve in assessing coronary artery function in a Chinese real-world cohort with non-ST-segment elevation acute coronary syndrome: a retrospective observational study

OBJECTIVE

The study aimed to investigate the correlation and consistency between resting full-cycle ratio (RFR) and fractional flow reserve (FFR) in functional assessment of coronary arteries in a Chinese real-world cohort with non-ST-segment elevation acute coronary syndrome (NSTE-ACS).

DESIGN

Retrospective study.

SETTING

A single-centre study in China.

PARTICIPANTS

A total of 292 diseased vessels of 226 Chinese patients with NSTE-ACS at Cangzhou Central Hospital of Hebei Medical University from September 2021 to June 2023 were included.

METHODS

The correlation between RFR and FFR, resting ratio of distal coronary artery pressure (Pd) to aortic pressure (Pa) and FFR were analysed by using Person correlation, and the consistency between RFR and FFR, resting Pd/Pa and FFR were assessed by Bland-Altman test. The diagnostic values of RFR and resting Pd/Pa for predicting FFR≤0.80 were evaluated according to the receiver operating characteristic (ROC) curves.

RESULTS

RFR and resting Pd/Pa were significantly correlated with FFR, and correlation coefficients were 0.787 (p<0.001) and 0.765 (p<0.001), respectively. We found no significant differences between RFR and FFR or between resting Pd/Pa and FFR. The areas under the ROC curves for predicting FFR≤0.80 were 0.883 (p<0.001) for RFR and 0.858 (p<0.001) for resting Pd/Pa, and the optimal critical values were 0.91 for RFR and 0.93 for resting Pd/Pa. The accuracy, sensitivity, specificity and positive and negative predictive values of RFR≤0.91 for predicting FFR≤0.80 were 79.1%, 84.0%, 76.6%, 65.1% and 90.2%, respectively.

CONCLUSION

The current study suggests that RFR exhibits a good correlation and consistency with FFR in patients with NSTE-ACS. RFR is expected to significantly enhance the application of coronary artery functional assessment in clinical practice, thereby providing patients with more precise revascularisation strategies.

The effectiveness of coronary computed tomography angiography and functional testing for the diagnosis of obstructive coronary artery disease: results from the individual patient data Collaborative Meta-Analysis of Cardiac CT (COME-CCT)

AIM

To determine the effectiveness of functional stress testing and computed tomography angiography (CTA) for diagnosis of obstructive coronary artery disease (CAD).

METHODS AND RESULTS

Two-thousand nine-hundred twenty symptomatic stable chest pain patients were included in the international Collaborative Meta-Analysis of Cardiac CT consortium to compare CTA with exercise electrocardiography (exercise-ECG) and single-photon emission computed tomography (SPECT) for diagnosis of CAD defined as ≥ 50% diameter stenosis by invasive coronary angiography (ICA) as reference standard. Generalised linear mixed models were used for calculating the diagnostic accuracy of each diagnostic test including non-diagnostic results as dependent variables in a logistic regression model with random intercepts and slopes. Covariates were the reference standard ICA, the type of diagnostic method, and their interactions. CTA showed significantly better diagnostic performance (p < 0.0001) with a sensitivity of 94.6% (95% CI 92.7-96) and a specificity of 76.3% (72.2-80) compared to exercise-ECG with 54.9% (47.9-61.7) and 60.9% (53.4-66.3), SPECT with 72.9% (65-79.6) and 44.9% (36.8-53.4), respectively. The positive predictive value of CTA was ≥ 50% in patients with a clinical pretest probability of 10% or more while this was the case for ECG and SPECT at pretest probabilities of ≥ 40 and 28%. CTA reliably excluded obstructive CAD with a post-test probability of below 15% in patients with a pretest probability of up to 74%.

CONCLUSION

In patients with stable chest pain, CTA is more effective than functional testing for the diagnosis as well as for reliable exclusion of obstructive CAD. CTA should become widely adopted in patients with intermediate pretest probability.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO Database for Systematic Reviews-CRD42012002780.

CRITICAL RELEVANCE STATEMENT

In symptomatic stable chest pain patients, coronary CTA is more effective than functional testing for diagnosis and reliable exclusion of obstructive CAD in intermediate pretest probability of CAD.

KEY POINTS

Coronary computed tomography angiography showed significantly better diagnostic performance (p < 0.0001) for diagnosis of coronary artery disease compared to exercise-ECG and SPECT. The positive predictive value of coronary computed tomography angiography was ≥ 50% in patients with a clinical pretest probability of at least 10%, for ECG ≥ 40%, and for SPECT 28%. Coronary computed tomography angiography reliably excluded obstructive coronary artery disease with a post-test probability of below 15% in patients with a pretest probability of up to 74%.

Sex Differences in Fractional Flow Reserve Utilization

Background: The literature review shows that female patients are more frequently underdiagnosed or suffer from delayed diagnosis. Recognition of sex-related differences is crucial for implementing strategies to improve cardiovascular outcomes. We aimed to assess sex-related disparities in the frequency of fractional flow reserve (FFR)-guided procedures in patients who underwent angiography and/or percutaneous coronary intervention (PCI). Methods: We have derived the data from the national registry of percutaneous coronary interventions and retrospectively analyzed the data of more than 1.4 million angiography and/or PCI procedures [1,454,121 patients (62.54% men and 37.46% women)] between 2014 and 2022. The logistic regression analysis was conducted to explore whether female sex was associated with FFR utilization. Results: The FFR was performed in 61,305 (4.22%) patients and more frequently in men than women (4.15% vs. 3.45%, p < 0.001). FFR was more frequently assessed in females with acute coronary syndrome than males (27.75% vs. 26.08%, p < 0.001); however, women with chronic coronary syndrome had FFR performed less often than men (72.25% vs. 73.92%, p < 0.001). Females with FFR-guided procedures were older than men (69.07 (±8.87) vs. 65.45 (±9.38) p < 0.001); however. less often had a history of myocardial infarction (MI) (24.79% vs. 36.73%, p < 0.001), CABG (1.62% vs. 2.55%, p < 0.005) or PCI (36.6% vs. 24.79%, p < 0.001) compared to men. Crude comparison has shown that male sex was associated with a higher frequency of FFR assessment (OR = 1.2152-1.2361, p < 0.005). Conclusions: Despite a substantial rise in FFR utilization, adoption in women remains lower than in men. Female sex was found to be an independent negative predictor of FFR use.

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

BACKGROUND

Despite the recommendation of coronary physiology to guide revascularization in angiographically intermediate stenoses without established correlation to ischemia, its uptake in clinical practice is slow.

AIMS

This study aimed to analyze the use of coronary physiology in clinical practice.

METHODS

Based 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.

RESULTS

F(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%).

CONCLUSIONS

In 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.

Quantitative flow ratio and graft outcomes of coronary artery bypass grafting surgery: A retrospective study

OBJECTIVE

Quantitative flow ratio (QFR) is a novel noninvasive tool for the functional assessment of coronary stenosis. Whether or not QFR could predict graft outcomes after coronary artery bypass grafting procedure is unknown. This study aimed to investigate the association of QFR value with graft outcomes after coronary artery bypass grafting surgery.

METHODS

The QFR values were retrospectively obtained from patients receiving coronary artery bypass grafting surgery from 2017 to 2019 in the Graft Patency Between No-Touch Vein Harvesting Technique and Conventional Approach in Coronary Artery Bypass Graft Surgery (PATENCY) trial. QFR calculation was conducted in eligible coronary arteries, defined as those with ≥50% stenosis and a diameter ≥1.5 mm. A threshold of QFR ≤0.80 was considered functionally significant stenosis. The primary outcome was graft occlusion at 12 months evaluated by computed tomography angiography.

RESULTS

Two thousand twenty-four patients with 7432 grafts (2307 arterial grafts and 5125 vein grafts) were included. For the arterial grafts, the risk of 12-month occlusion was significantly increased in the QFR >0.80 group than in the QFR ≤0.80 group (7.1% vs 2.6%; P = .001; unadjusted model: odds ratio, 3.08; 95% CI, 1.65-5.75; fully adjusted model: odds ratio, 2.67; 95% CI, 1.44-4.97). No significant association was observed in the vein grafts (4.6% vs 4.3%; P = .67; unadjusted model: odds ratio, 1.10; 95% CI, 0.82-1.47; fully adjusted model: odds ratio, 1.12; 95% CI, 0.83-1.51). Results were stable across sensitivity analyses with a QFR threshold of 0.78 and 0.75.

CONCLUSIONS

Target vessel QFR >0.80 was associated with a significantly higher risk of arterial graft occlusion at 12 months after coronary artery bypass grafting surgery. No significant association was found between target lesion QFR and vein graft occlusion.

Rapid and Precise Computation of Fractional Flow Reserve from Routine Two-Dimensional Coronary Angiograms Based on Fluid Mechanics: The Pilot FFR2D Study

Objective: To present a novel pipeline for rapid and precise computation of fractional flow reserve from an analysis of routine two-dimensional coronary angiograms based on fluid mechanics equations (FFR2D). Material and methods: This was a pilot analytical study that was designed to assess the diagnostic performance of FFR2D versus the gold standard of FFR (threshold ≤ 0.80) measured with a pressure wire for the physiological assessment of intermediate coronary artery stenoses. In a single academic center, consecutive patients referred for diagnostic coronary angiography and potential revascularization between 1 September 2020 and 1 September 2022 were screened for eligibility. Routine two-dimensional angiograms at optimal viewing angles with minimal overlap and/or foreshortening were segmented semi-automatically to derive the vascular geometry of intermediate coronary lesions, and nonlinear pressure-flow mathematical relationships were applied to compute FFR2D. Results: Some 88 consecutive patients with a single intermediate coronary artery lesion were analyzed (LAD n = 74, RCA n = 9 and LCX n = 5; percent diameter stenosis of 45.7 ± 11.0%). The computed FFR2D was on average 0.821 ± 0.048 and correlated well with invasive FFR (r = 0.68, p < 0.001). There was very good agreement between FFR2D and invasive-wire FFR with minimal measurement bias (mean difference: 0.000 ± 0.048). The overall accuracy of FFR2D for diagnosing a critical epicardial artery stenosis was 90.9% (80 cases classified correctly out of 88 in total). FFR2D identified 24 true positives, 56 true negatives, 4 false positives, and 4 false negatives and predicted FFR ≤ 0.80 with a sensitivity of 85.7%, specificity of 93.3%, positive likelihood ratio of 13.0, and negative likelihood ratio of 0.15. FFR2D had a significantly better discriminatory capacity (area under the ROC curve: 0.95 [95% CI: 0.91-0.99]) compared to 50%DS on 2D-QCA (area under the ROC curve: 0.70 [95% CI: 0.59-0.82]; p = 0.0001) in predicting wire FFR ≤ 0.80. The median time of image analysis was 2 min and the median time of computation of the FFR2D results was 0.1 s. Conclusion: FFR2D may rapidly derive a precise image-based metric of fractional flow reserve with high diagnostic accuracy based on a single two-dimensional coronary angiogram.

Consensus document on the clinical application of invasive functional coronary angiography from the Japanese Association of Cardiovascular Intervention and Therapeutics

Invasive functional coronary angiography (FCA), an angiography-derived physiological index of the functional significance of coronary obstruction, is a novel physiological assessment tool for coronary obstruction that does not require the utilization of a pressure wire. This technology enables operators to rapidly evaluate the functional relevance of coronary stenoses during and even after angiography while reducing the burden of cost and complication risks related to the pressure wire. FCA can be used for treatment decision-making for revascularization, strategy planning for percutaneous coronary intervention, and procedure optimization. Currently, various software-computing FCAs are available worldwide, with unique features in their computation algorithms and functions. With the emerging application of this novel technology in various clinical scenarios, the Japanese Association of Cardiovascular Intervention and Therapeutics task force was created to outline expert consensus on the clinical use of FCA. This consensus document advocates optimal clinical applications of FCA according to currently available evidence while summarizing the concept, history, limitations, and future perspectives of FCA along with globally available software.

Diagnostic Performance of Angiography-Derived Quantitative Flow Ratio in Complex Coronary Lesions

BACKGROUND

Quantitative flow ratio derived from computed tomography angiography (CT-QFR) and invasive coronary angiography (Murray law-based quantitative flow ratio [μQFR]) are novel approaches enabling rapid computation of fractional flow reserve without the use of pressure guidewires and vasodilators. However, the feasibility and diagnostic performance of both CT-QFR and μQFR in evaluating complex coronary lesions remain unclear.

METHODS

Between September 2014 and September 2021, 240 patients with 30% to 90% coronary diameter stenosis who underwent both coronary computed tomography angiography and invasive coronary angiography with fractional flow reserve within 60 days were retrospectively enrolled. The diagnostic performance of CT-QFR and μQFR in detecting functional ischemia among all lesions, especially complex coronary lesions, was analyzed using fractional flow reserve as the reference standard.

RESULTS

CT-QFR and μQFR analyses were performed on 309 and 289 vessels, respectively. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for CT-QFR in all lesions at the per-vessel level were 91% (with a 95% CI of 84%-96%), 92% (95% CI, 88%-95%), 83% (95% CI, 75%-90%), 96% (95% CI, 93%-98%), and 92% (95% CI, 88%-95%), with values for μQFR of 90% (95% CI, 81%-95%), 97% (95% CI, 93%-99%), 92% (95% CI, 84%-97%), 96% (95% CI, 92%-98%), and 94% (95% CI, 91%-97%), respectively. Among bifurcation, tandem, and moderate-to-severe calcified lesions, the diagnostic values of CT-QFR and μQFR showed great correlation and agreement with those of invasive fractional flow reserve, achieving an area under the receiver operating characteristic curve exceeding 0.9 for each complex lesion at the vessel level. Furthermore, the accuracies of CT-QFR and μQFR in the gray zone were 85% and 84%, respectively.

CONCLUSIONS

Angiography-derived quantitative flow ratio (CT-QFR and μQFR) demonstrated remarkable diagnostic performance in complex coronary lesions, indicating its pivotal role in the management of patients with coronary artery disease.

Using Physiology Pullback for Percutaneous Coronary Intervention Guidance: Is this the Future?

Modern coronary intervention requires integration of angiographic, physiologic, and intravascular imaging. This article describes the use and techniques needed to understand coronary physiology pullback data and how use it to make revascularization decisions. The article describes instantaneous wave-free ratio, fractional flow reserve, and the data that support their use and how they differ when used in tandem disease. Common practical mistakes and errors are discussed together with a brief review of the limited published research data.

Comparison of Intravascular Imaging, Functional, or Angiographically Guided Coronary Intervention

BACKGROUND

In patients undergoing percutaneous coronary intervention (PCI), it remains unclear whether intravascular imaging guidance or functional guidance is the best strategy to optimize outcomes and if the results are different in patients with vs without acute coronary syndromes (ACS).

OBJECTIVES

The purpose of this study was to evaluate clinical outcomes with imaging-guided PCI or functionally guided PCI when compared with conventional angiography-guided PCI.

METHODS

We searched PUBMED and EMBASE for randomized controlled trials investigating outcomes with intravascular imaging-guided, functionally guided, or angiography-guided PCI. The primary outcome from this network meta-analysis was trial-defined major adverse cardiovascular event (MACE)-a composite of cardiovascular death, myocardial infarction (MI), and target lesion revascularization (TLR). PCI strategies were ranked (best to worst) using P scores.

RESULTS

Our search identified 32 eligible randomized controlled trials and included a total of 22,684 patients. Compared with angiography-guided PCI, intravascular imaging-guided PCI was associated with reduced risk of MACE (relative risk [RR]: 0.72; 95% CI: 0.62-0.82), cardiovascular death (RR: 0.56; 95% CI: 0.42-0.75), MI (RR: 0.81; 95% CI: 0.66-0.99), stent thrombosis (RR: 0.48; 95% CI: 0.31-0.73), and TLR (RR: 0.75; 95% CI: 0.57-0.99). Similarly, when compared with angiography-guided PCI, functionally guided PCI was associated with reduced risk of MACE and MI. Intravascular imaging-guided PCI ranked first for the outcomes of MACE, cardiovascular death, stent thrombosis, and TLR. The results were consistent in the ACS and non-ACS cohorts.

CONCLUSIONS

Angiography-guided PCI had consistently worse outcomes compared with intravascular imaging-guided and functionally guided PCI. Intravascular imaging-guided PCI was the best strategy to reduce the risk of cardiovascular events.

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.

Complete Percutaneous Coronary Revascularization in Acute Coronary Syndromes With Multivessel Coronary Disease: A Systematic Review

Multivessel disease (MVD) affects approximately 50% of patients with acute coronary syndromes (ACS) and is significantly burdened by poor outcomes and high mortality. It represents a clinical challenge in patient management and decision making and subtends an evolving research area related to the pathophysiology of unstable plaques and local or systemic inflammation. The benefits of complete revascularization are established in hemodynamically stable ACS patients with MVD, and guidelines provide some reference points to inform clinical practice, based on an evidence level that is solid for ST-segment elevation myocardial infarction and less robust for non-ST-segment elevation myocardial infarction and cardiogenic shock. However, several areas of uncertainty remain, such as the optimal timing for complete revascularization or the best guiding strategy for intermediate stenoses. We performed a systematic review of current evidence in the field of percutaneous revascularization in ACS and MVD, also including future perspectives from ongoing trials that will directly compare different timing strategies and investigate the role of invasive and noninvasive guidance techniques. (Complete percutaneous coronary revascularization in patients with acute myocardial infarction and multivessel disease; CRD42022383123).

Practical Application of Coronary Physiologic Assessment: Asia-Pacific Expert Consensus Document: Part 1

Coronary physiologic assessment is performed to measure coronary pressure, flow, and resistance or their surrogates to enable the selection of appropriate management strategy and its optimization for patients with coronary artery disease. The value of physiologic assessment is supported by a large body of evidence that has led to major recommendations in clinical practice guidelines. This expert consensus document aims to convey practical and balanced recommendations and future perspectives for coronary physiologic assessment for physicians and patients in the Asia-Pacific region based on updated information in the field that including both wire- and image-based physiologic assessment. This is Part 1 of the whole consensus document, which describes the general concept of coronary physiology, as well as practical information on the clinical application of physiologic indices and novel image-based physiologic assessment.

Predictive value of intravascular ultrasound for the function of intermediate coronary lesions

BACKGROUND

Intravascular ultrasound (IVUS) can provide detailed coronary anatomic parameters. The purpose of our study was to evaluate the parameters measured by IVUS for the prediction of intermediate coronary lesions function by referencing quantitative fraction ratio (QFR) ≤ 0.80 (vs. > 0.80).

METHODS

Eighty four cases with 92 intermediate coronary lesions in vessels with a diameter ≥ 2.50 mm were enrolled. Paired assessment of IVUS and cQFR was available, and vessels with cQFR ≤ 0.8 were considered the positive reference standard. Logistic regression was used to select model variables by a maximum partial likelihood estimation test and receiver operating characteristic curve (ROC) analysis to evaluate the diagnostic value of different indices.

RESULTS

Plaque burden (PB) and lesion length (LL) of IVUS were independent risk factors for the function of coronary lesions. The predictive probability P was derived from the combined PB and LL model. The area under the curve (AUC) of PB, (minimum lumen area) MLA, and LL and the predicted probability P are 0.789,0.732,0731, and 0.863, respectively (P < 0.01). The AUC of the predicted probability P was the biggest among them; the prediction accuracy of cQFR ≤ 0.8 was 84.8%, and the sensitivity of the diagnostic model was 0.826, specificity was 0. 725, and P < 0.01.

CONCLUSION

PB and LL of IVUS were independent risk factors influencing the function of intermediate coronary lesions. The model combining the PB and LL may predict coronary artery function better than any other single parameter.

Long-term Safety of Revascularization Deferral Based on Instantaneous Wave-Free Ratio or Fractional Flow Reserve

Background

Deferral of coronary revascularization is safe whether guided by instantaneous wave-free ratio (iFR) or by fractional flow reserve (FFR). We aimed to assess long-term outcomes in patients deferred from revascularization based on iFR or FFR in a large real-world population.

Methods

From 2013 through 2017, 201,933 coronary angiographies were registered in the Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART). We included all patients (n = 11,324) with at least 1 coronary lesion deferred from PCI during an index procedure using iFR (>0.89; n = 1998) or FFR (>0.80; n = 9326). The primary outcome was major adverse cardiac events (MACE) defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization. A multivariable-adjusted Cox proportional hazards model was used, with analysis for interaction of prespecified subgroups.

Results

Patients presented with stable angina pectoris (iFR 46.9% vs FFR 48.6%), unstable angina or non-ST-elevation myocardial infarction (iFR 37.7% vs FFR 33.1%), ST-elevation myocardial infarction (iFR 1.9% vs FFR 1.6%), and other indications (iFR 12.5% vs FFR 15.7%). The median follow-up was 2 years for both iFR and FFR groups. At the conclusion of the study, the cumulative MACE risks were 26.7 for the iFR group and 25.9% for FFR group. In the adjusted analysis, no difference was found between the 2 groups (adjusted hazard ratio: iFR vs FFR, 0.947; 95% CI, 0.84-1.08; P = 39). Consistent with the overall findings, the prespecified subgroups showed no interaction with the FFR/iFR results.

Conclusions

Deferral of revascularization showed similar long-term safety whether based on iFR or on FFR.

Non-contrast CT-based radiomics nomogram of pericoronary adipose tissue for predicting haemodynamically significant coronary stenosis in patients with type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) patients have a higher incidence of coronary artery disease than the general population. The aim of this study was to develop a radiomics nomogram of pericoronary adipose tissue (PCAT) based on non-contrast CT to predict haemodynamically significant coronary stenosis in T2DM patients.

METHODS

The study enrolled 215 T2DM patients who underwent non-contrast CT and coronary computed tomography angiography (CCTA). CCTA derived fractional flow reserve (FFR_CT) ≤ 0.80 was defined as hemodynamically significant stenosis.1691 radiomics features were extracted from PCAT on non-contrast CT. Minimum redundancy maximum relevance (mRMR) and least absolute shrinkage and selection operator (LASSO) were used to select useful radiomics features to construct Radscore. Logistic regression was applied to select significant factors among Radscore, fat attenuation index (FAI) and coronary artery calcium score (CACS) to construct radiomics nomogram.

RESULTS

Radscore [odds ratio (OR) = 2.84; P < 0.001] and CACS (OR = 1.00; P = 0.023) were identified as independent predictors to construct the radiomics nomogram. The radiomics nomogram showed excellent performance [training cohort: area under the curve (AUC) = 0.81; 95% CI: 0.76-0.86; validation cohort: AUC = 0.83; 95%CI: 0.76-0.90] to predict haemodynamically significant coronary stenosis in patients with T2DM. Decision curve analysis demonstrated high clinical value of the radiomics nomogram.

CONCLUSION

The non-contrast CT-based radiomics nomogram of PCAT could effectively predict haemodynamically significant coronary stenosis in patients with T2DM, which might be a potential noninvasive tool for screening of high-risk patients.

Accuracy of the angiography-based quantitative flow ratio in intermediate left main coronary artery lesions and comparison with visual estimation

BACKGROUND

Revascularization of left main coronary artery (LMCA) stenosis is mostly based on angiography. Indices based on angiography might increase accuracy of the decision, although they have been scarcely used in LMCA. The objective of this study is to study the diagnostic agreement of QFR (quantitative flow ratio) with wire-based fractional flow reserve (FFR) in LMCA lesions and to compare with visual severity assessment.

METHODS

In a series of patients with invasive FFR assessment of intermediate LMCA stenoses we retrospectively compared the measured value of QFR with that of FFR and the estimate of significance from angiography.

RESULTS

107 QFR studies were included. The QFR intra-observer and inter-observer agreement was 87% and 82% respectively. The mean QFR-FFR difference was 0.047 ± 0.05 with a concordance of 90.7%, sensitivity 88.1%, specificity 92.3%, positive predictive value 88.1% and negative predictive value 92.3%. All these values were superior to those observed with the visual estimation which showed an intra- and inter-observer agreement of 73% and 72% respectively, besides 78% with the FFR value. The low diagnostic performance of the visual estimation and the acceptable performance of the QFR index measurement were observed in all subgroups analysed.

CONCLUSIONS

QFR allows an acceptable estimate of the FFR obtained with intracoronary pressure guidewire in intermediate LMCA lesions, and clearly superior to the assessment based on angiography alone. The decision to revascularize patients with moderate LMCA lesions should not be based solely on the degree of angiographic stenosis.

Comparison of vessel fractional flow reserve with invasive resting full-cycle ratio in patients with intermediate coronary lesions

BACKGROUND

Vessel fractional flow reserve (vFFR) is a novel angiography-derived index for the assessment of myocardial ischemia without the need for pressure wires and hyperemic agents. vFFR has demonstrated very good diagnostic performance compared with the hyperemic index fractional flow reserve (FFR). The aim of this study was to compare vFFR to the non-hyperemic pressure ratio resting full-cycle ratio (RFR).

METHODS

This was a retrospective, observational, single-center study of an all-comer cohort undergoing RFR assessment. Invasive coronary angiography was obtained without a dedicated vFFR acquisition protocol, and vFFR calculation was attempted in all vessels interrogated by RFR (1483 lesions of 1030 patients).

RESULTS

vFFR could be analyzed in 986 lesions from 705 patients. Median diameter stenosis was 37% (interquartile range (IQR): 30.0-44.0%), vFFR 0.86 (IQR: 0.81-0.91) and RFR 0.94 (IQR: (0.90-0.97). The correlation between vFFR and RFR was strong (r = 0.70, 95% confidence interval (CI): 0.66-0.74, p < 0.001). Using RFR ≤0.89 as reference, the sensitivity, specificity, positive predictive value, negative predictive value, and overall diagnostic accuracy for vFFR were 77%, 93%, 77%, and 92% and 89%. vFFR yielded a high area under the curve (AUC) of 0.92 (95% CI: 0.90-0.94). The good diagnostic performance of vFFR was confirmed among subgroups of patients with diabetes, severe aortic stenosis, female gender and lesions located in the left anterior descending artery.

CONCLUSION

vFFR has a high diagnostic performance taking RFR as the reference standard for evaluating the functional significance of coronary stenoses.

Angiography-derived assessment of coronary microcirculatory resistance in patients with suspected myocardial ischaemia and non-obstructive coronary arteries

BACKGROUND

Myocardial ischaemia with non-obstructive coronary arteries (INOCA) represents a challenging and frequent, but largely underdiagnosed, condition.

AIMS

We aimed to investigate the feasibility and diagnostic value of angiography-derived coronary microcirculatory resistance in patients with INOCA syndrome.

METHODS

This is an investigator-driven, prospective and blinded study. The diagnostic yield of angiography-derived index of coronary microcirculatory resistance (angio-IMR) was investigated against thermodilution-derived IMR (thermo-IMR) in patients with clinically indicated coronary angiography due to suspected myocardial ischaemia and angiographically normal or non-obstructive coronary arteries. The angio-IMR was derived from resting angiograms (contrast-flow angio-IMR [cAngio-IMR]) by an expert analyst blinded to the thermo-IMR. An independent, blinded, physiology core laboratory analysed the raw intracoronary physiology data and provided the final thermo-IMR values.

RESULTS

A total of 104 patients (108 coronary vessels) were analysed after fulfilling predefined inclusion criteria. Most patients were female (67%). Obstructive epicardial disease was angiographically (percent diameter stenosis <50%) and physiologically (fractional flow reserve>0.80) ruled out in all cases. Median thermo-IMR and cAngio-IMR were 16.6 (12.7, 23.0) and 16.8 (12.8, 23.1) units, respectively (median difference -0.31, 95% confidence interval: -1.53 to 1.00; p=0.654). cAngio-IMR showed good correlation (Pearson coefficient 0.76; p<0.001), agreement (mean bias 0.4), discriminatory power (area under the curve from the receiver operator characteristics 0.865; p<0.001) and accuracy (85%), compared to thermo-IMR (≥25 U).

CONCLUSIONS

Evaluating coronary microcirculatory resistance in patients with INOCA syndrome using cAngio-IMR is feasible and accurate. By circumventing the need of coronary instrumentation and hyperaemic drugs, this method may facilitate the assessment of coronary microcirculatory resistance in patients with suspected INOCA.

CLINICALTRIALS

gov: NCT04827498.

Coronary Physiology: Modern Concepts for the Guidance of Percutaneous Coronary Interventions and Medical Therapy

Recent evidence on ischemia, rather than coronary artery disease (CAD), representing a major determinant of outcomes, has led to a progressive shift in the management of patients with ischemic heart disease. According to most recent guidelines, myocardial revascularization strategies based on anatomical findings should be progressively abandoned in favor of functional criteria for the guidance of PCI. Thus, emerging importance has been assigned to the assessment of coronary physiology in order to determine the ischemic significance of coronary stenoses. However, despite several indexes and tools that have been developed so far, the existence of technical and clinical conditions potentially biasing the functional evaluation of the coronary tree still cause debates regarding the strategy of choice. The present review provides an overview of the available methods and the most recent acquirements for the invasive assessment of ischemia, focusing on the most widely available indexes, fractional flow reserve (FFR) and instant-wave free ratio (iFR), in addition to emerging examples, as new approaches to coronary flow reserve (CFR) and microvascular resistance, aiming at promoting the knowledge and application of those "full physiology" principles, which are generally advocated to allow a tailored treatment and the achievement of the largest prognostic benefits.

Pre-stenting angiography-FFR based physiological map provides virtual intervention and predicts physiological and clinical outcomes

BACKGROUND

Angiography-derived fractional flow reserve (FFR) (angio-FFR) has been validated against FFR and could provide virtual pullback. However, whether a physiological map can be generated by angio-FFR and its clinical value remains unclear. We aimed to investigate the feasibility of physiological map created from angio-FFR pullback and its value in predicting physiological and clinical outcomes after stenting.

METHODS

An angio-FFR physiological map was generated by overlaying the virtual pullback onto coronary angiogram, to calculate physiological stenosis severity, length, and intensity (Δangio-FFR/mm). This map in combination with virtual stenting was used to predict the best-case post-percutaneous coronary intervention (PCI) angio-FFR (angio-FFR_predicted ) according to the stented segments, and this was compared with the actual achieved post-PCI angio-FFR (angio-FFR_achieved ). Additionally, prognostic value of predicted angio-FFR was investigated.

RESULTS

Three hundred twenty-nine vessels with paired analyzable pre- and post-PCI angio-FFR were included. Physiological map was created successfully in all vessels. After successful PCI, angio-FFR_predicted and angio-FFR_achieved were significantly correlated (r = 0.82, p < 0.001) with small difference (mean difference: -0.010 ± 0.035). In the virtual PCI only covering the segment with high angio-FFR intensity, the same physiological outcome can be achieved with shorter stent length (14.1 ± 8.9 vs. 34.5 ± 15.8 mm, p < 0.001). Suboptimal angio-FFR_predicted was associated with increased risk of 2-year vessel-oriented composite endpoint (adjusted hazard ratio: 3.71; 95% confidence interval: 1.50-9.17).

CONCLUSIONS

Angio-FFR pullback could provide a physiological map of the interrogated coronary vessels by integrating angio-FFR pullback and angiography. Before a PCI, the physiological map can predict the physiological and clinical outcomes after stenting.

Coronary Physiologic Assessment Based on Angiography and Intracoronary Imaging

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

Fractional flow reserve versus angiography-guided strategy in acute myocardial infarction with multivessel disease: a randomized trial

AIMS

In patients with acute myocardial infarction (MI) and multivessel coronary artery disease, percutaneous coronary intervention (PCI) of non-infarct-related artery reduces death or MI. However, whether selective PCI guided by fractional flow reserve (FFR) is superior to routine PCI guided by angiography alone is unclear. The current trial sought to compare FFR-guided PCI with angiography-guided PCI for non-infarct-related artery lesions among patients with acute MI and multivessel disease.

METHODS AND RESULTS

Patients with acute MI and multivessel coronary artery disease who had undergone successful PCI of the infarct-related artery were randomly assigned to either FFR-guided PCI (FFR ≤0.80) or angiography-guided PCI (diameter stenosis of >50%) for non-infarct-related artery lesions. The primary end point was a composite of time to death, MI, or repeat revascularization. A total of 562 patients underwent randomization. Among them, 60.0% underwent immediate PCI for non-infarct-related artery lesions and 40.0% were treated by a staged procedure during the same hospitalization. PCI was performed for non-infarct-related artery in 64.1% in the FFR-guided PCI group and 97.1% in the angiography-guided PCI group, and resulted in significantly fewer stent used in the FFR-guided PCI group (2.2 ± 1.1 vs. 2.5 ± 0.9, P < 0.001). At a median follow-up of 3.5 years (interquartile range: 2.7-4.1 years), the primary end point occurred in 18 patients of 284 patients in the FFR-guided PCI group and in 40 of 278 patients in the angiography-guided PCI group (7.4% vs. 19.7%; hazard ratio, 0.43; 95% confidence interval, 0.25-0.75; P = 0.003). The death occurred in five patients (2.1%) in the FFR-guided PCI group and in 16 patients (8.5%) in the angiography-guided PCI group; MI in seven (2.5%) and 21 (8.9%), respectively; and unplanned revascularization in 10 (4.3%) and 16 (9.0%), respectively.

CONCLUSION

In patients with acute MI and multivessel coronary artery disease, a strategy of selective PCI using FFR-guided decision-making was superior to a strategy of routine PCI based on angiographic diameter stenosis for treatment of non-infarct-related artery lesions regarding the risk of death, MI, or repeat revascularization.

Changes in the treatment strategy following intracoronary pressure wire in a contemporaneous real-life cohort of patients with intermediate coronary stenosis. Results from a nationwide registry

BACKGROUND

Intracoronary pressure wire is useful to guide revascularization in patients with coronary artery disease.

AIMS

To evaluate changes in diagnosis (coronary artery disease extent), treatment strategy and clinical results after intracoronary pressure wire study in real-life patients with intermediate coronary artery stenosis.

METHODS

Observational, prospective and multicenter registry of patients in whom pressure wire was performed. The extent of coronary artery disease and the treatment strategy based on clinical and angiographic criteria were recorded before and after intracoronary pressure wire guidance. 12-month incidence of MACE (cardiovascular death, non-fatal myocardial infarction or new revascularization of the target lesion) was assessed.

RESULTS

1414 patients with 1781 lesions were included. Complications related to the procedure were reported in 42 patients (3.0 %). The extent of coronary artery disease changed in 771 patients (54.5 %). There was a change in treatment strategy in 779 patients (55.1 %) (18.0 % if medical treatment; 68.8 % if PCI; 58.9 % if surgery (p < 0.001 for PCI vs medical treatment; p = 0.041 for PCI vs CABG; p < 0.001 for medical treatment vs CABG)). In patients with PCI as the initial strategy, the change in strategy was associated with a lower rate of MACE (4.6 % vs 8.2 %, p = 0.034).

CONCLUSIONS

The use of intracoronary pressure wire was safe and led to the reclassification of the extent of coronary disease and change in the treatment strategy in more than half of the cases, especially in patients with PCI as initial treatment.

Potential value of saline-induced Pd/Pa ratio in patients with coronary artery stenosis

Background

Fractional flow reserve (FFR) is the current gold standard for identifying myocardial ischemia in individuals with coronary artery stenosis. However, FFR is not penetrated as much worldwide due to time consumption, costs associated with adenosine, FFR-related discomfort, and complications. Resting physiological indexes may be widely accepted alternatives to FFR, while the discrepancies with FFR were found in up to 20% of lesions. The saline-induced Pd/Pa ratio (SPR) is a new simplified option for evaluating coronary stenosis. However, the clinical implication of SPR remains unclear.

Objectives

In the present study, we aimed to compare the accuracies of SPR and resting full-cycle ratio (RFR) and to investigate the incremental value of SPR in clinical practice.

Methods

In this multicenter prospective study, 112 coronary lesions (105 patients) were evaluated by SPR, RFR, and FFR.

Results

The overall median age was 71 years, and 84.8% were men. SPR was correlated more strongly with FFR than with RFR (r = 0.874 vs. 0.713, respectively; p < 0.001). Using FFR < 0.80 as the reference standard variable, the area under the receiver-operating characteristic (ROC) curve for SPR was superior to that of RFR (0.932 vs. 0.840, respectively; p = 0.009).

Conclusion

Saline-induced Pd/Pa ratio predicted FFR more accurately than RFR. SPR could be an alternative method for evaluating coronary artery stenosis and further investigation including elucidation of the mechanism of SPR is needed (225 words).

Using Physiology Pullback for Percutaneous Coronary Intervention Guidance: Is this the Future?

Modern coronary intervention requires integration of angiographic, physiologic, and intravascular imaging. This article describes the use and techniques needed to understand coronary physiology pullback data and how use it to make revascularization decisions. The article describes instantaneous wave-free ratio, fractional flow reserve, and the data that support their use and how they differ when used in tandem disease. Common practical mistakes and errors are discussed together with a brief review of the limited published research data.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Long-Term Cost-Effectiveness of Fractional Flow Reserve-Based Percutaneous Coronary Intervention in Stable and Unstable Angina

Background

There are limited studies on the cost-effectiveness of fractional flow reserve (FFR)-based percutaneous coronary intervention (PCI) over angiography-based PCI.

Objectives

The current study sought to evaluate long-term cost-effectiveness of FFR-based PCI compared to angiography-based PCI.

Methods

A cost-effectiveness analysis was conducted using a nationwide cohort that consisted of patients with stable or unstable angina from the National Health Insurance Service (NHIS) and Health Insurance Review and Assessment (HIRA) database in Korea. The cost-effectiveness analysis was also performed by using a decision and Markov model with key values from the United States and the United Kingdom health care systems. Incremental cost-effectiveness ratio (ICER), an indicator of incremental cost on additional quality-adjusted life-years gained by FFR-based PCI, was evaluated.

Results

In the NHIS-HIRA data, FFR-based PCI was used during the index PCI in 5,116 patients (3.8%) among 134,613 eligible patients. FFR-based PCI showed significantly lower risk of all-cause death (5.8% vs 7.7%, P = 0.001) and spontaneous myocardial infarction (1.6% vs 2.2%, P = 0.022) than the angiography-based PCI at 4 years. In the NHIS-HIRA data, FFR-based PCI gained 0.039 quality-adjusted life-years at a lower cost ($303) than angiography-based PCI, yielding an ICER of -$7,748 during the 4-year follow-up. FFR-based PCI was dominant in the health care system of Korea (ICER = -$7,309), United States (ICER = -$31,267), and United Kingdom (ICER = -$1,341) during a 10-year time horizon. These results were consistently shown in probabilistic sensitivity analyses.

Conclusions

In the current cohort, FFR-based PCI was associated with higher quality of life at a lower cost than angiography-based PCI. FFR-based PCI was cost-effective in patients with stable or unstable angina undergoing PCI.

Tibio-pedal arterial pressure assessment during endovascular intervention to improve quality-of-life in patients with intermittent claudication

Objective

The aim of this study is to compare the quality-of-life (QOL) outcomes and the tibio-pedal arterial pressure post-endovascular intervention.

Background

Physiological assessment of peripheral arterial lesions is infrequently performed during endovascular interventions.

Materials and methods

We retrospectively reviewed all 343 patients with intermittent claudication who underwent an endovascular intervention via tibio-pedal artery access from October 2018 to May 2021. The baseline and post-intervention tibio-pedal arterial pressures from the pedal sheaths were measured. QOL was assessed using a pre-validated Walking Impairment Questionnaire (WIQ) score before and at 30-day after intervention. We compared the baseline tibio-pedal arterial pressure, post-intervention tibio-pedal arterial pressure, delta pressure (post-intervention minus baseline), baseline WIQ scores, 30-day WIQ scores, and delta score (30-day minus baseline).

Results

All 343 patients had successful tibio-pedal accesses. The average tibio-pedal arterial pressure at baseline was 87.0 ± 1.8 mmHg vs. 135.5 ± 1.7 mmHg post-intervention (p &lt; 0.001). Average baseline and 30-day WIQ scores were summation (99.8 ± 3.3 vs. 115.0 ± 3.1, p &lt; 0.001), walking distance (35.7 ± 1.3 vs. 42.5 ± 1.3, p &lt; 0.001), walking speed (21.1 ± 0.9 vs. 23.6 ± 0.8, p = 0.036), stair climbing (4.7 ± 1.4 vs. 24.2 ± 1.4, p = 0.019), and symptoms (18.8 ± 0.2 vs. 20.1 ± 0.2, p &lt; 0.001), respectively. When comparing the increased post-intervention tibio-pedal arterial pressure &lt;60 mmHg vs. ≥60 mmHg, the average delta WIQ scores were all significantly improved with summation (10.0 ± 3.9 to 25.8 ± 5.5, p = 0.01), walking distance (4.1 ± 1.7 to 9.8 ± 2.5, p = 0.02), walking speed (1.5 ± 1.1 to 4.3 ± 1.5, p = 0.02), stair climbing (2.3 ± 1.8 to 9.4 ± 2.5, p = 0.02), and symptoms (1.0 ± 0.3 to 1.8 ± 0.4, p = 0.04), respectively.

Conclusion

Increasing the post-intervention tibio-pedal arterial pressure by 60 mmHg can enhance QOL as suggested by improvement of WIQ scores.

Clinical assessment of resting full-cycle ratio and fractional flow reserve for coronary artery disease in a real-world cohort

Background

There are few reports published on the comparison of the resting full-cycle ratio (RFR) and fractional flow reserve (FFR) on the assessment of the severity of coronary stenosis. We aimed to investigate the diagnostic accuracy of RFR for detection of functionally significant coronary lesions.

Methods

This was an observational, retrospective, single-center study. We evaluated both RFR and FFR for 277 coronary lesions of 235 patients who underwent coronary angiography. Patients presenting with chronic coronary syndrome, unstable angina, or non-ST-elevation myocardial infarction were included.

Results

The mean FFR and RFR values were 0.84 ± 0.08 and 0.90 ± 0.08, respectively. RFR significantly correlated with FFR (r = 0.727, P &lt; 0.001). The agreement rate between the FFR and RFR was 79.8% (221/277). The diagnostic performance of RFR vs. FFR was accuracy 79.8%, sensitivity 70.4%, specificity 83.7%, positive predictive value 64.0%, and negative predictive value 87.2%. The discriminative power of RFR to identify lesions with FFR ≤ 0.80 was acceptable when the RFR value was within the gray zone [0.86 ≤ RFR ≤ 0.93; AUC: 0.72 (95% CI:0.63–0.81)], while it was excellent when the RFR value was out of the gray zone [RFR &gt; 0.93 or &lt; 0.86; AUC: 0.94 (95% CI:0.88–0.99)].

Conclusion

RFR was significantly correlated with FFR in the assessment of intermediate coronary stenosis. An RFR-FFR hybrid approach increases the diagnostic accuracy of RFR in the detection of functionally significant lesions.

Uric Acid to High-Density Lipoprotein Cholesterol Ratio is a Novel Marker to Predict Functionally Significant Coronary Artery Stenosis

Background

Intermediate coronary stenosis (ICS) is defined as a visually estimated percentage of diameter stenosis ranging between 40% and 70% by conventional coronary angiography (CAG). Whether to perform percutaneous coronary intervention (PCI) for these lesions is a challenge in clinical practice. The fractional flow reserve (FFR) can guide treatment by determining the functional significance of ICS. Studies have shown that some clinical indicators can be used to predict FFR. However, there is little research on this in the Chinese population.

Methods

We retrospectively analyzed 690 patients who underwent FFR measurements to determine the functional significance of a single ICS. Patients were divided into 2 groups: FFR ≤0.8 (n = 280) and FFR >0.8 (n = 410). We compared the clinical factors between the two groups and performed multivariate logistic regression analyses to explore the risk factors. In addition, receiver-operating characteristic (ROC) curves were constructed for FFR ≤0.8 diagnoses.

Results

The mean UHR (uric acid to high-density lipoprotein cholesterol ratio) level was significantly higher in the FFR ≤0.8 group (p < 0.001). UHR corrects negatively with FFR (r = −0.44, p < 0.001). High-level UHR was an independent risk factor for the FFR ≤0.8 (OR = 7.17, 95% CI 4.17–12.34). The area under the curve (AUC) of the UHR diagnostic capacity for the FFR ≤0.8 is 0.77, with 77.3% sensitivity and 68.2% specificity.

Conclusion

UHR levels were significantly increased in patients with hemodynamically significant coronary lesions. UHR is a novel predictor of functionally significant lesions in patients with a single-vessel disease of ICS.

Prognosis and Medical Cost of Measuring Fractional Flow Reserve in Percutaneous Coronary Intervention

Background

There are limited data regarding comparative prognosis and medical cost between fractional flow reserve (FFR)-based and angiography-based percutaneous coronary intervention (PCI) among revascularized patients.

Objectives

This study evaluates prognosis and medical cost of FFR use in revascularized patients by PCI.

Methods

Using the National Health Insurance Service database, stable or unstable angina patients who underwent PCI from 2011 to 2017 were evaluated. Eligible patients were divided into 2 groups according to use of FFR in PCI. Primary outcome was a composite of all-cause death or spontaneous myocardial infarction (MI). Secondary outcomes included individual components of the primary outcome, unplanned revascularization, and medical costs.

Results

Among 134,613 eligible patients, PCI was performed based on angiography (n = 129,497) and FFR (n = 5,116). During the study period, both the annual number and proportion of use of FFR in PCI increased (all P for trend <0.001). The FFR group showed significantly lower risk of the primary outcome (7.0% vs 9.5%; P < 0.001), all-cause death (5.8% vs 7.7%; P = 0.001), and spontaneous MI (1.6% vs 2.2%; P = 0.022) than the angiography group. Although the FFR group showed higher medical cost during index admission than angiography group (median: $6,265.10 vs $5,385.60; P < 0.001), cumulative medical cost after index admission was significantly lower ($2,696.50 vs. $3,142.10; P < 0.001).

Conclusions

Use of FFR in PCI in stable or unstable angina patients showed significantly lower risk of all-cause death and spontaneous MI compared to angiography-based PCI. Although the FFR group had higher initial medical cost than the angiography group, cumulative medical cost after index admission was significantly lower.

The guiding value of hybrid resting full-cycle ratio and fractional flow reserve strategy for percutaneous coronary intervention in a Chinese real-world cohort with non-ST elevation acute coronary syndrome

Objective

The study aimed to assess the correlation and agreement between resting full-cycle ratio (RFR) and fractional flow reserve (FFR), and evaluate the guiding value of a hybrid RFR-FFR strategy for percutaneous coronary intervention (PCI) in a Chinese real-world cohort with non-ST elevation acute coronary syndrome (NSTE-ACS).

Materials and methods

A total of 109 patients with NSTE-ACS (149 diseased vessels), who underwent an invasive physiological assessment in Cangzhou Central Hospital, Hebei Medical University, were prospectively enrolled from September 2021 to May 2022. FFR ≤ 0.80 was used as the gold standard for coronary artery functional ischemia. We utilized the Pearson correlation and Bland-Altman analysis to assess the correlation and agreement between RFR and FFR. The diagnostic value of RFR predicting FFR ≤ 0.80 was evaluated in accordance with the receiver operating characteristic (ROC) curve. The hybrid RFR-FFR strategy, which was established according to determining the “gray zone” of RFR (FFR was further assessed using vasodilators only for diseased vessels in the “gray zone”), needed to afford over 95% global agreement with the FFR-only strategy.

Results

Resting full-cycle ratio was significantly linearly linked with FFR (R² = 0.636, P < 0.001). The accuracy, specificity, and sensitivity for RFR ≤ 0.89 predicting FFR ≤ 0.80 were 81.2, 70.8, and 86.1%, respectively. The area under the ROC curve for RFR predicting FFR ≤ 0.80 was 0.881 (P < 0.001), and the cutoff value was 0.90. The “gray zone” of RFR was 0.85–0.93. The positive and negative predictive values of the hybrid RFR-FFR strategy were 0.95 and 0.93, respectively. The hybrid RFR-FFR strategy exhibited an agreement of 96.0% with FFR and obviated the need for a vasodilator by 60.4%.

Conclusion

Resting full-cycle ratio and FFR have high correlation and consistency. The hybrid RFR-FFR strategy highlights considerably enhanced agreement with the FFR-only strategy, whilst making the requirement of vasodilator administration less than a half.

Impact of overestimation of fractional flow reserve by adenosine on anatomical-functional mismatch

Adenosine occasionally results in overestimation of fractional flow reserve (FFR) values, compared with other hyperemic stimuli. We aimed to elucidate the association of overestimation of FFR by adenosine with anatomically significant but functionally non-significant lesions (anatomical-functional mismatch) and its influence on reclassification of functional significance. Distal-to-aortic pressure ratio (Pd/Pa) was measured using adenosine (Pd/PaADN) and papaverine (Pd/PaPAP) in 326 patients (326 vessels). The overestimation of FFR was calculated as Pd/PaADN-Pd/PaPAP. The anatomical-functional mismatch was defined as diameter stenosis > 50% and Pd/PaADN > 0.80. Reclassification was indicated by Pd/PaADN > 0.80 and Pd/PaPAP ≤ 0.80. The mismatch (n = 72) had a greater overestimation of FFR than the non-mismatch (n = 99): median 0.02 (interquartile range 0.01-0.05) versus 0.01 (0.00-0.04), p = 0.014. Multivariable analysis identified the overestimation of FFR (p = 0.003), minimal luminal diameter (p = 0.001), and non-left anterior descending artery (LAD) location (p < 0.001) as determinants of the mismatch. Reclassification was indicated in 29% of the mismatch and was more frequent in the LAD than in the non-LAD (52% vs. 20%, p = 0.005). The overestimation of FFR is an independent determinant of anatomical-functional mismatch. Anatomical-functional mismatch, specifically in the LAD, may suggest a false-negative result.

Diagnostic performance of quantitative flow ratio versus fractional flow reserve and resting full-cycle ratio in intermediate coronary lesions

BACKGROUND

Quantitative flow ratio (QFR) is a novel angiography-derived index aimed to assess the functional relevance of coronary stenoses without pressure wires and adenosine. Good diagnostic yield with the hyperemic fractional flow reserve (FFR) have been reported, while data on the comparison of QFR to non-hyperemic pressure ratios (NHPR) are scarce.

METHODS

In this retrospective, observational and single-center study with a large population representative of the real practice, we assessed and compared the diagnostic performance of contrast flow (cQFR) and fixed flow (fQFR) QFR against the NHPR resting full-cyle ratio (RFR) using FFR as reference standard.

RESULTS

A total of 626 lesions from 544 patients were investigated. Mean diameter stenosis, FFR, cQFR, fQFR and RFR were 44.8%, 0.842, 0.847, 0.857 and 0.912, respectively. The correlation between cQFR and FFR was stronger (r = 0.830, P < 0.001) compared to that between FFR and RFR (r = 0.777, P < 0.001) and between cQFR and RFR (r = 0.687, P < 0.001). Using FFR ≤0.80 as reference, the sensitivity, specificity, positive predictive value, negative predictive value, and overall diagnostic accuracy for cQFR were 82%, 95%, 87%, 92%, and 91%, respectively. cQFR displayed a higher area under the curve (AUC) than fQFR and RFR (0.938 vs. 0.891 vs. 0.869, P < 0.01). The good diagnostic yield of cQFR appeared to be maintained in different clinical subsets including female gender, aortic valve stenosis and atrial fibrillation, and in different anatomical subsets including focal and non-focal lesions.

CONCLUSION

cQFR has a high and better diagnostic performance than the NHPR RFR in predicting FFR-based functional significance of coronary stenoses.

Heart Team risk assessment with angiography-derived fractional flow reserve determining the optimal revascularization strategy in patients with multivessel disease: Trial design and rationale for the DECISION QFR randomized trial

In patients with multivessel disease (MVD), functional information on lesions improves the prognostic capability of the SYNTAX score. Quantitative flow ratio (QFR®) is an angiography-derived fractional flow reserve (FFR) that does not require a pressure wire or pharmacological hyperemia. We aimed to investigate the feasibility of QFR-based patient information in Heart Teams' discussions to determine the optimal revascularization strategy for patients with MVD. We hypothesized that there is an acceptable agreement between treatment recommendations based on the QFR approach and recommendation based on the FFR approach. The DECISION QFR study is a prospective, multicenter, randomized controlled trial that will include patients with MVD who require revascularization. Two Heart Teams comprising cardiologists and cardiac surgeons will be randomized to select a revascularization strategy (percutaneous coronary intervention or coronary artery bypass graft) according to patient information either based on QFR or on FFR. All 260 patients will be assessed by both teams with reference to the anatomical and functional SYNTAX score/SYNTAX score II 2020 derived from the allocated physiological index (QFR or FFR). The primary endpoint of the trial is the level of agreement between the treatment recommendations of both teams, assessed using Cohen's κ. As of March 2022, the patient enrollment has been completed and 230 patients have been discussed in both Heart Teams. The current trial will indicate the usefulness of QFR, which enables a wireless multivessel physiological interrogation, in the discussions of Heart Teams to determine the optimal revascularization strategy for MVD.

Clinical impact of FFR-guided PCI compared to angio-guided PCI from the France PCI registry

OBJECTIVES

We sought to compare, in a national French registry (FrancePCI), the clinical impact of fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) compared with angio-guided PCI at 1 year.

BACKGROUND

FFR has become the invasive gold standard to quantify myocardial ischemia generated by a coronary stenosis in patients with chronic coronary syndrome, but in clinical practice it is still underutilised to guide PCI compared to angiography (angio).

METHODS

We extracted from the FrancePCI database all chronic coronary syndrome patients treated with PCI for coronary stenosis <90% between 2014 and 2019. Our composite clinical endpoint was the rate of major adverse clinical events (MACE).

RESULTS

Fourteen thousand three hundred eighty-four patients with 1-year clinical follow-up were included. Among them, 13,125 had angio-guided PCI (91%) and 1259 (9%) had FFR-guided PCI. We observed a significantly higher rate of MACE in the angio-guided group versus the FFR-guided group: 1478 (11.3%) versus 100 (7.9%) (p < 0.0001), respectively, with hazard ratio (HR) of 1.440, 95% confidence interval (CI) [1.211-1.713] (p = 0.0004). This result was driven by the higher occurrence of death in the angio-guided group versus the FFR-guided-group: 506 (3.9%) versus 17 (1.4%) (p < 0.0001), respectively, with HR of 2.845, 95% CI [2.099-3.856] (p < 0.0001). After adjustment for potential confounding factors, HRs were 1.287, 95% CI [1.028-1.613] (p = 0.028) for MACE and 2.527, 95% CI [1.452-4.399] (p = 0.001) for death. No significant differences between angio-guided PCI and FFR-guided PCI were observed for other clinical endpoints.

CONCLUSIONS

FFR-guided PCI improves outcome at 1 year compared to angio-guided PCI with a reduction of 64% of death.

Case Report: Invasive and Non-invasive Hemodynamic Assessment of Coronary Artery Disease: Strengths and Weaknesses

Coronary angiography has been the gold standard for assessment of coronary artery disease (CAD) and guidance for percutaneous coronary interventions (PCI). Physiology-guided PCI has shown increased safety and efficacy, improved resource utilization, and better clinical outcomes in patients with stable angina and acute coronary syndromes. The three cases presented and discussed in this report illustrate the strengths and weaknesses of the available invasive and non-invasive methods for the physiological assessment of CAD. As technology evolves, invasive non-wire-based (angiography-derived FFR) and non-invasive (FFR_CT) modalities for the hemodynamic assessment of CAD appear to provide reliable and user-friendly alternatives to the gold standard invasive wire-based techniques. Interventional cardiologists and cardiovascular healthcare providers should be familiar with the strengths and weaknesses of the available hemodynamic assessment modalities.

Non-Invasive Quantification of Fraction Flow Reserve Based on Steady-State Geometric Multiscale Models

Background: The underuse of invasive fraction flow reserve (FFR) in clinical practice has motivated research towards its non-invasive prediction. The early attempts relied on solving the incompressible three-dimensional Navier–Stokes equations in segmented coronary arteries. However, transient boundary condition has a high resource intensity in terms of computational time. Herein, a method for calculating FFR based on steady-state geometric multiscale (FFR_SS) is proposed.

Methods: A total of 154 moderately stenotic vessels (40–80% diameter stenosis) from 136 patients with stable angina were included in this study to validate the clinical diagnostic performance of FFR_SS. The method was based on the coronary artery model segmented from the patient’s coronary CTA image. The average pressure was used as the boundary condition for the inlet, and the microcirculation resistance calculated by the coronary flow was used as the boundary condition for the outlet to calculate the patient-specific coronary hyperemia. Then, the flow velocity and pressure distribution and the FFRss of each coronary artery branch were calculated to evaluate the degree of myocardial ischemia caused by coronary stenosis. Also, the FFR_SS and FFR_CT of all patients were calculated, and the clinically measured FFR was used as the “gold standard” to verify the diagnostic performance of FFR_SS and to compare the correlation between FFR_SS and FFR_CT.

Results: According to the FFR_SS calculation results of all patients, FFR_SS and FFR have a good correlation (r = 0.68, p < 0.001). Similarly, the correlation of FFR_SS and FFR_CT demonstrated an r of 0.75 (95%CI: 0.67–0.72) (p < 0.001). On receiver-operating characteristic analysis, the optimal FFR_SS cut point for FFR≤0.80 was 0.80 (AUC:0.85 [95% confidence interval: 0.79 to 0.90]; overall accuracy:88.3%). The overall sensitivity, specificity, PPV, and NPV for FFR_SS ≤0.80 versus FFR ≤0.80 was 68.18% (95% CI: 52.4–81.4), 93.64% (95% CI: 87.3–97.4), 82.9%, and 91.1%, respectively.

Conclusion: FFR_SS is a reliable diagnostic index for myocardial ischemia. This method was similar to the closed-loop geometric multiscale calculation of FFR accuracy but improved the calculation efficiency. It also improved the clinical applicability of the non-invasive computational FFR model, helped the clinicians diagnose myocardial ischemia, and guided percutaneous coronary intervention.

Pericoronary fat attenuation index and coronary plaque quantified from coronary computed tomography angiography identify ischemia-causing lesions

BACKGROUND

The association between pericoronary fat attenuation index (FAI), plaque characteristics, and lesion-specific ischemia identified by fractional flow reserve (FFR) remains unclear.

METHODS

Coronary computed tomography angiography (CCTA) stenosis, FAI, plaque characteristics, FFR derived from computed tomography (FFR_CT) and FFR were assessed in 280 vessels of 247 patients. Stenosis ≥50% was considered obstructive. Optimal thresholds of FAI and plaque variables were defined by the area under the receiver-operating characteristics curve (AUC) analysis. Ischemia was defined by FFR ≤ 0.80.

RESULTS

FAI ≥ -71.9 HU, low-attenuation plaque (LAP) ≥ 49.62 mm³ and aggregate plaque volume (APV) ≥ 28.91% predicted ischemia independent of other plaque characteristics. The addition of FAI ≥ -71.9 HU improved discrimination (AUC, 0.720 vs. 0.674, P = 0.035) and reclassification abilities (category-free net reclassification index [NRI], 0.470, P < 0.001; relative integrated discrimination improvement [IDI], 0.047, P < 0.001) of ischemia compared with stenosis evaluation alone, with further discrimination (AUC, 0.772 vs. 0.720, P = 0.028) and reclassification abilities (NRI, 0.385, P = 0.001; relative IDI, 0.077, P < 0.001) of ischemia by adding information regarding LAP ≥49.62 mm³ + APV ≥ 28.91%. And the diagnostic performance of combination approach was comparable to that of FFR_CT alone (AUC, 0.772 vs. 0.762, P = 0.771).

CONCLUSIONS

Stenosis severity, FAI, plaque characteristics predicted lesion-specific ischemia. The combination of FAI and plaque assessment improved the discrimination of ischemia compared with stenosis assessment alone.

Pre-angioplasty instantaneous wave-free ratio pullback predicts hemodynamic outcome in diffuse coronary artery disease

Background: Serial stenoses or diffuse vessel narrowing hamper pressure wire–guided management of coronary stenoses. Characterization of functional relevance of individual stenoses or narrowed segments constitutes an unmet need in ischemia-driven percutaneous revascularization. Aim of the Study: To perform hemodynamic mapping of the entire vessel using pullback technique of a pressure guidewire with continuous instantaneous wave-free ratio (iFR) measurement compared coronary angiography aiming to minimize the procedure, decrease number and length of stents used. Materials and Methods: This study was conducted on 40 patients presented with diffuse coronary artery disease and undergoing elective PCI. Diagnostic coronary angiography using the routine angiographic projections was done with assessment of non-obstructive coronary lesions by 2D quantitative coronary angiography and iFR pullback measurement Results: Percentage of difference between probable sig lesions via pullback technique and No of actual sig lesions for studied group, was (59.5%). The difference was statistically highly significant p=0.0001. Conclusion: Compared with angiography alone, availability of iFR pullback data significantly decreased the number and length of hemodynamically significant lesions identified for revascularization.