Diagnostic Concordance and Discordance Between Angiography-Based Quantitative Flow Ratio and Fractional Flow Reserve Derived from Computed Tomography in Complex Coronary Artery Disease

Diagnostic performance of the quantitative flow ratio and CT-FFR for coronary lesion-specific ischemia

Fractional flow reserve (FFR) has become the gold standard for evaluating coronary lesion-specific ischemia. However, FFR is an invasive method that may cause possible complications in the coronary artery and requires expensive equipment, which limits its use. Promising noninvasive diagnostic methods, such as computed tomography angiography-derived FFR (CT-FFR) and the quantitative flow ratio (QFR), have been proposed. In this study, we evaluated the diagnostic performance of the QFR and CT-FFR in predicting coronary lesion-specific ischemia, with the FFR serving as the reference standard. Patients with suspected or known coronary artery disease who underwent coronary CT angiography revealing 30-90% diameter stenosis in the main coronary artery (≥ 2.0 mm reference diameter) were enrolled. The FFR was measured during invasive coronary angiography (within 15 days after coronary CT angiography). An FFR ≤ 0.8 was the reference standard for coronary lesion-specific ischemia. A total of 103 vessels from 92 consecutive patients (aged 59.8 ± 9.2 years; 60.9% were men) were evaluated. The diagnostic performance of a QFR ≤ 0.80 for predicting coronary lesion-specific ischemia demonstrated good diagnostic accuracy, sensitivity, and specificity (92.2%, 87.2%, and 96.4%, respectively), with an area under the receiver operating characteristic curve (AUC) of 0.987 (P < 0.0001). The diagnostic performance of a CT-FFR ≤ 0.80 for predicting coronary lesion-specific ischemia also demonstrated good diagnostic accuracy, sensitivity, and specificity (96.1%, 95.7%, and 96.4%, respectively), with an AUC of 0.967 (P < 0.0001). However, there was no significant difference in the AUC between a QFR ≤ 0.80 and a CT-FFR ≤ 0.80 for predicting coronary lesion-specific ischemia (P = 0.319). There was an excellent correlation between the QFR and FFR (r = 0.856, P < 0.0001). The CT-FFR and FFR also showed a good direct correlation (r = 0.816, P < 0.0001). The QFR and CT-FFR are strongly correlated with the FFR and can provide excellent clinical diagnostic performance for coronary lesion-specific ischemia detection.

Non-invasive fractional flow reserve estimation in coronary arteries using angiographic images

Coronary artery disease is the leading global cause of mortality and Fractional Flow Reserve (FFR) is widely regarded as the gold standard for assessing coronary artery stenosis severity. However, due to the limitations of invasive FFR measurements, there is a pressing need for a highly accurate virtual FFR calculation framework. Additionally, it's essential to consider local haemodynamic factors such as time-averaged wall shear stress (TAWSS), which play a critical role in advancement of atherosclerosis. This study introduces an innovative FFR computation method that involves creating five patient-specific geometries from two-dimensional coronary angiography images and conducting numerical simulations using computational fluid dynamics with a three-element Windkessel model boundary condition at the outlet to predict haemodynamic distribution. Furthermore, four distinct boundary condition methodologies are applied to each geometry for comprehensive analysis. Several haemodynamic features, including velocity, pressure, TAWSS, and oscillatory shear index are investigated and compared for each case. Results show that models with average boundary conditions can predict FFR values accurately and observed errors between invasive FFR and virtual FFR are found to be less than 5%.

Concordance between vessel-specific and vascular territory coronary functional assessment: A comparison of quantitative flow ratio and myocardial perfusion scintigraphy

BACKGROUND

Quantitative flow ratio (QFR) and myocardial perfusion scintigraphy (MPS) are utilized for assessing coronary artery disease (CAD) significance. We aimed to analyze their concordance and prognostic impact.

AIMS

We aimed to analyze the concordance between QFR and MPS and their risk stratification.

METHODS

Patients with invasive coronary angiography and MPS were categorized as concordant if QFR ≤ 0.80 and summed difference score (SDS) ≥ 4 or if QFR > 0.80 and SDS < 4; otherwise, they were discordant. Concordance was classified by coronary territory involvement: total (three territories), partial (two territories), poor (one territory), and total discordance (zero territories). Leaman score assessed coronary atherosclerotic burden.

RESULTS

2010 coronary territories (670 patients) underwent joint QFR and MPS analysis. MPS area under the curve for QFR ≤ 0.80 was 0.637. Concordance rates were total (52.5%), partial (29.1%), poor (15.8%), and total discordance (2.6%). Most concordance occurred in patients without significant CAD or with single-vessel disease (89.5%), particularly without MPS perfusion defects (91.5%). Leaman score (odds ratio [OR]: 0.839, 95% confidence interval [CI]: 0.805-0.875, p < 0.001) and MPS perfusion defect (summed stress score [SSS] ≥ 4) (OR: 0.355, 95% CI: 0.211-0.596, p < 0.001) were independent predictors for discordance. After 1400 days, no significant difference in death/myocardial infarction was observed based on MPS assessment, but Leaman score, functional Leaman score, and average QFR identified higher risk patients.

CONCLUSIONS

MPS showed good overall accuracy in assessing QFR significance but substantial discordance existed. Predictors for discordance included higher atherosclerotic burden and MPS perfusion defects (SSS ≥ 4). Leaman score, QFR-based functional Leaman score, and average QFR provided better risk stratification for all-cause death and myocardial infarction than MPS.

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

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

Impact of quantitative flow ratio on graft function in patients undergoing coronary artery bypass grafting

Recent studies showed that preoperative functional assessment with fractional flow reserve (FFR) could predict a long-term patency of arterial bypass grafts in patients with coronary artery bypass grafting (CABG). Quantitative flow ratio (QFR) is a novel angiography-based approach to estimate FFR. This study aimed to investigate whether preoperative QFR could discriminate arterial bypass function at 1 year after surgery. The PRIDE-METAL registry was a prospective, multicenter observational study that enrolled 54 patients with multivessel coronary artery disease. By protocol, left coronary stenoses were revascularized by CABG with arterial grafts, whereas right coronary stenoses were treated with coronary stenting. Follow-up angiography at 1 year after surgery was scheduled to assess arterial graft patency. QFR was performed using index angiography by certified analysts, blinded to bypass graft function. The primary end point of this sub-study was the discriminative ability of QFR for arterial graft function, as assessed by receiver-operating characteristic curve. Among 54 patients enrolled in the PRIDE-METAL registry, index and follow-up angiography was available in 41 patients with 97 anastomoses. QFR were analyzed in 35 patients (71 anastomoses) with an analyzability of 85.5% (71/83). Five bypass grafts were found to be non-functional at 1 year. The diagnostic performance of QFR was substantial (area under the curve: 0.89; 95% confidence interval: 0.83 to 0.96) with an optimal cutoff of 0.76 to predict functionality of bypass grafts. Preoperative QFR is highly discriminative for predicting postoperative arterial graft function.Trial registration: Clinical.gov reference: NCT02894255.

The journal of cardiovascular computed tomography: A year in review: 2022

This review aims to summarize key articles published in the Journal of Cardiovascular Computed Tomography (JCCT) in 2022, focusing on those that had the most scientific and educational impact. The JCCT continues to expand; the number of submissions, published manuscripts, cited articles, article downloads, social media presence, and impact factor continues to grow. The articles selected by the Editorial Board of the JCCT in this review highlight the role of cardiovascular computed tomography (CCT) to detect subclinical atherosclerosis, assess the functional relevance of stenoses, and plan invasive coronary and valve procedures. A section is dedicated to CCT in infants and other patients with congenital heart disease, in women, and to the importance of training in CT. In addition, we highlight key consensus documents and guidelines published in JCCT last year. The Journal values the tremendous work by authors, reviewers, and editors to accomplish these contributions.

QFR-Based Virtual PCI or Conventional Angiography to Guide PCI: The AQVA Trial

BACKGROUND

Post-percutaneous coronary intervention (PCI) quantitative flow ratio (QFR) values ≥0.90 are associated with a low incidence of adverse events.

OBJECTIVES

The AQVA (Angio-based Quantitative Flow Ratio Virtual PCI Versus Conventional Angio-guided PCI in the Achievement of an Optimal Post-PCI QFR) trial aims to test whether a QFR-based virtual percutaneous coronary intervention (PCI) is superior to a conventional angiography-based PCI at obtaining optimal post-PCI QFR results.

METHODS

The AQVA trial is an investigator-initiated, randomized, controlled, parallel-group clinical trial. Three hundred patients (356 study vessels) undergoing PCI were randomized 1:1 to receive either QFR-based virtual PCI or angiography-based PCI (standard of care). The primary outcome was the rate of study vessels with a suboptimal post-PCI QFR value, which was defined as <0.90. Secondary outcomes were procedure duration, stent length/lesion, and stent number/patient.

RESULTS

Overall, 38 (10.7%) study vessels missed the prespecified optimal post-PCI QFR target. The primary outcome occurred significantly more frequently in the angiography-based group (n = 26, 15.1%) compared with the QFR-based virtual PCI group (n = 12 [6.6%]; absolute difference = 8.5%; relative difference = 57%; P = 0.009). The main cause of a suboptimal result in the angiography-based group is the underestimation of a diseased segment outside the stented one. There were no significant differences among secondary endpoints, although stent length/lesion and stent number/patient were numerically lower in the virtual PCI group (P = 0.06 and P = 0.08, respectively), whereas procedure length was higher in the virtual PCI group (P = 0.06).

CONCLUSIONS

The AQVA trial demonstrated the superiority of QFR-based virtual PCI over angiography-based PCI with regard to post-PCI optimal physiological results. Future larger randomized clinical trials that demonstrate the superiority of this approach in terms of clinical outcomes are warranted. (Angio-based Quantitative Flow Ratio Virtual PCI Versus Conventional Angio-guided PCI in the Achievement of an Optimal Post-PCI QFR [AQVA]; NCT04664140).