Diagnostic Performance Of Quantitative Flow Ratio Research Articles

Correlation and Agreement of Quantitative Flow Ratio With Fractional Flow Reserve in Saphenous Vein Grafts.

The applicability of quantitative flow ratio (QFR), a nonhyperemic, invasive coronary angiography-derived computation of fractional flow reserve (FFR), has not been studied in coronary artery bypass grafts. We sought to explore the correlation and diagnostic agreement between QFR and FFR in saphenous vein grafts (SVGs). A total of 129 prospectively included patients (mean age 73±8 years, 84% male) with prior coronary artery bypass grafting underwent invasive coronary angiography and pressure-derived functional assessment in 150 nonoccluded SVGs. QFR dedicated angiography images of the SVGs were acquired and used for offline QFR computation. The diagnostic performance of QFR was compared with 2-dimensional quantitative coronary angiography, using FFR as a reference. A threshold of ≤0.80 was used to define functional significance. QFR was successfully computed in 140 (93%) SVGs. We found a significant correlation between QFR and FFR (r=0.72, P<0.001). FFR indicated significant disease in 43 (31%) SVGs, whereas QFR analysis showed significant lesions in 53 (38%) bypass grafts. QFR exhibited a higher sensitivity and diagnostic accuracy compared with angiographic lesion assessment (84% versus 63%, P=0.030 and 83% versus 74%, P=0.036, respectively), whereas specificity did not differ (82% versus 79%, P=0.466). Lastly, QFR demonstrated a higher area under the receiver operating curve than quantitative coronary angiography (0.90 versus 0.82, P=0.008) for the detection of FFR-defined significant vein graft disease. This study shows the potential applicability of contemporary QFR computation in venous bypass grafts with a moderate correlation and good diagnostic accuracy compared with functional assessment using FFR.

Diagnostic performance of quantitative flow ratio in non-ST elevation acute coronary syndromes in comparison to non-hyperemic pressure ratios: a prospective study.

Quantitative flow ratio (QFR) is a new angiography-based coronary physiology tool aimed to evaluate functional relevance of intermediate coronary lesions. Aim of the study is to assess diagnostic performance of QFR in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) in comparison to currently used non-hyperaemic pressure ratios (NHPRs). In this prospective, single-centre study, coronary physiology of intermediate coronary stenoses of non-culprit vessels in patients presenting with NSTE-ACS was evaluated using NHPRs (iFR, DFR or RFR). Subsequently, QFR was computed offline by a QFR analyst blinded to the NHPR results. Diagnostic performance of QFR was assessed in comparison to NHPRs as reference standard. A total of 60 vessels with intermediate coronary stenoses was investigated. The NHPRs were used as follows: RFR 38%, DFR 47% and iFR 15% of the cases. The NHPR result was positive, showing significant lesion, in 19 cases. A significant correlation was found between NHPR and QFR (r = 0.84, p < 0.001). Classification agreement of the two methods (95%) and diagnostic performance of QFR in comparison to NHPR (AUC: 0.962 [0.914-1.00]) were both high. Sensitivity, specificity, positive and negative predictive value of QFR in comparison to NHPR were 84.2%, 100%, 100% and 93.2% respectively. QFR has high diagnostic performance in detecting functionally significant lesions of non-culprit arteries in patients with NSTE-ACS and multivessel disease. Due to its high negative predictive value, it can be used to safely avoid unnecessary invasive physiological assessment of these lesions.

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 1year 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 1year 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 1year. 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.

Diagnostic performance of QFR vs FFR

Fractional flow reserve (FFR) is an invasive assessment of the functional significance of coronary stenosis utilizing a pressure wire. Quantitative flow ratio (QFR) is an angiography-based approximate of FFR. This new technology appears to be accurate and may be a useful alternative to FFR.

Diagnostic performance and clinical implications for enhancing a hybrid quantitative flow ratio\u2013FFR revascularization decision-making strategy

Invasive fractional flow reserve (FFR) adoption remains low mainly due to procedural and operator related factors as well as costs. Alternatively, quantitative flow ratio (QFR) achieves a high accuracy mainly outside the intermediate zone without the need for hyperaemia and wire-use. We aimed to determine the diagnostic performance of QFR and to evaluate a QFR–FFR hybrid strategy in which FFR is measured only in the intermediate zone. This retrospective study included 289 consecutive patients who underwent invasive coronary angiography and FFR. QFR was calculated for all vessels in which FFR was measured. The QFR–FFR hybrid approach was modelled using the intermediate zone of 0.77–0.87 in which FFR-measurements are recommended. The sensitivity, specificity, and accuracy on a per vessel-based analysis were 84.6%, 86.3% and 85.6% for QFR and 88.0%, 92.9% and 90.3% for the QFR–FFR hybrid approach. The diagnostic accuracy of QFR–FFR hybrid strategy with invasive FFR measurement was 93.4% and resulted in a 56.7% reduction in the need for FFR. QFR has a good correlation and agreement with invasive FFR. A hybrid QFR–FFR approach could extend the use of QFR and reduces the proportion of invasive FFR-measurements needed while improving accuracy.

Performance of quantitative flow ratio in patients with aortic stenosis undergoing transcatheter aortic valve implantation.

This study aims to evaluate the diagnostic performance of quantitative flow ratio (QFR) pre transcatheter aortic valve implantation (TAVI) in patients with aortic valve stenosis (AS) and coronary artery disease (CAD). Post-TAVI fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) was used as reference. CAD is prevalent in patients with AS, but the hemodynamics of AS confounds evaluation using pressure wire-based assessments. QFR might be less sensitive to the presence of AS thereby allowing for CAD evaluation before aortic valve replacement. Further, QFR does not require the use of pressure wire and therefore has the potential for reducing costs and complications related to insertion of a coronary pressure wire. The diagnostic performance of QFR in coronary angiograms from 28 patients undergoing TAVI was evaluated. In all patients, both FFR and iFR were measured pre- and immediately post-TAVI while QFR was measured pre-TAVI. Using post-TAVI FFR and iFR as reference the diagnostic accuracy of pre-TAVI QFR were 83% (95%CI; 68-97) and 52% (95%CI; 30-74) p=.008, respectively. Pre-TAVI QFR showed a good diagnostic performance using post-TAVI FFR as reference. QFR could become a wire-free, safe, and quick way of evaluating CAD in patients with severe AS undergoing TAVI.

Diagnostic performance and clinical implications for enhancing a hybrid quantitative flow ratio and fractional flow reserve revascularization decision making strategy

Abstract Background Fractional flow reserve (FFR) adoption persists low mainly due to procedural and operator related factors as well as costs. An alternative for FFR, quantitative flow ratio (QFR) achieves a high accuracy mainly outside the intermediate zone without the need for hyperemia and wire-use. Currently, no outcome trials assess the role of QFR in the guidance of revascularization. Therefore, we evaluate a QFR-FFR hybrid strategy in which FFR is measured inside of the intermediate zone. Methods This retrospective multi-center study included consecutive patients who underwent both invasive coronary angiography and FFR in the participating centers. QFR was calculated for all vessels in which FFR was measured. Diagnostic performance of QFR was assessed using an FFR cut-off of 0.80 as reference standard. The QFR-FFR hybrid approach was modeled using the intermediate zone of 0.77 to 0.87 assuming that lesions within the intermediate zone follow the FFR binary cutoff. Results In total, 381 vessels in 289 patients were analyzed. The sensitivity, specificity and accuracy on a per vessel-based analysis were 84.6%, 86.3% and 85.6% for QFR and 91.1%, 95.3% and 93.4% for the QFR-FFR hybrid approach. The diagnostic accuracy of QFR-FFR hybrid strategy with invasive FFR measurement is 93.4% and results in a FFR reduction of 56.7%. Conclusion QFR has a good correlation and agreement with invasive FFR and a high diagnostic accuracy. A hybrid QFR-FFR approach could extend the use of QFR and reduces the proportion of invasive FFR-measurements needed while maintaining a high accuracy. Hybrid QFR-FFR strategy Funding Acknowledgement Type of funding source: None

Angiography-derived functional assessment of non-culprit coronary stenoses in primary percutaneous coronary intervention.

Functional assessment of non-culprit lesions (NCL) in patients presenting with ST-elevation myocardial infarction (STEMI) and multivessel disease constitutes an unmet need. This study aimed to evaluate the diagnostic accuracy of quantitative flow ratio (QFR) in the functional assessment of NCL during the acute phase of STEMI. This was a retrospective, observational, multicentre study including patients with STEMI and staged fractional flow reserve (FFR) assessment of NCL. QFR in NCL was calculated from the coronary angiogram acquired during primary PCI in a blinded fashion with respect to FFR. The diagnostic value of QFR in the STEMI population was compared with a propensity score-matched population of stable angina patients. Eighty-two patients (91 NCL) were included. Target lesions were of both angiographic and functional (mean FFR 0.82±0.09) intermediate severity. The diagnostic performance of QFR was high (AUC 0.91 [95% CI: 0.85-0.97]) and similar to that observed in the matched control population (AUC 0.91 vs 0.94, p=0.5). The diagnostic accuracy of QFR was very high (>95%) in those vessels (61.5%) with QFR values out of a ROC-defined "grey zone" (0.75-0.85). A hybrid FFR/QFR approach (FFR only when QFR is in the grey zone) would adequately classify 96.7% of NCL, avoiding 58.5% of repeat diagnostic procedures. QFR has a good diagnostic accuracy in assessing the functional relevance of NCL during primary PCI, similar to the accuracy observed in stable patients.

Comparison of quantitative flow ratio and fractional flow reserve with myocardial perfusion scintigraphy and cardiovascular magnetic resonance as reference standard. A Dan-NICAD substudy

Quantitative flow ratio (QFR) and fractional flow reserve (FFR) have not yet been compared head to head with perfusion imaging as reference for myocardial ischemia. We aimed to compare the diagnostic accuracy of QFR and FFR with myocardial perfusion scintigraphy (MPS) or cardiovascular magnetic resonance (CMR) as reference. This study is a predefined post hoc analysis of the Dan-NICAD study (NCT02264717). Patients with suspected coronary artery disease by coronary computed tomography angiography (CCTA) were randomized 1:1 to MPS or CMR and were referred to invasive coronary angiography with FFR and predefined QFR assessment. Paired data with FFR, QFR and MPS or CMR were available for 232 vessels with stenosis in 176 patients. Perfusion defects were detected in 57 vessel territories (25%). For QFR and FFR the diagnostic accuracy was 61% and 57% (p = 0.18) and area under the receiver operating curve was 0.64 vs. 0.58 (p = 0.22). Stenoses with absolute indication for stenting due to diameter stenosis > 90% by visual estimate were not classified as significant by either QFR or MPS/CMR in 21% (7 of 34) of cases. The diagnostic performance of QFR and FFR was similar but modest with MPS or CMR as reference. Comparable performance levels for QFR and FFR are encouraging for this pressure wire-free diagnostic method.

Diagnostic performance of quantitative flow ratio in prospectively enrolled patients: An individual patient-data meta-analysis.

We aimed to provide robust performance estimates for quantitative flow ratio (QFR) in assessment of intermediary coronary lesions. Angiography-based functional lesion assessment by QFR may appear as a cost saving and safe approach to expand the use of physiology-guided percutaneous coronary interventions. QFR was proven feasible and showed good diagnostic performance in mid-sized off-line and on-line studies with fractional flow reserve (FFR) as reference standard. We performed a collaborative individual patient-data meta-analysis of all available prospective studies with paired assessment of QFR and FFR using the CE-marked QFR application. The main outcome was agreement of QFR and FFR using a two-step analysis strategy with a multilevel mixed model accounting for study and center level variation. Of 16 studies identified, four studies had prospective enrollment and provided patient level data reaching a total of 819 patients and 969 vessels with paired FFR and QFR: FAVOR Pilot (n = 73); WIFI II (n = 170); FAVOR II China (n = 304) and FAVOR II Europe-Japan (n = 272). We found an overall agreement (mean difference 0.009 ± 0.068, I2 = 39.6) of QFR with FFR. The diagnostic performance was sensitivity 84% (95%CI: 77-90, I2 = 70.1), specificity 88% (95%CI: 84-91, I2 = 60.1); positive predictive value 80% (95%CI: 76-85, I2 = 33.4), and negative predictive value 95% (95%CI: 93-96, I2 = 75.9). Diagnostic performance of QFR was good with FFR as reference in this meta-analysis of high quality studies. QFR could provide an easy, safe, and cost-effective solution for functional evaluation of coronary artery stenosis.

Evaluation of Coronary Artery Stenosis by Quantitative Flow Ratio During Invasive Coronary Angiography: The WIFI II Study (Wire-Free Functional Imaging II).

Quantitative flow ratio (QFR) is a novel diagnostic modality for functional testing of coronary artery stenosis without the use of pressure wires and induction of hyperemia. QFR is based on computation of standard invasive coronary angiographic imaging. The purpose of WIFI II (Wire-Free Functional Imaging II) was to evaluate the feasibility and diagnostic performance of QFR in unselected consecutive patients. WIFI II was a predefined substudy to the Dan-NICAD study (Danish Study of Non-Invasive Diagnostic Testing in Coronary Artery Disease), referring 362 consecutive patients with suspected coronary artery disease on coronary computed tomographic angiography for diagnostic invasive coronary angiography. Fractional flow reserve (FFR) was measured in all segments with 30% to 90% diameter stenosis. Blinded observers calculated QFR (Medis Medical Imaging bv, The Netherlands) for comparison with FFR. FFR was measured in 292 lesions from 191 patients. Ten (5%) and 9 patients (5%) were excluded because of FFR and angiographic core laboratory criteria, respectively. QFR was successfully computed in 240 out of 255 lesions (94%) with a mean diameter stenosis of 50±12%. Mean difference between FFR and QFR was 0.01±0.08. QFR correctly classified 83% of the lesions using FFR with cutoff at 0.80 as reference standard. The area under the receiver operating characteristic curve was 0.86 (95% confidence interval, 0.81-0.91) with a sensitivity, specificity, negative predictive value, and positive predictive value of 77%, 86%, 75%, and 87%, respectively. A QFR-FFR hybrid approach based on the present results enables wire-free and adenosine-free procedures in 68% of cases. Functional lesion evaluation by QFR assessment showed good agreement and diagnostic accuracy compared with FFR. Studies comparing clinical outcome after QFR- and FFR-based diagnostic strategies are required. URL: https://www.clinicaltrials.gov. Unique identifier: NCT02264717.