Diagnostic Agreement of Quantitative Flow Ratio with Fractional Flow Reserve in a Latin-American Population

Purpose: Quantitative flow ratio (QFR) is a recently proposed angiographic index that allows to assess the pressure loss in coronary arteries in a similar fashion as the accepted standard fractional flow reserve (FFR). The purpose of this study was to evaluate the diagnostic performance of QFR as compared to FFR, in a Latin-American population of patients with suspected ischaemic heart disease.Methods: QFR was retrospectively derived from coronary angiograms. The association, diagnostic performance, and continuous agreement of fixed-flow QFR (fQFR) and contrast-flow QFR (cQFR) with FFR was assessed by continuous and dichotomous methods.Results: 90 vessels form 63 patients were finally included. The study comprised coronary stenoses of intermediate severity, both angiographically (diameter stenosis: 46.6 ± 12.8%) and physiologically [median FFR=0.86 (quartile 1-3, 0.76-0.89)]. The correlation of FFR with both fQFR [ρ=0.841, (95% CI: 0.767 to 0.893), p<0.001] and cQFR [ρ=0.833, (95% CI: 0.755 to 0.887), p<0.001] was strong. The diagnostic performance of cQFR was numerically better [area under the ROC curve of 0.92 (95% CI: 0.86 to 0.97, p<0.001)], with 0.80 as the optimal cQFR cut-off against FFR≤0.80. This 0.80 cQFR cut-off classified correctly 83.3% of total stenoses, with a sensitivity of 85.2% and specificity of 80.6%.Conclusions: QFR was strongly associated with FFR and exhibited a high diagnostic performance in this Latin-American population.

Diagnostic Performance of Immediate Angiography Derived Quantitative Flow Ratio In Patients After Second Generation Drug Eluting Stent And Bioresorable Scaffold Implantation

The full text of this preprint has been withdrawn by the authors due to author disagreement with the posting of the preprint. Therefore, the authors do not wish this work to be cited as a reference. Questions should be directed to the corresponding author.

Bilateral pulmonary artery stenosis with pulmonary hypertension due to Takayasu’s arteritis, examined using quantitative flow ratio during revascularisation

Therapeutic effect evaluation is based on morphology performed by angiography conventionally. QFR is a new angiography-based tool for vascular assessment of functional severity. We report the first QFR examination in the field of Takayasu's arteritis patient with pulmonary artery stenosis and pulmonary arterial hypertension. It seems simple and practicable during off-line pulmonary artery intervention assessment.

448 Comparison of quantitative flow ratio, Pd/Pa, and diastolic hyperaemia-free ratio vs. fractional flow reserve in non-culprit lesion of patients with non-ST-segment elevation myocardial infarction

Aims To investigate the correlation between quantitative flow ratio (QFR), Pd/Pa, diastolic hyperaemia-free ratio (DFR), and fractional flow reserve (FFR, gold standard) in non-culprit lesion (NCL) of patients with non ST-segment elevation myocardial infarction (NSTEMI). The non-hyperemic pressure ratio (NHPR) and the angiography-based indexes have been developed to overcome the limitation of the use of the FFR. Methods and results Between January and December 2019, 184 NCL from 116 NSTEMI patients underwent physiologic assessment and were included in the study. NCLs were investigated with QFR, Pd/Pa, DFR, and FFR. Mean values of QFR, Pd/Pa, DFR, and FFR were 0.85 ± 0.10, 0.92 ± 0.07, 0.93 ± 0.05, and 0.84 ± 0.07, respectively. DFR and FFR showed a good correlation (r = 0.76). Bland and Altman plot showed a mean difference of 0.080. DFR diagnostic accuracy was 88%. The area under the ROC curve (AUC) for DFR was 0.946 (95% CI: 0.90–0.97, P = 0.0001). Similar findings were reported for Pd/Pa [r = 0.73; mean difference 0.095, diagnostic accuracy 84%, AUC 0.909 (95% CI: 0.85–0.94, P = 0.0001)] and QFR [r = 0.68; mean difference: 0.01; diagnostic accuracy: 88%, AUC: 0.964 (95% CI: 0.91–0.98, P = 0.0001)]. FFR, QFR, Pd/Pa, and DFR identified 31%, 32%, 30%, and 32% potentially flow-limiting lesions, respectively. Conclusions In NSTEMI patients, QFR, Pd/Pa, and DFR showed equivalence as compared to gold standard FFR in the discrimination of non-culprit lesions requiring revascularization.

197 Angio-based index of microcirculatory resistance for the assessment of the coronary resistance: a proof of concept study

Aims The study of coronary microcirculation has gained increasing consideration and importance in cath-lab. Despite the increase of evidence its use still remains very limited. QFR is a novel angio-based approach for the evaluation of coronary stenosis. The aim of our study was to use the QFR assessment in stable patients to recreate the IMR formula and to correlate the result of the two techniques. Methods and results From 1 June 2019 to 29 February 2019, 200 patients with CCS and indication of coronary artery angiography and referred to the cath-lab of the University Hospital of Ferrara (Italy) were enrolled. After baseline coronary angiogram, quantitative flow ratio, fractional flow reserve and index of microcirculatory resistance evaluation were performed. Pearson correlation (r) between Angio-based index of microcirculatory resistance (A-IMR) and IMR 0.32 with R2 = 0.098, P = 0.03: McNemar test showed a difference between the two test of 6.82% with 95% CI from −12.05% to 22.89%, which is not significant (P = 0.60). Bland and Altman plot showed a mean difference of 23.3 (from −26.5 to 73.1). Sensitivity, specificity, NPV and PPV were 70%, 83.3%, 75% and 70% for A-IMR value &gt; 44.2. The area under the ROC curve for A-IMR was 0.76 (95% CI: 0.61–0.88, P = 0.0003). Conclusions We have validated for the first time the formula of the A-IMR, a tool for the calculation of microvascular resistance which does not require the use of pressure guides and the induction of hyperemia