Diagnostic Performance of Quantitative Flow Ratio Compared to Fractional Flow Reserve and Instantaneous Wave-Free Ratio for Physiology Evaluation of Intermediate Coronary Artery Stenosis - European Medical Journal


Diagnostic Performance of Quantitative Flow Ratio Compared to Fractional Flow Reserve and Instantaneous Wave-Free Ratio for Physiology Evaluation of Intermediate Coronary Artery Stenosis

2 Mins
EMJ Interventional Cardiology 9.1 2021 Feature Image
*Greta Ziubryte,1,2 Gediminas Jarusevicius1,2

The authors have declared no conflicts of interest.


The authors would like to thank Prof Remigijus Žaliūnas, Head of the Department of Cardiology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, and Prof Ramūnas Unikas, Chief of the Department of Interventional Cardiology, Hospital of Lithuanian University of Health Sciences Kaunas Clinics, Kaunas, Lithuania, for their comprehensive support for this study.

EMJ Int Cardiol. ;9[1]:27-28. Abstract Review No. AR2.

Each article is made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.

Receive our free quarterly newsletters and your choice of journal publication alerts, straight to your inbox.

Join our mailing list


European and American experts recommend physiology-guided myocardial revascularisation.1,2,3 Nevertheless, physiology-guided revascularisation does not exceed 10% in the best scenario, worldwide.4 The most widely used pressure wire-based methods are associated with rare but potentially threatening complication;5 therefore, a novel minimally invasive fractional flow reserve (FFR) value computation method known as quantitative flow ratio (QFR) has been developed.6,7,8 This study was aimed to investigate the agreement between QFR, FFR, and instantaneous wave-free ratio (iFR), in addition to evaluating the difference between QFR and both FFR and iFR on making a treatment decision.


Two-hundred and thirteen patients, who had undergone a coronary angiography that revealed intermediate stenosis (lumen stenosis of 35–75%) by visual evaluation and for whom FFR or iFR measurements were performed between 1st January 2019 and 31st December 2020, were prospectively included into the study. FFR and iFR values were averaged from three independent measurements during the same procedure and FFR and iFR results were blinded online. QFR analyses were performed three times. Average QFR values were compared to average FFR or iFR values. FFR measurements were divided according to the diseased coronary artery (CA). The selected level of significance was p< 0.01.


In total, 240 lesions, including 146 left anterior descending (LAD), 25 left circumflex (LCX), and 69 right CA (RCA), were analysed. In total, 25 were iFRs. In the analyses of all lesions, a strong significant correlation coefficient between QFR and both FFR and iFR was found: r=0.782 and 0.871, respectively; p<0.001. After dividing lesions according to CA, the following results have been found: LAD: r=0.749, p<0.001; LCX: r=0.757, p<0.001; and RCA: r=0.839, p<0.001. The secondary outcome was the agreement of clinical decision-making between contrast QFR and both FFR and iFR. In the analyses of all lesions, a strong, significant correlation between QFR and FFR have been found (r=0.948; p<0.001). A weaker correlation between QFR and iFR was reported (r=0.600; p=0.002). Detailed analysis of separate CA has shown the following results: LAD: r=0.941, p<0.001; LCX: r=1.00, p<0.001; and RCA: r=0.954, p<0.001. Compared to FFR as a reference, QFR had a sensitivity of 100%, specificity of 97.63%, and accuracy of 98.14%, and when compared to iFR the values were 100%, 95%, and 88%, respectively.


The variety of methods that are currently available encourages the search for the most economical, most convenient, and most reliable method. Repeatedly proved excellent agreement between FFR and QFR supports the wider acceptance into clinical practice, while at the same time encourages further research. Excellent QFR agreement to both FFR and iFR, especially in regard to clinical decision making, makes the method more acceptable to everyday clinical practice. QFR is a safe, cheap, and convenient method, with an excellent correlation to both FFR and iFR in CA stenosis functional significance assessment and clinical decision making, with a great sensitivity, specificity, and accuracy.

Neumann FJ et al; ESC Scientific Document Group. 2018 ESC/EACTS Guidelines on myocardial revascularization. Eur Heart J. 2019;40(2):87–165. Patel MR et al. ACC/AATS/AHA/ASE/ASNC/SCAI/SCCT/STS 2017 appropriate use criteria for coronary revascularization in patients with stable ischemic heart disease: a report of the American College of Cardiology Appropriate use Criteria Task Force, American Association for Thoracic Surgery, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, and Society of Thoracic Surgeons. J Am Coll Cardiol. 2017; 69(17):2212–41. Westra J et al. Diagnostic performance of quantitative for ratio in prospective enrolled patients: an individual patient-data meta-analysis. Catheter Cardiovasc Interv. 2019;94(5):693–701. Davies JE et al. Use of the instantaneous wave-free ratio or fractional flow reserve in PCI. N Engl J Med. 2017;376(19):1824–34. Johnson NP, Koo BK. Coronary psychology: do you believe? JACC Cardiovasc Interv. 2018;11(15):1492–4. Westra J et al. Diagnostic performance of in-procedure angiography-derived quantitative flow reserve compared to pressure-derived fractional flow reserve: the FAVOR II Europe-Japan study. J Am Heart Assoc. 2018;7(14):e009603. Westra J et al. Evaluation of coronary artery stenosis by quantitative flow ratio during invasive coronary angiography: the WIFI II study (wire-free functional imaging II). Circ Cardiovasc Imaging. 2018;11(3):e007107. Xu B et al. Diagnostic accuracy of angiography-based quantitative flow ratio measurements for online assessment of coronary stenosis. J Am Coll Cardiol. 2017;70(25):3077–87.