For physiology assessment of coronary artery (CA), FFR is a gold standard method. FFR value can also be computed from ordinary coronary angiograms by Quantitative flow ratio (QFR). iFR is a physiology assessment method that does not use a hyperemic agent.

Aim: The concurrence between quantitative flow ratio, FFR, and the influence of QFR on decision-making compared to FFR and iFR was intended to be established by the study.

Methods and Results: A prospective study included 213 patients who had undergone coronary angiography between January 1, 2019, to December 31, 2020. Intermediate stenosis was defined as 35 to 75% lumen stenosis. FFR or iFR values were also performed for all the subjects. 3 independent measurements during the same procedure were taken to derive the average iFR and FFR values. An average QFR value was obtained after performing the QFR analysis thrice. A comparison between the average iFR or FFR and average QFR was drawn.

On the basis of the diseased CA, FFR measurements were made. A significance level of p < 0.001 was chosen.

The 240 lesions included:

  • Left circumflex (LCX): 25, r = 0.757

  • Right coronary artery (RCA): 69, r = 0.839

  • Left anterior descending (LAD): 146, r = 0.749 

r = 0.871 and 0.782, p <0.001 was noted as a strong significant correlation between QFR and both iFR and FFR.

QFR and iFR displayed a weaker correlation with r = 0.600, p = 0.002, with respect to clinical-decision making.

A strong significant correlation of r = 0.948, p <0.001 was observed between QFR and FFR 

On performing a detailed analysis of separate CA the following results were obtained:

  • LCX: r = 1.00, p = 1.00

  • RCA: r = 0.954, p < 0.001

  • LAD: r = 0.941, p < 0.001


QFR, when compared with iFR, showed a sensitivity of 100%, specificity of 95%, and accuracy of 88%. In comparison to FFR, it showed better results, with a sensitivity of 100%, specificity of 97.63%, and accuracy of 98.14%.

Conclusion: The study noted that in terms of clinical decision-making, QFR provided an exceptional agreement with both iFR and FFR. QFR being a safe, convenient, and cheap method, can be adopted in everyday clinical practice.




Disease Condition ,Coronary Artery Disease,Acute Coronary Syndrome,Angina Pectoris,Cardiac Syndrome X,Coronary Artery Vasospasm