Comparison of quantitative flow ratio with instantaneous wave‐free ratio and resting full‐cycle ratio during daily routine in the catheterization laboratory

Background Quantitative flow ratio (QFR) is a novel, software‐based method to evaluate the physiology of coronary lesions. The aim of this study was to compare QFR with the established invasive measurements of coronary blood flow using instantaneous wave‐free ratio (iFR) or resting full‐cycle ratio (RFR) in daily cathlab routine. Methods 102 patients with stable coronary artery disease and a coronary stenosis of 40%−90% were simultaneously assessed with QFR and iFR or RFR. QFR‐computation was performed by two certified experts using the appropriate software (QAngio XA 3D 3.2). Results QFR showed a significant correlation ( r = 0.75, p < 0.001) to iFR and RFR. The area under the receiver curve for all measurements was 0.93 (95% confidence interval, 0.87–0.98) for QFR compared to iFR or RFR. QFR based assessment required less time with a median of 501 s (IQR 421–659 s) compared to iFR or RFR which required a median of 734 s to obtain the result (IQR 512–967 s; p < 0.001). The median use of contrast medium was similar with 21 mL (IQR 16–30 mL) for the QFR‐based and 22 mL (IQR 15–35 mL) for the iFR‐ or RFR‐based diagnostic. QFR diagnostic required less radiation. The median dose area product for QFR was 307cGycm 2 (IQR 151–429 cGycm 2 ) compared to 599 cGycm 2 (IQR 345–1082 cGycm 2 ) for iFR or RFR, p < 0.001. Conclusion QFR measurements of coronary artery blood flow correlate with iFR or RFR measurements and are associated with shorter procedure times and reduced radiation dose.