Diastolic hyperemia-free ratio (DFR)The DFR identifies portions of the pressure tracingbelow the mean Pa with a negative slope thatapproximates diastole and averages the Pd/Pa ratio ofthese subsets over 5 consecutive cardiac cycles. Thecutoff value of DFR for predicting myocardial ischemiawas 0.89, which was identical to that of iFR. A subgroupanalysis study20 involving 893 lesions of 833participants included in the previously published AComparative Study of Resting Coronary PressureGradient, Instantaneous Wave-Free Ratio andFractional Flow Reserve in an Unselected PopulationReferred for Invasive Angiography (VERIFY II)21 andContinuum of Vasodilator Stress From Rest to ContrastMedium to Adenosine Hyperemia for Fractional FlowReserve Assessment (CONTRAST)22 trials reported nodifference between DFR and iFR (combined differencewith iFR for DFR -0.006 t 0.011, R2 = 0.993, accuracy97.6%).