AbstractAssessment of coronary physiology in intermediate coronary lesions plays a vital role in strategic intervention. Although instantaneous free wave ratio (IFR) have been validated in coronary physiology assessment, evidence in support for novel resting full cycle ratio (RFR) is growing. In our present single center prospective study, we uniquely compared RFR with Fractional Flow Reserve (FFR) in assessment of intermediate coronary lesions and evaluated the influence of coronary hyperemia with adenosine, nitroglycerine and contrast on nonhyperemic index RFR in predicting the lesion significance. We observed RFR correlated well with FFR (agreement K:0.781) and RFR cut off of 0.89 correlated with FFR of 0.8. RFR had sensitivity of 89%, specificity of 92%, positive predictive value of 80% and negative predictive value of 96% (p<0.001, AUC 0.89) for delineating lesion severity. Effect of hyperemia in nonhyperemic indices were as follows: Hyperemic agents improve the diagnostic accuracy of nonhyperemic index RFR, contrast RFR with cut off of 0.875 correlated with an FFR of 0.8, adenosine RFR with cut off of 0.795 correlated with FFR of 0.8 in our study. Presence of diabetes and Smoking had no effect on RFR as observed in our study.