Nonhyperemic intracoronary pressure waveform analysis predicts the fractional flow reserve

The fractional flow reserve (FFR) is measured during maximal hyperemia achieved by intracoronary or intravenous vasodilatator. It has been regarded that the nonhyperemic resting pressure ratio (RPR) was not appropriate for exact evaluation of the functional severity of coronary lesion. Some studies suggest, however, that the comparison of the proximal and distal resting waveform of the stenosis may predict the fractional flow reserve (FFR), because the intracoronary waveform has such a high-frequency pressure signal at the closing of aortic valve (notch) that can be decreased by the filter-effect of the stenosis. In our investigation we analyzed the derivatives of the pre- and post-stenotic basal pressure waves of 40 pressure measurements, and the resting pressure ratio (RPR). These data were compared to the measured FFR values during hyperemia. We introduced the delta dp_N/dt value (δdp_N/dt) to characterize (describe?) the ascending slope of the dicrotic notch. This is the difference between the local minimum and maximum values of the derivatives of the pressure waveform during the dicrotic notch period. We have experienced significant correlation between the δdp_N/dt and FFR (r= 0.59, p <; 0.001) as well as the RPR and the (r= 0.65, p= 0.004) FFR By using the Receiver Operating Curve (ROC) analysis, the value of 3>;δdp_N/dt (sensitivity 100%, specificity 91%), and an RPR>;0.87 (sensitivity 88%, specificity 84%) were found to be the optimal cutoff values for predicting FFR<;0.75. The areas under the ROC were 0.99 in case of δdp_N/dt and 0.92 in case of RPR. The δdp_N/dt can be a new useful nonhyperemic parameter for the assessment of the coronary artery stenosis during the intracoronary pressure measurements.