Efficacy of pressure parameters obtained during contrast medium-induced submaximal hyperemia in the functional assessment of intermediate coronary stenosis in comparison with instantaneous wave-free ratio

BackgroundDespite evidence demonstrating the benefits of percutaneous coronary intervention guided by fractional flow reserve (FFR), FFR evaluation has not been widely adopted. We sought to compare the diagnostic performances of instantaneous wave-free ratio (iFR) to a novel contrast medium-induced index in FFR prediction, hypothesizing that the latter parameter would offer superior diagnostic agreement with FFR.Methods & resultsWe studied 132 intermediate stenoses in 97 patients prospectively. iFR was measured first, followed by intracoronary injection of 6 mL contrast medium at 3 mL/s to obtain end-diastolic instantaneous distal coronary pressure/aortic pressure ratio (Pd/Pa) 60 ms before the electrocardiographic R-wave (C-ED-Pd/Pa). Subsequently, conventional hyperemic FFR was measured as a reference standard. Of the 132 lesions, 120 were available for final analysis. The FFR values of 95/120 lesions (79.2%) were between 0.60 and 0.90. C-ED-Pd/Pa values (median 0.79 [interquartile range 0.69–0.87]) were significantly lower than FFR values (0.81 [0.75–0.88], P < 0.01), whereas iFR values (0.91 [0.86–0.94], P < 0.01) were significantly higher. Correlation coefficients with FFR were 0.78 (standard error of the estimate [SEE] 0.067, P < 0.0001) and 0.93 (SEE 0.052, P < 0.0001) for iFR and C-ED-Pd/Pa, respectively (P < 0.001). The areas under the receiver operating characteristic curves were 0.88 and 0.96 for iFR and C-ED-Pd/Pa, respectively (P < 0.01). Diagnostic accuracy was 85.0% and 92.5% for iFR and C-ED-Pd/Pa, respectively (P = 0.06).ConclusionsC-ED-Pd/Pa is a novel, practical, and accurate measure for the physiological assessment of intermediate coronary stenosis compared to iFR.