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.

Abstract Background Despite 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 & results We studied 132 intermediate stenoses in 97 patients prospectively. iFR was measured first, followed by intracoronary injection of 6mL contrast medium at 3mL/s to obtain end-diastolic instantaneous distal coronary pressure/aortic pressure ratio (Pd/Pa) 60ms 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 P P P P P P =0.06). Conclusions C-ED-Pd/Pa is a novel, practical, and accurate measure for the physiological assessment of intermediate coronary stenosis compared to iFR.