Ventricular-Coronary Interaction Delay is Associated with Discordance Between Fractional Flow Reserve and Coronary Flow Reserve in Intermediate Coronary Stenoses

Abstract

Recently, the multicenter DEFINE-FLOW and ILIAS registry studies revealed that a preserved coronary flow reserve (CFR) (≥2.0) may justify the deferral of revascularization for lesions with abnormal fractional flow reserve (FFR) (≤0.8). We used wave intensity analysis (WIA) in lesions with concordant and discordant FFR-CFR to elucidate underlying cardiac-coronary coupling dynamics and how these indices relate to the magnitude and timing of the net coronary WI profile. Preserved FFR is primarily associated with earlier coronary flow-accelerating effect of ventricular compression and expansion (peak times of FCW-BEW: tFCWpeak: r = −0.275 p <0.001, tBEWpeak: r = −0.388 p <0.001) while preserved CFR is associated with earlier peaks of backward travelling waves of microvascular origin, which may be decelerating (tBCWpeak r= −0.281 p <0.001) or accelerating (tBEWpeak r = −0.221 p <0.001). Concordant abnormal FFR-CFR lesions exhibited delayed peaks of FCW, BCW and BEW compared to concordant normal lesions (p <0.001), whereas discordant FFR-CFR lesions had preserved tBEWpeak despite dyssynchrony of systolic WI peaks (relative FCW-BCW peak times: tFCWpeak: 48% ± 22% vs 34% ± 18% p <0.001, tBCWpeak:38% ± 26% vs 51% ± 33% ± of compression period p <0.001). A resting BEW peak within the first 13% of the ventricular expansion phase had a 87% negative predictive value for concordant abnormal FFR-CFR lesions. In conclusion, discordantly abnormal FFR or CFR are associated with dyssynchrony of ventricular-coronary interactions revealed by WIA. The relative time to peak microvascular suction effect, which is responsible for diastolic filling, is preserved in discordant lesions. This is marked by reference level tBEWpeak,similar to that of lesions with concordant normal FFR and CFR, that may explain the good prognosis of discordant lesions without revascularization. In contrast, the concordantly abnormal FFR-CFR group exhibits a substantial delay of tBEWpeak, which may serve as a potential unified marker for lesions that would benefit from revascularization.