SIMULTANEOUS CORONARY PRESSURE AND FLOW VELOCITY-MEASUREMENTS IN HUMANS - FEASIBILITY, REPRODUCIBILITY, AND HEMODYNAMIC DEPENDENCE OF CORONARY FLOW VELOCITY RESERVE, HYPEREMIC FLOW VERSUS PRESSURE SLOPE INDEX,AND FRACTIONAL FLOW RESERVE

Background To assess coronary lesion severity in the catheterization l aboratory, several guide wire-based methods have been proposed. The pu rpose of the present study was to compare the feasibility and the repr oducibility of coronary how velocity reserve (CFVR), instantaneous hyp eremic diastolic velocity-pressure slope index (IHDVPS), and pressure- derived myocardial fractional flow reserve (FFR(myo)). Methods and Res ults From distal coronary pressure and flow velocity signals (0.014-in guide wires), CFVR, IHDVPS, and FFR(myo) were computed in 15 stenoses (13 patients) under the four following pairs of conditions: (1) twice under baseline conditions; (2) during atrial pacing at 80 and 110 bpm ; (3) before and during intravenous infusion of nitroprusside; and (4) before and during intravenous infusion of dobutamine. A total of 104 measurements were obtained. Both CFVR and FFR(myo) could be calculated in all cases. IHDVPS could be calculated in only 79% of cases. The me an value of CFVR did not change between the two baseline measurements and during infusion of nitroprusside but decreased from 1.85+/-0.41 to 1.66+/-0.45 (P<.05) during atrial pacing and from 1.90+/-0.50 to 1.41 +/-0.28 (P<.05) during dobutamine infu sion. The mean values of IHDVPS and FFR(myo) remained similar, whichever the changes in hemodynamic c onditions. The coefficient of variation between two consecutive measur ements was significantly lower for FFR(myo) (4.2%) than for CFVR (17.7 %) and for IHDVPS (24.7%). Conclusions CFVR is easy to measure but sen sitive to hemodynamic changes. IHDVPS can be measured only in <80% of cases and is highly variable even without changes in hemodynamic condi tions. FFR(myo) is easy to measure and almost independent of hemodynam ic changes.