Comparison of the novel vasodilator uridine triphosphate and adenosine for the measurement of fractional flow reserve.

Aim. Examination of the fractional flow reserve [FFR] responses of intravenous [IV] adenosine with increasing doses of intracoronary [IC] adenosine versus IC uridine triphosphate [UTP] in patients with coronary artery disease. Methods and Results. We measured FFR in 25 patients during continuous IV and IC infusion [using a microcatheter in the coronary ostium]. Standard IV adenosine infusion [140 mu g/kg/min] was compared to 8 equimolar incremental doses of IC UTP and IC adenosine [20, 40, 60, 80, 160, 240, 320 and 640 mu g/min] in a randomized order. Across all doses, Delta FFRIC (UTP) (-) (IC) (adenosine) was -0.038 +/- 0.008, P<.001. At the highest dose of IC UTP, FFR was significantly lower [FFRIC UTP = 0.62 +/- 0.04] than during IV adenosine [FFIV adenosine = 0.72 +/- 0.05; P=.02] and IC adenosine [FFRIc (adenosine) = 0.68 +/- 0.05, P=.03]. Furthermore, UTP had significantly fewer side effects compared to IV [P<.001] and IC adenosine [P<.05]. Conclusion. IC UTP lowered FFR significantly more than both IV and IC adenosine and with fewer side effects, and could be a more precise alternative to adenosine.