Effects of caffeine on fractional flow reserve values measured using intravenous adenosine triphosphate.

Abstract

We investigated the effects of caffeine intake on fractional flow reserve (FFR) values measured using intravenous adenosine triphosphate (ATP) before cardiac catheterization. Caffeine is a competitive antagonist for adenosine receptors; however, it is unclear whether this antagonism affects FFR values. Patients were evenly randomized into 2 groups preceding the FFR study. In the caffeine group (n=15), participants were given coffee containing 222mg of caffeine 2h before the catheterization. In the non-caffeine group (n=15), participants were instructed not to take any caffeine-containing drinks or foods for at least 12h before the catheterization. FFR was performed in patients with more than intermediate coronary stenosis using the intravenous infusion of ATP at 140μg/kg/min (normal dose) and 170μg/kg/min (high dose), and the intracoronary infusion of papaverine. FFR was followed for 30s after maximal hyperemia. In the non-caffeine group, the FFR values measured with ATP infusion were not significantly different from those measured with papaverine infusion. However, in the caffeine group, the FFR values were significantly higher after ATP infusion than after papaverine infusion (P=0.002 and P=0.007, at normal and high dose ATP vs. papaverine, respectively). FFR values with ATP infusion were significantly increased 30s after maximal hyperemia (P=0.001 and P<0.001 for normal and high dose ATP, respectively). The stability of the FFR values using papaverine showed no significant difference between the 2 groups. Caffeine intake before the FFR study affected FFR values and their stability. These effects could not be reversed by an increased ATP dose.