A randomized comparison of 4 doses of intracoronary adenosine in the assessment of fractional flow reserve.

BACKGROUND

Fractional flow reserve (FFR) is a measure of coronary stenosis severity that is based on pressure measurements obtained at maximal hyperemia. Therefore, achievement of maximal vasodilatation of the coronary microcirculation is a prerequisite for the measurement of FFR. The study was designed to address the hypothesis that intracoronary adenosine yields more complete vasodilatation of the coronary microcirculation when high doses are used, resulting in a more accurate FFR measurement.

METHODS

Thirty-six patients with 43 moderate lesions underwent determination of FFR during cardiac catheterization. FFR was calculated in all lesions as the ratio of the distal coronary pressure to the aortic pressure at hyperemia. Different incremental doses of intracoronary adenosine (16, 24, 32 and 40 microg for both coronary arteries) were administered in a randomized fashion.

RESULTS

No adverse events occurred with any intracoronary adenosine bolus. At baseline there were no significant differences for mean aortic and distal coronary pressure, heart rate as well as FFR values between the different doses. FFR was not significantly altered from the different incremental adenosine doses. However, in 27 (63%) out of 43 lesions there was a further reduction of FFR up to 0.23 when a dose >16 microg was injected.

CONCLUSIONS

This study suggests that doses of adenosine up to 40 microg are safe and can be used to achieve a more pronounced vasodilatation in individual patients compared to the standard doses. This may have therapeutic impact with FFR values near cut-off points in patients undergoing diagnostic coronary angiography as well as in patients in whom FFR is used to assess the outcome of interventions.