Maximal hyperemia in the assessment of fractional flow reserve: intracoronary adenosine versus intracoronary sodium nitroprusside versus intravenous adenosine: the NASCI (Nitroprussiato versus Adenosina nelle Stenosi Coronariche Intermedie) study.

OBJECTIVES

This study sought to compare increasing doses of intracoronary (i.c.) adenosine or i.c. sodium nitroprusside versus intravenous (i.v.) adenosine for fractional flow reserve (FFR) assessment.

BACKGROUND

Maximal hyperemia is the critical prerequisite for FFR assessment. Despite i.v. adenosine currently representing the recommended approach, i.c. administration of adenosine or other coronary vasodilators constitutes a valuable alternative in everyday practice. However, it is surprisingly unclear which i.c. strategy allows the achievement of FFR values comparable to i.v. adenosine.

METHODS

Fifty intermediate coronary stenoses (n = 45) undergoing FFR measurement were prospectively and consecutively enrolled. Hyperemia was sequentially induced by incremental boli of i.c. adenosine (ADN) (60 μg ADN60, 300 μg ADN300, 600 μg ADN600), by i.c. sodium nitroprusside (NTP) (0.6 μg/kg bolus) and by i.v. adenosine infusion (IVADN) (140 μg/kg/min). FFR values, symptoms, and development of atrioventricular block were recorded.

RESULTS

Incremental doses of i.c. adenosine and NTP were well tolerated and associated with fewer symptoms than IVADN. Intracoronary adenosine doses (0.881 ± 0.067, 0.871 ± 0.068, and 0.868 ± 0.070 with ADN60, ADN300, and ADN600, respectively) and NTP (0.892 ± 0.072) induced a significant decrease of FFR compared with baseline levels (p < 0.001). Notably, ADN600 only was associated with FFR values similar to IVADN (0.867 ± 0.072, p = 0.28). Among the 10 patients with FFR values ≤0.80 with IVADN, 5 were correctly identified also by ADN60, 6 by ADN300, 7 by ADN600, and 6 by NTP.

CONCLUSIONS

Intracoronary adenosine, at doses higher than currently suggested, allows obtaining FFR values similar to i.v. adenosine. Intravenous adenosine, which remains the gold standard, might thus be reserved for those lesions with equivocal FFR values after high (up to 600 μg) i.c. adenosine doses.