Fractional flow reserve derived from microcatheters versus standard pressure wires: a stenosis-level meta-analysis

To determine the agreement between sensor-tipped microcatheter (MC) and pressure wire (PW)-derived fractional flow reserve (FFR).

Studies comparing FFR obtained from MC (FFR_MC, Navvus Microcatheter System, ACIST Medical Systems, Eden Prairie, Minnesota, USA) versus standard PW (FFR_PW) were identified, and a meta-analysis of numerical and categorical agreement was performed. The relative levels of drift and device failure of MC and PW systems from each study were assessed. Six studies with 440 lesions (413 patients) were included. The mean overall bias between FFR_MC and FFR_PW was -0.029 (FFR_MC lower). Bias and variance were greater for lesions with lower FFR_PW (p<0.001). Using a cut-off of 0.80, 18 % of lesions were reclassified by FFR_MC versus FFR_PW (with 15 % being false positives). The difference in reported drift between FFR_PW and FFR_MC was small. Device failure was more common with MC than PW (7.1% vs 2%).

FFR_MC systematically overestimates lesion severity, with increased bias in more severe lesions. Using FFR_MC changes revascularisation guidance in approximately one out of every five cases. PW drift was similar between systems. Device failure was higher with MC.