Impact of stenosis resistance and coronary flow capacity on fractional flow reserve and instantaneous wave-free ratio discordance: a combined analysis of DEFINE-FLOW and IDEAL

Abstract

Background: The pressure-derived parameters fractional flow reserve (FFR) and the emerging instantaneous wave-free ratio (iFR) are the most widely applied invasive coronary physiology indices to guide revascularisation. However, approximately 15-20% of intermediate stenoses show discordant FFR and iFR, and therapeutical consensus is lacking.

Aims: We sought to associate hyperaemic stenosis resistance index, coronary flow reserve (CFR) and coronary flow capacity (CFC) to FFR/iFR discordance.

Methods: We assessed pressure and flow measurements of 647 intermediate lesions (593 patients) of two multi-centre international studies.

Results: FFR and iFR were discordant in 15% of all lesions (97 out of 647). FFR+/iFR- lesions had similar hyperaemic average peak velocity (hAPV), CFR and CFC as FFR-/iFR- lesions, whereas FFR-/iFR+ lesions had similar hAPV, CFR and CFC as FFR+/iFR+ lesions (p > 0.05 for all). FFR+/iFR- lesions were associated with lower baseline stenosis resistance, but not hyperaemic stenosis resistance, compared with FFR-/iFR+ lesions (p < 0.001).

Conclusions: Discordance with FFR+/iFR- is characterised by maximal flow values, CFR, and CFC patterns similar to FFR-/iFR- concordance that justifies conservative therapy. Discordance with FFR-/iFR+ on the other hand, is characterised by low flow values, CFR, and CFC patterns similar to iFR+/FFR+ concordance that may benefit from percutaneous coronary intervention.

Keywords: Coronary flow capacity; Coronary flow reserve; Fractional flow reserve; Instantaneous wave-free ratio.