Predictors of discordance between fractional flow reserve and instantaneous wave-free ratio in the real world

Abstract

Introduction: Invasive physiologic variables such as fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are used in clinical practice to assess the functional significance of epicardial coronary stenosis and guide the management. However, these two variables may show discrepancies when binary cut-offs are used to decide for revascularization strategy. We investigated the clinical characteristics of lesions with discordance between iFR and FFR. Methodology: 256 vessels (220 patients mean age 61 ± 12, 77% males) with available pre-intervention FFR and iFR values were included in the study. The vessels were classified according to FFR and iFR into concordant normal (Group 1 [n = 112]; FFR > 0.8 and iFR > 0.89); discordant with abnormal FFR and normal iFR (Group 2 [n = 12); FFR 0.89); discordant with normal FFR and abnormal iFR (Group 3 [n = 43], FFR > 0.8 and iFR < 0.89) and concordant abnormal (Group 4 [n = 89]FFR < 0.8 and iFR < 0.89). Results: Haemodynamically significant lesions were found in 51.5% and 40% for FFR and iFR respectively. Overall, 22% of lesions were discordant with a significantly higher number of females showing disagreement than males (p < 0.001); 5% of the lesions showed Group 2 discordance (abnormal FFR and normal iFR) and some 17% showed Group 3 discordance (normal FFR and abnormal iFR). In a multivariate GEE model, Group 2 discordance was more likely to be associated with male gender, absence of hypertension, diabetes and high percent diameter stenosis (all p < 0.001). Conversely, Group 3 discordance was more likely to be associated with female gender, diagnosis of diabetes and hypertension, and lower percent diameter stenosis (all p < 0.001). Conclusion: Our study shows that almost a quarter of lesions show discordance for FFR and iFR with a female preponderance. The four groups classified according to FFR and iFR are characterized by differences in clinical characteristics and predictors of discordance. The lesions with discordant FFR and iFR may have a different pathophysiology which warrants further investigation.