Can we rely on iFR for avoiding FFR? Conclusions of a 5-year experience

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017
Background: Recently, the instantaneous wave free ratio (iFR), has been proposed an alternative or complementary method to fractional flow reserve (FFR). This new method does not require the use of adenosine and may expedite the speed of functional assessment. The iFR “hybrid strategy” relies on values 0,93 as definitive results which would not require the use of FFR. However, this strategy is much less consensual than FFR alone. Purpose: We aimed to assess the concordance of FFR and iFR results using the principle of the “hybrid strategy”, based on the 5-year experience of a single center. We also aimed to analyse the effect of iFR in the operator's decision to proceed to FFR, and its impact on procedure duration and radiation time/dosage. Methods: Single-center registry of all patients undergoing functional coronary lesion assessment during 5 years. FFR was used as a gold standard (with a cut-off point for intervention ≤0,80) for assessing the diagnostic accuracy of iFR in every patient who underwent measurements with both techniques. For analysis purposes, an iFR value 0,93 was considered negative (i.e. defer intervention). Values in between were deemed inconclusive. For statistical analysis we used the T student and Chi-Square tests. Results: Functional testing was undertaken in 326 patients (67±11 years, 65,6% male), encompassing 402 lesions. 154 lesions underwent assessment with both techniques, 222 by FFR only and 26 cases iFR only. The average iFR was 0,9±0,1. 60 lesions had an iFR >0,93 and 21 an iFR 0,93 (71,4% vs 68%; p=0,792). In these cases, there was a statistically significant concordance of 87% between the iFR and FFR results (χ2=22,43; p