Association Between FFR_CT and Instantaneous Wave-Free Ratio (iFR) of Intermediate Lesions on Coronary Computed Tomography Angiography

Background: New data suggests long term outcomes of coronary revascularization based on instantaneous wave free ratio (iFR) are equivalent to invasive fractional flow reserve (FFR). We aimed to evaluate the correlation between non-invasive FFR derived from cardiac CT (FFR_CT) and iFR. Methods: Data from 21 patients with 26 vessels, who underwent both FFR_CT computation and invasive iFR measurement, were analysed. We evaluated diagnostic performance of FFR_CT according to two cut-off values of ≤0.80 and ≤0.70 with iFR ≤0.89 as the reference standard. Results: In a per vessel analysis, the average diameter stenosis was 59%, mean FFR_CT was 0.81 while mean iFR was 0.90. Using an FFR_CT cut-off of 0.80, the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy for FFR_CT were 86%, 84%, 67%, 94%, and 85% respectively. When the cut-off was lowered to 0.70, the sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy for FFR_CT were 57%, 100%, 100%, 86% and 88% respectively. Conclusion: FFR_CT correlates well with iFR in this small retrospective study. Larger studies are required to confirm this finding.