# Simplifying the Assessment of Coronary Artery Stenosis by Enhancing Instantaneous Wave-Free Ratio

## TL;DR

This study shows that contrast-enhanced iFR improves accuracy in assessing coronary artery stenosis compared to standard iFR.

## Contribution

Contrast-enhanced iFR (iFRc) is introduced as a more accurate method for evaluating intermediate coronary artery stenosis.

## Key findings

- iFRc showed stronger correlation with FFR (r = 0.710) than standard iFR (r = 0.578).
- iFRc had higher diagnostic performance with an AUC of 0.922 compared to iFR's AUC of 0.856.
- An optimal iFRc cutoff of ≤0.88 achieved high sensitivity and specificity for detecting stenosis.

## Abstract

Background and objective

The intermediate range of instantaneous wave-free ratio (iFR) measurements presents various diagnostic uncertainties. This study aimed to evaluate contrast-enhanced iFR (iFRc) to determine its correlation with fractional flow reserve (FFR). Our objective was to assess whether iFRc improves diagnostic alignment with FFR in coronary artery stenosis with intermediate iFR values (0.86-0.93).

Patients and methods

Thirty patients with intermediate iFR values were enrolled. The measurements included resting Pd/Pa, standard iFR, iFRc, and adenosine-mediated FFR. Detailed procedural protocols, including the type of pressure wire, guiding catheter, and contrast administration, were standardized.

Results

Pearson correlation between iFR and FFR was moderate (r = 0.578, p < 0.001), while iFRc showed a stronger correlation (r = 0.710, p < 0.001). The receiver operating characteristic (ROC) analysis demonstrated superior diagnostic performance for iFRc (area under the ROC curve (AUC) = 0.922, 95% confidence interval (CI): 0.799-1.0) compared with iFR (AUC = 0.856, 95% CI: 0.656-1.0). Optimal iFRc cutoff ≤0.88 yielded 88.9% sensitivity (95% CI: 51.8-99.7), 96% specificity (95% CI: 79.7-99.9), 88.9% positive predictive value (PPV) (95% CI: 51.8-99.7), and 96% negative predictive value (NPV) (95% CI: 79.7-99.9).

Conclusions

iFRc improves diagnostic certainty in intermediate iFR values and shows strong concordance with FFR. However, the findings are hypothesis-generating and warrant larger, multicenter validation studies.