A Validation Study of Image-Based Fractional Flow Reserve (FFR_angio) during Coronary Angiography

Background:
Fractional flow reserve (FFR) is considered the standard of care for evaluating the functional severity of coronary stenosis and the expected benefit from revascularization. Angiography-derived FFR measurements (FFR_angio) may have several advantages.

Objective:
To evaluate the diagnostic performance (accuracy and reproducibility) of angiography-based FFR (FFR_angio) in comparison with invasive FFR.

Methods:
FFR_angio is a novel technology providing functional angiographic mapping of the coronaries in 3D. It is based on a dynamically-derived model of flow that can assess FFR using routine angiograms while integrating hemodynamic data.

Results:
A total of 203 lesions were analyzed in 184 patients from 4 centers. Values derived using FFRangio ranged from 0.5 to 0.97 (Median 0.85) and correlated closely (Spearman’s ρ=0.90, P<0.001) with the invasive FFR measurements (0.5 to 1, Median 0.84). In Bland-Altman analyses, the 95% limits of agreement between these methods ranged from -0.096 to 0.112. Using an FFR cut-off value of 0.80, the sensitivity, specificity, and diagnostic accuracy of FFRangio were 88%, 95%, and 94%, respectively. In receiver operator characteristic analyses, FFRangio had a significantly higher c-statistic, denoting its superior predictive value compared to percent diameter stenosis determined visually or by two-dimensional quantitative angiographic assessment (P<0.05). The intra-class coefficient between 2 blinded operators was 0.962 with a 95% confidence interval from 0.950 to 0.971, P< 0.001.

Conclusions:
FFR_angio demonstrated an excellent concordance with invasive FFR in this multi-center cohort of patients in whom the measurements were performed in a blinded manner. If these data can be further validated prospectively, FFR_angio may be a promising and less invasive adjunctive diagnostic tool to foster clinical decision-making in patients with coronary artery disease.