Accuracy of instantaneous wave-free ratio and fractional flow reserve derived from single coronary angiographic projections.

Background: Angiography-derived fractional flow reserve (FFR) software has been developed using pressure wire based FFR as the reference, however most software requires 2 angiographic views ≥25 degrees apart limiting their clinical utility. This study aims to validate in a prospective multi-center registry the diagnostic performance of a novel angiography derived instantaneous wave-free ratio (Angio-iFR, Royal Philips, Amsterdam) with pressure wire-based iFR as reference.

Methods: Coronary angiograms were obtained from patients with coronary artery lesions of between 40% and 90% severity and both iFR and FFR measurements. The pressure wire's position was documented during contrast injection in 2 angiographic views. Angio-iFR/FFR was computed at this exact position by independent corelab analysts blinded to physiological data. The primary end point was the sensitivity and specificity of the Angio-iFR compared to the corresponding invasively measured iFR values. The study was powered to meet prespecified performance goals for sensitivity (75%) and specificity (80%).

Results: A total of 441 patients were enrolled in 32 centers in Europe, Japan, and the United States. Paired Angio-iFR and wire-iFR were available in 398 vessels. The mean iFR was 0.90 (standard deviation: 0.11) with 31.9% of vessels having an iFR≤0.89. Angio-iFR software showed excellent feasibility (97%), and a median analysis time of 55 s. The per-vessel sensitivity and specificity of Angio-iFR was 77% (95% confidence interval [CI]: 69%-84%) and 49% (95% CI: 41%-54%) respectively, which fell below the performance goals.

Conclusions: Angio-iFR did not achieve prespecified diagnostic performance against pressure wire-based iFR. Further software refinements are warranted.

Trial Registration: Radiographic Imaging Validation and EvALuation for Angio iFR (ReVEAL iFR), NCT0385750, https://clinicaltrials.gov/study/NCT03857503.