Diagnostic Performance of Angiography-Derived FFR According to the Analysis Factors.

Background and objectives: Quantitative flow ratio (QFR) is a method for estimating fractional flow reserve (FFR) without the use of an invasive pressure wire or hyperemic agent. However, the reasons for variation in QFR accuracy across studies and the factors associated with its accuracy remain unclear. The aim of this study was to investigate the diagnostic performance of QFR under different clinical and analysis conditions.

Methods: This multicenter trial prospectively enrolled patients undergoing coronary angiography with an indication for invasive FFR. The composite score for the QFR analysis factors was calculated based on the presence or absence of the angiographic factor, system factor, lesion factor, and subjective difficulty factor. The diagnostic performance of the QFR was assessed for each composite score using FFR ≤0.80 as the reference.

Results: A total of 285 vessels from 239 patients were analyzed. The median FFR and QFR values were 0.83 (interquartile range [IQR], 0.78-0.88) and 0.83 (IQR, 0.76-0.89), respectively. Using FFR ≤0.80 as a reference, QFR showed an overall diagnostic accuracy of 81.4%. Higher composite scores were associated with lower diagnostic performance of QFR in predicting FFR ≤0.80 (p-for-trend=0.010). The diagnostic accuracy of QFR ranged from 94.1% in vessels with low composite scores to 73.7% in those with high composite scores.

Conclusions: The diagnostic accuracy of QFR decreases with increasing lesion complexity, system factors, lower angiographic image quality, and analysis difficulty. These findings suggest that specific lesion, system, and imaging-related factors can significantly impact the reliability of QFR in clinical practice.

Trial registration: ClinicalTrials.gov Identifier: NCT06305572.