Objectives
We evaluated the diagnostic performance of quantitative flow ratio (QFR) assessment of nonculprit lesions (NCLs) based on acute setting angiograms obtained in patients with ST‐segment elevation myocardial infarction (STEMI) with QFR, fractional flow reserve (FFR), and instantaneous wave‐free ratio (iFR) in the staged setting as reference.
Background
QFR is an angiography‐based approach for the functional evaluation of coronary artery lesions.
Methods
This was a post‐hoc analysis of the iSTEMI study. NCLs were assessed with iFR in the acute setting and with iFR and FFR at staged (median 13 days) follow‐up. Acute and staged QFR values were computed in a core laboratory based on the coronary angiography recordings. Diagnostic cut‐off values were ≤0.80 for QFR and FFR, and ≤0.89 for iFR.
Results
Staged iFR and FFR data were available for 146 NCLs in 112 patients in the iSTEMI study. Among these, QFR analysis was feasible in 103 (71%) lesions assessed in the acute setting with a mean QFR value of 0.82 (IQR: 0.73–0.91). Staged QFR, FFR, and iFR were 0.80 (IQR: 0.70–0.90), 0.81 (IQR: 0.71–0.88), and 0.91 (IQR: 0.87–0.96), respectively. Classification agreement of acute and staged QFR was 93% (95%Cl: 87–99). The classification agreement of acute QFR was 84% (95%CI: 76–90) using staged FFR as reference and 74% (95%CI: 65–83) using staged iFR as reference.
Conclusions
Acute QFR showed a very good diagnostic performance with staged QFR as reference, a good diagnostic performance with staged FFR as reference, and a moderate diagnostic performance with staged iFR as reference.