Instantaneous Wave-Free Ratio for the Assessment of Intermediate Coronary Artery Stenosis in Patients With Severe Aortic Valve Stenosis: Comparison With Myocardial Perfusion Scintigraphy.

Objectives: This study investigated the diagnostic performance of instantaneous wave-free ratio (iFR) in patients with aortic valve stenosis (AS).

Background: The iFR was introduced as a new, nonpharmacologic stress index of coronary stenosis severity. However, the diagnostic performance of iFR has not been sufficiently explored in patients with severe AS.

Methods: We analyzed 95 consecutive patients with AS (57 women) demonstrating intermediate coronary artery stenosis (116 vessels), and compared the iFR values with fractional flow reserve (FFR) values and with adenosine-stress myocardial perfusion imaging as indicators of myocardial ischemia.

Results: The median value and interquartile range (first quartile [Q1], third quartile [Q3]) of the iFR was 0.86 (Q1 to Q3 range, 0.76 to 0.93), and that of the FFR was 0.84 (Q1 to Q3 range, 0.76 to 0.91). The iFR values correlated well with the FFR values (R = 0.854; p < 0.0001). A receiver operating characteristic analysis demonstrated an optimal cutoff of 0.82 for the iFR to indicate an FFR ≤0.75, with an area under the curve of 0.92. The optimal iFR cutoff value indicating myocardial ischemia on perfusion scintigraphy was 0.82 (area under the curve: 0.84).

Conclusions: In patients with severe AS, a good correlation exists between iFR and FFR. Both the iFR and FFR values exhibit good correlation with perfusion scintigraphy-identified myocardial ischemia. The iFR could be a safe diagnostic tool for patients with severe AS. (The Impact of FFR and iFR in Patients with Severe Aortic Stenosis; UMIN000024479).