Hybrid Instantaneous Wave-Free Ratio–Fractional Flow Reserve versus Fractional Flow Reserve in the Real World

Abstract

BackgroundThe instantaneous wave-free ratio (iFR) is a novel method to assess the ischemic potential of coronary artery stenoses. Clinical trial data have shown that iFR has acceptable diagnostic agreement with fractional flow reserve (FFR), the reference standard for the functional assessment of coronary stenoses. This study compares iFR measurements with FFR measurements in a real world, single-center setting.Methods and resultsInstantaneous wave-free ratio and FFR were measured in 50 coronary artery lesions in 42 patients, with FFR ≤ 0.8 classified as functionally significant. An iFR-only technique, using a treatment cut-off value, iFR ≤ 0.89, provided a classification agreement of 84% with FFR ≤ 0.80. Use of a hybrid iFR–FFR technique, incorporating FFR measurement for lesions within the iFR gray zone of 0.86–0.93, would improve classification agreement with FFR to 94%, with diagnosis achieved without the need for hyperemia in 57% patients.ConclusionThis study in a real-world setting demonstrated good classification agreement between iFR and FFR. Use of a hybrid iFR–FFR technique would achieve high diagnostic accuracy while minimizing adenosine use, compared with routine FFR.

High precision invasive FFR, low‐cost invasive iFR, or non‐invasive CFR?: optimum assessment of coronary artery stenosis based on the patient‐specific computational models

“…This conflict is exactly in the range of 0.86 ≤ iFR ≤0.93. Consequently, similar to the clinical studies by Petraco et al 70 and Shuttleworth et al, 71 the current numerical study agrees with the hybrid strategy to assess the physiological significance of coronary artery stenosis. According to this hybrid strategy, at first, the iFR test is implemented on patients.…”

“…According to Figure 7A, the slope of fitted curves on the data has improved during hyperemia, for both clinical and numerical studies, and has got closer to Y = X. Besides, Petraco et al 70 and Shuttleworth et al 71 have addressed some concerns regarding the differences between iFR and FFR in the range of 0.86 ≤ iFR ≤0.93. They believed that, in the mentioned range, the results of iFR could not predict epicardial stenosis severity and the FFR test had to be implemented.…”

“…Thus, these studies recommended using iFR instead of FFR in order to eliminate the risk of adenosine injection and also to minimize the cost. Nevertheless, the reliability of iFR still undergoes significant scrutiny and debate 16,70,71 . For instance, Berry et al 16 clinically have shown that iFR is not completely independent of the coronary hyperemia.…”

“…Nevertheless, the reliability of iFR still undergoes significant scrutiny and debate. 16,70,71 For instance, Berry et al 16 clinically have shown that iFR is not completely independent of the coronary hyperemia. This result is also indicated numerically with the data of this simulation and is depicted in Figure 7A.…”

Invasive physiological indices to determine the functional significance of coronary stenosis

“…iFR can also be used by way of a hybrid approach whereby iFR <0.86 is considered functionally significant and iFR >0.93 is considered not functionally significant, and if iFR falls within the grey zone of between 0.86 and 0.93, then the operator should perform FFR. The hybrid iFR approach can correctly classify patients into functionally significant or non-significant FFR 95% of the time, and obviated the need for adenosine 57% of the time [ 15 , 16 ]. Using this approach in the ADVISE II study, which involved 598 patients, resulted in 94.2% agreement between iFR and FFR, and eliminated the need for adenosine in 69.1% of the time [ 17 ].…”