Hemodynamic and Lesion Characteristics Associated with Discordance between the Instantaneous Wave-Free Ratio and Fractional Flow Reserve

Abstract

Background. The instantaneous wave-free ratio (iFR) is an invasive coronary physiological index that is not inferior to fractional flow reserve- (FFR-) guided revascularization. The indexes of iFR and FFR are similar and closely correlated, but there are a few key differences. Previous studies suggested that patient characteristics and lesion severity could induce discordance between iFR and FFR. This study aimed to clarify the hemodynamics and lesion characteristics that influence discordance between iFR and FFR. Methods. In this retrospective study, we enrolled 225 patients (304 lesions) who underwent clinically indicated invasive coronary angiography and both iFR and FFR examinations between 2012 and 2017. We included only patients who underwent right heart catheterization and had blood pressure and heart rates recorded immediately prior to iFR and FFR. Results. Discordance (iFR ≤0.89 and FFR >0.8 or iFR >0.89 and FFR ≤0.8) was observed in 80 lesions (26.3%). The heart rate, rate-pressure product, and cardiac index tended to be higher in the iFR ≤0.89 group than in the iFR >0.89 group. These trends were not seen between the FFR ≤0.8 group and FFR >0.8 group. A multivariate analysis showed that independent predictors of iFR ≤0.89 and FFR >0.8 discordance were female sex and higher rate-pressure product. iFR >0.89 and FFR ≤0.8 discordance was rare in hemodialysis patients. Conclusion. Even if iFR is functionally significant in intermediate stenosis, additional FFR evaluations should be considered for women, especially those with a high rate-pressure product, to avoid unnecessary percutaneous coronary intervention. If iFR is not functionally significant with intermediate stenosis in hemodialysis patients, then further FFR evaluations are unnecessary.

Comparison of Resting Full-Cycle Ratio and Fractional Flow Reserve in a German Real-World Cohort

“…Two randomized trials have demonstrated that iFR-guided treatment is non-inferior to FFR-guided treatment (11,12), while other NHPRs were not yet validated in randomized trials. However, discrepancies between NHPRs and FFR have been reported, and literature about this topic is growing (17,20,25), but still limited by a small number of examined patients (26).…”

“…This might be caused by limitations such as the assumption of maximal flow and minimal resistance occurring during the wave-free period of the diastole, which is the rationale of iFR (17,18). Several clinical, angiographic, and hemodynamic factors contribute to iFR/FFR discordance (19)(20)(21). Available data do not represent a broader population in a real-world setting.…”

Non-hyperaemic pressure ratios to guide percutaneous coronary intervention

“…49 89 Other areas where discordance has been identified include the pattern of coronary disease (focal vs diffuse), 90 and patient characteristics such as gender, presence of diabetes mellitus and beta blocker use. [91][92][93][94] A summary of these discordant groups associated with FFR and iFR is presented in table 2.…”

Stability of Flow Velocity and Intracoronary Resistance in the Intracoronary Electrocardiogram-triggered Pressure Ratio

“…Furthermore, we have previously reported that the prolongation of the QTUc during papaverine-induced hyperemia markedly lowered the iFR values [11]. However, the WFP is de ned as representing approximately 75% of mid to late diastole, excluding the initial 25% and the nal 5 msec, and neither myocardial activation nor the repolarization time changes the proportion of the WFP in diastole [8,21. The heart rate was an important factor accounting for the discrepancy between the ischemic diagnosis of FFR and the iFR because the heart rate only affected the iFR value and not the FFR value [22,23]. Therefore, distinguishing the low intracoronary resistance phase from the aortic pressure might be di cult.…”