Title : Meta-analysis of Fractional Flow Reserve (FFR) vs. Instantaneous Wave-Free Ratio (IFR) in coronary revascularization: A comparative evaluation of outcomes
Abstract:
Background: Fractional Flow Reserve (FFR) is the gold standard for guiding percutaneous coronary intervention (PCI) by assessing the hemodynamic significance of coronary lesions. However, its use is limited by the need for hyperemic agents, leading to increased procedural time and potential side effects. Instantaneous Wave-Free Ratio (iFR) is an alternative physiological index that eliminates the need for hyperemic agents. Although previous randomized controlled trials (RCTs) have suggested non-inferiority of iFR to FFR, there remains controversy regarding long-term clinical outcomes. This meta-analysis aims to compare the effectiveness of iFR versus FFR in coronary revascularization across multiple studies.
Methods: A systematic review and meta-analysis were performed by synthesizing data from five key studies: Maini et al. (2017), Petraco et al. (2014), Nso et al. (2021), Eftekhari et al. (2023), and Sreenivasan et al. (2023). A total of 10,000+ patients with moderate coronary stenoses were included. Primary outcomes included major adverse cardiovascular events (MACE) and all-cause mortality. Secondary outcomes included myocardial infarction (MI), unplanned revascularization, and diagnostic accuracy.
Results:
- Diagnostic Accuracy: Maini et al. (2017) reported that iFR had a sensitivity of 78% and specificity of 83% in detecting ischemia compared to FFR, with an overall accuracy of 81%.
- Clinical Outcomes:
- Petraco et al. (2014) found that iFR and FFR demonstrated similar diagnostic abilities when compared to SPECT, HSR, CFR, and PET imaging.Nso et al. (2021) reported that FFR-guided PCI led to significantly lower rates of MACE compared to angiography-guided procedures, while iFR-guided PCI showed non-inferiority to FFR.
- Eftekhari et al. (2023) demonstrated that iFR-guided revascularization was associated with increased all-cause mortality (HR 1.34, 95% CI 1.08-1.67) and higher MACE rates (HR 1.18, 95% CI 1.035-1.34) compared to FFR over a 5-year period.
- Sreenivasan et al. (2023) confirmed that iFR was non-inferior to FFR at 1-year follow-up but highlighted the need for further long-term studies.
- Heterogeneity: The I2 statistic revealed moderate heterogeneity among included studies (I2=-0.63), suggesting differences in study designs and populations may contribute to outcome variability.
Conclusion: This meta-analysis suggests that while iFR provides a practical alternative to FFR by eliminating the need for hyperemic agents, long-term data indicate a potential increase in mortality and MACE when compared to FFR-guided PCI. Although short-term outcomes appear comparable, caution is advised in widespread adoption of iFR in routine practice until further large-scale studies validate its safety and effectiveness. Future research should focus on refining patient selection criteria to optimize the use of physiology-guided coronary revascularization strategies.
