Physiological Assessment with iFR prior to FFR Measurement in Left Main Disease

Despite guideline-based recommendation of the interchangeable use of instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) to guide revascularization decision-making, iFR/FFR could demonstrate different physiological or clinical outcomes in some specific patient or lesion subsets. Therefore, we sought to investigate the impact of difference between iFR and FFR-guided revascularization decision-making on clinical outcomes in patients with left main disease (LMD). In this international multicenter registry of LMD with physiological interrogation, we identified 275 patients in whom physiological assessment was performed with both iFR/FFR. Major adverse cardiovascular event (MACE) was defined as a composite of death, non-fatal myocardial infarction, and ischemia-driven target lesion revascularization. The receiver-operating characteristic analysis was performed for both iFR/FFR to predict MACE in respective patients in whom revascularization was deferred and performed. In 153 patients of revascularization deferral, MACE occurred in 17.0% patients. The optimal cut-off values of iFR and FFR to predict MACE were 0.88 (specificity:0.74; sensitivity:0.65) and 0.76 (specificity:0.81; sensitivity:0.46), respectively. The area under the curve (AUC) was significantly higher for iFR than FFR (0.74; 95%CI 0.62–0.85 vs. 0.62; 95%CI 0.48–0.75; p = 0.012). In 122 patients of coronary revascularization, MACE occurred in 13.1% patients. The optimal cut-off values of iFR and FFR were 0.92 (specificity:0.93; sensitivity:0.25) and 0.81 (specificity:0.047; sensitivity:1.00), respectively. The AUCs were not significantly different between iFR and FFR (0.57; 95%CI 0.40–0.73 vs. 0.46; 95%CI 0.31–0.61; p = 0.43). While neither baseline iFR nor FFR was predictive of MACE in patients in whom revascularization was performed, iFR-guided deferral seemed to be safer than FFR-guided deferral. Graphical abstract: Impact of Physiological Assessment with iFR and FFR on Clinical Outcomes of Patients with LMD. In the present study, physiological assessment, both with iFR and FFR, provided a high predictability of adverse cardiovascular event in LMD patients with revascularization deferral. Furthermore, the iFR-guided deferral strategy was safer as compared to FFR. Conversely, in patients in whom revascularization was performed for LMD, neither iFR nor FFR was predictive of cardiovascular event. AUC: area under the curve; FFR: fractional flow reserve; iFR: instantaneous wave-free ratio; LMD: left main coronary artery disease. (Figure presented.)