Pre-Angioplasty Instantaneous Wave-Free Ratio Pullback Predicts Hemodynamic Outcome In Humans With Coronary Artery Disease: Primary Results of the International Multicenter iFR GRADIENT Registry

Objectives: The authors sought to evaluate the accuracy of instantaneous wave-Free Ratio (iFR) pullback measurements to predict post-percutaneous coronary intervention (PCI) physiological outcomes, and to quantify how often iFR pullback alters PCI strategy in real-world clinical settings. Background: In tandem and diffuse disease, offline analysis of continuous iFR pullback measurement has previously been demonstrated to accurately predict the physiological outcome of revascularization. However, the accuracy of the online analysis approach (iFR pullback) remains untested. Methods: Angiographically intermediate tandem and/or diffuse lesions were entered into the international, multicenter iFR GRADIENT (Single instantaneous wave-Free Ratio Pullback Pre-Angioplasty Predicts Hemodynamic Outcome Without Wedge Pressure in Human Coronary Artery Disease) registry. Operators were asked to submit their procedural strategy after angiography alone and then after iFR-pullback measurement incorporating virtual PCI and post-PCI iFR prediction. PCI was performed according to standard clinical practice. Following PCI, repeat iFR assessment was performed and the actual versus predicted post-PCI iFR values compared. Results: Mean age was 67 ± 12 years (81% male). Paired pre- and post-PCI iFR were measured in 128 patients (134 vessels). The predicted post-PCI iFR calculated online was 0.93 ± 0.05; observed actual iFR was 0.92 ± 0.06. iFR pullback predicted the post-PCI iFR outcome with 1.4 ± 0.5% error. In comparison to angiography-based decision making, after iFR pullback, decision making was changed in 52 (31%) of vessels; with a reduction in lesion number (−0.18 ± 0.05 lesion/vessel; p = 0.0001) and length (−4.4 ± 1.0 mm/vessel; p < 0.0001). Conclusions: In tandem and diffuse coronary disease, iFR pullback predicted the physiological outcome of PCI with a high degree of accuracy. Compared with angiography alone, availability of iFR pullback altered revascularization procedural planning in nearly one-third of patients.