Residual pressure gradient across the implanted stent: An important factor of post-PCI physiological results

•Instantaneous wave-free ratio predicted–observed difference was 0.036±0.037.•Residual pressure gradient was an independent risk factor for the failed prediction.•There were two risk factors for the presence of residual pressure gradient. Instantaneous wave-free ratio (iFR) has the potential to improve the accuracy of the prediction of the physiological result of percutaneous coronary intervention (PCI). The aim of this study was to evaluate the accuracy of iFR to predict the final physiological results following PCI, and investigate the factors for failed prediction. In 73 lesions, iFR pullback recordings were measured and comparisons were made between the predicted improvement following PCI and the observed result. iFR predicted–observed difference was 0.036±0.037. Multivariate analysis showed residual iFR pressure gradient across the implanted stent (odds ratio, 2.329; 95% confidence interval, 1.408–3.853; p=0.0010) as an independent risk factor for error in iFR prediction. iFR predicted–observed difference was 0.036±0.037. Residual in-stent iFR pressure gradient following PCI is the only independent risk factor for failed prediction.