Article Text

Download PDFPDF

Original article
Improvement in coronary haemodynamics after percutaneous coronary intervention: assessment using instantaneous wave-free ratio


Objective To determine whether the instantaneous wave-free ratio (iFR) can detect improvement in stenosis significance after percutaneous coronary intervention (PCI) and compare this with fractional flow reserve (FFR) and whole cycle Pd/Pa.

Design A prospective observational study was undertaken in elective patients scheduled for PCI with FFR ≤0.80. Intracoronary pressures were measured at rest and during adenosine-mediated vasodilatation, before and after PCI. iFR, Pd/Pa and FFR values were calculated using the validated fully automated algorithms.

Setting Coronary catheter laboratories in two UK centres and one in the USA.

Patients 120 coronary stenoses in 112 patients were assessed. The mean age was 63±10 years, while 84% were male; 39% smokers; 33% with diabetes. Mean diameter stenosis was 68±16% by quantitative coronary angiography.

Results Pre-PCI, mean FFR was 0.66±0.14, mean iFR was 0.75±0.21 and mean Pd/Pa 0.83±0.16. PCI increased all indices significantly (FFR 0.89±0.07, p<0.001; iFR 0.94±0.05, p<0.001; Pd/Pa 0.96±0.04, p<0.001). The change in iFR after intervention (0.20±0.21) was similar to ΔFFR 0.22±0.15 (p=0.25). ΔFFR and ΔiFR were significantly larger than resting ΔPd/Pa (0.13±0.16, both p<0.001). Similar incremental changes occurred in patients with a higher prevalence of risk factors for microcirculatory disease such as diabetes and hypertension.

Conclusions iFR and FFR detect the changes in coronary haemodynamics elicited by PCI. FFR and iFR have a significantly larger dynamic range than resting Pd/Pa. iFR might be used to objectively document improvement in coronary haemodynamics following PCI in a similar manner to FFR.


This is an Open Access article distributed in accordance withunder the terms of the Creative Commons Attribution (CC BY 3.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See:

View Full Text

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.