The use of non-hyperaemic indices of stenosis severity in clinical practice

Introduction

Non-hyperaemic indices constitute a further step in the evolution of pressure wire use to evaluate coronary stenosis severity. Although these indices were first developed as a faster, adenosine free, alternative to FFR, available evidence, for iFR in particular, demonstrates that its use results not only in faster and cheaper procedures, with better patient comfort, but also in specific advantages for vessel examination and decision making during PCI. As a result, iFR can now be used to perform accurate longitudinal vessel mapping and co-registration with angiography, allowing prediction of the haemodynamic result of interventions and contributing to accurate stent length selection and placement during PCI. In this chapter we will review the practical aspects of using iFR and other pressure based non-hyperaemic indices that have been recently made available for clinical use.

Background

Physiological assessment of coronary arteries has become an important adjunctive diagnostic technique in the assessment of intermediate stenosis in the catheterisation laboratory. Blood delivery to the myocardium is a function of pressure, flow and resistance in the coronary tree and is altered by the presence of epicardial stenosis. Currently used physiological indices utilise this relationship between pressure, flow and resistance in order to determine the functional relevance of an...