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World J Cardiol. Dec 26, 2018; 10(12): 267-277
Published online Dec 26, 2018. doi: 10.4330/wjc.v10.i12.267
Instantaneous wave-free ratio (iFR®) to determine hemodynamically significant coronary stenosis: A comprehensive review
Stefan Baumann, Leonard Chandra, Elizaveta Skarga, Matthias Renker, Martin Borggrefe, Ibrahim Akin, Dirk Lossnitzer
Stefan Baumann, Leonard Chandra, Elizaveta Skarga, Martin Borggrefe, Ibrahim Akin, Dirk Lossnitzer, First Department of Medicine-Cardiology, University Medical Center Mannheim, Mannheim, Germany and DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Mannheim 68167, Baden-Württemberg, Germany
Matthias Renker, Department of Cardiology, Kerckhoff-Klinik GmbH, Bad Nauheim 61231, Hesse, Germany
Author contributions: All authors contributed equally to the conception of the literature review and the drafting, critical revision, and editing of the paper. All authors approved the final version of the manuscript.
Conflict-of-interest statement: Dr. Baumann is a consultant for Volcano Corporation Koninklijke Philips N.V. (Amsterdam, Netherlands). All other authors declare that they have no financial disclosure.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author to: Stefan Baumann, MD, Doctor, First Department of Medicine-Cardiology, University Medical Center Mannheim, Mannheim, Germany and DZHK (German Center for Cardiovascular Research), partner site Heidelberg/Mannheim, Theodor-Kutzer-Ufer 1-3, Mannheim 68167, Baden-Württemberg, Germany. stefan.baumann@umm.de
Telephone: +49-621-3834701 Fax: +49-621-3832025
Received: August 25, 2018
Peer-review started: August 25, 2018
First decision: October 5, 2018
Revised: October 23, 2018
Accepted: November 26, 2018
Article in press: November 27, 2018
Published online: December 26, 2018
Abstract

Coronary angiography is considered to be the gold standard in the morphological evaluation of coronary artery stenosis. The morphological assessment of the severity of a coronary lesion is very subjective. Thus, the invasive fractional flow reserve (FFR) measurement represents the current standard for estimation of the hemodynamic significance of coronary artery stenosis. The FFR-guided revascularization strategy was initially classified as a Class-IA-recommendation in the 2014 European Society of Cardiology/European Association for Cardio-Thoracic Surgery guidelines on myocardial revascularization. Both the Deferral vs Performance of Percutaneous Coronary Intervention of Functionally Non-Significant Coronary Stenosis and Flow Reserve vs Angiography for Multivessel Evaluation studies showed no treatment advantage for hemodynamically insignificant stenoses. With the help of FFR (and targeted interventions), clinical results could be improved; however, the use in clinical practice is still limited due to the need of adenosine administration and a significant prolongation of the length of the procedure. Instantaneous wave-free ratio (iFR®) is a new innovative approach for the determination of the hemodynamic significance of coronary stenosis, which can be obtained at rest without the use of vasodilators. Regarding the periprocedural complications as well as prognosis, iFR® showed non-inferiority to FFR in the SWEDEHEART and DEFINE-FLAIR trials. Furthermore, iFR®, enhanced by iFR®-pullback, provides the possibility to display the iFR®-change over the course of the vessel to create a hemodynamic map.

Keywords: Coronary stenosis, Coronary angiography, Fractional flow reserve, Instantaneous wave-free ratio, Myocardial ischemia, Coronary revascularization

Core tip: Invasive fractional flow reserve measurement represents the current standard for estimation of the hemodynamic significance of coronary artery stenosis and was initially classified as a Class-IA-recommendation in the 2014 European Society of Cardiology/European Association for Cardio-Thoracic Surgery guidelines on myocardial revascularization. Instantaneous wave-free ratio (iFR®) is a new innovative approach for the functional evaluation of a coronary stenosis, which can be obtained at rest without the use of vasodilators. The diagnostic value of iFR® showed non-inferiority compared to fractional flow reserve. It can be enhanced by iFR®-pullback, which provides the possibility to display the iFR®-change over the course of the vessel to create a hemodynamic map.