Instantaneous wave-free ratio (iFR^®) to determine hemodynamically significant coronary stenosis: A comprehensive review

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.

Fractional flow reserve, quantitative flow ratio, and instantaneous wave-free ratio: a comparison of the procedure-related dose of ionising radiation

“…Moreover, an FFR measurement requires intravenous or intracoronary adenosine injection which occasionally may cause drug-related adverse reactions including dyspnoea, chest discomfort, bradycardia, atrioventricular blocks, ventricular arrhythmias, cardiac arrest, asystole and even death [ 10 ]. An iFR is advantageous due to redundancy of adenosine due to exploitation of the natural heart cycle hyperaemic phase [ 11 ]. Its performance and agreement with FFR has been proved in numerous clinical trials [ 12 , 13 ].…”

Bridging the Gap in a Rare Cause of Angina

“…[ 6 , 33 ] Certain studies suggest that iFR ≤0.89 or FFR ≤0.80 with signs of chest pain and heaviness should be managed with medical or surgical intervention. [ 31 ] MB that runs deep (>5 mm deep) should be treated with CABG because it has been shown to be better than surgical myotomy. [ 58 ] MB that is short or intermediate in depth and severity should be treated with medication alone.…”

Endpoint selection for noninferiority percutaneous coronary intervention trials: a methodological description

“…Comprehensive reviews on iFR and FR were recently provided by Baumann and coworkers. 46,47 New clinical endpoints Despite the fact that, to the best of the authors' knowledge, there have been no reports with ST rates as primary endpoints, this potential endpoint is worth mentioning. There is sufficient interest for some novel DES to reduce the DAPT.…”