Percutaneous coronary intervention (PCI) is warranted if a coronary artery stenosis is hemodynamically important. Through large randomized clinical trials the Fractional flow reserve (FFR) has become an established method to guide PCI as it is superior to angiography alone and improves clinical outcome. The FFR is an index derived from the ratio of the pressure distal to the stenosis versus the pressure proximal to the stenosis during hyperemia, usually by administration of adenosine intravenously.
The instantaneous wave-free ratio (iFR) is a recently developed method to guide PCI and to determine the severity of a coronary stenosis that correlates closely with FFR. The index is measured in a wave-free diastolic window when resistance is stable without requiring an hyperemic agent.
The last year two large randomized trials have shown concordant results regarding non-inferiority of iFR-guided revascularization versus FFR-guided revascularization with respect to the rate of major adverse cardiac events (MACE) at one year. The iFR significantly reduces chest discomfort and in one of the trials the procedural time was significantly shorter.
The results of the two studies have lead to that it now appears that iFR may be the new standard for evaluation of intermediate lesions in patients with stable angina. However, there are still issues that remain unanswered and physiologically measuring of the coronary arteries are not as implemented as it should be in every day clinical practice. The aim of this project is to answer the questions that remain unanswered.