A Prospective, observational, single center diagnostic study to investigate the the diagnostic agreement between QFR and the pressure wire-based iFR in a real world setting.

During coronary angiography, intermediate stenoses can not be adequately assessed by visual assessment alone. It is necessary to evaluate the functional significance to guide their treatment.

Fractional Flow Reserve (FFR) is the current gold standard for determining this functional significance but its adoption in clinical practice remains low. The instantaneous wave-free ratio (iFR) is an alternative way to determine the flow-limiting characteristics of a coronary stenosis with a pressure wire but without the need to induce hyperemia. Large randomised trials have confirmed the non-inferiority of iFR in respect to FFR in terms of outcome.

Quantitative Flow Ratio (QFR) is another new method for evaluating the functional significance of coronary stenosis It is a software-based analysis of conventional angiographic images to estimate the pressure drop caused by a coronary stenosis. The diagnostic agreement with FFR seemed promising in the FAVOR Pilot Study and a larger trial is enrolling for confirmation.

A stepwise approach of QFR and iFR could make the functional assessment of intermediate stenoses more practical and cost-effective. However before being used as a combination in daily practice, QFR has to be validated in respect to iFR.

The primary objective of the trial is to investigate the diagnostic agreement between QFR and the pressure wire-based iFR in a real world setting

Inclusion Criteria:

• Age > 18 with symptoms of myocardial ischemia and angina or angina equivalent (chest pain, abnormal stress testing, abnormal noninvasive testing)
• Patients witch semi recent (>3 days) acute coronary syndromes can be included but only for the non-culprit vessels and outside of primary intervention during acute myocardial infarction.
• Willing to participate and able to understand, read and sign the informed consent document before the planned procedure
• Eligible for coronary angiography and/or percutaneous coronary intervention
• Coronary artery disease with at least 1 or more visually assessed de novo coronary stenosis (30-90% diameter stenosis) in native major epicardial vessel or its branches by coronary angiogram.

Exclusion criteria:

• Contraindication to adenosine administration
• Previous Coronary Artery Bypass surgery with patent grafts to the interrogated vessel

Patients that undergo angiography because of symptoms of myocardial ischemia and angina or angina equivalent (chest pain, abnormal stress testing or abnormal noninvasive testing) and in whom hemodynamic evaluation of an intermediate stenosis is indicated should be screened and considered for participation in the trial

The trial design is set up to be representative for the patient population that under current guidelines should be evaluated with FFR. Therefore the exclusion criteria are limited to the contraindications for adenosine and previous CABG which would not allow accurate evaluation by FFR and QFR respectively.