The Wire-free Invasive Functional Imaging (WIFI) Study

Background:

Patients at high risk of having one or more coronary stenosis are evaluated routinely by invasive coronary angiography (CAG) and often in combination with measurement of fractional flow reserve (FFR) to assess the functional significance of identified stenosis. FFR is assessed during CAG by advancing a wire with a pressure transducer towards the stenosis and measure the ratio in pressure between the two sides of the stenosis during maximum blood flow (hyperaemia) induced by adenosine infusion.

The solid evidence for FFR evaluation of coronary stenosis and the relative simplicity in performing the measurements have supported adoption of an FFR based strategy in many centers but the need for interrogating the stenosis by a pressure wire and the cost of the wire and the drug inducing hyperaemia limits more widespread adoption.

Quantitative Flow Ratio is a novel method for evaluating the functional significance of coronary stenosis by calculation of the pressure in the vessel based on two angiographic projections.

The purpose of the WIFI study is to evaluate feasibility of QFR when performed during coronary angiography and compare diagnostic accuracy to standard FFR.

Hypothesis:

QFR can be assessed during CAG for stenosis interrogated by FFR

Methods:

Proof-of-concept, prospective, observational, single arm study with inclusion of 100 patients. Clinical follow-up by telephone call after one year.

A stenosis with indication for FFR is identified and at least two angiographic projections rotated at least 25 degrees around the target vessel are acquired during resting conditions. QFR is calculated on-line using the Medis Suite application and simultaneously to the operator performing the FFR measurement using I.V. adenosine. The QFR observer is blinded to the FFR measurement.

QFR is reassessed off-line by internal observer and by an external core laboratory. Both blinded to FFR results.

FFR is assessed in core laboratory by a different blinded observer

All data are entered and stored in a protected and logged trial management system (TrialPartner).

Inclusion criteria

• Stable angina pectoris and secondary evaluation of stenosis after acute myocardial infarction (AMI)
• Age > 18 years
• Signed informed consent

Exclusion criteria

• Myocardial infarction within 72 hours
• Severe asthma and chronic obstructive pulmonary disease
• Severe heart failure (NYHA≥III)
• S-creatinine>120µmol/L
• Allergy to contrast media or adenosine
• Stenosis in vein graft
• Ostial left main stenosis
• Severe tortuosity
• Atrial fibrillation