Diagnostic Accuracy of On-line Quantitative Flow Ratio (QFR). FAVOR II Europe-Japan

Background:

Patients at high risk of having one or more coronary stenosis are evaluated routinely by invasive coronary angiography (CAG). Lesions are often quantified by QCA, but fractional flow reserve is increasingly used to assess 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 medical induced maximum blood flow (hyperaemia).

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, 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 drop in the vessel based on two angiographic projections.

The FAVOR I study (Tu et al.), showed promising results for core laboratory QFR analysis in selected patients.

The purpose of the FAVOR II study is to evaluate the feasibility and diagnostic precision of in-procedure QFR during CAG in comparison to QCA with FFR as gold standard for physiological lesion evaluation.

Hypothesis: QFR has superior sensitivity and specificity for detection of functional significant lesions in comparison to QCA with FFR as gold standard

Methods: Prospective, observational, multicenter study with inclusion of 310 patients.

Patients with indication for FFR are enrolled. At least two angiographic projections are acquired during resting conditions. QFR is calculated in-procedure using the Medis Suite application and simultaneously to the operator performing the FFR measurement. The QFR observer is blinded to the FFR measurement.

QFR is reassessed off-line by the Interventional Coronary Imaging Core Laboratory, Aarhus University, Denmark, blinded to FFR and in-procedure QFR results.

FFR is assessed by core laboratory reading, blinded to QFR results. All data are entered and stored in a protected and logged trial management system (TrialPartner, Aarhus University, Denmark).

Inclusion criteria

• Stable angina pectoris or secondary evaluation of stenosis after acute MI
• Age > 18 years
• Able to provide signed informed consent
• Angiographic inclusion criteria:
• Indication for FFR in at least one stenosis:
• Diameter stenosis of 30%-90% by visual estimate
• Reference vessel size > 2 mm in stenotic segment by visual estimate

Exclusion criteria

• Myocardial infarction within 72 hours
• Severe asthma or severe chronic obstructive pulmonary disease
• Severe heart failure (NYHA≥III)
• S-creatinine>150µmol/L or GFR<45 ml/kg/1.73m2
• Allergy to contrast media or adenosine
• Atrial fibrillation
• Angiographic exclusion criteria:

Lesion specific

• Below 30% and above 90% diameter stenosis by visual estimate.
• Reference size of vessel below 2 mm by visual estimation.
• Ostial LMCA lesions
• Ostial RCA lesions
• Distal LMCA lesions in combination with proximal Cx lesions
• Other bifurcation stenosis with lesions on both sides of a major shift (>1mm) in reference diameter Angiographic quality
• Poor image quality precluding contour detection
• Good contrast filling not possible
• Severe overlap of stenosed segments
• Severe tortuosity of target vessel