Feasibility Study of an Angiographic Quantitative Flow Ratio-guided Endovascular Procedure in Patients With Lower Limbs Peripheral Arterial Disease.

Approximately 202 million people are affected with lower extremity artery disease (LEAD) worldwide, of whom almost 40 million are living in Europe. LEAD usually appears after the age of 50 years, with an exponential increase after the age of 65. This rate reaches around 20% by the age of 80. In most studies, the proportion of symptomatic LEAD is 1:3 to 1:5 of all LEA.

The global burden of LEAD is considerable. In 2010, the years of life lost due to LEAD were estimated at 31.7, 15.1, and 3.7 years per 100,000 inhabitants in Western, Central, and Eastern Europe, respectively.

During the two last decade, indications of endovascular approach of femoropopliteal lesions have dramatically increased, to become the gold standard with a first endo strategy approach. In 2000, endovascular treatment was recommended for stenosis ≤ 5cm or occlusions ≤ 3cm. Today, the guidelines suggest endo approach for lesion until 25 cm In 2019, in France, 50 000 patients underwent an endovascular femoral popliteal revascularization, and drug eluting devices (Stents or Balloons). According to the Excellence in Peripheral Artery Disease Registry, early stent occlusion is about 5% during the 6 first months after procedure. Success rate of endovascular procedure is high, but many thrombosis are due to incomplete endovascular treatment, leading to early re-occlusion. Usually, quality and success assessment are made by the operator, based on images provided by a single plan angiography. Vascular surgeons face a lack of devices helping us to appreciate the quality of our revascularization per procedure. Endovascular ultrasounds (IVUS) or Optical Coherence Tomography(OCT) are not reimbursed in many countries. These devices are quite expensive and, like the FFR, require the introduction of dedicated devices into the arteries, thus increasing procedure's duration.

Similar situation can be seen in patients undergoing coronary percutaneous coronary intervention (PCI), current evidence indicates post-PCI suboptimal results. However, the combination of quantitative vessel analysis (QVA) with angiography-derived fractional flow reserve (FFR) assessment has shown promising improvements in PCI outcomes. A notable non-invasive solution for angiography derived FFR is Quantitative Flow Ratio (QFR), which includes quantitative vessel analysis (QVA) reporting significant enhancement in revascularization therapy.

Extending its potential benefits, QFR emerges as a non-invasive and cost-effective solution to improve revascularization outcomes for lower extremities.

MAIN OBJECTIVE The main objective of this study is to explore the feasibility of using QFR as a tool to predict the success rate of endovascular revascularization in patients with superficial artery disease.

METHODS:

1. Study design and Population This is a prospective feasibility study. We aim to include 35 patients with indication for endovascular revascularization of a short stenosis of the superficial femoral artery (TASC A, Rutherford stage 2 to 6). Intraoperative angiography will be performed immediately prior to revascularization. Quantitative analysis of angiography images will be performed post-procedure using Medis QFR®2.2 software.
2. Clinical variables:

• Age
• Sex
• Height/Weight
• Previous medical history
• Rutherford classification
• TASC lesion (only for sfa)
• Procedure: - Type of treatment
• Stents (type, length, diameter, number)
• Amount of contrast
• Xray duration
• Xray Dose (Gy)
• Technical success
• Outcomes: 30 days patency

1. Angiography procedure and acquisition protocol Selective PCI will be performed using standard catheterization according to European society of Cardiology guidelines for lower extremity artery disease. At least two projections angles separated at least 25 degrees were acquired for the optimal view of the lesions. Details of the acquisition protocol are described in appendix B.
2. QCA and QFR analysis The 3D QCA and QFR analysis will be performed using a research version of software package QFR 2.2. QFR allows to match two diagnostic angiographic projections and create a 3D reconstruction of the interrogated vessel. From this reconstruction the following parameters will be derived: lesions length, QFR, delta(△) QFR, % diameter of stenosis, minimum lumen diameter, residual QFR, QFR pullback curve and derivative of QFR pullback curve (dQFR/ds).