# Optical coherence tomography and fractional flow reserve in below-the-knee percutaneous transluminal angioplasty: a pilot study

## TL;DR

This study tests the safety and usefulness of OCT and FFR in treating leg artery disease below the knee, finding they can change surgical decisions.

## Contribution

Demonstrates the feasibility and potential impact of OCT and FFR in below-the-knee angioplasty procedures.

## Key findings

- OCT and FFR measurements were safely performed in all ten patients without complications.
- OCT and FFR altered intra-operative decisions in 7 out of 10 patients.
- FFR showed hemodynamic insignificance in 6 cases and residual significance in 3 post-treatment cases.

## Abstract

Determining the safety of Optical Coherence Tomography (OCT) and Fractional Flow Reserve (FFR) in Percutaneous Transluminal Angioplasty (PTA) for below-the-knee vascular disease.

In this prospective single-center non-randomized trial, patients who underwent PTA for below-the-knee vascular disease with lesions no longer than 3 cm were included. Based on digital subtraction angiography (DSA) using iodine contrast agent, the physician was asked to estimate the diameter of the target vessel and degree of stenosis of the target lesion. The investigated tools are OCT, which is an intravascular imaging technique using near-infrared light and iodine contrast agent to visualize the vessel wall, and FFR, which measures the pressure gradient along a stenosis in a hyperemic state. The primary outcomes were the safety and feasibility of performing these measurements. OCT and FFR measurements were conducted before and after PTA. Physicians were not allowed to interpret study measurements during the procedure, as the safety and feasibility of these novel techniques have not yet been proven. To assess the secondary outcomes, physicians interpreted the measurements after the procedure to determine whether OCT or FFR would have changed intra-operative decision-making such as not performing PTA, the use of other balloons or stents, and additional revascularization based on the OCT and FFR measurements.

Ten patients were included. The target lesion was significant in nine patients based on angiography, who were therefore treated. Seven patients were treated with PTA using plain-old-balloon and two patients were treated using atherectomy devices.

No complications occurred during or after the procedures and measurements were successfully conducted in all patients. Overall, OCT and FFR would have led to a change in intra-operative decision-making in 7 patients. Estimation of the diameter of the target vessel varied from the value measured with OCT with more than 0.5 mm in 4 cases. FFR measurements demonstrated target lesions to be hemodynamically insignificant in 6 cases, while it showed target lesions to remain hemodynamically significant despite treatment in 3 cases.

OCT and FFR are feasible to use in below-the-knee PTA and may cause significant alterations in perioperative decision-making by providing previously unavailable information on lesion size and morphology and hemodynamic significance.