Despite advancements in endovascular therapy (EVT), the optimal below-the-knee (BTK) treatment in chronic limb-threatening ischemia (CLTI) remains unclear. Intravascular ultrasound (IVUS), successful in interventional cardiology, may offer similar benefits in CLTI. IVUS provides better evaluation of vessel size and plaque morphology and of treatment’s result by evaluating residual stenosis, recoil and post-treatment dissection. We aim to study the impact of IVUS on treatment strategy and postoperative results in BTK EVT.

This is a retrospective observational single center cohort study of all patients who underwent IVUS in BTK arterial disease in a tertiary center between April 2024 to July 2024. A standardized protocol incorporating IVUS in BTK EVT for de novo stage IV peripheral arterial disease (PAD) has been tested. Initial femoro-popliteo-BTK angiography was performed, followed by selective angiography of the diseased vessel. The Opticross 18 HD IVUS (Boston Scientific) was advanced beyond the lesion to capture images with manual pullback. Evaluated parameters were calcium distribution, plaque type and vessel size to better select adjunctive therapies (drug-coated balloon angioplasty, stenting, atherectomy or intravascular lithotripsy). Post-treatment parameters evaluated were residual stenosis, stent apposition and arterial dissection.

Seven cases of BTK PAD stage IV patients were treated using the standardized protocol. IVUS facilitated better identification of calcification distribution, leading to atherectomy in 2 patients and lithotripsy in 2 other patients for vessel preparation, previously less used in BTK EVT. Accurate vessel sizing led to the use of larger balloons, in average 1mm larger than when based only on angiography. Post-treatment IVUS confirmed the absence of dissection or residual stenosis. Procedural success was achieved in all cases except one, which required a femoro-distal bypass due to acute reocclusion.

Complementary IVUS in BTK EVT enhances understanding of plaque morphology and allows for more tailored treatment strategies with appropriate balloon sizes and adjunctive therapies, improving procedural outcomes. Based on these early results, we are conducting a study to further evaluate IVUS-guided versus angiography-guided EVT in CLTI patients, focusing on procedural success, lesion characterization, and long-term clinical outcomes.