A Prospective Evaluation of Optical Coherence Tomography in Below-the-Knee Endovascular Interventions.

BACKGROUND: Image-guided therapy has become the standard of care for most, if not all, coronary interventions. However, the utility of imaging, in particular, intravascular ultrasound (IVUS) and optical coherence tomography (OCT), in endovascular interventions of the lower extremities has been limited by a lack of quantitative data and evidence-based protocols. This prospective, multicenter, core-lab adjudicated study aimed to correlate IVUS, OCT, and fluoroscopic quantitative findings in the below-the-knee tibial arteries. METHODS: Patients with chronic limb-threatening ischemia were prospectively recruited from 2 sites. All patients underwent predefined protocols for obtaining angiography, IVUS, and OCT. All images were analyzed by the University Hospitals Harrington HVI Cardiovascular Imaging Core Laboratory. IVUS and OCT images were compared for vessel and lesion minimum lumen diameter, average lumen diameter, area, calcium arc, calcium thickness, and cap thickness. Clinical outcomes were ascertained per standard-of-care surveillance visits and hemodynamic data for 1 year. RESULTS: Forty-four patients were enrolled between August 2021 and June 2023. Most (92.5%) had Rutherford V to VI disease, and nearly half had chronic total occlusion. Undiluted (100%) contrast provided better image quality and longer clear image length (70.2 vs 54.7 mm, P = .03) compared to diluted (50%) contrast. Quantitative measurements by OCT correlated well with IVUS and angiographic analysis, though the former provides the most defined calcium analysis. Patients with increased calcium thickness in OCT analysis trended toward increased target lesion revascularization and major amputation, though with no difference in all-cause mortality. CONCLUSIONS: Optical coherence tomography of tibial arteries is feasible and correlates well with IVUS. However, its unique ability to better define tibial artery calcification burden compared to IVUS and fluoroscopy may alter treatment strategies for below-the-knee vessels in chronic limb-threatening ischemia as the landscape of therapies continues to transform.