Feasibility and Safety of Lactated Ringer's Solution as a Flushing Agent for a Novel, Fast-Pullback, High-Frequency OCT Imaging System.

Background: Intracoronary optical coherence tomography (OCT) is widely utilized for high-resolution imaging of coronary arteries, typically requiring contrast agents to displace blood from the imaging field. However, the use of contrast media poses increased risk, especially in patients with impaired renal function and heart failure.

Aims: This study evaluates the feasibility and safety of lactated Ringer's solution (LRS) as a flushing medium for a novel fast-pullback, high-frequency OCT (HF-OCT) imaging system.

Methods: This observational study included HF-OCT imaging of 52 coronary arteries from 21 patients with stable coronary artery disease. Imaging was performed using either a contrast agent (iohexol 350) or LRS as the flushing medium. Clear image length (CIL), defined as the segment with a visible lumen-to-vessel wall boundary over at least 270°, was compared between the two groups. Quantitative and qualitative OCT image analyses were also obtained and compared between the contrast and LRS groups.

Results: A total of 52 paired HF-OCT imaging data sets were analyzed. CIL (mm) and CIL (%) were found to be similar between the contrast and the LRS groups (median 81.0 mm, interquartile range [IQR] 74.5-92.0 vs. median 79.2 mm, IQR 68.8-89.6, p = 0.526 and median 100%, IQR 100-100 vs. median 100, IQR 99-100, respectively). Quantitative OCT parameters, that is, minimum lumen area and diameter, were found to be comparable between the two groups (median 2.75 mm², IQR 1.85-4.48, vs. 2.85 mm², IQR 2.03-4.58, p = 0.654, and median 1.85 mm, IQR 1.53-2.40, vs. 1.90 mm, IQR 1.60-2.40, p = 0.651, respectively). Qualitative OCT findings, such as presence of a lipid-rich plaque, thin-cap fibroatheroma, and macrophages, were equally visualized using both flushing media.

Conclusions: OCT imaging using LRS as a flushing medium is safe and effective and can reduce the amount of contrast agent required while maintaining comparable lesion assessment quality to contrast-based OCT imaging.