Abstract 4372797: Saline vs. Contrast Optical Coherence Tomography—A Prospective Multicenter Trial

Background: Frequency-domain Optical Coherence Tomography (FD-OCT) is increasingly used for intravascular imaging and optimizing percutaneous coronary interventions. Conventional OCT requires iodinated contrast for blood clearance, raising concerns about contrast-induced nephropathy (CIN) in high-risk patients. Heparinized saline has been proposed as a safer alternative, but robust data are lacking for further validation. Research Questions: To evaluate the feasibility, image quality, and accuracy of vessel measurements using heparinized saline compared to iodinated contrast as flushing media during OCT-guided PCI. Methods: This prospective multicenter observational study enrolled (n=166) patients undergoing OCT-optimized PCI for acute or chronic coronary syndrome in 4 high-volume PCI centers across India with 7 operators. Each patient underwent sequential OCT imaging with contrast, followed by heparinized saline, using similar catheter positions ensured by anatomical landmarks such as side branches, macrophages, cholesterol crystals, and dissections. OCT runs were analyzed for 256 paired segments (2072 matched frames) for proximal reference diameters (PRD), minimal lumen area (MLA), minimal lumen diameter (MLD), and distal reference diameter (DRD). Image quality and success rates were evaluated by two blinded reviewers. Results: There were no significant differences in the quantitative vessel parameters between contrast and saline: PRD: 2.76±0.59 mm vs. 2.74±0.60mm (p=0.65); MLA: 5.33±2.48 mm 2 vs. 5.36±2.52 mm 2 (p=0.85); MLD: 2.55±0.68 mm vs. 2.56±0.68 mm (p=0.78); and DRD: 2.54±0.55 mm vs. 2.55±0.55 mm (p=0.83). Bland-Altman analysis revealed good agreement between contrast and saline for all measurements, with no proportional bias, with p=0.335 for PRD, p=0.140 for MLA, p=0.422 for MLD, and p=0.058 for DRD. Success rates for obtaining clinically effective runs (CER) were high: right coronary system: 95.7% (contrast) vs. 92.7% (saline), and left coronary system: 91.5% (contrast) vs. 78.1% (saline). All the rest of the vessel characteristics, including stent expansion, dissections, thrombus, and plaque morphology, were adequately studied by saline OCT. Conclusion: Heparinized saline provides comparable imaging quality and vessel measurements to iodinated contrast in OCT-guided PCI. It is a feasible and safer alternative in the subset of patients at high risk of CIN, with high success rates and adequate visualization of all lesion morphologies.