[Comparison among different flushing media for intracoronary imaging with optical coherence tomography]

Objective: To explore the effects and safety of saline mixed 1∶1 with contrast medium (mixed medium) and pure heparinized saline as alternative media for optimal Optical Coherence Tomography (OCT) guided percutaneous coronary intervention (PCI). Methods: This single-center, prospective cohort study enrolled patients who underwent PCI with OCT guidance for chronic stable angina or acute coronary syndrome at the Department of Cardiology, the Second Hospital of Jilin University from October 2021 to August 2022. The target vessels were examined using OCT with three different flushing media at the same anatomical positions: contrast agent, mixed medium, and pure heparinized saline. An independent observer analyzed all imaging results and evaluated the lumen imaging quality, using the proportion of the clear imaging field (CIF%) as a quantitative measure for analysis. The average luminal diameter was compared among different flushing media. The study also assessed the image quality of the luminal anatomical structures, lesion pathologies, and stents. Results: A total of 105 patients were enrolled in the study, including 110 target vessels. The age of the enrolled patients was (60.5±8.4) years, with 60 male patients (57.1%). OCT examinations were successfully completed using all three media, and no related complications were observed in any groups. The three flushing media presented with the same image quality in terms of depicting the lumen anatomical structures, lesion characteristics, and stent-related features. The mixed medium group achieved a comparable CIF% to the contrast group with both right and left coronary arteries (right coronary 100.0% (100.0%, 100.0%) vs. 100.0% (100.0%, 100.0%), P>0.05; left coronary 100.0% (95.9%, 100.0%) vs. 100.0% (100.0%, 100.0%), P>0.05). While the saline group reached a comparable CIF% to the contrast group with right coronary arteries (100.0% (97.6%, 100.0%) vs. 100.0% (95.9%, 100.0%), P>0.05) but showed a significantly lower CIF% with left coronary arteries (84.9% (75.9%, 93.4%) vs. 100.0% (100.0%, 100.0%), P<0.05). For the average diameter of the coronary lumen, there was no statistically significant difference between the mixed medium group and the saline group compared to the contrast group with both right and left coronary arteries (P>0.05). Conclusions: A 1∶1 heparinized saline and contrast mixture can serve as a substitute flushing medium for OCT examination during PCI procedure. Pure saline can also yield good results in OCT examination of the right coronary artery, and both alternatives are safe for use as flushing medium in OCT imaging.