Saline Optical Coherence Tomography (OCT) In A High Risk Patient With ACS

Coronary revascularisation using imaging guidance is becoming the standard of care. Intravascular OCT uses near infrared light to obtain intravascular images. It also talks about the nature of plaque like fibrous or calcific. In ACS, it talks about plaque rupture, thrombus. It has an edge over CAG regarding stent apposition. Standard OCT employs iodinated contrast dye for flushing the blood which might lead to contrast induced nephropathy in high risk patients specially with pre-existing reduced renal function, age >75 years, heart failure, diabetes mellitus and female gender. In such high-risk cases, there is a need to find a contrast-saving alternative. Low-molecular-weight dextran is one of the options that has been explored as an alternative to contrast for coronary FD-OCT. Studies that compared low-molecular-weight dextran with iodine-based contrast media for coronary OCT image acquisition, revealed no significant difference regarding image quality between the two methods. However, the use of dextran has been found to be associated with nephrotoxicity and anaphylactoid reactions. Heparinised saline is a safe, cheap contrast saving alternative to prevent contrast-induced nephropathy (CIN). There is no difference in image quality in comparison to iodinated contrast.

A 48-year-old man, a known case of Diabetes Mellitus, CKD, came with complaints of chest pain for 3-hour. At presentation, he was haemodynamically stable. His ECG revealed IWMI. Coronary angiography revealed single vessel disease, mid-RCA 90% thrombus containing the lesion. In view of CKD OCT run, using saline as a flushing media was done preprocedure. OCT revealed a red thrombus at the lesion site with a minimal luminal diameter of 1.62 mm and a distal luminal diameter of 3.44 mm. Stenting to RCA was done using 3 x 32 mm DES, followed by post-dilation using 3.5 x 12 mm balloon with good TIMI III flow. Post-procedure OCT revealed good stent apposition. There was no adverse effect during or after Saline OCT.

Optical Coherence Tomography (OCT) is a recently developed intravascular imaging modality using near-infrared light to create images. The high resolution of OCT identifies plaque characteristics that predispose to rupture, including thin fibrous caps, large lipid cores, and accumulation of macrophages. OCT can provide critical information to guide coronary interventions, in addition to characterising atherosclerotic plaques. Standard OCT employs iodinated contrast dye for flushing the blood, which might lead to Contrast-induced nephropathy in high-risk patients, specially with pre-existing reduced renal function, age >75 years, heart failure, diabetes mellitus and female gender. In such high-risk cases, there is a need to find a contrast-saving alternative. Low-molecular-weight dextran is one of the options that have been explored as an alternative to contrast for coronary FD-OCT. Dextran has been associated with nephrotoxicity and anaphylatic reaction. Heparanised saline is another cheap and safe alternative for high-risk patients. Before OCT run with Saline, intracoronary nitroglycerine should be given to avoid saline-induced coronary spasm and as saline has low viscosity there might be more blood artefacts which can be reduced with either an increase rate or duration of flush. Although there might be transient electrocardiographic changes after flushing with saline, there is a rare chance of significant cardiac arrhythmias. A recent case series that assessed the

feasibility of the use of FD-OCT using iodinated contrast diluted with heparinised normal saline also reported no haemodynamic or electrocardiographic changes or any other complications. The use of Saline OCT in large type III LAD as there might be reflux of blood from septals or diagonals.

This case illustrates the use of saline as a flushing media in OCT in ACS patients without any adverse effects.

Saline OCT is an excellent tool for imaging during ACS in patients with a high-risk of contrast-induced nephropathy. It is not associated with any significant adverse effect, and image quality is also not compromised vis-a-vis iodinated contrast.