Study of Lipid Core Plaque Shift at Sites of Native Coronary Artery Bifurcation

Coronary artery bifurcations (branching areas) are predisposed to atherosclerosis from turbulent flow and increased shear stress. Dilating lesions that involve a branch vessel is associated with the risk of closure of the side branch. Plaque redistribution or 'plaque shift' across the carina of the bifurcation is regarded as the responsible mechanism for the side branch stenosis and occlusion after angioplasty and stenting. Modern techniques of side branch protection require positioning of a second wire into the side branch before starting the treatment of the main branch. Placing an additional wire in the side branch is more laborious and complex than the wiring of the main branch only, is associated with additional use of contrast media and radiation, and may associated with additional risk of complications. Being able to determine which side branches require wiring for protection while treating the main vessel stenosis may make the procedure simpler and safer.

Lipid core plaque (LCP) in the coronary arteries is very common in acute coronary syndrome, but can often be found also in patients with stable angina. Lipid core plaque cannot be detected by angiography or intra-vascular ultrasound. Near infrared spectroscopy (NIRS) has the ability to identify chemicals in mixture. LipiScan, a catheter based NIRS coronary imaging system can detect intra-vascular LCP. This catheter has been shown to be able to identify LCP through blood in a prospective autopsy study, and that the LCP detection algorithm developed and validated on ex vivo data is applicable in vivo. The image generated by this system is called 'chemogram'. The catheter has also been tested successfully in a clinical study in the United States and Canada. Based on these studies the FDA approved the use of the LipiScan coronary imaging system. In CUMC, we have started to use this catheter to identify LCP, and have gained experience with its simple use.

This study is intended as a pilot study to identify angioplasty related redistribution or shift of lipid core plaque (LCP) lesions that are located at sites of artery bifurcation. We hypothesize that during angioplasty and stenting, soft plaque that contains lipid cores may be prone to shift more than (hard) fibrotic or calcified lesions. This pilot study may help to better characterize lesions likely to shift and to provide imaging-based information like NIRS that will improve the interventional treatment of bifurcation lesions.

A total of 20 patients with significant coronary artery disease with a bifurcation lesion suitable for angioplasty and stenting will be studied. The lesions that will be studied contain significant stenosis (≥50% stenosis) located in proximity (less than 2 mm) to a side branch. Prior to angioplasty, the main vessel involved in the bifurcation will be imaged using the LipiScan Coronary Imaging System. Angioplasty and stenting will be performed in the usual conventional way, and then re-imaged with the LipiScan system. Intravascular ultrasound will be done as standard interventional imaging procedure, when directed by the treating interventional cardiologist. Angiographic and Chemographic data will be qualitatively and quantitatively analyzed to assess LCP and plaque shift into the side branch. Subjects that have intravascular ultrasound as part of routine care, will have this data analyzed and compared to the chemogram data.

Improved understanding of how plaques and lipid cores redistribute and under what conditions redistribution occurs could assist interventional cardiologists to better plan and perform complex procedures that involve bifurcation plaques. Improved procedural planning and prediction of shift can reduce instances of difficult side branch rescue and reduce occurrence of peri-procedural events, such as myocardial infarction. This may in turn lead to a reduction in overall complexity of treatment procedures, complication, and procedure recovery times.