Present Status and Future Direction of NIRS-IVUS Multimodality Direct Coronary Imaging

Abstract

Intracoronary near-infrared spectroscopy (NIRS)-IVUS is a direct coronary imaging catheter for the identification and quantification of lipid core plaque (LCP). NIRS is combined with traditional grayscale IVUS in a hybrid catheter that provides co-registered architectural and compositional plaque characterization data. The novel capability of the NIRS catheter component is its ability to directly identify LCP, which underlies the majority of vulnerable and unstable plaques. NIRS-IVUS has potential to optimize percutaneous coronary intervention (PCI) by delineating precise lesion length, assuring adequate stent expansion and apposition, detection of stent edge dissection, and predicting periprocedural myocardial infarction (PMI). NIRS-IVUS may also be important in the identification of vulnerable plaques at risk to cause future events.Catheterization laboratory decision-making in individual patients requires challenging decisions regarding revascularization strategies (i.e., percutaneous coronary intervention (PCI) versus bypass surgery) and performance of PCI (e.g., choosing target lesions, identifying length of vessel to treat, optimization of stent deployment, and prevention of distal embolization and PMI).Based on first principles, optimal stenting would fully cover the target lesion, landing stent edges in normal zones of the vessel. However, atherosclerosis is typically a diffuse process, with disease often extending beyond the critical stenosis. Failure to cover the full length of the target diseased coronary arterial segment with drug-eluting stent (DES) has been associated with increased rates of sub-acute stent thrombosis and late restenosis [1, 2, 3••, 4••], particularly if the uncovered lesion segment is composed of lipid core plaque (LCP) [5,6]. Unfortunately, coronary angiography alone is inadequate. Although important to delineate the presence of disease and quantification of lumen stenosis, angiography underestimates the magnitude of atherosclerosis, particularly in early disease when positive vascular remodeling maintains Bnormal^lumen caliber despite substantial plaque in the vascular wall. In addition, angiography does not provide data on chemical composition of plaque.