From the Guidelines
The central area of atherosclerosis containing cholesterol crystals, foam cells, erythrocytes, and necrosis is a necrotic core, which is a characteristic feature of an advanced atherosclerotic plaque. This region represents the advanced stage of atherosclerosis where lipid accumulation, inflammation, and cell death have occurred in the arterial wall. The presence of foam cells (lipid-laden macrophages) and cholesterol crystals indicates lipid deposition, while necrosis shows tissue death in the core of the plaque 1.
Key Characteristics
- The necrotic core is a signal-poor region within an atherosclerotic plaque, with poorly delineated borders, a fast IVOCT signal drop-off, and little or no OCT signal backscattering 1.
- Cholesterol crystals by IVOCT may appear as thin, linear regions of high intensity, usually associated with a fibrous cap or necrotic core 1.
- The lipid core of plaques prone to rupture has a high concentration of cholesteryl esters with a high proportion of polyunsaturated fatty acids 1.
Clinical Implications
- The presence of a necrotic core is associated with an increased risk of plaque rupture and thrombosis, which can lead to acute coronary syndromes 1.
- The management of acute coronary syndromes involves careful risk stratification, novel therapeutic agents, and revascularization 1.
- The diagnosis of a necrotic core can be made using intravascular optical coherence tomography (IVOCT), which provides high-resolution images of the plaque morphology 1.
From the Research
Characteristics of Atherosclerotic Plaques
- Atherosclerotic plaques are characterized by the presence of cholesterol crystals, foam cells, erythrocytes (red blood cells), and necrosis 2, 3
- The atheromatous core of plaques becomes necrotic, consisting of lipids, cholesterol crystals, and cell debris as the disease progresses 2
- Cholesterol crystals are causally associated with plaque vulnerability in vivo, and their formation results from spontaneous self-assembly of cholesterol molecules 3
Formation of Foam Cells
- Foam cells are formed from monocytes that migrate into the subendothelial layer of the intima, where they differentiate into macrophages or dendritic cells 2, 4, 5
- Macrophages transform into foam cells in the subendothelial space enriched with atherogenic lipoproteins 2
- Foam cells can also be derived from vascular smooth muscle cells, stem/progenitor cells, and endothelium cells 4, 5, 6
Composition of Atherosclerotic Plaques
- Atherosclerotic plaques are composed of lipoproteins, cholesterol, extracellular matrix elements, and various types of immune and non-immune cells, including foam cells 4, 6
- The necrotic core of plaques contains cholesterol crystals, lipids, and cell debris, which can lead to plaque instability and rupture 2, 3