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Plaque pathology and coronary thrombosis in the pathogenesis of acute coronary syndromes
1Institute of Experimental Clinical Research, Aarhus University Hospital (SKS), Denmark.
Insights
Coronary plaque rupture, not size, triggers heart attacks. Vulnerable plaques with lipid cores and thin caps are prone to thrombosis, leading to acute coronary syndromes.
Area of Science:
- Cardiovascular Medicine
- Pathology
- Biomedical Engineering
Background:
- Coronary atherosclerosis is the primary cause of ischemic heart disease.
- Acute coronary syndromes result from plaque disruption and thrombosis.
- Understanding plaque vulnerability is crucial for preventing life-threatening events.
Purpose of the Study:
- To shift focus from plaque size to plaque vulnerability and thrombogenicity.
- To identify key determinants of plaque rupture.
- To understand factors influencing plaque stability and instability.
Main Methods:
- Analysis of plaque composition and characteristics.
- Evaluation of factors contributing to plaque rupture.
- Correlation of plaque vulnerability with clinical outcomes.
Main Results:
- Plaque vulnerability, not stenosis severity, dictates rupture risk.
- Lipid-rich, thin-capped plaques are highly vulnerable and thrombogenic.
- Inflammation and smooth muscle cell (SMC) activity influence plaque stability.
Conclusions:
- Focusing on vulnerable plaque characteristics is vital for preventing acute coronary syndromes.
- Plaque size and stenosis severity are poor indicators of rupture risk.
- Targeting plaque vulnerability offers a promising strategy for event-free survival.
Abstract:
Coronary atherosclerosis is by far the most frequent cause of ischemic heart disease and plaque disruption with superimposed thrombosis is the main cause of the acute coronary syndromes of unstable angina, myocardial infarction, and sudden coronary death. Therefore, for event-free survival, the vital question is not why atherosclerosis develops but rather why, after years of indolent growth, it suddenly becomes complicated by life-threatening thrombosis. Therefore, we have to focus on plaque composition and vulnerability to rupture and plaque thrombogenicity rather than on plaque size and stenosis severity. The risk for plaque disruption depends more on plaque vulnerability (plaque type) than on degree of stenosis (plaque size). Lipid-rich and soft plaques are more vulnerable and prone to rupture than collagen-rich and hard plaques. They are also highly thrombogenic after disruption because of high content of tissue factor. There seems to be three major determinants of a plaque's vulnerability to rupture: 1) the size and consistency of the lipid-rich atheromatous core, 2) the thickness of the fibrous cap covering the core, and 3) ongoing inflammation and repair processes within the fibrous cap. Lipid accumulation, cap thinning, lack of smooth muscle cells (smc), and macrophage-related inflammation destabilize plaques, making them vulnerable to rupture. In contrast, smc-related healing and repair processes stabilize plaques, protecting them against disruption. Plaque size or stenosis severity tell nothing about a plaque's vulnerability. Many vulnerable plaques are invisible angiographically due to their small size and compensatory vascular remodeling.