Concepts in acute coronary syndromes
1Division of Cardiology, Department of Medicine and Therapeutics, Leicester University, Glenfield Hospital, Clinical Sciences Wing, Leicester LE3 9QP, UK. rf226@medschl.cam.ac.uk
Insights
Acute coronary syndromes involve thrombosis, often linked to vulnerable atherosclerotic plaques. Identifying plaque composition, not size, is key to predicting rupture risk and guiding treatment.
Area of Science:
- Cardiovascular Pathology
- Atherosclerosis Research
Background:
- Acute coronary syndromes (ACS) pathogenesis is increasingly understood through pathological studies.
- Thrombosis is a central, unifying feature in ACS development.
- Platelet-rich thrombus formation on disrupted or eroded atherosclerotic plaques is consistently observed.
Purpose of the Study:
- To elucidate the pathological features of atherosclerotic plaques contributing to ACS risk.
- To identify key characteristics of vulnerable plaques prone to rupture.
Main Methods:
- Analysis of pathological findings from postmortem, angiographic, and angioscopic studies.
- Evaluation of plaque characteristics, including cap thickness, lipid core size, cellular infiltrate, and enzyme activity.
Main Results:
- Plaque content, specifically thin caps and large lipid cores, is more critical than plaque size in ACS risk.
- Vulnerable plaques exhibit a predominance of activated macrophages and T-lymphocytes.
- High matrix metalloproteinase activity and downregulated smooth muscle cell proliferation/collagen synthesis characterize vulnerable plaques.
Conclusions:
- Atherosclerotic plaque vulnerability, not just size, dictates the risk of acute coronary events.
- Specific cellular and molecular features of vulnerable plaques offer potential targets for risk detection and mitigation.
Abstract:
Landmark pathological studies have deepened our understanding of the mechanisms behind acute coronary syndromes over the last decade. Thrombosis plays a key role and is a unifying feature in the pathogenesis. Platelet-rich thrombus superimposed over the disrupted atherosclerotic plaque or eroded plaque endothelium, with or without fibrin-thrombus extension, is evident in postmortem necropsy, angiographic and angioscopic studies. However features which contribute to the risk of acute events lie in the atherosclerotic plaque itself. Plaque content and not plaque size is the important factor. A vulnerable plaque may be invisible on clinical stress testing and even coronary angiography; but it is prone to rupture if it has only a thin cap and a proportionally larger lipid core. There is a cellular preponderance of activated macrophages and T-lymphocytes; and high activity of matrix metalloproteinases in vulnerable plaques. Smooth muscle cell proliferation and collagen synthesis are downregulated. These features may serve as possible targets for detecting plaques at risk or for reversing the risk of vulnerable plaques.
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