What is the Origin of Plaque Instability?

The term arose from the shift in cardiovascular pathology research from focusing solely on the size of arterial plaques to understanding the critical role of their composition and mechanical integrity. Clinical observations revealed that smaller, highly inflammatory plaques were often more prone to rupture than larger, stable ones. This understanding redefined the focus of cardiovascular risk assessment.

What is the Mechanism of Plaque Instability?

The mechanism of instability involves a thin, fibrous cap covering a large, lipid-rich, necrotic core within the plaque. Inflammatory cells, particularly macrophages, infiltrate the cap and release enzymes that degrade the collagen matrix, weakening the structural integrity. When this thin cap ruptures, the highly thrombogenic contents of the core are exposed to the bloodstream, triggering the rapid coagulation cascade and forming a clot that blocks blood flow, necessitating immediate clinical intervention.

Plaque Instability ∞ Area

Plaque Instability

Meaning

Plaque Instability refers to the structural vulnerability of an atherosclerotic plaque within an artery wall, which makes it susceptible to rupture or erosion, leading to the formation of an occlusive thrombus (blood clot). This condition is the primary pathological mechanism underlying acute cardiovascular events like myocardial infarction and ischemic stroke. Hormonal factors, particularly the loss of cardioprotective effects from estrogen post-menopause, are known to contribute to the increased vulnerability and inflammatory status of these plaques. It represents a critical, life-threatening clinical risk.