plaque rupture

Plaque rupture is the moment a slow, chronic disease turns into a sudden crisis. The protective skin over a fatty plaque tears open, and what was a quiet bump in the artery wall becomes the trigger for an emergency.

The key player is the fibrous cap covering the plaque's lipid core. In a vulnerable plaque this cap is thin and inflamed, weakened by enzymes released by immune cells inside the lesion. When it cracks, the highly clot-promoting contents of the core are exposed to flowing blood. Platelets rush to the breach and a thrombus forms, often within seconds to minutes.

This single event is the usual starting point of acute coronary syndromes. If the resulting clot blocks the artery completely, the result is a STEMI; if partially, an NSTEMI or unstable angina. It explains why heart attacks often strike without warning and why they can arise from plaques that were never severe enough to cause symptoms before.

Plaque erosion — where the cap stays intact but the surface lining is stripped away — is a related but distinct trigger of coronary thrombosis, more common in younger patients and women.