After plaque has formed it can cause problems in a number of different ways. If an established plaque ruptures, the resulting events can cause a heart attack or stroke.
Plaque ruptures if the tissue covering it erodes sufficiently to allow blood to come into contact with the lipid core. This causes the blood to clot (thrombose). If the clot is in one of the coronary arteries it can cause symptoms such as chest pain or it can cause a fatal heart attack. It can also lodge in the brain and cause a stroke.
Plaque can also become thickened with calcium deposits, or the inner lipid core can crystallise. This stops the plaque from rupturing as easily, but further stiffens the artery – so-called hardening of the arteries.
(The Heart and Stroke Foundation South Africa/Health24, updated January 2009)