Why are blood levels of cholesterol important?
The blockage that ultimately triggers a heart attack is most often a blood clot that forms at a site where a coronary artery has developed atherosclerosis. This involves the formation of deposits called plaques within the walls of arteries. The plaques are composed of cholesterol-laden foam cells, smooth muscle cells, fibrous proteins, and calcium. As the plaques build up, the arterial walls thicken and narrow. Increased total and LDL cholesterol levels boost the risk of coronary heart disease by increasing the amount of cholesterol deposited within the walls of the arteries.
Symptoms of coronary heart disease, including angina, result when an advanced plaque narrows a coronary artery so much that it hinders blood flow to the heart. Plaque deposits also roughen arterial walls and make it easier for a blood clot to form along their surface. Complete blockage of a coronary artery by a clot can cause a heart attack. A portion of a clot can also break loose from its place of origin and cause a heart attack by lodging in a narrower section of the artery or in a smaller artery supplying blood to the heart.
