Too much cholesterol in the blood, or high blood cholesterol, can be serious. People with high blood cholesterol have a greater chance of getting heart disease. High blood cholesterol on its own does not cause symptoms, so many people are unaware that their cholesterol level is too high.
Cholesterol can build up in the walls of your arteries. This buildup of cholesterol is called plaque. Over time, plaque can cause narrowing of the arteries. This is called atherosclerosis, or hardening of the arteries.
The illustration shows a normal artery with normal blood flow (figure A) and an artery containing plaque buildup (figure B).
Special arteries, called coronary arteries, bring blood to the heart. Narrowing of your coronary arteries due to plaque can stop or slow down the flow of blood to your heart. When the arteries narrow, the amount of oxygen-rich blood is decreased. This is called coronary heart disease (CHD). Large plaque areas can lead to chest pain called angina. Angina happens when the heart does not receive enough oxygen-rich blood. Angina is a common symptom of CHD.
Some plaques have a thin covering and can burst (rupture), releasing cholesterol and fat into the bloodstream. The release of cholesterol and fat may cause your blood to clot. A clot can block the flow of blood. This blockage can cause angina or a heart attack.
Lowering your cholesterol level decreases your chance for having a plaque burst and cause a heart attack. Lowering cholesterol may also slow down, reduce, or even stop plaque from building up.
Plaque and resulting health problems can also occur in arteries elsewhere in the body.