Calcification is a process in which calcium is deposited over arterial plaque. It is one possible stage of atherosclerosis, or “hardening of the arteries.” When atherosclerosis occurs in the coronary arteries, it is called coronary artery disease and is the leading cause of heart attacks. When it occurs in the carotid arteries in the neck, it is associated with increased risk for stroke.

The degree of coronary calcification is often related to the age of the patient. Generally, the percentage of patients with coronary calcification increases with age in patients with or without coronary atherosclerosis.

In recent years, scientists have made great strides forward in understanding the atherosclerotic process. The disease tends to be gradual, often taking decades before the affected person is in danger of cardiovascular or cerebrovascular problems.

In the early stages of the disease, the inner lining of the artery (e.g., the endothelium) is damaged. This causes white blood cells to gather at the site of the injury. This in turn provokes an inflammatory immune response that causes further damage to the artery wall, attracting yet more white blood cells. Over time, the endothelium is compromised and large, toxic LDL cholesterol molecules can penetrate into the artery wall.

The white blood cells and cholesterol, along with cell products, combine to form a lipid foam that penetrates the arterial wall and forms a plaque deposit on the inside of the artery. In the early stages of atherosclerosis, these fatty streaks form the foundation of growing plaque deposits. Fatty streaks have been detected in the arteries of teenagers who were genetically predisposed to develop atherosclerosis.

Calcium becomes involved when calcium deposits collect on these growing atherosclerotic plaques. Calcium is present in the blood and may form a hard, brittle shell over the plaque. This does not happen in all cases of atherosclerosis. Plaque deposits that are covered with calcium may be stable or unstable. Some researchers have suggested that calcified plaque may even be safer than non-calcified plaque, because pieces of it are less likely to break off into the bloodstream (plaque rupture) and cause either a stroke or a heart attack.

The role that calcium deposits play in atherosclerosis has nothing to do with the calcium that comes from food or supplements, so reducing one’s calcium intake will not prevent or treat atherosclerosis.

Calcification itself may not produce any symptoms and may be identified only through tests or surgery. Nevertheless, people with atherosclerosis accompanied by calcification may experience symptoms common to any form of coronary artery disease, such as chest pain or leg pain. However, for many people, such disease produces no symptoms before a heart attack or sudden death.

Age is the most common risk factor for calcification of the arteries, mostly because of the association between age and atherosclerosis. Other risk factors for heavy arterial calcification include:

Calcification may also occur around the heart’s four valves, narrowing the valve and leading to conditions such as calcific aortic valve stenosis.