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Atherosclerosis ˌath-ə-rō-sklə-ˈrō-səs

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  • Blood vessel blockage due to atherosclerosis is a common cause of heart attack and stroke.

  • Often, the first symptom is pain or cramps at times when blood flow cannot keep up with the tissues' need for oxygen.



In the United States and most other developed countries, atherosclerosis is the leading cause of illness and death. In 2015, cardiovascular disease, primarily coronary artery disease (atherosclerosis that affects the arteries supplying blood to the heart) and stroke (atherosclerosis affecting the arteries to the brain —see Figure: Supplying the Brain with Blood), caused almost 15 million deaths worldwide, making atherosclerosis the leading cause of death worldwide.



Arteriosclerosis, which means hardening (sclerosis) of the arteries (arterio-), is a general term for several disorders in which the wall of an artery becomes thicker and less elastic. There are three types:

  • Atherosclerosis

  • Arteriolosclerosis

  • Mönckeberg arteriosclerosis

Atherosclerosis, the most common type, means hardening related to plaques, which are deposits of fatty materials. It affects medium-sized and large arteries.

Arteriolosclerosis means hardening of the arterioles, which are small arteries. It affects primarily the inner and middle layers of the walls of arterioles. The walls thicken, narrowing the arterioles. As a result, organs supplied by the affected arterioles do not receive enough blood. The kidneys are often affected. This disorder occurs mainly in people who have high blood pressure or diabetes. Either of these disorders may stress the walls of arterioles, resulting in thickening.

Mönckeberg arteriosclerosis affects small to medium-sized arteries. Calcium accumulates within the walls of arteries, making them stiff but not narrow. This essentially harmless disorder usually affects men and women older than 50.

Causes of Atherosclerosis



  • Inflammatory stresses involving the immune system (such as when people smoke cigarettes)

  • Chemical abnormalities in the bloodstream (such as high cholesterol or high blood sugar as occurs in diabetes mellitus)

Infections with some bacteria or viruses (such as Chlamydia pneumoniae or cytomegalovirus) may also increase inflammation in the artery's inner lining (endothelium) and lead to atherosclerosis.

Plaque formation


How Atherosclerosis Develops



Plaque rupture


Risk Factors for Atherosclerosis

Some risk factors for atherosclerosis can be modified (see also Overview of Coronary Artery Disease (CAD) : Prevention).

Modifiable risk factors include

  • Tobacco use

  • High levels of cholesterol in the blood

  • High blood pressure

  • Diabetes

  • Obesity

  • Physical inactivity

  • Low daily consumption of fruits and vegetables

Risk factors that cannot be modified include

  • Having a family history of early atherosclerosis (that is, having a close male relative who developed the disease before age 55 or having a close female relative who developed the disease before age 65)

  • Advancing age

  • Male sex

There are many risk factors that are still being studied, such as high levels of C-reactive protein (an inflammatory protein) in the blood, high levels of some components of cholesterol such as apolipoprotein B or lipoprotein(a), and psychosocial factors (such as anxiety and low socioeconomic status).


One of the most important modifiable risk factors is smoking. (Using other forms of tobacco, such as snuff and chewing tobacco, also increases risk.) A smoker‘s risk of developing some forms of atherosclerosis such as coronary artery disease is directly related to the amount of tobacco smoked daily. The risk of a heart attack is increased threefold in men and sixfold in women who smoked 20 or more cigarettes per day compared with nonsmokers. In people who already have a high risk of heart disease, tobacco use is particularly dangerous.

Tobacco use decreases the level of high-density lipoprotein (HDL) cholesterol—the “good” cholesterol—and increases the level of low-density lipoprotein (LDL) cholesterol—the “bad” cholesterol. Smoking increases the level of carbon monoxide in the blood, which may increase the risk of injury to the lining of the artery‘s wall. Tobacco use causes arteries already narrowed by atherosclerosis to constrict, further decreasing the amount of blood reaching the tissues. In addition, tobacco use increases the blood‘s tendency to clot (by making platelets stickier), so that it increases the risk of peripheral arterial disease (atherosclerosis affecting arteries other than those that supply the heart and brain), coronary artery disease, stroke, and blockage of an arterial graft placed during coronary artery bypass surgery or surgery to bypass a blocked artery elsewhere in the body.



Did You Know...

  • Smoking is an important risk factor for atherosclerosis.

Cholesterol levels

A high level of LDL cholesterol is another important modifiable risk factor. A diet that is high in saturated fats (see Types of Fat) causes LDL cholesterol levels to increase in susceptible people. Cholesterol levels also increase as people age and are normally higher in men than in women, although levels increase in women after menopause. Several hereditary disorders result in high levels of cholesterol or other fats. People with these hereditary disorders can have extremely high levels of cholesterol and (if untreated) die of coronary artery disease at an early age.

Lowering high LDL cholesterol levels through the use of drugs can significantly reduce the risk of heart attacks, strokes, and death. Many types of lipid-lowering drugs are available (see Table: Lipid-Lowering Drugs). Statins are the most common type.

Not all high cholesterol levels increase the risk of atherosclerosis. A high level of HDL (good) cholesterol decreases the risk of atherosclerosis.

The desired level of total cholesterol, which includes LDL cholesterol, HDL cholesterol, and triglycerides, is 140 to 200 mg/dL (3.6 to 5.2 mmol/L). Risk of a heart attack more than doubles when the total cholesterol level approaches 300 mg/dL (7.8 mmol/L). The risk is decreased when the LDL cholesterol level is below 130 mg/dL (3.4 mmol/L), and the HDL cholesterol level is above 40 mg/dL (1 mmol/L). High-risk people, such as those who have diabetes or atherosclerotic heart disease or have had a heart attack, stroke, or bypass surgery, would benefit from high-dose statins to lower their LDL cholesterol as much as possible. However, the percentage of HDL cholesterol in relation to total cholesterol is a more reliable measure of risk than is the total or LDL cholesterol level. HDL cholesterol should account for more than 25% of total cholesterol. High triglyceride levels are often associated with low HDL cholesterol levels. However, evidence suggests that high triglyceride levels alone may also slightly increase the risk of atherosclerosis.

High blood pressure

Uncontrolled high blood pressure is a risk factor for heart attack and stroke, which are caused by atherosclerosis. The risk of cardiovascular disease starts increasing when blood pressure levels are above 110/75 mm Hg. Reducing high blood pressure clearly lowers risk. Doctors usually try to achieve a blood pressure of less than 140/90 mm Hg, and often less than 130/80 mm Hg in people at risk of cardiovascular disease, such as people with diabetes or kidney disease.

Diabetes mellitus

People who have diabetes mellitus tend to develop disease that affects small arteries, such as those in the eyes, nerves, and kidneys, leading to vision loss, nerve damage, and chronic kidney disease. People with diabetes also tend to develop atherosclerosis in large arteries. Atherosclerosis tends to develop at an earlier age and more extensively than it does in people who do not have diabetes. The risk of developing atherosclerosis is 2 to 6 times higher for people with diabetes, particularly women. Women who have diabetes, unlike those who do not, are not protected from atherosclerosis before menopause. People who have diabetes have the same risk of death as someone who has had a prior heart attack, and doctors usually try to help these people keep other risk factors (such as high cholesterol levels and high blood pressure) under careful control.



Physical inactivity






  • Saturated and trans fats





Alcohol intake


High blood levels of homocysteine (hyperhomocysteinemia)

People who have very high levels of homocysteine (an amino acid) in their blood, usually because of a hereditary disorder, have an increased risk of coronary artery disease, usually at a young age. However, it is unclear why high homocysteine levels are associated with atherosclerosis. Giving people drugs that lower homocysteine levels does not seem to reduce risk of death.

Symptoms of Atherosclerosis

Symptoms depend on

  • Where the affected artery is located

  • Whether the affected artery is gradually narrowed or suddenly blocked

Symptoms of gradual narrowing



Symptoms of sudden artery blockage


Diagnosis of Atherosclerosis

  • Blood tests to look for risk factors for atherosclerosis

  • Imaging tests to look for dangerous plaques

How atherosclerosis is diagnosed depends on whether the person is having symptoms.

People with symptoms



Doctors also test for certain risk factors in people who have an atherosclerotic blockage. For example, they measure the levels of glucose, cholesterol, and triglycerides in the blood. Doctors usually also do these tests as part of the routine yearly examination in adults.


People without symptoms (screening)

In people who have some risk factors for atherosclerosis but no symptoms, doctors usually do blood tests to measure the levels of glucose, cholesterol, and triglycerides in the blood. Doctors usually also do these tests as part of the routine yearly examination in adults.

Some doctors recommend imaging tests to look for atherosclerotic blockage in people who have risk factors but no symptoms as part of a prevention strategy. Such tests include an electron beam CT of the heart and ultrasonography of the arteries in the neck (carotid arteries). CT can also be used to detect hardened (calcified) plaque in the coronary arteries. Ultrasonography of the carotid arteries can detect thickening of the artery wall, which suggests atherosclerosis. However, many doctors think that these tests rarely change the advice they would give based on the person‘s other, more easily recognized, risk factors.

Prevention and Treatment of Atherosclerosis

  • Lifestyle changes to reduce risk of complications

  • Sometimes drugs

To help prevent atherosclerosis, people need to


People who are at high risk of atherosclerosis also may benefit from taking certain drugs. Helpful drugs include the statins (even if cholesterol levels are normal or only slightly high) and aspirin or other antiplatelet drugs.


Treatment of atherosclerosis complications


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