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What Are the Causes of Coronary Artery Disease?

What is coronary artery disease?

Coronary artery disease (CAD), or coronary heart disease, is the most common type of heart disease. CAD occurs when your blood vessels can’t carry blood and oxygen to your heart. This is typically because they’re damaged, diseased, or blocked, disrupting the blood flow. The most frequent cause of this is plaque buildup in these vessels, which are called coronary arteries.

When your arteries narrow, it leaves less space for blood to flow. This decreases blood flow and makes it difficult for your body to supply your heart with the blood it needs. A lack of blood flow can cause chest pain, shortness of breath, and other symptoms of cardiac disease.

Plaque usually builds up over many years. For some people, the first sign of CAD may be a heart attack. In the United States, CAD is the leading cause of death. However, as people around the world live longer, CAD is expected to be the leading cause of death in 2020, according to the Merck Manual.

Understanding the different causes of CAD may help you reduce your risk of developing it later on. If your doctor diagnoses you with CAD early on, you may be able to prevent or reduce the risk of CAD through lifestyle changes.

What causes coronary artery disease?

Atherosclerosis, or the hardening or clogging of arteries, is the number one cause of CAD.


Healthy coronary arteries have smooth walls through which blood can easily flow through. When there’s damage to an artery wall, plaque gets trapped in those crevices. Plaque deposits are made of cholesterol, inflammatory and smooth muscle cells, and connective tissue. Over time, the plaque on those walls hardens and restricts blood flow. This process is called atherosclerosis.


Other substances traveling through your arteries, such as proteins and cellular waste products, can stick to the plaque as well. It usually takes years for the buildup to become noticeable. Often, you won’t know you have plaque buildup until it becomes bad enough to cause serious symptoms.

Plaque buildup can lead to reduced blood flow to the heart. This can cause:

  • chest pain or discomfort
  • blockage, which prevents your heart from receiving enough blood
  • a weak heart muscle
  • heart failure

Atherosclerosis is thought to happen in areas of the arteries that have turbulence, or unsteady blood flow, but other factors such as hypertension, infections, and chemicals can damage the artery walls. While some buildup is the result of aging, other factors can increase the rate at which atherosclerosis occurs.

This includes:

  • smoking because tobacco chemicals irritate the artery walls
  • high levels of fat, or triglycerides, in the blood
  • high levels of cholesterol in the blood
  • diabetes or high blood sugar
  • hypertension, or high blood pressure

Other causes that limit blood flow

Other rare causes of damage or blockage to the coronary artery also limit blood flow to the heart. These causes, which are typically related to atherosclerosis, are:

  • an embolism, or a blockage in the coronary artery
  • an aneurysm, or inflamed coronary arteries
  • artery vasculitis, or thickened coronary artery walls
  • a spontaneous coronary artery dissection, or buildup of blood in between the layers of the coronary artery wall

Sometimes, plaques burst open and release blood cells called "platelets" into the artery. This then cause blood clots and further buildup. These blood clots can become dislodged and block blood flow to your heart, which leads to a heart attack. You may lose the blocked artery in the event of a heart attack.

Who is at risk for coronary artery disease?

The risk factors for CAD are the same as those for atherosclerosis.

Other common factors that increase your risk are:

  • age, with people over 65 at a heightened risk
  • sex, with men at a higher risk than women until age 70
  • a family history of the disease
  • being overweight
  • obesity
  • uncontrolled diabetes, especially type 2
  • a lack of physical activity
  • smoking
  • continuous stress
  • excessive alcohol consumption

A poor diet, especially one that’s high in fat and low in vitamins, such as vitamins C, D, and E can also increase your risk.

High levels of C-reactive protein may also be evidence of plaque instability and inflammation. While it’s not tied directly to CAD, it can be a strong indicator of blood restriction, according to the Merck Manual.

How is coronary artery disease diagnosed?

Because CAD and atherosclerosis can show no symptoms, your doctor may perform extra tests to confirm their diagnosis.

These tests include:

  • an electrocardiogram, or EKG, to measure your heartbeat
  • an echocardiogram to get a picture of your heart
  • an exercise stress test to measure heart rate while your heart is at work
  • a chest X-ray to create a picture of your heart, lungs, and other chest organs
  • cardiac catheterization to check your arteries for blockage
  • a coronary angiogram to monitor the blockage and flow of your blood

Your treatment will depend on your diagnosis.

Tips for preventing coronary artery disease

You can make many lifestyle changes to decrease your risk of developing CAD and its complications.

Eating a healthy diet and reducing your salt intake is a great way to prevent CAD. Other means of prevention include:

  • losing weight if you’re overweight
  • increasing your physical activity
  • controlling high blood pressure
  • managing diabetes
  • managing high cholesterol

If you smoke, quitting will help prevent the development of CAD. If you already have a severe blockage, surgical procedures can help restore blood flow to the heart.


Your doctor may prescribe or recommend daily preventive medications, such as aspirin, if lifestyle changes aren’t enough. Aspirin can help prevent CAD by stopping blood cells from clumping and forming plaques.

But the type of drug you take will depend on your risk factors. For example, if your blood clots easily, you may need to take Integrillin. Your doctor might prescribe gemfibrozil (Lopid). This drug can help decrease fat in your bloodstream and increase good cholesterol.

Look at the graph below of common drugs used to treat CAD and their prices.

The goal of your treatment is to improve blood flow, prevent or delay the buildup of plaque in your arteries, and make it easier for your heart to pump blood. 

Content licensed from:

Written by: Lauren Reed-Guy
Medically reviewed on: Aug 09, 2016: University of Illinois-Chicago, School of Medicine

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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