What is coronary artery disease (CAD)?

Coronary artery disease^[1], or CAD, develops when the coronary arteries^[2] (the major blood vessels supplying your heart with blood, oxygen, and nutrients) become damaged or diseased. CAD often takes decades to develop. Because of this, you may not notice a problem until you have a significant blockage or a heart attack.

What is atherosclerotic coronary artery disease?

While coronary artery disease can be caused by inflammation, it is often caused by atherosclerosis^[3]—the buildup of fatty deposits (called plaque) in the arteries. This type of CAD is called atherosclerotic coronary artery disease. Plaque deposits are made up of cholesterol, fatty substances, cellular waste, calcium, and fibrin (a clotting material in the blood). When plaque builds up, it thickens the wall of the blood vessels, causing them to narrow. This decreases the flow of blood and oxygen to the heart and the rest of the body. This decreased blood flow can eventually cause chest pain (angina^[4]), shortness of breath, and other CAD signs and symptoms. A complete blockage of the coronary arteries can cause a heart attack^[5] or stroke^[6].

How common is coronary artery disease?

Coronary artery disease is a type of heart disease. According to the CDC, heart disease is the leading cause of death for both men and women—about 610,000 people^[7] in the United States die of heart disease every year. Coronary heart disease (CHD) is the most common type of heart disease and kills over 370,000 people annually.

Coronary artery disease causes

Coronary artery disease is thought to begin^[8] with damage or injury to the inner layer of a coronary artery. This damage can occur as early as childhood and may be caused by a number of factors, including:

• Smoking or tobacco use
• High blood pressure (hypertension^[9])
• High cholesterol^[10]
• Diabetes or insulin resistance
• Sedentary lifestyle

Once the inner wall of an artery is damaged, plaque deposits tend to accumulate at the site of injury. This process of plaque buildup in the coronary arteries, called atherosclerosis, is what causes coronary artery disease. Too much plaque buildup causes the inside of the arteries to narrow over time, which can partially or completely block the flow of blood through the arteries. Furthermore, if the surface of a plaque buildup breaks or ruptures, blood cells called platelets will clump at the site in an attempt to repair the artery, which can cause blockage that may lead to a heart attack. Coronary artery disease can weaken the heart muscle over time. This may lead to heart failure^[11], a serious condition in which the heart loses the ability to sufficiently pump blood. CAD may also cause an irregular heart beat (called arrhythmia^[12]) to develop.

Coronary artery disease symptoms

When the coronary arteries are narrowed due to plaque buildup, they can’t supply enough oxygen-rich blood to the heart. Initially, decreased blood flow may not cause any symptoms of coronary artery disease. However, as plaque continues to build up and cause potential blockages, you may develop pronounced signs and symptoms of CAD. Common symptoms^[13] of coronary artery disease include:

• Chest pain (angina): Angina involves pressure or tightness in the chest, and usually occurs on the middle or left side of the chest. It is generally triggered by physical or emotional stress, and usually goes away within minutes after stressors have gone away. In some people (especially women), this pain may be fleeting or sharp and felt in the neck, arm, or back.
• Shortness of breath: If your heart can’t pump enough blood to meet your body’s needs, you may become short of breath or extremely fatigued under physical exertion.
• Heart attack: A coronary artery that is completely blocked will cause a heart attack. The signs and symptoms characteristic of a heart attack include crushing pressure in the chest and pain in the shoulder or arm, sometimes accompanied by shortness of breath and sweating. In some cases, a heart attack occurs without any apparent signs or symptoms. Women are somewhat more likely than men to experience less typical signs and symptoms of a heart attack, such as pain in the neck or jaw.

If you suspect yourself of having coronary artery disease, or if you develop new or worsened symptoms, it is important that you contact your healthcare provider or seek medical care as soon as possible.

Coronary artery disease risk factors

There are a number of factors that may increase your risk of developing CAD or complications from the condition. The risk factors for CAD are often related, occurring in clusters and potentially building on one another (for example, obesity leading to type 2 diabetes and hypertension). The presence of multiple risk factors puts you at an even greater risk for developing CAD. While some risk factors for CAD are hereditary or inevitable (such as aging), others are manageable through healthy lifestyle choices. Some common risk factors^[14] for coronary artery disease include:

• Age: Aging increases your risk of developing damaged and narrowed arteries.
• Sex: Men are at greater risk of developing CAD than women. However, the risk for women developing CAD increases after menopause^[15].
• Family history: A family history of heart disease is associated with a higher risk of developing CAD—especially if a close relative developed heart disease at an early age. However, while genetic factors do likely play a role in high blood pressure, heart disease, and other related conditions, it is also likely that people with a family history of heart disease share common environments and other potential factors that increase their risk. The risk of heart disease can increase even more when hereditary factors are combined with unhealthy lifestyle choices.
• High blood pressure: High blood pressure (hypertension) that is left untreated can cause the arteries to harden and thicken, making it more difficult for blood to flow.
• High cholesterol: High blood cholesterol levels can increase the risk of plaque formation and atherosclerosis. While atherosclerosis can be caused by a high level of “bad” cholesterol (low-density lipoprotein, or LDL, cholesterol), a low level of “good” cholesterol (high-density lipoprotein, or HDL, cholesterol) can also contribute to developing atherosclerosis.
• Diabetes: Diabetes^[16] is associated with an increased risk of developing CAD. Type 2 diabetes^[17] and CAD share similar risk factors, such as obesity and high blood pressure.
• Being overweight or obese: Excess weight typically worsens the other risk factors for developing CAD.
• Physical inactivity: A lack of exercise is associated with CAD and some of its risk factors.
• High stress: Unmanaged stress may damage the arteries, as well as worsen other risk factors for CAD.
• Unhealthy diet: Eating too much food with high amounts of saturated fat, trans fat, salt, and sugar can increase your risk of developing CAD.
• Race or ethnicity: According to the CDC^[18], in 2013 heart disease was the leading cause of death in the United States for non-Hispanic whites, non-Hispanic blacks, and Indigenous Americans. For Hispanics, Asian Americans, and Pacific Islanders, heart disease is second only to cancer as a leading cause of death.
• Excessive alcohol consumption: Drinking too much alcohol can raise blood pressure levels and increase the risk of heart disease. It also increases levels of triglycerides (a form of cholesterol), which can harden the arteries. According to the CDC^[19], women should have no more than 1 drink a day, while men should have no more than 2 drinks a day.
• Smoking: Cigarette smoking can damage the heart and blood vessels, which increases your risk for heart conditions like atherosclerosis (which causes coronary artery disease) and heart attack. Furthermore, nicotine raises your blood pressure, and carbon monoxide reduces the amount of oxygen that your blood can carry. Exposure to secondhand smoke can also increase the risk for heart disease—even in nonsmokers.

Coronary artery disease complications

There are a number of complications that coronary artery disease can lead to, including:

• Chest pain (angina): When the coronary arteries narrow, the heart may not receive enough oxygen-rich blood when the demand for it is greatest (particularly during physical activity). This can cause chest pain (angina) or shortness of breath.
• Abnormal heart rhythm (arrhythmia): Inadequate blood supply to the heart or damage to heart tissues can interfere with the heart’s electrical impulses, causing abnormal heart rhythms.
• Heart failure: If some areas of the heart are chronically deprived of oxygen and nutrients due to reduced blood flow, or if the heart has been damaged by a heart attack, the organ may become too weak to pump enough blood to meet the body’s needs. This condition is known as heart failure.
• Heart attack: If a cholesterol plaque ruptures and a blood clot forms, the complete blockage of blood flow through the coronary arteries can trigger a heart attack. The lack of blood flow to your heart may also damage your heart muscle. The amount of damage done partially depends on how quickly you receive treatment for a heart attack.