Coronary Artery Disease (CAD)

Coronary artery disease (CAD) is the most common type of heart disease in the United States. It is sometimes called coronary heart disease or ischemic heart disease.

For some people, the first sign of CAD is a heart attack. You and your health care team may be able to help reduce your risk for CAD.

Coronary artery disease is a narrowing or blockage of your coronary arteries usually caused by the buildup of fatty material called plaque. Coronary artery disease is also called coronary heart disease, ischemic heart disease and heart disease.

Coronary arteries are the blood vessels that supply oxygen-rich blood to your heart muscle to keep it pumping. The coronary arteries are directly on top of your heart muscle. You have four main coronary arteries:

• The right coronary artery.
• The left coronary artery.
• The left anterior descending artery.
• The left circumflex artery.

Coronary artery disease is caused by atherosclerosis. Atherosclerosis is the buildup of plaque inside your arteries. Plaque consists of cholesterol, fatty substances, waste products, calcium and the clot-making substance fibrin. As plaque continues to collect on your artery walls, your arteries narrow and stiffen. Plaque can clog or damage your arteries, which limits or stops blood flow to your heart muscle. If your heart does not get enough blood, it can't get the oxygen and nutrients it needs to work properly. This condition is called ischemia. Not getting enough blood supply to your heart muscle can lead to chest discomfort or chest pain (called angina). It also puts you at risk for a heart attack.

Coronary artery disease happens in everyone. The speed at which it develops differs from person to person. The process usually starts when you are very young. Before your teen years, the blood vessel walls start to show streaks of fat. As plaque deposits in your artery’s inner walls, your body fights back against this ongoing process by sending white blood cells to attack the cholesterol, but the attack causes more inflammation. This triggers yet other cells in the artery wall to form a soft cap over the plaque.

This thin cap over the plaque can break open (due to blood pressure or other causes). Blood cell fragments called platelets stick to the site of “the injury,” causing a clot to form. The clot further narrows arteries. Sometimes a blood clot breaks apart on its own. Other times the clot blocks blood flow through the artery, depriving the heart of oxygen and causing a heart attack.

You have an increased risk of coronary artery disease if you:

Have a high cholesterol level (especially a high LDL “bad” cholesterol level and a low HDL “good” cholesterol level).

• Have high blood pressure.
• Family history of heart disease.
• Have diabetes.
• Are a smoker.
• Are a man over 45 years of age or a post-menopausal woman.
• Are overweight.
• Are physically inactive.

Are Black, Mexican American, Native American, Native Hawaiian or Asian American. The increased risks are caused by higher rates of high blood pressure, obesity and diabetes in these populations.

If you have these risk factors, talk with your healthcare provider. They may want to test you for coronary artery disease.

Symptoms

If your coronary arteries narrow, they can't supply enough oxygen-rich blood to your heart — especially when it's beating hard, such as during exercise. At first, the decreased blood flow may not cause any symptoms. As plaque continues to build up in your coronary arteries, however, you may develop the following coronary artery disease signs and symptoms:

Chest pain (angina). You may feel pressure or tightness in your chest, as if someone were standing on your chest. This pain, called angina, usually occurs on the middle or left side of the chest. Angina is generally triggered by physical or emotional stress. The pain usually goes away within minutes after stopping the stressful activity. In some people, especially women, the pain may be brief 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 develop shortness of breath or extreme fatigue with activity.

Heart attack. A completely blocked coronary artery will cause a heart attack. The classic signs and symptoms of a heart attack include crushing pressure in your chest and pain in your shoulder or arm, sometimes with shortness of breath and sweating.

Women are somewhat more likely than men are to have less typical signs and symptoms of a heart attack, such as neck or jaw pain. And they may have other symptoms such as shortness of breath, fatigue and nausea.

Sometimes a heart attack occurs without any apparent signs or symptoms.

When to see a doctor

If you think you're having a heart attack, immediately call 911 or your local emergency number. If you don't have access to emergency medical services, have someone drive you to the nearest hospital. Drive yourself only as a last option.

If you have risk factors for coronary artery disease — such as high blood pressure, high cholesterol, tobacco use, diabetes, obesity a strong family history of heart disease — talk to your doctor. Your doctor may want to test you for coronary artery disease, especially if you have signs or symptoms of narrowed arteries.

Causes

Coronary artery disease is thought to begin with damage or injury to the inner layer of a coronary artery, sometimes as early as childhood. The damage may be caused by various factors, including:

• Smoking
• High blood pressure
• High cholesterol
• Diabetes or insulin resistance
• Not being active (sedentary lifestyle)

Once the inner wall of an artery is damaged, fatty deposits (plaque) made of cholesterol and other cellular waste products tend to collect at the site of injury. This process is called atherosclerosis. If the plaque surface breaks or ruptures, blood cells called platelets clump together at the site to try to repair the artery. This clump can block the artery, leading to a heart attack.

Risk factors

Risk factors for coronary artery disease include:

Age. Getting older increases your risk of damaged and narrowed arteries.

Sex. Men are generally at greater risk of coronary artery disease. However, the risk for women increases after menopause.

Family history. A family history of heart disease is associated with a higher risk of coronary artery disease, especially if a close relative developed heart disease at an early age. Your risk is highest if your father or a brother was diagnosed with heart disease before age 55 or if your mother or a sister developed it before age 65.

Smoking. People who smoke have a significantly increased risk of heart disease. Breathing in secondhand smoke also increases a person's risk of coronary artery disease.

High blood pressure. Uncontrolled high blood pressure can result in hardening and thickening of your arteries, narrowing the channel through which blood can flow.

High blood cholesterol levels. High levels of cholesterol in your blood can increase the risk of formation of plaque and atherosclerosis. High cholesterol can be caused by a high level of low-density lipoprotein (LDL) cholesterol, known as the "bad" cholesterol. A low level of high-density lipoprotein (HDL) cholesterol, known as the "good" cholesterol, can also contribute to the development of atherosclerosis.

Diabetes. Diabetes is associated with an increased risk of coronary artery disease. Type 2 diabetes and coronary artery disease share similar risk factors, such as obesity and high blood pressure.

Overweight or obesity. Excess weight typically worsens other risk factors.

Physical inactivity. Lack of exercise also is associated with coronary artery disease and some of its risk factors, as well.

High stress. Unrelieved stress in your life may damage your arteries as well as worsen other risk factors for coronary artery disease.

Unhealthy diet. Eating too much food that has high amounts of saturated fat, trans fat, salt and sugar can increase your risk of coronary artery disease.

Risk factors often occur together and one may trigger another. For instance, obesity can lead to type 2 diabetes and high blood pressure. When grouped together, certain risk factors make you even more likely to develop coronary artery disease. For example, metabolic syndrome — a cluster of conditions that includes high blood pressure; high triglycerides; low HDL, or "good," cholesterol; high insulin levels and excess body fat around the waist — increases the risk of coronary artery disease.

Sometimes coronary artery disease develops without any classic risk factors. Researchers are studying other possible risk factors, including:

Sleep apnea. This disorder causes you to repeatedly stop and start breathing while you're sleeping. Sudden drops in blood oxygen levels that occur during sleep apnea increase blood pressure and strain the cardiovascular system, possibly leading to coronary artery disease.

High-sensitivity C-reactive protein (hs-CRP). This protein appears in higher-than-normal amounts when there's inflammation somewhere in your body. High hs-CRP levels may be a risk factor for heart disease. It's thought that as coronary arteries narrow, you'll have more hs-CRP in your blood.

High triglycerides. This is a type of fat (lipid) in your blood. High levels may raise the risk of coronary artery disease, especially for women.

Homocysteine. Homocysteine is an amino acid your body uses to make protein and to build and maintain tissue. But high levels of homocysteine may increase your risk of coronary artery disease.

Preeclampsia. This condition that can develop in women during pregnancy causes high blood pressure and a higher amount of protein in urine. It can lead to a higher risk of heart disease later in life.

Alcohol use. Heavy alcohol use can lead to heart muscle damage. It can also worsen other risk factors of coronary artery disease.

Autoimmune diseases. People who have conditions such as rheumatoid arthritis and lupus (and other inflammatory conditions) have an increased risk of atherosclerosis.

Complications

Coronary artery disease can lead to:

Chest pain (angina). When your coronary arteries narrow, your heart may not receive enough blood when demand is greatest — particularly during physical activity. This can cause chest pain (angina) or shortness of breath.

Heart attack. If a cholesterol plaque ruptures and a blood clot forms, complete blockage of your heart artery may trigger a heart attack. The lack of blood flow to your heart may damage your heart muscle. The amount of damage depends in part on how quickly you receive treatment.

Heart failure. If some areas of your heart are chronically deprived of oxygen and nutrients because of reduced blood flow, or if your heart has been damaged by a heart attack, your heart may become too weak to pump enough blood to meet your body's needs. This condition is known as heart failure.

Abnormal heart rhythm (arrhythmia). Inadequate blood supply to the heart or damage to heart tissue can interfere with your heart's electrical impulses, causing abnormal heart rhythms.

Prevention

The same lifestyle habits used to help treat coronary artery disease can also help prevent it. A healthy lifestyle can help keep your arteries strong and clear of plaque. To improve your heart health, follow these tips:

• Quit smoking.
• Control conditions such as high blood pressure, high cholesterol and diabetes.
• Stay physically active.
• Eat a low-fat, low-salt diet that's rich in fruits, vegetables and whole grains.
• Maintain a healthy weight.
• Reduce and manage stress.

Diagnosis

Coronary artery disease FAQs

The doctor will ask questions about your medical history, do a physical exam and order routine blood tests. He or she may suggest one or more diagnostic tests as well, including:

Electrocardiogram (ECG). An electrocardiogram records electrical signals as they travel through your heart. An ECG can often reveal evidence of a previous heart attack or one that's in progress.

Echocardiogram. An echocardiogram uses sound waves to produce images of your heart. During an echocardiogram, your doctor can determine whether all parts of the heart wall are contributing normally to your heart's pumping activity.

Parts that move weakly may have been damaged during a heart attack or be receiving too little oxygen. This may be a sign of coronary artery disease or other conditions.

Exercise stress test. If your signs and symptoms occur most often during exercise, your doctor may ask you to walk on a treadmill or ride a stationary bike during an ECG. Sometimes, an echocardiogram is also done while you do these exercises. This is called a stress echo. In some cases, medication to stimulate your heart may be used instead of exercise.

Nuclear stress test. This test is similar to an exercise stress test but adds images to the ECG recordings. It measures blood flow to your heart muscle at rest and during stress. A tracer is injected into your bloodstream, and special cameras can detect areas in your heart that receive less blood flow.

Cardiac catheterization and angiogram. During cardiac catheterization, a doctor gently inserts a catheter into an artery or vein in your groin, neck or arm and up to your heart. X-rays are used to guide the catheter to the correct position. Sometimes, dye is injected through the catheter. The dye helps blood vessels show up better on the images and outlines any blockages.

If you have a blockage that requires treatment, a balloon can be pushed through the catheter and inflated to improve the blood flow in your coronary arteries. A mesh tube (stent) is typically used to keep the dilated artery open.

Cardiac CT scan. A CT scan of the heart can help your doctor see calcium deposits in your arteries that can narrow the arteries. If a substantial amount of calcium is discovered, coronary artery disease may be likely.

A CT coronary angiogram, in which you receive a contrast dye that is given by IV during a CT scan, can produce detailed images of your heart arteries.