Coronary Artery Disease

Illustration of a normal artery (A) with normal blood flow, and an artery with plaque buildup (B) resulting in abnormal or reduced blood flow. Source: NHLBI.

Other Names

• Atherosclerosis (ATH-er-o-skler-O-sis)
• Coronary heart disease
• Hardening of the arteries
• Heart disease
• Ischemic (is-KE-mik) heart disease
• Narrowing of the arteries

Signs and Symptoms

Figure A shows an overview of the heart and coronary arteries. Figure B shows a cross-section of a coronary artery with plaque buildup and a blood clot. Source: NHLBI.

If symptoms do occur with CAD, they can include the following:

• Angina. Angina is chest pain or discomfort that occurs when the heart muscle doesn't get enough oxygen-rich blood. Angina may feel like pressure or a squeezing pain in the chest. Pain may also be felt in the shoulders, arms, neck, jaw, or back. This pain tends to get worse with activity and go away at rest. Emotional stress can also trigger the pain.

• Shortness of breath. This symptom happens if CAD causes heart failure. In heart failure, the heart can't pump enough blood throughout the body. Fluid builds up in the lungs, making it hard to breathe.

• Heart arrhythmia. An arrhythmia is a problem with the speed or rhythm of the heartbeat. The heart feels as if it is skipping beats or beating too fast. Some people describe arrhythmias as a fluttering feeling in their chests. These feelings are called palpitations.

The severity of these symptoms varies. The symptoms may get more severe as the buildup of plaque continues to narrow the coronary arteries.

Causes

Research suggests that coronary artery disease starts when certain factors damage the inner layers of the coronary arteries. These factors include the following:

• Smoking.
• High amounts of certain fats and cholesterol in the blood.
• High blood pressure.
• High amounts of sugar in the blood due to insulin resistance or diabetes.

When damage to the coronary arteries occurs, the body starts a healing process. Excess fatty tissues release compounds that promote this process. This healing causes plaque to build up where the arteries are damaged leading to narrowing of the artery and a decrease in blood flow to heart muscle. Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood.

Over time, the plaque may crack. Blood cells called platelets (PLATE-lets) clump together to form blood clots where the cracks are. This narrows the arteries more, and blood flow to the heart muscle may be further decreased. This can result in lack of oxygen to the heart muscle which can be damaged or can die from this lack of oxygen

Heart muscle needs a continuous flow of well-oxygenated blood. If heart muscle is starved of oxygen due to decreased coronary blood flow, particularly if the heart is under stress, the muscle can be damaged or can even die. The result can be angina, a heart attack, heart failure, or a heart arrhythmia.

Diagnosis

The diagnose of coronary artery disease is usually based on a person's medical and family histories, risk factors, and the results of a physical exam and diagnostic tests.

Exams and tests

No single test can diagnose CAD. If a doctor suspects CAD, he or she will probably do one or more of the following tests.

ECG (Electrocardiogram)

An ECG is a simple test that detects and records the electrical activity of the heart. An ECG shows how fast the heart is beating and whether it has a regular rhythm. It also shows the strength and timing of electrical signals as they pass through each part of the heart.

Certain electrical patterns detected on the ECG can suggest whether CAD is likely. An ECG can also show signs of a previous or current heart attack.

Stress testing

During stress testing (also called a stress ECG), a person exercises to make the heart work hard and beat fast while heart tests are performed. If a person can't exercise, he or she is given medicine to speed up the heart rate. A stress test can show possible signs of CAD, such as the following:

• Abnormal changes in the heart rate or blood pressure.
• Symptoms such as shortness of breath or chest pain.
• Abnormal changes in the heart rhythm or the heart's electrical activity.
• Inability to exercise on the stress test machine for as long as what is normal for a person's age.

Some stress tests use a radioactive dye, sound waves, positron emission tomography (PET), or cardiac magnetic resonance imaging (MRI) to take pictures of the heart when a person is exercising and when at rest.

These imaging stress tests can show how well blood is flowing in the different parts of the heart. They also can show how well the heart pumps blood when it beats.

Echocardiography

This test uses sound waves to create a moving picture of the heart. Echocardiography provides information about the size and shape of the heart and how well the heart chambers and valves are working. This test also can identify areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.

Chest x-ray

A chest x-ray takes a picture of the organs and structures inside the chest, including the heart, lungs, and blood vessels. A chest x-ray can reveal signs of heart failure, as well as lung disorders and other causes of symptoms that aren't due to CAD.

Blood tests

Blood tests check the levels of certain fats, cholesterol, sugar, and proteins in the blood. Abnormal levels may show that a person has risk factors for CAD.

Electron-beam computed tomography

A doctor may recommend electron-beam computed tomography (EBCT) in the management of CAD. This test finds and measures calcium deposits (called calcifications) in and around the coronary arteries. The more calcium detected, the more likely a person is to have CAD. EBCT isn't used routinely to diagnose CAD, because its accuracy isn't yet known.

Coronary angiography and cardiac catheterization

A doctor may request coronary angiography if other tests or factors show that a person is likely to have CAD. This test uses dye and special x-rays to show the insides of a person's coronary arteries. To get the dye into a person's coronary arteries, the doctor will use a procedure called cardiac catheterization. A long, thin, flexible tube called a catheter is put into a blood vessel in the arm, groin (upper thigh), or neck. The tube is then threaded into the coronary arteries, and the dye is released into the bloodstream. Special x-rays are taken while the dye is flowing through the coronary arteries.

Treatment

Treatment for coronary artery disease may include lifestyle changes, medicines, and medical procedures. The goals of treatment are: to relieve symptoms; reduce risk factors in an effort to slow, stop, or reverse plaque buildup; lower the risk of blood clot formation; widen or bypass clogged coronary arteries; and prevent complications of CAD.

Medications

If lifestyle changes aren't enough, medicines may be needed to treat CAD. The effects of these medicines include the following:

• Decreased workload on the heart, which relieves CAD symptoms.
• Decreased chance of having a heart attack or dying suddenly.
• Lowered cholesterol and blood pressure.
• Prevention of blood clots.
• Preventing or delaying the need for a special procedure (for example angioplasty or coronary artery bypass grafting.

Medicines used to treat CAD include anticoagulants (drugs that thin the blood), aspirin and other antiplatelet medicines, ACE inhibitors, beta blockers, calcium channel blockers, nitroglycerin, glycoprotein IIb-IIIa inhibitors, statins, fish oil and other supplements high in omega-3 fatty acids.

Medical procedures

A medical procedure may be needed to treat CAD. Both angioplasty and CABG are used as treatments.

Angioplasty opens blocked or narrowed coronary arteries. During angioplasty, a thin tube with a balloon or other device on the end is threaded through a blood vessel to the narrowed or blocked coronary artery. Once in place, the balloon is inflated to push the plaque outward against the wall of the artery. This widens the artery and restores the flow of blood. Angioplasty can improve blood flow to the heart, relieve chest pain, and possibly prevent a heart attack. Sometimes a small mesh tube called a stent is placed in the artery to keep it open after the procedure.

In CABG, arteries or veins are removed from other areas in the body and are used to bypass (that is, go around) narrowed coronary arteries. CABG can improve blood flow to the heart, relieve chest pain, and possibly prevent a heart attack.

Cardiac rehabilitation

The doctor may prescribe cardiac rehabilitation (rehab) for angina, or after CABG, angioplasty, or a heart attack. Cardiac rehab, when combined with medicine and surgical treatments, can help a person recover faster, feel better, and develop a healthier lifestyle. Almost everyone with CAD can benefit from cardiac rehab. The cardiac rehab team may include doctors, nurses, exercise specialists, physical and occupational therapists, dietitians, and psychologists or other behavioral therapists.

Cardiac rehab involves exercise training which helps a person learn how to exercise safely, strengthen muscles, and improve stamina; it also involves education, counseling, and training to help people with CAD understand their heart condition and find ways to reduce the risk for future heart problems.

Prevention

Making lifestyle changes can often help prevent or treat CAD. For some people, these changes may be the only treatment needed.

• Follow a heart healthy eating plan^[1] to prevent or reduce high blood pressure^[2] and high blood cholesterol, and to maintain a healthy weight.

• Increase physical activity. It is a good idea to check with a doctor first to find out how much and what kinds of activity are safe. Regular physical activity can lower many CAD risk factors, including LDL ("bad") cholesterol, high blood pressure, and excess weight. Physical activity also can lower a person's risk for diabetes and raise levels of HDL cholesterol (the "good" cholesterol that helps prevent CAD).

• Lose weight, if overweight or obese. Maintaining a healthy weight can decrease risk factors for CAD. In an overweight person, aiming to reduce weight by 7 to 10 percent during your first year of treatment can decrease CAD risk and other health problems.

• Quit smoking, or avoid exposure to secondhand smoke. Quitting smoking or using tobacco is an important way to reduce risk for CAD. Smoking can damage and tighten blood vessels and raise the risk for CAD.

• Learn to cope with and reduce stress. Research shows that the most commonly reported "trigger" for a heart attack is an emotionally upsetting event, particularly one involving anger. Also, some of the ways people cope with stress, such as drinking, smoking, or overeating, aren't heart healthy. Physical activity can help relieve stress and reduce other CAD risk factors. Many people also find that meditation or relaxation therapy helps them reduce stress.

Living with Coronary Artery Disease

Coronary artery disease can cause serious complications. However, following a doctor's advice and changing lifestyle habits can prevent or reduce the chances of the following:

• Dying suddenly from heart problems.
• Having a heart attack and permanently damaging the heart muscle.
• Damaging the heart because of reduced oxygen supply.
• Having arrhythmias (irregular heartbeats).

Doing physical activity regularly, taking prescribed medicines, following a heart healthy eating plan, and watching one's weight can help control CAD. Visiting a doctor regularly to keep track of blood pressure, blood cholesterol, and blood sugar levels also helps control the disease.

Because CAD raises the risk for having a heart attack, people with CAD should learn the symptoms of a heart attack which can include the following: chest tightness, discomfort, or pain; discomfort or pain in the upper body or in one or both arms; shortness of breath. It is important to know the difference between the symptoms of angina and a heart attack. During a heart attack, the pain is usually more severe than the pain of angina, and it doesn't go away with rest or with medications.

It is important to let close associates know that a person is at risk for a heart attack. They can seek emergency care if the affected person suddenly faints, collapses, or develops other severe symptoms.

A person may feel depressed or anxious if he or she has been diagnosed with CAD and/or had a heart attack. The person may worry about heart problems or making lifestyle changes that are necessary for health reasons. A doctor may recommend medicine, professional counseling, or relaxation therapy if a person has depression or anxiety.

Physical activity can improve mental well-being, but a person should talk to a doctor before starting any fitness activities. It's important to treat any anxiety or depression that develops because it raises the risk of having a heart attack.

Chances of Developing Coronary Artery Disease

Risk factors

Coronary artery disease is the leading cause of death in the United States for both men and women. Each year, more than half a million Americans die from CAD.^[3]

Certain traits, conditions, or habits may raise a person's chance of developing CAD. These conditions are known as risk factors. Most risk factors for CAD can be controlled, which can help prevent or delay CAD. Other risk factors can't be controlled. Risk factors for the development of CAD include the following:

• Abnormal blood cholesterol levels. This includes high LDL cholesterol (sometimes called bad cholesterol) and low HDL cholesterol (sometimes called good cholesterol).
• High blood pressure. Blood pressure is considered high if it stays at or above 140/90 mmHg over a period of time.
• Smoking. This can damage and tighten blood vessels, raise cholesterol levels, and raise blood pressure. Smoking also doesn't allow enough oxygen to reach the body's tissues.
• Insulin resistance. This condition occurs when the body can't use its own insulin properly. Insulin is a hormone that helps move blood sugar into cells where it is used by the cell.
• Diabetes. This is a disease in which the body's blood sugar level is high because the body doesn't make enough insulin or doesn't use insulin properly.
• [Overweight or obesity]]. Being overweight is having extra body weight from muscle, bone, fat, and/or water. Obesity is having a high amount of extra body fat.
• Metabolic syndrome. Metabolic syndrome is the name for a group of risk factors linked to overweight and obesity that raise a person's chance for heart disease and other health problems, such as diabetes and stroke.
• Lack of physical activity. Lack of activity can worsen other risk factors for CAD.
• Age. As a person gets older, their risk for CAD increases. Genetic or lifestyle factors cause plaque to build in the arteries as they age. By the time a person is middle-aged or older, enough plaque may have built up to cause signs or symptoms.
  • In men, the risk for CAD increases after age 45.
  • In women, the risk for CAD risk increases after age 55.
• Family history of early heart disease. A person's risk increases if his or her father or a brother was diagnosed with CAD before 55 years of age, or if his or her mother or a sister was diagnosed with CAD before 65 years of age.

Although age and a family history of early heart disease are risk factors, it doesn't mean that a person will develop CAD if he or she has one or both risk factors. Making lifestyle changes and/or taking medicines to treat other risk factors can often lessen genetic influences and prevent CAD from developing, even in older adults.

Emerging risk factors

Scientists continue to study other possible risk factors for CAD. High levels of a protein called C-reactive protein (CRP) in the blood may raise the risk for CAD and heart attack. High levels of CRP indicate there is inflammation in the body. Inflammation is the body's response to injury or infection. Damage to the arteries' inner walls seems to trigger inflammation and helps plaque grow. Research is under way to find out whether reducing inflammation and lowering CRP levels also can reduce the risk of developing CAD and having a heart attack.

High levels of fats called triglycerides in the blood also may raise the risk of CAD, particularly in women.

Other factors

Other factors also may contribute to CAD. These include:

• Sleep apnea. Sleep apnea is a disorder in which a person's breathing stops or gets very shallow while sleeping. Untreated sleep apnea can raise a person's chances of having high blood pressure, diabetes, and even a heart attack or stroke.
• Stress. Research shows that the most commonly reported "trigger" for a heart attack is an emotionally upsetting event, particularly one involving anger.
• Alcohol. Heavy drinking can damage the heart muscle and worsen other risk factors for heart disease.

Clinical Trials

A list of open research trials that are studying coronary artery disease can be found [here]

For information on trials conducted at the National Heart, Lung, and Blood Institute of the NIH, please visit Patient Recruitment for Studies Conducted by NHLBI, NIH.

Controversy

Recent research has suggested that there may be a link between the development of CAD and infection with a bacterium called Chlamydia pneumoniae. In a study from Japan comparing 31 patients who had CAD with 119 controls (people without CAD), evidence of infection with Chlamydia pneumoniae was found in 77.4% of the CAD group versus 54.6% of the controls. This study also found an elevated level of homocysteine (an amino acid) in the blood of people with CAD (13.67 µmol/l) compared with the control group (9.95 µmol/l).^[4] A larger study from Austria found a correlation between elevated homocysteine levels and evidence of C. pneumoniae infection in patients with CAD.^[5] Other studies have found similar correlations between C. pneumoniae and CAD.^{[6] [7]}

Several studies have also found Chlamydia pneumoniae in plaque lesions from a number of blood vessels.^{[8] [9]}

Not all researchers, however, agree on a causal role for C. pneumoniae in CAD.^[10] Some have suggested that Toll-like receptors, triggered by microbes, can lead to ongoing inflammation in the artery wall even when the microbe is no longer present.^[11]

Expected Outcome

CAD is the most common type of heart disease. It's the leading cause of death in the United States for both men and women. Lifestyle changes, medicines, and/or medical procedures can effectively prevent or treat CAD in most people.

Other Resources

National Heart, Lung, and Blood Institute of the NIH - Patient Guides:

• "Aim for a Healthy Weight"
• "The Healthy Heart Handbook for Women"
• "Your Guide to a Healthy Heart"
• "Your Guide to Living Well With Heart Disease"
• "Your Guide to Lowering Your Blood Pressure"
• "Your Guide to Lowering Your Blood Pressure With DASH"
• "Your Guide to Lowering Your Cholesterol With TLC"
• "Your Guide to Physical Activity and Your Heart"

References

1. ↑ National Heart, Lung and Blood Institute. Aim for a healthy weight.
2. ↑ National Heart, Lung, and Blood Institute. Lowering your blood pressure with DASH.
3. ↑ American Heart Association. Heart Disease and Stroke Statistics. (PDF)
4. ↑ Sawayama Y, Tatsukawa M, Maeda S, Ohnishi H, Furusyo N, Hayashi J. Association of hyperhomocysteinemia and Chlamydia pneumoniae infection with carotid atherosclerosis and coronary artery disease in Japanese patients. J Infect Chemother. 2008 Jun;14(3):232-7. Abstract
5. ↑ Stanger OH, Semmelrock HJ, Rehak P, et al. Hyperhomocyst(e)inemia and Chlamydia pneumoniae IgG seropositivity in patients with coronary artery disease. Atherosclerosis. 2002 May;162(1):157-62. Abstract
6. ↑ Saikku P, Leinonen M, Tenkanen L, et al. Chronic Chlamydia pneumoniae infection as a risk factor for coronary heart disease in the Helsinki Heart Study. Ann Intern Med. 1992 Feb 15;116(4):273-8. Abstract
7. ↑ our I, Vahdat K, Jafari SM, et al. Correlation of hyperhomocysteinaemia and Chlamydia pneumoniae IgG seropositivity with coronary artery disease in a general population. Heart Lung Circ. 2007 Dec;16(6):416-22. Abstract
8. ↑ Shor A, Phillips JI, Ong G, Thomas BJ, Taylor-Robinson D. Chlamydia pneumoniae in atheroma: consideration of criteria for causality. J Clin Pathol. 1998 Nov;51(11):812-7. Abstract | PDF
9. ↑ Borel N, Summersgill JT, Mukhopadhyay S, Miller RD, Ramirez JA, Pospischil A. Evidence for persistent Chlamydia pneumoniae infection of human coronary atheromas. Atherosclerosis. 2008 Jul;199(1):154-61. Abstract
10. ↑ Reszka E, Jegier B, Wasowicz W, Lelonek M, Banach M, Jaszewski R. Detection of infectious agents by polymerase chain reaction in human aortic wall. Cardiovasc Pathol. 2008 Feb 4. (Epub ahead of print.) Abstract
11. ↑ Stassen FR, Vainas T, Bruggeman CA. Infection and atherosclerosis. An alternative view on an outdated hypothesis. Pharmacol Rep. 2008 Jan-Feb;60(1):85-92. Abstract | PDF

External Links

National Heart, Lung, and Blood Institute of the NIH:

• Atherosclerosis (Diseases and Conditions Index)
• Cardiovascular Information for the Public
• Act in Time to Heart Attack Signs

Medline Plus: Coronary Artery Disease