| What is coronary artery disease? |
Coronary artery disease is the most common type of heart disease, affecting some 7 million Americans. It results from atherosclerosis — the gradual buildup of plaques in blood vessels that feed your heart (your coronary arteries).
Over time these plaques — deposits of fat, cholesterol, calcium and other cellular sludge from your blood — can narrow your coronary arteries, so less blood flows to your heart muscle. Diminished blood flow to your heart can cause chest pain (angina). A sudden, complete blockage can lead to a heart attack. In fact, each year, some 500,000 Americans die of heart attacks caused by coronary artery disease.
The problem is that many people who have this form of heart disease aren't aware they have it. Coronary artery disease, or coronary heart disease, develops slowly and silently, over decades. It can go virtually unnoticed until it produces a heart attack.
How do you know whether you have this silent, potential killer? Your doctor can help answer that question based on test results and your level of risk. Risk factors for coronary artery disease include family history of heart disease, high blood cholesterol, high blood pressure, smoking, obesity and physical inactivity.
You can prevent or slow coronary artery disease by taking steps to improve the health of your heart and blood vessels. Drugs and surgical techniques can repair narrowed coronary arteries, but the best long-term solution is to make lifestyle choices that can control risk factors for coronary artery disease.
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| Signs and symptoms |
Coronary artery disease varies both in symptoms and severity. It may produce no symptoms, or it can produce chest pain of varying degrees as well as shortness of breath. It may also result in a heart attack.
Like any muscle, your heart needs a steady supply of oxygen-rich and nutrient-full blood to function. Your coronary arteries encircle your heart like a crown — hence the name "coronary" — and send branches into your heart muscle, supplying it with blood.
If your coronary arteries become narrowed, they can't supply enough blood to your heart when it's beating hard, such as when you exert yourself. Insufficient oxygen supply to the heart is called ischemia. Ischemia can result in:
- No symptoms. This is referred to as silent ischemia. Blood supply to your heart may be restricted due to coronary artery disease, but you don't feel any effects of that.
- Chest pain. If your coronary arteries can't supply enough blood to meet the oxygen demands of your heart, the result may be chest pain called angina. It's often described as a pressure or tightness in the chest — as if someone were standing on your chest. Angina is usually brought on by physical or emotional stress. The pain typically goes away within minutes after stopping the stressful activity.
- Shortness of breath. Some people may not be aware they have coronary artery disease until they develop symptoms of congestive heart failure — extreme fatigue with exertion, shortness of breath and swelling in their feet and ankles. Congestive heart failure occurs when your heart becomes so weakened from insufficient blood supply or from a heart attack that it can't pump enough blood to meet your body's needs. Some people may feel angina as shortness of breath, without heart failure.
- Heart attack. A heart attack results when an artery to your heart muscle becomes completely blocked and the part of your heart muscle fed by that artery dies. This is usually caused by a blood clot or other blockage in an already narrowed coronary artery. Pain from a heart attack is often described as crushing and may feel similar to angina, but lasts longer.
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| Causes |
Arteries are blood vessels that carry oxygen-rich blood away from your heart, to all of the tissues of your body — including your heart itself, a muscular pump in your chest.
Healthy arteries — including healthy coronary arteries — are clean, smooth and slick. The artery walls are flexible and can expand to let more blood through when necessary. Artery disease is thought to begin with an injury to the linings of the walls of arteries. This injury makes them susceptible to atherosclerosis.
Atherosclerosis is the slow, progressive buildup of deposits called plaques on the inner walls of your arteries. Plaques are deposits of fat, cholesterol, calcium and other cellular sludge from your blood.
These plaques both narrow and harden arteries. Plaques alone can significantly block your coronary arteries and arteries throughout your body. They can also become fragile and rupture, forming blood clots at the site that can block blood flow to your heart or elsewhere in your body.
Atherosclerosis is a complex disease that starts in childhood and often progresses as you age. In some people, atherosclerosis progresses rapidly, especially in older age.
Atherosclerosis often occurs when you have high levels of low-density lipoprotein (LDL) cholesterol — so-called "bad" cholesterol — in your blood. High blood cholesterol can be an inherited problem, but it's also typically a byproduct of poor health habits — such as eating a high-fat, high-cholesterol diet, which is common in Western societies. When the level of cholesterol in your blood is high, there's a greater chance that it will be deposited onto your artery walls.
In addition to high blood cholesterol, high blood pressure and smoking contribute to atherosclerosis and, thus, to coronary artery disease. Obesity and physical inactivity are other factors that can contribute to this disease.
Some research also suggests that a bacterium, such as Chlamydia pneumoniae, may play a role in the narrowing of coronary arteries. But whether infectious agents play an important role in this process isn't well defined. It's also unclear whether inflammation of the arteries caused by an infection or other factor could, in part, underlie coronary artery disease.
Atherosclerosis can occur not only in your coronary arteries but also in arteries throughout your body. Narrowing of arteries to your brain puts you at risk of stroke. Insufficient blood supply to your legs can cause pain during walking, a condition known as claudication.
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| Risk factors |
Researchers have identified several factors that put you at added risk for coronary artery disease. Some of these you can control, and some you cannot.
Uncontrollable risk factors for coronary artery disease include:
- Sex. Men are generally at greater risk than women for heart disease. However, the risk for
women increases after menopause. In fact, coronary artery disease is the leading cause of death for
both men and women in the United States.
- Heredity and race. If your siblings, parents or grandparents have heart disease, you may be
at risk, too. Your family may have a genetic condition that contributes to higher blood cholesterol
levels. High blood pressure can also run in families. In addition, families may contribute to coronary
artery disease by practicing or promoting poor health habits, such as eating unhealthy diets and
smoking. Race can be a factor. Blacks have a higher risk of heart disease than whites, Hispanics or
Asian-Americans, and their heart disease is often more severe. In America, high blood pressure is also
more common among blacks.
- Age. About four out of five people who die of coronary artery disease are age 65 or older. However, with an increase in obesity in America, doctors are now seeing more people in their 30s and 40s who have coronary artery disease.
- High blood pressure. Over time, high blood pressure — 140/90 millimeters of mercury (mm Hg)
or higher — can damage your coronary arteries by accelerating atherosclerosis.
- High blood cholesterol. The risk of coronary artery disease increases as your blood
cholesterol levels rise.
- Smoking. Exposure to cigarette smoke acts with other factors to greatly increase your risk
of coronary artery disease by damaging blood vessels.
- Physical inactivity. Regular exercise is important in preventing heart disease.
- Obesity. Excess weight increases the strain on your heart, raises your blood pressure,
increases your blood cholesterol levels and increases your risk of diabetes.
- Diabetes. Uncontrolled blood sugar (glucose) levels — the hallmark of diabetes — seriously
increase your risk of heart disease by damaging your blood vessels.
- Stress and anger. Some scientists have noted a relationship between coronary artery disease and stress and anger in a person's life.
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| Screening and diagnosis |
If you have risk factors for coronary artery disease, your doctor may advise diagnostic testing, even if you have no symptoms of narrowed arteries. You may be referred to a cardiologist, a doctor who specializes in diagnosing and treating cardiovascular problems. The term cardiovascular refers to your body's circulatory system — your heart, arteries and veins.
In addition to a physical examination, taking your medical history and routine blood tests, your doctor may recommend these tests to diagnose coronary artery disease:
- Electrocardiogram (ECG). In this test, patches with wires (electrodes) are attached to your skin to measure electrical impulses given off by your heart. This test can show evidence of a previous heart attack or one that's in progress. It can also yield other useful information, such as the status of your heart's electrical system. ECG readings taken continuously over a period of 24 hours or longer may help detect silent ischemia. This technique is called ambulatory electrocardiography monitoring,
or Holter monitoring. Electrodes attached to your chest are connected to a portable monitor — about the size of a paperback book — that attaches to your belt or is carried by a shoulder strap. You wear the monitor for 24 hours as you go about your normal activities. Recorded abnormalities may show evidence of inadequate blood supply to your heart.
- Stress test. Stress tests help measure whether your heart is getting adequate blood supply. They may be used to evaluate symptoms such as chest pain or shortness of breath during exertion. Or if you have significant risk factors for coronary artery disease — even if you have no symptoms — a stress test can be used as a screening tool. There are several kinds of stress tests. During an exercise stress test, you walk on a treadmill or pedal a stationary bike while an ECG records your heart's response to an increasing workload. For those who can't exercise, a medication may be used to "stress" the heart and mimic the effects of exercise instead. Imaging tests — an echocardiogram or a nuclear scan — may be used in combination and can provide additional information by generating pictures of your heart during and after exercise or pharmacologic stress.
- Coronary angiography (or arteriography). This has long been considered the definitive test for coronary artery disease. It can show specific sites of narrowing in coronary arteries. A small tube (catheter) is inserted into an artery in your arm or groin and threaded to your heart. A dye is injected into the catheter. As the dye flows through your coronary arteries, your doctor can see narrow spots and blockages with the help of X-rays.
- Coronary magnetic resonance angiography. This technique uses magnetic waves to produce a three-dimensional image of your coronary arteries to check for narrowings or blockages. This technique is still being developed, but it has the advantage of producing images of your coronary arteries with a noninvasive procedure.
- Nuclear scan. This test also helps identify blood flow problems to your heart. Trace amounts of radioactive material, such as thallium or a compound known as Cardiolite, are injected into your bloodstream. Special cameras can detect areas in your heart that receive less blood flow.
- Echocardiogram. This test uses sound waves to produce an image of your heart. An echocardiogram can help identify whether an area of your heart has been damaged from lack of blood supply by assessing how well that area moves during each heartbeat. When combined with a stress test, an echocardiogram can also help identify areas of diminished blood flow to the heart.
- Electron beam computerized tomography (EBCT). This test, also called an ultrafast CT scan, can detect calcium within plaques that narrow coronary arteries. Most, but not all, plaques contain some calcium. If a substantial amount of calcium is discovered, coronary artery disease is likely.
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| Treatment |
If coronary artery disease is found, it can be treated in a number of ways, depending on the seriousness of the disease. Many people are able to manage coronary artery disease with lifestyle changes and medications. Other people with severe coronary artery disease may need coronary angioplasty or surgery.
Lifestyle changes
Although great advances have been made in treating coronary artery disease, changing your habits remains the single most effective way to stop the disease from progressing. These are the most beneficial changes you can make:
- Change your diet. If you know that you have coronary artery disease, changing your diet to one low in fat — especially saturated fat — and cholesterol will help reduce high blood cholesterol, a primary cause of atherosclerosis. It's important to keep your cholesterol low after a heart attack to help lower your risk of having another one. Eating less fat should also help you lose weight. If you're overweight, losing weight can help you further lower blood cholesterol. Eating a diet rich in fruits and vegetables and having at least one to two servings of fish per week can also reduce your risk of a heart attack and help you lose weight.
- Exercise regularly. People with coronary artery disease can also benefit from exercise. Even moderate amounts of physical activity — 30 minutes a day — can lower your risk of death from coronary artery disease. However, people with severe coronary artery disease may have to restrict their exercise somewhat. If you have coronary artery disease, check with your doctor to find out what kinds of exercise are best for you.
- Don't smoke. Smoking is a major risk factor for coronary artery disease. Quitting smoking dramatically lowers your risk of a first or second heart attack.
Medications
In addition to lifestyle changes, your doctor may recommend drug therapy to treat coronary artery disease. Medications commonly used to prevent or treat coronary artery disease include:
- Cholesterol-lowering drugs. Cholesterol is a large part of the deposits that can narrow heart arteries. A high level of cholesterol in your blood increases your risk of coronary artery disease. Cholesterol-lowering drugs, also called lipid-lowering drugs, help lower the level of "bad" cholesterol in your blood while raising the level of "good" cholesterol. One type of cholesterol, HDL, actually helps protect against coronary artery disease. Examples of cholesterol-lowering drugs include statins, niacin, fibrates and bile acid sequestrants.
- Aspirin. Aspirin, as well as other blood thinners, can reduce the tendency of your blood to clot, which may help prevent obstruction of your coronary arteries.
- Beta blockers. These drugs slow your heart rate and decrease blood pressure, which in turn decreases your heart's demand for oxygen. Beta blockers also have been shown to reduce the risk of death in people during and after a heart attack. In addition, they're beneficial for people with a weakened heart muscle and congestive heart failure.
- Nitroglycerin. Nitroglycerin tablets, spray and patches are used to control chest pain (angina) by both opening up your coronary arteries and reducing your heart's demand for blood.
- Calcium channel blockers. These medications cause the muscles that surround your coronary arteries to relax and the vessels to open more, increasing blood flow to your heart. They also control high blood pressure.
- Angiotensin-converting enzyme (ACE) inhibitors. These drugs allow blood to flow from your heart more easily, decreasing your heart's workload. ACE inhibitors are the mainstay treatment for congestive heart failure, which can be a complication of coronary artery disease.
- Other drugs that lower blood pressure. These medications help open up your blood vessels, including those to your heart, decreasing your heart's workload.
Surgical procedures
Types of surgical procedures to treat coronary artery disease include:
- Coronary angioplasty. This is a common treatment for severe blockage of the coronary arteries. In this procedure, a doctor inserts a catheter with typically a small balloon at the tip into an artery in your groin or arm. The catheter is then threaded to the region of a coronary artery that's narrowed. When the catheter reaches the blockage, the balloon is inflated to widen the artery and improve blood flow. Often small wire tubes (stents) are placed into the area where the blockage occurred to keep the artery from narrowing again. Strictly speaking, coronary angioplasty isn't surgery. Only a small cut is required in the skin to put the catheter into the blood vessel. If angioplasty doesn't widen the artery or if complications occur, bypass surgery may be needed.
- Coronary bypass surgery. This requires open heart surgery. It's a procedure used to create a route for blood to go around a blocked stretch of a coronary artery. A blood vessel, usually taken from your leg or chest, is grafted directly onto a narrowed artery, bypassing the blocked area. If more than one artery is blocked, a bypass can be done on each. The blood can then go around the obstruction to supply your heart with enough blood to relieve chest pain.
- Radiation (brachytherapy) following coronary angioplasty. The majority of people who undergo coronary angioplasty for coronary artery disease receive small wire tubes (stents) to hold the arteries open longer. Generally, stents work well at keeping arteries open. However, in some people, blockage reoccurs following coronary angioplasty. Researchers are studying whether treating narrowed coronary arteries with radiation at the time of angioplasty will prevent blockages from forming within the stents used to prop open the blood vessels.
- Gene therapy. Scientists are using genes that produce growth factor proteins to stimulate growth of new blood vessels (angiogenesis) and restore blood flow to the heart. They're studying delivery of the genes and proteins to the heart via a direct injection into the heart through a small incision or by a catheter-delivery technique.
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| Prevention |
How you live your life can greatly affect the health of your heart and your coronary arteries. Taking the following steps can help you prevent coronary artery disease, as well as a heart attack and congestive heart failure:
- Get regular medical checkups. Some of the main risk factors for coronary artery disease — high blood cholesterol, high blood pressure and diabetes — have no symptoms in the early stages. Coronary artery disease itself may produce no symptoms. But your doctor can perform tests to check that you're free of these conditions. If a problem is found, you and your doctor can manage it early to prevent complications.
- Control your blood pressure. All adults should have their blood pressure checked every 2 years. Your doctor may recommend more frequent measurement if you have blood pressure higher than 115/75 mm Hg or a history of heart disease.
- Check your cholesterol. Have your blood cholesterol levels checked regularly. If your blood cholesterol levels are undesirably high, your doctor can prescribe changes in your diet and medications to help lower the numbers and protect your cardiovascular health.
- Don't smoke. Smoking and secondhand smoke are major risk factors for coronary artery disease. Nicotine constricts blood vessels and forces your heart to work harder. Carbon monoxide reduces oxygen in blood and damages the lining of blood vessels. Smoking also increases fibrinogen, a blood-clotting protein.
- Exercise regularly. Exercise helps prevent coronary artery disease by helping you to achieve and maintain a healthy weight and control diabetes, elevated cholesterol and high blood pressure.
- Maintain a healthy weight. Being only 10 percent overweight increases your risk of heart disease. Losing just 5 to 10 pounds may lower your blood pressure.
- Eat a heart-healthy diet. Too much saturated fat and cholesterol in your diet can narrow arteries to your heart. A diet high in salt can raise your blood pressure. Follow your doctor and dietitian's advice on eating a heart-healthy diet. Fish is part of a heart-healthy diet. It contains omega-3 fatty acids, which help improve blood cholesterol levels and prevent blood clots. Eating plenty of fruits and vegetables is also encouraged. Fruits and vegetables contain antioxidants — vitamins and minerals that help prevent everyday wear and tear on your coronary arteries. Your doctor may recommend certain vitamin supplements, such as vitamin E, that show promise in reducing heart disease.
- Manage stress. To reduce your risk of cardiovascular disease, reduce stress in your daily activities. Rethink workaholic habits and find healthy ways to minimize or deal with stressful events as well as anger in your life.
— May 15, 2003 —