Coronary artery disease (CAD) is the narrowing of coronary arteries. These are the blood vessels that supply blood and oxygen to the heart. The condition is also called coronary heart disease (CHD).
CAD is usually caused by atherosclerosis. Atherosclerosis is the buildup of plaque inside the coronary arteries. These plaques are made up of fatty deposits and fibrous tissue.
Atherosclerosis can significantly narrow the coronary arteries. This decreases the blood supply to the heart muscle. It triggers a type of chest pain called angina.
Atherosclerosis also can cause a blood clot to form inside a narrowed coronary artery. This causes a heart attack. A heart attack can significantly damage the heart muscle.
The risk factors for atherosclerosis and CAD are basically the same. These risk factors include:
- High blood cholesterol level
- High level of LDL (bad) cholesterol
- Low level of HDL (good) cholesterol
- High blood pressure (hypertension)
- Family history of CAD at a younger age
- Cigarette smoking
- Physical inactivity
CAD is the most common chronic, life-threatening illness in most of the world's developed nations.
In most people, the most common symptom of CAD is angina. Angina, also called angina pectoris, is a type of chest pain.
Angina usually is described as a squeezing, pressing or burning chest pain. It tends to be felt mainly in the center of the chest or just below the center of the rib cage. It also can spread to the arms (especially the left arm), abdomen, neck, lower jaw or neck.
Other symptoms can include:
- Dizziness or lightheadedness
A patient may mistake heart symptoms, such as burning chest pain and nausea, for indigestion.
There are two types of chest pain related to CAD. They are stable angina and acute coronary syndrome.
Stable angina. In stable angina, chest pain follows a predictable pattern. It usually occurs after:
- Extreme emotion
- A large meal
- Cigarette smoking
- Exposure to extreme hot or cold temperatures
Symptoms usually last one to five minutes. They disappear after a few minutes of rest. Stable angina is caused by a smooth plaque. This plaque partially obstructs blood flow in one or more coronary arteries.
Acute coronary syndrome (ACS). ACS is much more dangerous. In most cases of ACS, fatty plaque inside an artery has developed a tear or break. The uneven surface can cause blood to clot on top of the disrupted plaque. This sudden blockage of blood flow results in unstable angina or a heart attack.
In unstable angina, chest pain symptoms are more severe and less predictable than in stable angina. Chest pains occur more frequently, even at rest. They last several minutes to hours. People with unstable angina often sweat profusely. They develop aches in the jaw, shoulders and arms.
Many people with CAD, especially women, do not have any symptoms. Or, they have unusual symptoms. In these people, the only sign of CAD may be a change in the pattern of an electrocardiogram (EKG). An EKG is a test that records the heart's electrical activity.
An EKG can be done at rest or during exercise (exercise stress test). Exercise increases the heart muscle's demand for blood. The body can't meet this demand when the coronary arteries are significantly narrowed. When the heart muscle is starved for blood and oxygen, its electrical activity changes. This altered electrical activity affects the patient's EKG results.
In many people, the first symptom of coronary artery narrowing is a heart attack.
Coronary artery disease usually is diagnosed after a person has chest pain or other symptoms.
Your doctor will examine you, paying special attention to your chest and heart. Your doctor will press on your chest to see if it is tender. Tenderness could be a sign of a non-cardiac problem. Your doctor will use a stethoscope to listen for any abnormal heart sounds.
Your doctor will do one or more diagnostic tests to look for CAD. Possible tests include:
- An EKG. An EKG is a record of the heart's electrical impulses. It can identify problems in heart rate and rhythm. It can also provide clues that part of your heart muscle isn't getting enough blood.
- Blood test for heart enzymes. Damaged heart muscle releases enzymes into the bloodstream. Elevated heart enzymes suggest a heart problem.
- An exercise stress test. This test monitors the effects of treadmill exercise on blood pressure and EKG to identify heart problems.
- An echocardiogram. This test uses ultrasound to produce images of the heart's movement with each beat.
- Imaging test with radioactive tracers. In this test, a radioactive material helps certain features of the heart show up on images taken with special cameras.
- A coronary angiogram This is a series of X-rays of the coronary arteries. The coronary angiogram is the most accurate way to measure the severity of coronary disease.
During an angiogram, a thin, long, flexible tube (catheter) is inserted into an artery in the forearm or groin. The tip of the tube is pushed up the body's main artery until it reaches the heart. Then it is pushed into the coronary arteries. Dye is injected to show blood flow within the coronary arteries. It also identifies any areas of narrowing or blockage.
Angiography can now also be performed with a CT scan of the chest. It is done while dye is injected in a vein. The newer process is called CT angiography.
CAD is a long-term condition. People can have different patterns of symptoms.
Plaque in coronary arteries never will disappear completely. However, with diet, exercise and medication, the heart muscle adapts to decreased blood flow.
New small blood channels can develop to increase the blood flow to the heart muscle.
You can help to prevent CAD by controlling your risk factors for atherosclerosis. To do this:
- Quit smoking.
- Eat a healthy diet.
- Reduce your LDL (bad) cholesterol.
- Reduce high blood pressure.
- Lose weight.
CAD caused by atherosclerosis is treated with one or more of the following treatments.
Lifestyle changes include:
- Weight loss in obese patients
- Quitting smoking
- Diet and medications to lower high cholesterol and high blood pressure
- Regular exercise
- Stress reduction techniques, such as meditation and biofeedback
Nitrates (including nitroglycerin). These medications are vasodilators. They widen the coronary arteries to increase blood flow to the heart muscle. They also widen the body's veins. This lightens the heart's workload by temporarily decreasing the volume of blood returning to the heart.
Beta-blockers. These medications decrease the heart's workload. They do this by slowing the heart rate. They also reduce the force of heart muscle contractions, especially during exercise. People who have had a heart attack should stay on a beta-blocker for life. This will reduce the risk of a second heart attack. Atenolol (Tenormin) and metoprolol (Lopressor) are beta blockers.
Aspirin. Aspirin helps to prevent blood clots from forming inside narrowed coronary arteries. It reduces the risk of heart attack in people who already have CAD. Doctors often advise people older than 50 to take a low dose of aspirin every day to help prevent a heart attack.
Calcium channel blockers. These medications may help to decrease the frequency of chest pain in patients with angina. Examples include nifedipine (Adalat, Procardia) and diltiazem (Cardizem).
Cholesterol-lowering medications. The choice of medication depends upon your cholesterol profile.
- Statins reduce the risk of heart attack and death in people with CAD and those at risk of CAD. Statins lower LDL cholesterol and may raise HDL cholesterol slightly. Taking a statin regularly also helps to reduce inflammation inside plaques of atherosclerosis. This is why doctors prescribe statins for people who have signs of inflammation, even if their cholesterol levels are normal. Examples of statins include simvastatin (Zocor), pravastatin (Pravachol), atorvastatin (Lipitor) and rosuvastatin (Crestor).
- Niacin lowers LDL cholestrol, raises HDL cholesterol, and also lowers triglyceride levels.
- Medications called fibrates are used primarily in people with high triglyceride levels. Gemfibrozil (Lopid) and fenofibrate (Tricor, many generic versions) are fibrates.
- Ezetimbe (Zetia) works within the intestine. It decreases the absorpiton of cholesterol from food.
Coronary artery angiography. Some people are physically limited by stable angina because of chest pain. In this case, your doctor likely will advise you to have a coronary artery angiography to look for significant blockages. This procedure is also called a cardiac catheterization.
Balloon angioplasty. When one or more significant blockages are found, the cardiologist will determine if the blockage(s) can be opened. He or she will consider a procedure called balloon angioplasty. Balloon angioplasty is also called percutaneous transluminal coronary angioplasty, or PTCA.
In balloon angioplasty, a catheter is inserted into an artery in the groin or forearm. The catheter is threaded into the blocked coronary artery. A small balloon at the catheter tip is inflated briefly to open the narrowed blood vessel.
Usually, balloon inflation is followed by the placement of a stent. A stent is a wire mesh that expands with the balloon. The wire mesh remains inside the artery to keep it open. The balloon is deflated and the catheter is removed.
Coronary artery bypass surgery (CABG). If the blockages cannot be opened with balloon angioplasty, the cardiologist will likely suggest CABG.
CABG involves grafting one or more blood vessels onto the coronary arteries. This allows blood to bypass the narrowed or blocked areas. The blood vessels to be grafted can be taken from an artery inside the chest or arm, or from a long vein in the leg.
Treating heart attack or sudden worsening of angina
The goal of treating heart attacks or sudden worsening of angina is to rapidly restore blood flow to the section of heart muscle no longer getting blood flow.
Patients immediately receive:
- Medication to relieve pain
- A beta-blocker to slow the heart rate and decrease the work of the heart
- Aspirin combined with other medications to dissolve or inhibit blood clotting
When possible, patients are transferred to a cardiac catheterization laboratory. There, they have an immediate angiography and balloon angioplasty of the most significant blockage.
In some people with CAD, other symptoms or complications will require additional treatment. For example, medication may be needed to treat abnormal heart rhythms or low blood pressure.
Seek emergency help immediately if you have chest pain. In patients whose chest pain signals heart attack, prompt treatment can limit heart muscle damage.
Do not waste precious time hoping that your chest pain disappears.
In people with CAD, the outlook depends on many factors.
People with stable angina who are taking medications regularly, eating properly and exercising as instructed by their doctors generally remain active. The prognosis for heart attacks when people reach the emergency room promptly has improved dramatically. However, many people still die before reaching the hospital. This is why it is so important to prevent CAD.
American Heart Association (AHA)
7272 Greenville Ave.
Dallas, TX 75231
National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
American College of Cardiology
2400 N Street NW
Washington, DC 20037