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Angina, also
called angina pectoris, is temporary chest pain or a sensation of
pressure that occurs while the heart muscle is not receiving enough
oxygen.
In the United States, almost 6.5 million people have angina, and it is newly diagnosed in about 350,000 people each year. Angina tends to develop in women at a later age than in men.
Causes
Usually, angina occurs when the heart's workload (and need for oxygen) exceeds the ability of the coronary arteries to supply an adequate amount of blood to the heart. Coronary blood flow can be limited when the arteries are narrowed. Narrowing usually results from fatty deposits in the arteries (atherosclerosis—see Atherosclerosis) but may result from coronary artery spasm. Inadequate blood flow to any tissue is termed ischemia.
When angina is due to atherosclerosis, it usually first occurs during physical exertion or emotional distress, which make the heart work harder and increase its need for oxygen. If the artery is narrowed enough (usually by more than 70%), angina can occur even at rest, when the demands on the heart are at their minimum.
Severe anemia increases the likelihood of angina. In anemia, the number of red blood cells (which contain hemoglobin—the molecule that carries oxygen) or the amount of hemoglobin in the cells is below normal. As a result, the oxygen supply to the heart muscle is reduced.
Unusual Causes:
Syndrome X is a form of angina caused neither by spasm nor by any apparent blockage in the large coronary arteries. Temporary narrowing of much smaller coronary arteries may be responsible, at least in some people. The reasons for the temporary narrowing are unknown but may involve a chemical imbalance in the heart or abnormalities in the functioning of small arteries (arterioles). This syndrome is sometimes called cardiac syndrome X to distinguish it from another disorder also called syndrome X (metabolic syndrome X or the syndrome of insulin resistance—see Obesity and the Metabolic Syndrome: Metabolic Syndrome).
Other unusual causes of angina include the following:
These conditions increase the heart's workload) and thus the amount of oxygen needed by the heart muscle. When the need for oxygen exceeds the supply, angina results. Abnormalities of the aortic valve may reduce blood flow through the coronary arteries, because the openings of the coronary arteries are located just beyond this valve.
Classification
Nocturnal
angina is angina that occurs at night, during sleep.
Stable angina is chest pain or discomfort that typically occurs with activity or stress. Episodes of pain or discomfort are provoked by similar or consistent amounts of activity or stress.
Angina decubitus is angina that occurs when a person is lying down (not necessarily only at night) without any apparent cause. Angina decubitus occurs because gravity redistributes fluids in the body. This redistribution makes the heart work harder.
Variant angina results from a spasm of one of the large coronary arteries on the surface of the heart. It is called variant because it is characterized by pain during rest, not during exertion, and by specific changes detected with ECG during an episode of angina.
Unstable angina refers to angina in which the pattern of symptoms changes. Because the characteristics of angina in a particular person usually remain constant, any change—such as more severe pain, more frequent attacks, or attacks occurring with less exertion or during rest—is serious. Such change usually reflects a sudden narrowing of a coronary artery because an atheroma has ruptured or a clot has formed. The risk of a heart attack is high. Unstable angina is considered an acute coronary syndrome (see Coronary Artery Disease: Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina)).
Symptoms
Most commonly, a person feels angina as pressure or an ache beneath the breastbone (sternum). People often interpret the sensation as discomfort or heaviness rather than pain. Discomfort also may occur in either shoulder or down the inside of either arm; through the back; and in the throat, jaw, or teeth.
In older people, symptoms may be different and therefore easily misdiagnosed. For instance, the pain is less likely to occur beneath the breastbone. Pain may occur in the back and shoulders and may be incorrectly blamed on arthritis. Discomfort, bloating, and gas may occur in the stomach area, particularly after meals (because extra blood is needed to help in digestion). People may mistake such discomfort for indigestion or blame it on a stomach ulcer. Belching may even seem to relieve these symptoms. Also, older people who have confusion or dementia may have difficulty in communicating that they have pain.
Symptoms are very often different in women. Women are more likely to have a burning sensation or tenderness in the back, shoulders, arms, or jaw.
Typically, angina is triggered by exertion, lasts no more than a few minutes, and subsides with rest. Some people experience angina predictably with a specific degree of exertion. In other people, episodes occur unpredictably. Often, angina is worse when exertion follows a meal. It is usually worse in cold weather. Walking into the wind or moving from a warm room into the cold air may trigger angina. Emotional stress may also cause or worsen angina. Sometimes, experiencing a strong emotion while resting or having a bad dream during sleep can cause angina.
Silent Ischemia:
Not everyone with ischemia experiences angina. Ischemia without angina is called silent ischemia. Doctors do not understand why ischemia is sometimes silent, and some debate its significance. However, most experts consider silent ischemia as serious as ischemia with angina.
Diagnosis
Doctors diagnose angina largely based on a person's description of the symptoms. A physical examination and ECG (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Electrocardiography) may detect little, if anything, abnormal between and sometimes even during attacks of angina, even in people with extensive coronary artery disease. During an attack, the heart rate may increase slightly, blood pressure may go up, and with a stethoscope, doctors may hear a change in the heartbeat. ECG may detect changes in the heart's electrical activity.
When symptoms are typical, the diagnosis is usually easy for doctors. The kind of pain, its location, and its association with exertion, meals, weather, and other factors help doctors make the diagnosis. The presence of risk factors for coronary artery disease also helps establish the diagnosis. If a person experiences chest pain during the examination, a doctor may place a dose of nitroglycerin (a drug that dilates blood vessels) under the person's tongue as a test, because if the pain is due to angina, relief should occur in less than 3 minutes.
The following procedures may help evaluate the inadequate blood supply (ischemia) to the heart muscle and determine whether coronary artery disease is present and how extensive it is.
For exercise
stress testing (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Exercise Stress Testing), the person walks on a treadmill or rides a stationary bicycle while being monitored by ECG. This procedure can help doctors determine whether coronary angiography or coronary artery bypass grafting (CABG) is needed. If people cannot exercise, testing is done after a drug that makes the heart work harder is injected (a procedure called pharmacologic stress testing).
For radionuclide
imaging (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Radionuclide Imaging), a tiny amount of a radioactive substance is injected into a vein. Radionuclide imaging can identify the location and extent of ischemia and show the amount of blood reaching the heart muscle. This procedure is usually combined with stress testing.
Echocardiography (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Echocardiography and Other Ultrasound Procedures) uses ultrasound waves to produce images of the heart (echocardiograms). This procedure shows heart size, movement of the heart muscle, blood flow through the heart valves, and valve function. Echocardiography is done during rest and exercise. When ischemia is present, the pumping motion of the left ventricle is abnormal.
For coronary
angiography (see Symptoms and Diagnosis of Heart and Blood Vessel Disorders: Coronary Angiography), x-rays of arteries are taken after a radiopaque dye is injected. Coronary angiography, the most accurate procedure for diagnosing coronary artery disease, may be done when a diagnosis is uncertain. Coronary angiography is commonly used to help evaluate whether CABG or percutaneous coronary intervention (PCI) is appropriate. Angiography can also detect spasm of an artery. A drug that can produce a spasm may be used during angiography if a spasm does not occur.
In a few people who have typical symptoms of angina and abnormal results on an exercise stress test, coronary angiography does not confirm the presence of coronary artery disease. Some of these people have syndrome X, but for most, the source of the symptoms does not involve the heart.
Continuous
ECG monitoring with a Holter monitor (see Holter Monitor: Continuous ECG Readings ) may detect abnormalities indicating symptomatic or silent ischemia or variant angina (which typically occurs during rest).
Electron
beam computed tomography (CT) scans can detect the amount of calcium deposits in the coronary arteries. The amount of calcium present (the calcium score) is roughly proportional to the likelihood of the person having angina or a heart attack. However, because calcium deposits may be present even in people whose arteries are not very narrowed, the score does not reliably predict the need for PCI or CABG. Electron beam CT scans are not recommended for screening all people, in part because it exposes people to a significant amount of radiation. However, the test is often valuable for evaluating people who have a relatively high risk of death or heart attack. People at risk include those who have diabetes, high blood pressure, or both; high cholesterol levels; and abnormal or unclear stress test results.
Multidetector
row CT is a new technique that uses a high speed CT scanner with many small detectors that can accurately identify coronary artery narrowing. The technique is noninvasive and highly accurate in excluding coronary artery narrowing as a source of a person's symptoms (particularly in those who were not able to have a stress test or had a stress test that was inconclusive). It can also be used to determine whether a stent or bypass graft is unobstructed, to display cardiac and coronary venous anatomy, and to assess whether atheromas contain calcium. However, the technique cannot be used in women who are pregnant or in people who are unable to hold their breath for 15 to 20 seconds three or four times during the procedure. Also, because the test does not work well if the heart is beating fast, people whose heart rate is above 65 beats per minute are given drugs to slow the heart rate. People who cannot tolerate such drugs or a low heart rate cannot have the test. People are also exposed to significant amounts of radiation.
Cardiac
magnetic resonance imaging (MRI) is valuable in evaluating the heart and the large vessels coming from the heart (the aorta and the pulmonary arteries). This technique avoids any radiation exposure. In people with coronary artery disease, MRI may be used to evaluate narrowing of the arteries, measure the blood flow in the coronary arteries, and test how well the heart is being supplied with oxygen. MRI can also be used to assess abnormalities of heart wall motion during stress (which may indicate poor blood supply to that area) and whether areas of heart muscle damaged by a heart attack may recover (testing viability).
Prognosis
Key factors that can worsen the outcome (prognosis) for people who have angina include advancing age, extensive coronary artery disease, diabetes, other risk factors (particularly smoking), severe pain, and, most importantly, reduced pumping ability of the heart (ventricular function). For example, the more coronary arteries affected or the larger the blockage of the arteries, the worse is the prognosis. The prognosis is surprisingly good for people with stable angina and normal pumping ability. Reduced pumping ability dramatically worsens the prognosis. The prognosis for people with syndrome X does not differ from that for people without coronary artery disease.
The death rate each year for people with angina and no other risk factors is about 1.4%. The rate is higher for people with risk factors such as high blood pressure, abnormal ECG results, or a previous heart attack, particularly in those who have diabetes.
Treatment
Treatment begins with attempts to slow or reverse the progression of coronary artery disease by dealing with risk factors. Risk factors, such as high blood pressure and high cholesterol levels, are treated promptly. Quitting smoking is crucial. A low-fat, varied diet that is low in simple sugar carbohydrates and exercise (for most people) are recommended. Weight loss, if needed, is also recommended.
Treatment of angina depends partly on the stability and severity of the symptoms. When symptoms are stable and mild to moderate, the most effective treatment may be modification of risk factors and the use of certain drugs. If modification of risk factors and drug therapy do not cause symptoms to subside markedly, a procedure to restore blood flow to affected areas of the heart (a revascularization procedure) may be needed. When symptoms worsen rapidly, immediate hospitalization is usually required and the person is evaluated for an acute coronary syndrome (see Coronary Artery Disease: Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina)).
Drug Therapy
Drug treatment of stable angina is designed to prevent or reduce ischemia and to minimize symptoms. Five types of drugs are available: beta-blockers, nitrates (including nitroglycerin and long-acting nitrates), calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, and antiplatelet drugs.
Beta-blockers interfere with the effects of the hormones epinephrine (adrenaline) and norepinephrine
(noradrenaline) on the heart and other organs. These hormones stimulate the heart to beat faster and more forcefully and most arterioles to constrict (causing blood pressure to increase—see High Blood Pressure: Drug Therapy). Thus, beta-blockers reduce the resting heart rate and blood pressure. During exercise, they limit the increase in heart rate and in blood pressure and so reduce the demand for oxygen. Beta-blockers reduce the risk of heart attacks and sudden death, improving the long-term outcome for people with coronary artery disease.
Nitroglycerin is
a very short-acting nitrate drug that dilates blood vessels. Taking nitroglycerin usually relieves an episode of angina in 1 to 3 minutes, and the effects last 30 minutes. Nitroglycerin is usually taken as a tablet placed under the tongue (sublingual administration) or as a spray inhaled through the mouth. Alternatively, the tablet may be placed next to the gum. People with chronic stable angina should keep nitroglycerin tablets or spray with them at all times. Taking nitroglycerin just before reaching a level of exertion known to induce angina may be useful.
Long-acting nitrates (such as isosorbide) are taken by mouth 1 to 4 times a day. Nitrate skin patches and paste, in which the drug is absorbed through the skin over many hours, are also effective. Long-acting nitrates taken regularly can soon lose their ability to provide relief. Most experts recommend that people not take the drug for an 8- to 12-hour period each day, usually at night unless that is when angina occurs. This approach helps maintain the long-term effectiveness of the drug. Unlike beta-blockers, nitrates do not reduce the risk of heart attacks and sudden death, but they greatly reduce symptoms in people with coronary artery disease.
Calcium
channel blockers prevent blood vessels from narrowing (constricting) and can counter coronary artery spasm. These drugs are also effective in treating variant angina. All calcium channel blockers reduce blood pressure. Some of these drugs, such as verapamil and diltiazem , may also reduce the heart rate. This effect can be useful to many people, especially those who cannot take beta-blockers or who do not get enough relief from nitrates.
ACE
inhibitors, such as ramipril , are often given to people who have evidence of coronary artery disease, including angina. These drugs do not treat angina itself, but they can reduce the risk of heart attack and of death due to coronary artery disease.
Antiplatelet
drugs, such as aspirin , ticlopidine , and clopidogrel , modify platelets so that they do not clump and stick on blood vessel walls. Platelets, which circulate in the blood, promote clot formation (thrombosis) when a blood vessel is injured. However, when platelets collect on atheromas in an artery's walls, the resulting clot can narrow or block the artery and result in a heart attack. Aspirin modifies platelets irreversibly and thus reduces the risk of death from coronary artery disease. Doctors recommend that most people who have coronary artery disease take both aspirin and clopidogrel daily to reduce the risk of a heart attack. Ticlopidine , which has similar effects but more potential side effects than clopidogrel , may be used if the person is allergic or cannot tolerate clopidogrel . Antiplatelet drugs are given to people with angina unless there is a reason not to. For example, they are not given to people who have a bleeding disorder.
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Drugs Used to Treat Coronary Artery Disease
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Examples
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Side Effects
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Comments
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Anticoagulants
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Argatroban
Bivalirudin
Enoxaparin
Fondaparinux
Heparin
Warfarin
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Bleeding, especially when used with other drugs that have a similar effect (such as aspirin and other nonsteroidal anti-inflammatory drugs)
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These drugs prevent blood from clotting. They are used to treat people who have unstable angina or who have had a heart attack.
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Antiplatelet drugs
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Aspirin
Clopidogrel
Ticlopidine
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Bleeding, especially when used with other drugs that have a similar effect (such as anticoagulants)
With aspirin , stomach irritation
With ticlopidine and less so with clopidogrel , a small risk of reducing the white blood cell count
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These drugs prevent platelets from clumping and blood clots from forming. They also reduce the risk of a heart attack. They are used to treat people who have stable or unstable angina or who have had a heart attack.
Aspirin is taken as soon as a heart attack is suspected. People with an allergy to aspirin may take clopidogrel or ticlopidine as an alternative.
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Glycoprotein IIb/IIIa inhibitors (a type of antiplatelet drug)
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Abciximab
Eptifibatide
Tirofiban
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Bleeding, especially when used with other drugs that have a similar effect (such as anticoagulants or thrombolytic drugs)
Reduction of the platelet count
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These drugs prevent platelets from clumping and blood clots from forming. They are used to treat people who have unstable angina or who are undergoing percutaneous coronary intervention after a heart attack.
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Beta-blockers
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Acebutolol
Atenolol
Betaxolol
Bisoprolol
Carteolol
Carvedilol
Celiprolol
Metoprolol
Nadolol
Penbutolol
Propranolol
Timolol
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Spasm of airways (bronchospasm)
Abnormally slow heart rate (bradycardia)
Heart failure
Cold hands and feet
Insomnia
Fatigue
Shortness of breath
Depression
Raynaud's syndrome
Vivid dreams
Hallucinations
Sexual dysfunction
With many beta-blockers, an increased triglyceride level and a decrease in HDL level
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These drugs reduce the workload of the heart and the risk of a heart attack and sudden death. They are used to treat people who have stable or unstable angina or syndrome X or who have had a heart attack.
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Calcium channel blockers
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Amlodipine
Diltiazem
Felodipine
Nifedipine (sustained-release only)
Verapamil
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Dizziness
Fluid accumulation (edema) in the ankles
Flushing
Headache
Heartburn
Enlarged gums
Abnormal heart rhythms (arrhythmias)
With verapamil , constipation
With short-acting, but not long-acting, calcium channel blockers, possible increased risk of death due to heart attack, especially in people who have unstable angina or who have had a heart attack recently
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These drugs prevent blood vessels from narrowing and can reverse artery spasm. Diltiazem and verapamil reduce the heart rate. Calcium channel blockers are used to treat people who have stable angina.
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Nitrates
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Isosorbide dinitrate
Isosorbide mononitrate
Nitroglycerin
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Flushing
Headache
Temporarily fast heart rate (tachycardia)
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These drugs relieve angina, prevent episodes of angina, and reduce the risk of a heart attack and sudden death. (However, risk reduction is much less than that with beta-blockers.) They are used to treat people who have stable or unstable angina or syndrome X. For these drugs to remain effective over the long term, people need to go 8 to 12 hours without taking the drug each day.
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Opioids
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Morphine
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Low blood pressure when a person stands
Constipation
Nausea
Vomiting
Confusion (especially in older people)
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In people who have had a heart attack, these drugs are used to relieve anxiety and pain if the pain persists despite use of other drugs.
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Thrombolytic drugs
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Anistreplase
Recombinant tissue plasminogen activator (alteplase)
Reteplase
Streptokinase
Tenecteplase
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Bleeding after injuries
Rarely, bleeding within the brain (intracerebral hemorrhage)
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These drugs dissolve blood clots. They are used to treat people who have had a heart attack.
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Angiotensin-converting enzyme (ACE) inhibitors
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Benazepril
Captopril
Enalapril
Fosinopril
Quinapril
Lisinopril
Moexipril
Perindopril
Ramipril
Trandolapril
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Cough, usually dry and “metallic”
Rash
Rarely, a severe allergic reaction (angioedema)
Possibly worsening of kidney function when people already have kidney disease or when the artery to one of the kidneys is greatly narrowed
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These drugs lower blood pressure and treat heart failure and prevent kidney damage in people with high blood pressure or diabetes. They also benefit people who have had heart attacks.
People with high blood pressure, heart failure, or prior heart attacks who are treated with an ACE inhibitor live longer than people who do not take an ACE inhibitor.
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Angiotensin II receptor blockers
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Candesartan
Irbesartan
Losartan
Telmisartan
Valsartan
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Similar to ACE inhibitors, but cough is much less common
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These drugs have equivalent effects and benefits to those of ACE inhibitors. In people with severe high blood pressure or heart failure, these drugs may be used in combination with ACE inhibitors.
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Statins*
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Atorvastatin
Fluvastatin
Lovastatin
Pravastatin
Simvastatin
Rosuvastatin
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Occasionally, muscle aches and pains, but rarely severe muscle pain (myositis)
Rarely, liver damage, but not more commonly than in people who are not taking the drug
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These drugs lower cholesterol levels and help to heal damaged arteries, decreasing the chance of having a first or repeated heart attack or stroke.
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*Also known as hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitors.
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Revascularization
Procedures
These procedures include percutaneous coronary intervention (PCI) procedures (also called angioplasty) and coronary artery bypass grafting (CABG). These invasive techniques are effective, but they are only mechanical measures for correcting the immediate problem. They do not stop the progression of the underlying disease. People still need to modify risk factors.
PCI (see Coronary Artery Disease: Percutaneous Coronary Intervention) is often preferred to CABG because it is less invasive, although it is not appropriate for every situation. PCI is usually preferred when only one or two arteries are affected, and the blocked area is not very long. However, new technology and increasing experience are allowing doctors to use PCI for more and more people.
CABG (see Coronary Artery Disease: Coronary Artery Bypass Grafting) is highly effective for people who have angina and coronary artery disease. It can improve exercise tolerance, relieve symptoms, and decrease the number or dose of drugs needed. CABG is most likely to benefit people who have severe angina that is not relieved by drug therapy, a normally functioning heart, no previous heart attacks, and no other conditions that would make surgery hazardous (such as chronic obstructive pulmonary disease). For such people, CABG that is not done on an emergency basis carries a risk of death of 1% or less and a risk of heart damage (such as a heart attack) during surgery of less than 5%. About 85% of people have complete or dramatic relief of symptoms after surgery.
Last full review/revision February 2008 by James Wayne Warnica, MD
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