Angina

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  • Also Known As:
  • Angina pectoris
  • Stable angina
  • Unstable angina
  • Variant angina
  • Prinzmetal's angina
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Troponin

What is angina?

Angina is a term for chest pain caused by an inadequate supply of blood and oxygen to the heart. More than 7 million people in the United States are thought to have angina. It is usually associated with the narrowed arteries found in coronary artery disease. This narrowing is caused by the buildup of plaques (thickenings in the lining) in the arteries, due to a process called atherosclerosis. With angina, the affected person’s heart may get sufficient blood for daily activities, but the arteries may not be able to deliver adequate blood and oxygen during times of increased demand, such as exercise, emotional or physical stress, and extremes of temperature.

There are three main types of angina:

  • Stable angina is characterized by predictable patterns of symptoms and periods of discomfort that occur during exercise or periods of stress. This pain is usually relieved with rest and/or treatment with nitroglycerin or another appropriate medication. Many people with this type of angina can live a relatively normal life for many years, but some will progress over time, or relatively rapidly, to unstable angina. Stable angina is caused by the slow buildup of plaque composed primarily of fibrosis (scar tissue).
  • Unstable angina, one of the acute coronary syndromes that includes heart attack, is characterized by a change in the pattern of angina episodes, occurring more frequently, at rest, and/or not responding to treatment. It is usually a sign that the person’s condition is worsening. The pain someone experiences with unstable angina may be more severe and prolonged than that of stable angina. People with unstable angina are at increased risk of a heart attack, severe cardiac arrhythmia, and cardiac arrest. This is an acute emergency and should be evaluated and treated immediately. Unstable angina is caused by plaque that contains more lipid and debris than found in the plaque of people with stable angina. When some of this material leaks into the vessel, clots form.
  • Variant angina (Prinzmetal’s angina) almost always occurs during periods of rest, usually at night. The cause is a spasm of a coronary artery. Many people who have this type also have severe atherosclerosis in at least one major blood vessel on the heart. It can also occur, although much less often, in people with heart valve disease or uncontrolled high blood pressure (hypertension), and may be seen with the use of cocaine and methamphetamines. This type of angina is caused by spasm of the arteries, temporarily narrowing them but without producing any permanent damage.

 

About Angina

Signs and Symptoms

Symptoms of angina appear and then may or may not disappear when the person is at rest. A person may have chest pain, discomfort and/or pressure, or experience referred pain – pain that is felt in the left shoulder, arm, back, or jaw.

Angina may be more difficult to identify in some elderly people when they have symptoms such as abdominal pain after eating (due to increased blood demand for digestion) or have back or shoulder pain (which may be attributed to arthritis).

The amount of activity that is required to trigger an episode of angina and the symptoms involved vary from person to person and may also vary between episodes and over time. Since coronary artery disease tends to be progressive, angina may worsen over time – either with more severe symptoms, more frequent episodes, and/or less response to rest and treatment.

Tests

The goal of testing for angina is to distinguish between:

  • Chest pain that is not heart-related, such as that due to skeletal muscle injury
  • Chest pain that is due to treatable angina and not heart damage
  • Chest pain that is due to a heart attack

When someone presents to the emergency room with an acute coronary syndrome – a group of symptoms that suggest heart injury – they are evaluated with a variety of laboratory and non-laboratory tests. These are used to determine the cause of the pain and the severity of the condition. Since some treatments for a heart attack must be given within a short period of time to minimize heart damage, an accurate diagnosis must be quickly confirmed.

Laboratory Tests
Cardiac biomarkers, proteins that are released when muscle cells are damaged, are ordered to help differentiate angina from a heart attack. These include:

  • Troponin – the most commonly ordered and cardiac-specific of the markers. Blood levels of troponin will be elevated within a few hours of heart damage and remain elevated for up to two weeks. Troponin tests are usually ordered initially in the ER when a person presents with symptoms of unstable angina and then a few more times in the next several hours to look at changes in concentrations. If the levels are normal, then it is much less likely that the symptoms and chest pain are due to heart muscle damage and more likely that the pain is due to stable angina. A rise and/or fall in the series of troponin results indicates a heart attack.
  • A test called high-sensitivity troponin detects the same protein that the standard test does, just at much lower levels. Because this version of the test is more sensitive, it becomes positive sooner and may help detect heart injury and acute coronary syndrome earlier than the standard test. The hs-troponin test may also be positive in people with stable angina and even in people with no symptoms. When it is elevated in these individuals, it indicates an increased risk of future heart events, such as heart attacks.
  • CK-MB – one particular form of the enzyme creatine kinase that is found mostly in heart muscle and rises when there is damage to the heart muscle cells; this test is used less frequently now.

Other tests that may be performed include:

  • Myoglobin – a protein released into the blood when heart or other skeletal muscle is injured; this test is used less frequently now.
  • BNP or NT-proBNP – released by the body as a natural response to heart failure; increased levels of BNP, while not diagnostic for a heart attack, indicate an increased risk of cardiac problems in persons with acute coronary syndrome.

Other more general screening tests may also be ordered to help evaluate the person’s major body organs, electrolyte balance, blood glucose, and red and white blood cells to see whether there are any excesses, deficiencies, or dysfunctions that may be causing or worsening the person’s symptoms. These include:

  • Comprehensive Metabolic Panel – a group of usually 14 tests that is used as a broad screening tool to assess the current status of an individual’s kidneys, liver, electrolyte and acid/base balance, blood glucose, and blood proteins.
  • Complete Blood Count – a test used to screen for a variety of disorders that can affect blood cells, such as anemia and infection.

Non-Laboratory Evaluations
A range of non-laboratory evaluations and tests may be used to assess chest pain and other symptoms. These include:

  • A medical history, including an evaluation of risk factors such as age, coronary artery disease (CAD), diabetes, and smoking
  • A physical examination
  • An electrocardiogram (ECG or EKG) – a test that looks at the heart’s electrical activity and rhythm
  • Continuous ECG monitoring – a person wears a monitor that evaluates heart rhythm over a period of time

Based on the findings of these tests, other procedures may be necessary, including:

  • An exercise stress test
  • Chest X-ray
  • Coronary calcium scan – special X-ray exam that detects calcium in the coronary vessels, a sign of significant plaque development
  • Radionuclide imaging – a radioactive compound is injected into the blood to evaluate blood flow and show images of narrowed blood vessels around the heart.
  • Echocardiography – ultrasound imaging of the heart
  • Cardiac catheterization – in this procedure, a thin flexible tube is inserted into an artery in the leg and threaded up to the coronary arteries to evaluate blood flow and pressure in the heart and the status of the arteries in the heart.
  • Coronary angiography – X-rays of arteries using a radiopaque dye to help diagnose CAD; this procedure is performed during cardiac catheterization.

For more information on these, visit the National Heart, Lung and Blood Institute: How is a Angina Diagnosed?

Treatment

Treatments for angina incorporate several different aspects. They include lifestyle changes, medications, and surgical procedures when necessary. Lifestyle changes are recommended to help reduce risk factors, to help slow the progression of underlying coronary artery disease (when present), and to help anticipate, control, and sometimes prevent angina episodes. These changes include controlling high blood pressure, reducing high cholesterol levels, exercising (under a healthcare provider’s supervision), losing excess weight, and quitting smoking.

In people with stable angina, monitoring the pattern over time and becoming aware of what activities tend to trigger an angina episode can be helpful. For example, taking steps to manage stress, avoiding sudden changes in activity and temperature, and avoiding large meals can reduce the number of episodes in some people. For unstable angina, a baby aspirin is considered a first-line treatment. Sometimes medical procedures are needed, such as angioplasty or coronary artery bypass grafting.

New medications, procedures, and guidelines for addressing angina are constantly being evaluated. Those who have been diagnosed with angina should talk to their healthcare practitioner about the best treatment options for their current condition.

Related Images

  • Diagram of the heart. Image credit: Chung, M.K., and Rich, M.W. Introduction to the cardiovascular system. Alcohol Health and Research World 14(4):269–276, 1990. Reprinted with permission from NIAAA.

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