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Unstable angina

Definition

Unstable angina is a condition in which your heart doesn't get enough blood flow and oxygen. It may be a prelude to a heart attack.

Angina is a type of chest discomfort caused by poor blood flow through the blood vessels (coronary vessels) of the heart muscle (myocardium).

See also:

• Stable angina
• Variant angina

Alternative Names

Accelerating angina; New-onset angina; Angina - unstable; Progressive angina

Causes, incidence, and risk factors

Coronary artery disease due to atherosclerosis is by far the most common cause of unstable angina. Atherosclerosis is the buildup of fatty material called plaque along the walls of the arteries. This causes arteries to become less flexible and narrow, which interrupts blood flow to the heart, causing chest pain.

At first, angina may be considered stable. The chest pain only occurs with activity or stress. The pain does not become more frequent or severe over time. Unstable angina is chest pain that is sudden and gets increasingly worse. The chest pain:

• Occurs without cause (for example, it wakes you up from sleep)
• Lasts longer than 15 - 20 minutes
• Responds poorly to a medicine called nitroglycerin
• May occur along with a drop in blood pressure or significant shortness of breath

People with unstable angina are at increased risk of having a heart attack.

Coronary artery spasm is a rare cause of angina.

Risk factors for coronary artery disease include:

• Diabetes
• Family history of coronary heart disease before age 50
• High blood pressure
• High LDL cholesterol
• Low HDL cholesterol
• Male gender
• Not getting enough exercise
• Obesity
• Older age
• Smoking

Symptoms

Symptoms include:

• Sudden chest pain that may also be felt in the shoulder, arm, jaw, neck, back, or other area
• Pain that feels like tightness, squeezing, crushing, burning, choking, or aching
• Pain that occurs at rest and does not easily go away when using medicine
• Shortness of breath

If you have stable angina, you may be developing unstable angina if the chest pain:

• Starts to feel different
• Lasts longer than 15 - 20 minutes
• Occurs at different times

Signs and tests

The doctor will perform a physical examination and check your blood pressure. The doctor may hear abnormal sounds, such as a heart murmur or irregular heartbeat, when listening to your chest with a stethoscope.

Tests to evaluate angina include:

• Blood tests to show if you have heart tissue damage or are at a high risk for heart attack, including troponin I and T-00745, creatine phosphokinase (CPK), and myoglobin
• ECG
• Echocardiography
• Stress tests
  • Chemical or pharmacologic stress test (adenosine, dobutamine)
  • Exercise tolerance test (stress test or treadmill test)
  • Stress echocardiogram
  • Thallium stress test
• Non-imaging (exercise treadmill) or imaging (nuclear stress test, echo stress test)
• Coronary angiography (taking pictures of the heart arteries using x-rays and dye; it is the best test to diagnose significant heart disease)

Treatment

Your doctor may want you to check into the hospital to get some rest and prevent complications.

Blood thinners (antiplatelet drugs) are commonly used to treat and prevent unstable angina. Such medicines include aspirin and the prescription drug clopidogrel. Aspirin (and sometimes clopidogrel) may reduce the chance of a heart attack in certain patients.

During an unstable angina event, you may receive heparin (or another blood thinner) and nitroglycerin (under the tongue or through an IV). Other treatments may include medicines to control blood pressure, anxiety, abnormal heart rhythms, and cholesterol (such as a statin drug).

Often if a blood vessel is found to be narrowed or blocked, a procedure called angioplasty and stenting can be performed to open the artery.

• Angioplasty is a procedure to open narrowed or blocked blood vessels that supply blood to the heart.
• A coronary artery stent is a small, metal mesh tube that opens up (expands) inside a coronary artery. A stent is often placed after angioplasty. It helps prevent the artery from closing up again. A drug-eluting stent has medicine in it that helps prevent the artery from closing.

Heart bypass surgery may be done for some people, depending on which and how many of their coronary arteries are narrowed and the severity of the narrowings.

Support Groups

Expectations (prognosis)

How well you do depends on many different things, including:

• The severity of coronary artery disease
• The severity of the most current unstable angina attack
• Whether you've ever had a heart attack
• The medicines you were taking when the angina attack started
• How well your heart muscle is pumping

Arrhythmias and heart attacks can cause sudden death.

Complications

Unstable angina may lead to a heart attack.

Calling your health care provider

Seek medical attention if you have new, unexplained chest pain or pressure. If you have had angina before, call your doctor.

Call 911 if your angina pain:

• Does not go away after 15 minutes
• Does not go away after three doses of nitroglycerin
• Is getting worse
• Returns after the nitroglycerin helped at first

Call your doctor if:

• You are having angina symptoms more often.
• You are having angina when you are sitting. This is called rest angina.
• You are feeling tired more often.
• You are feeling faint or light-headed, or you pass out.
• Your heart is beating very slowly (less than 60 beats a minute) or very fast (more than 120 beats a minute), or it is not steady.
• You are having trouble taking your heart medicines.
• You have any other unusual symptoms.

If you think you are having a heart attack, seek immediate medical treatment.

Prevention

Lifestyle changes can help prevent some angina attacks. Your doctor may tell you to:

• Lose weight if you are overweight
• Stop smoking

You should also keep strict control of your blood pressure, diabetes, and cholesterol levels. Some studies have shown that making a few lifestyle changes can prevent blockages from getting worse and may actually improve them.

If you have one or more risk factors for heart disease, talk to your doctor about possibly taking aspirin or other medicines to help prevent a heart attack. Aspirin therapy (75 - 325 mg a day) or a drug called clopidogrel may help prevent heart attacks in some people. Aspirin therapy is recommended if the benefit is likely to outweigh the risk of gastrointestinal side effects.

References

Anderson JL, Adams CD, Antman EM, Bridges CR, Califf RM, Casey DE Jr., et al. ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-Elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) developed in collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine. J Am Coll Cardiol. 2007;50:e1-e157.

Antman EM. ST-Elevation Myocardial Infarction: Management. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 51.