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Unstable angina


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.


See also:

Alternative Names


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


Coronary artery spasm is a rare cause of angina.

Risk factors for coronary artery disease include:


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


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
  • Coronary angiography (taking pictures of the heart arteries using x-rays and dye; it is the best test to diagnose significant heart disease)




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.


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.

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.


Unstable angina may lead to a heart attack.

Calling your health care provider


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.
  • 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.



  • Lose weight if you are overweight
  • Stop smoking


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.



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.

Review Date: 6/21/2010