Unstable Angina

Unstable angina is a dangerous type of chest pain that can be the start of a heart attack. Get help as soon as possible for unstable angina, which comes from a blood clot in your coronary artery. When this happens, your heart muscle can’t get enough oxygen. In addition to medicines, you may need to have a medical procedure at the hospital.


What is unstable angina?

When you have unstable angina, your heart muscle doesn't get as much oxygen-rich blood as it should because of plaque blockages and usually a blood clot in one or more of the arteries that feed your heart (coronary arteries). Unstable angina is a type of angina (chest pain) that often doesn’t have a pattern and usually gets worse. It happens with only mild physical activity or may happen without warning when you’re at rest, relaxing or even asleep.

This is a dangerous type of angina that puts you at a big risk of having a heart attack if it’s not quickly treated. Many people who have heart attacks get unstable angina, exhaustion or shortness of breath days or weeks before their heart attack happens.

You should get medical help immediately.

In rare situations, your heart can stop beating, which is fatal.

How common is unstable angina?

Stable angina is more common than unstable angina in the 10 million Americans who have some type of angina. Estimates say unstable angina occurs in about 200,000 Americans each year. Stable and unstable angina are both more common with older adults, in men and in people who smoke, have diabetes or have high blood pressure. But people without any of these risks can also have unstable angina and should pay attention and act if they are having symptoms.


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How does unstable angina affect my body?

Your heart muscle doesn’t get enough blood for as long as the blood clot blocks your coronary artery. In some cases, this can lead to permanent heart muscle damage, a heart attack.

How to know if you have stable vs. unstable angina

Stable angina

  • Occurs with physical activity or with anger, anxiety or stress.
  • Lasts a short amount of time (usually only a few minutes).
  • Occurs regularly or predictably — usually with the same amount of activity or emotional stress every time.

Unstable angina

  • Happens without warning.
  • Can happen even if you’re resting or sleeping.
  • Doesn’t last the same amount of time (and can last a long time) or has the same cause each time.

Symptoms and Causes

What are the symptoms of unstable angina?

Symptoms of unstable angina include:

  • Tight or crushing pain in your chest that may spread to other areas in your upper body.
  • Chest pain that happens even when you’re not exerting yourself.
  • Shortness of breath.
  • Chest pain that doesn’t stop after you take medicine.
  • Sweating.
  • Anxiety.

What causes unstable angina?

When plaque (cholesterol and fat) collects inside your arteries and keeps blood from flowing well, that’s known as atherosclerosis. This leads to coronary artery disease, the top cause of unstable angina.

Your risk factors for coronary artery disease are:

Coronary artery spasms cause a rare type of unstable angina called variant or Prinzmetal angina.


Diagnosis and Tests

How is unstable angina diagnosed?

Your provider will take your blood pressure and give you a physical exam. They will also order tests and give you medicines.

What tests will be done to diagnose unstable angina?

Tests to diagnose unstable angina can include:

Management and Treatment

How is unstable angina treated?

Your provider may give you blood thinners like aspirin or clopidogrel to keep you from having a heart attack. While you’re experiencing unstable angina, your provider may give you nitroglycerin and a blood thinner called heparin. You may also need medicine for:

  • High cholesterol.
  • High blood pressure.
  • A problem with your heart rhythm.

What treatments are used for unstable angina?

Unstable angina treatments may include:

Complications/side effects of the treatment

Although medications sometimes have side effects, your provider prescribes medicine for you because its benefits are greater than its risks. Stopping your medications without discussing with your provider may cause a heart attack. Your other medical problems and your age will affect your surgical risks.

How do I take care of myself?

Be sure to take any medicines your provider ordered for you. Make changes to improve your lifestyle, like eating healthier, exercising and quitting smoking or using tobacco products.


How can I reduce my risk of unstable angina?

You have the power to change some of the things that cause heart disease and unstable angina, such as:

  • Not smoking or using drugs.
  • Exercising often.
  • Eating healthy food.
  • Losing weight.
  • Limiting how much alcohol you drink.

Outlook / Prognosis

What can I expect if I have unstable angina?

Like many people with unstable angina, you could have a heart attack in the next three months.

How long does unstable angina last?

Episodes of unstable angina can last for 15 minutes or more. Without treatment, you can have many episodes of unstable angina.

Outlook for unstable angina

If you have unstable angina, you have heart disease and you’re at risk for a heart attack, heart failure or heart rhythm problems. Your outlook depends on how well your heart is working, how bad your artery blockages are and whether you had a heart attack.

Living With

How do I take care of myself?

Be sure to manage your diabetes, high blood pressure and high cholesterol. Keep taking any medicines your provider ordered for you.

When should I see my healthcare provider?

You should see your provider when:

  • Your heartbeat is not normal.
  • Your symptoms are happening more often.
  • You feel lightheaded.
  • You get pain even when you’re not moving.

When should I go to the ER?

Call 911 when:

  • Your chest pain lasts a long time (more than 15 minutes) or you think you’re having a heart attack.
  • Nitroglycerin isn’t working in five minutes (or after three doses).
  • Your pain comes back or gets worse.

What questions should I ask my doctor?

  • What lifestyle changes should I make?
  • What medicines do I need to take and for how long?
  • What are my odds of having a heart attack?

Additional Common Questions

Is unstable angina a heart attack?

No, but it’s a strong warning sign that you may have a heart attack soon.

Can unstable angina lead to a heart attack?

Yes, it can. If your provider doesn’t clear the blood clot and plaque in your coronary artery, you could have a heart attack.

What triggers unstable angina?

A blood clot forming on plaque, creating a blockage in your coronary artery, causes a lack of oxygen to the heart. This triggers unstable angina.

A note from Cleveland Clinic

When you’re having chest pain, it’s not the time to be indecisive. Get medical help right away. Unstable angina is a warning that you could be having a heart attack before long. Follow your provider’s orders for making changes in your lifestyle and keep taking your medicines. Teaching your family what to watch for and when to call 911 for you can give you some peace of mind.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 08/19/2021.

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