Unstable angina, or acute coronary syndrome, is a type of chest pain or discomfort that typically occurs when a person is resting.

Unstable angina is a medical emergency, and people should seek medical help if they experience new, worsening, or persistent chest pain or discomfort.

This article will explore what unstable angina is, its symptoms, causes, treatment options, and diagnosis.

A person who may have unstable angina putting their hand over their heart.Share on Pinterest
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Unstable angina is a form of angina that normally occurs at rest, during sleep, or with little physical exertion. Angina is a type of chest pain that occurs due to restricted blood supply to the heart.

Some people may experience discomfort as opposed to pain.

According to one 2020 article, unstable angina affects approximately 18 million people in the United States.

A person can experience unstable angina for the first time, or it can be a sudden worsening of existing angina symptoms.

According to the United Kingdom’s National Health Service (NHS), the symptoms of unstable angina are the same as the symptoms of stable angina. However, they do not follow the same pattern.

Symptoms can begin quickly and be persistent. They can also worsen over time, meaning that they are more severe, come on with less exertion, or last longer.

The symptoms include pain or discomfort that begins in the chest. It can then radiate to:

  • the throat
  • the jaw
  • the left or right arm
  • the back or stomach
  • the shoulders

People may feel heaviness or pressure in their chest or a squeezing sensation. Others note that the pain may be tight, burning, or sharp.

Other symptoms of unstable angina include:

In females

According to the American Heart Association (AHA), the symptoms of unstable angina may present differently in females.

In males, the blood flow blockage can occur in the large coronary arteries. However, in females, this can occur in the smaller arteries that branch off from the coronary arteries, a condition called microvascular disease.

Additional unstable angina symptoms that females may experience include:

Unstable angina is a medical emergency, as it is a sign of a severely restricted blood supply to the heart, which compromises the heart’s ability to function. This increases the risk that a person will experience a heart attack.

Stable angina, on the other hand, is not typically life threatening. However, it is a sign that the heart is not getting enough blood flow when it needs it more, due to possible blockages in the arteries.

Stable angina occurs when the heart is working harder and therefore needs more oxygen, typically following physical activity or stress. By contrast, unstable angina occurs when a person is resting.

Both stable and unstable angina cause the same symptoms. However, the main difference between these two conditions is that their symptoms follow different patterns.

Symptoms of stable angina typically develop gradually and follow a particular pattern. They can last for seconds to minutes, and the discomfort normally resolves after rest. Sometimes, it resolves immediately upon rest. Other times, it can take a few minutes.

The symptoms can also improve after a person takes nitroglycerin, which is a type of medication that relaxes the arteries around the heart to improve blood flow.

Learn more about stable angina here.

The AHA note that unstable angina symptoms can develop quickly and persist even when a person is resting. They may also last for longer and can worsen over time. Unstable angina is a medical emergency.

Unstable angina occurs when there is a severe restriction of blood supply to the heart due to blood clots.

Over the years, fatty deposits, or atheromas, can build up in the arteries. As a result, the arteries become narrowed, restricting the amount of blood that can reach the heart.

If these fatty deposits burst or break off, this interferes with the blood flow, causing blood clots to form. These can become enlarged and cause a blockage in the arteries, triggering the symptoms of unstable angina.

The AHA note that these blood clots can partially dissolve and form again. The symptoms of unstable angina can occur each time a blood clot restricts the blood flow in the artery.

Certain dietary habits, health conditions, and lifestyle habits can increase the likelihood of developing unstable angina.

Risk factors include:

The primary goal of unstable angina treatment is to improve the blood flow of the coronary arteries.

Treatment options include medication and surgery.

Many of these options will depend on the severity of unstable angina.


A doctor may prescribe aspirin, as it helps prevent the blood from sticking together and clotting.

A doctor may also prescribe clopidogrel, which is another drug that stops blood from sticking together. They may suggest a beta-blocker to “rest” the heart and a statin medication to reduce inflammation and cholesterol.

A doctor may also prescribe nitroglycerin, which helps expand the arteries and improve blood flow.


A person with unstable angina may need surgery to remove blockages in the arteries.

This can include:

  • Angioplasty, or percutaneous coronary intervention: This is where a surgeon inserts into the artery a small inflatable balloon, a stent, or both. This can help keep the artery open and improve blood flow.
  • Coronary artery bypass graft surgery: During this procedure, a surgeon uses a blood vessel to create a detour around the blocked section of the artery.

A person can reduce the risk of developing unstable angina by making changes to their diet and taking part in regular physical activity.

However, according to a 2020 article, those at risk of unstable angina should avoid engaging in intense physical activity, particularly in cold weather, until a doctor has addressed the blockage.

Moreover, people should consult a doctor if they have high blood pressure or diabetes.

If possible, people should also:

  • quit smoking
  • limit alcohol consumption
  • reduce sodium intake
  • reduce cholesterol
  • reach or maintain a moderate body weight

Those with high blood pressure, diabetes, or high cholesterol should contact a doctor to ensure that they are managing their medical conditions.

A healthcare professional will diagnose unstable angina after completing a physical exam and getting a full medical history. This will include distinguishing between the symptoms of stable and unstable angina.

The doctor may also request additional tests to reach a proper diagnosis.

These additional tests can include:

  • Electrocardiogram: This test records the heart’s electrical activity and can help show whether there is reduced blood flow to the heart.
  • Blood tests: These can help determine whether there is an increase in an enzyme called troponin. The release of this enzyme takes place when there is damage to the heart.

Further tests may include:

  • Cardiac stress tests: This may include walking on a treadmill, a stress echocardiogram, or a stress nuclear test.
  • Cardiac catheterization: During this procedure, the heart blood vessels have a tube, or catheter, passed through them. This allows the doctor to examine the heart muscles and see whether there is any blockage or narrowing of the blood vessels.

A healthcare professional may order the following imaging tests:

  • CT scans
  • myocardial perfusion, a test that shows how well the blood flows through the heart muscles

A person should consult a doctor if they experience any chest pain or discomfort. They should also talk with a doctor if their symptoms worsen in duration and intensity.

A person experiencing unstable angina symptoms should seek emergency medical attention.

Unstable angina is a type of chest pain or discomfort that occurs when there is a severe restriction of the blood flow to the heart. It typically occurs when a person is resting or sleeping or after a small amount of physical exertion. It can also occur when stable angina symptoms worsen over time.

Symptoms can also include chest pain or chest pressure, shortness of breath, nausea, dizziness, sweating, rapid heartbeat, and vomiting.

Females with unstable angina may experience abdominal pain, anxiety, and sharp chest pain alongside the other symptoms.

A person should contact a healthcare professional if they experience any symptoms of unstable angina, as it is a medical emergency.

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