Determining whether angina is stable or unstable

After you have been diagnosed with coronary artery disease (CAD), your doctor will need to know whether your chest pain (angina) is stable or unstable. If you have unstable angina, you are more likely to have a heart attack and will therefore need more aggressive treatment.

What is angina?

Angina is chest pain or discomfort that happens because not enough blood is getting to your heart muscle. This lack of blood flow to your heart is often caused by the buildup of plaque in your coronary arteries, which narrows your arteries and limits blood flow.

What is stable angina?

When the plaque in your arteries is stable and not changing, it can cause angina if it obstructs blood flow when you exert yourself in certain predictable ways (such as when you walk up three flights of stairs). "Stable angina" is the term that doctors use to describe this type of predictable chest pain or discomfort.

What is unstable angina?

The plaque in arteries may break or crack open. The body's response is to form a blood clot over the crack in the plaque. The clot that forms may further limit blood flow inside the artery.

This new blockage may cause angina even when you are at rest. The clot may form, break up, and form again, causing angina that comes and goes. "Unstable angina" is the term that doctors use to describe this type of chest pain or discomfort that comes and goes unpredictably, even when you are at rest, or to describe a worsening of previously stable angina into an unstable state.

Sometimes, instead of breaking up, the clot may get larger and completely clog up the artery, resulting in a heart attack.

How does my doctor evaluate my angina?

The best way for your doctor to tell whether your angina is stable or unstable is to ask you questions about your symptoms. It is important to remember that angina is not just chest pain. It can also be described as discomfort, heaviness, or squeezing. In addition, there are other symptoms that often go hand in hand with chest pain or discomfort, such as shortness of breath, sweating, and a feeling of nausea. Your doctor will want you to consider all of these symptoms when describing your angina.

Doctors typically ask five questions to find out whether someone has stable or unstable angina:

• Have you had angina before?
• How long does your angina last?
• Has your angina gotten more severe?
• How often does your angina happen?
• What were you doing when you experienced angina?

The table below shows how your doctor distinguishes between stable and unstable angina based on your answers to these questions.

Diagnosing whether angina is stable or unstable

Question that your doctor asks	Answer that suggests stable angina	Answer that suggests unstable angina
Has it happened before?	I have had angina before.	This is the first time I've had angina.
How long does it last?	My angina usually lasts for the same amount of time.	My angina is lasting longer.
Is it getting more severe?	The severity of my angina has stayed the same.	My angina is getting more severe.
How often does it happen?	My angina happens with consistent frequency (for example, once per week).	My angina is happening more often (for example, once per day instead of once per week).
What were you doing when it happened?	My angina happens when I'm exerting myself (such as walking up a hill) or when I'm feeling very stressed.	My angina happens with little exertion or even when I am resting or asleep.

If you have had angina before, then you should think about your experience of angina over time when answering these questions. It is very important that you tell your doctor if your symptoms have changed because it could mean that your CAD is getting worse, which increases your risk of a heart attack. If this is your first experience with angina, most doctors would consider your angina unstable. However, if this first episode of angina occurred during a lot of exertion, it is less worrisome than if it occurred at rest.