Although stable and unstable angina have similar symptoms, they differ in terms of severity and when the symptoms occur. Stable angina is chest discomfort, shortness of breath (or any of the symptoms described above) that happens with a predictable, reliable amount of exertion or stress, and when that pattern has been present for more that four weeks. Stable angina usually starts when you exert yourself or feel stressed. If you stop what you are doing, the pain or discomfort usually stops too. Activity—exercise, eating a big meal, or having an argument—makes your heart rate go up and your blood pressure higher, so your heart works harder. To do the work, the heart needs more oxygen. If it is not getting enough, it can cause the pain and discomfort of angina. When your pattern of angina has been stable for several months, it may be referred to chronic stable angina.

Unstable angina is when symptoms of chest pressure, shortness of breath (or any of the others described above) occur for the first time, or have been happening for less that two weeks. Also, if you have had a change in your usual pattern of angina that occurs with exertion, that also is unstable angina.  Unstable angina can happen any time, even when you are resting or sitting in front of the television doing nothing. It’s hard to ignore. If the symptoms stop, they usually return again soon.

Stable angina can become unstable. For instance, if you usually have chest discomfort every time you walk two blocks, that would be considered stable angina. However, if that pattern of chest discomfort changes over the course of a short period of time, then the angina has become unstable. For example, if discomfort comes on with less activity (after walking only half of a block instead of two) or is occurring more frequently than previously, that would be an example of stable angina that has become unstable.

Here are some additional tips for distinguishing between stable and unstable angina:

Stable Angina…

• is pain or discomfort similar to past episodes of angina with similar amounts of exertion and usually resolves in less than five minutes.
• is chest pain or other symptoms that usually stop after you take medication or stop to rest.
• is triggered by activities that make the heart work harder—physical and emotional exertion or stress, extreme temperatures, or a big meal.

Unstable Angina or a Heart Attack…

• can happen anytime. You could be taking a nap or having a cup of coffee.
• may feel different than the pain or discomfort of stable angina.
• is often more painful or severe and lasts longer than stable angina—more than a few minutes.
• may not go away with rest or use of angina medication.

Click here to learn more about the underlying causes of angina and how they differ for stable and unstable angina.