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In this article:
Key Points
- Patients may have angina pain or discomfort called Cardiac Syndrome X when very tiny arteries in the heart (the microvasculature) are not working properly, even though the coronary arteries appear to be normal.
- An angina attack that occurs without angina pain or discomfort but can be detected during an electrocardiogram is called silent ischemia.
- Unstable angina often occurs during exercise or rest and happens unpredictably. Patients may also have unstable angina if their attacks have recently become more severe and frequent and are not relieved by usual angina medications.
- Patients with variant angina, also known as Prinzmetal's angina, can have sudden angina attacks at any time. Attacks may occur in clusters of two or three at the same time each day, usually during the night or early in the morning.
In addition to chronic angina, people may develop other kinds of angina. Always ask your doctor for more information about the type of angina you may have.
Cardiac Syndrome X
When the type of chest pain or discomfort you describe and the results of your exercise tolerance test point to angina, your doctor may order an angiography (sometimes called an angiogram or arteriography), an X-ray that highlights the arteries of your heart. This test checks to see whether your coronary arteries are partially blocked. Usually, some blockage is evident, but sometimes none is noticeable. If your arteries show no sign of heart disease, do you really have angina?
Yes, it’s possible. Angina pain or discomfort and a positive stress test with a normal angiography is called Cardiac Syndrome X. You may feel chest pain or discomfort when very tiny arteries in the heart are not working correctly,1 even though the coronary arteries appear to be normal.2 These small vessels are called the microvasculature.
No one knows exactly why the microvasculature malfunctions. The angina pain or discomfort is thought to be caused by inadequate blood
flow through the microvasculature, which may cause these tiny vessels to tighten up.2 If this occurs, less oxygen-rich blood flows through and your heart doesn’t get all the oxygen it needs to perform effectively. The end result: You may have an angina attack.
Cardiac Syndrome X afflicts more women than men, and doctors aren’t sure why. Learn more about women and chronic angina in Women
and Heart Disease.
Silent ischemia
Sometimes you may have an angina attack and not even know it. Ischemia means not enough oxygen is available for the heart to work effectively. Angina attacks without angina pain or discomfort are called silent ischemia.
Your doctor may happen to notice you have silent ischemia if your
electrocardiogram
(EKG) during a routine checkup shows abnormal changes that usually only happen with noticeable angina attacks. To follow up, your doctor may have you wear a Holter monitor, a type of portable EKG machine, for 24 hours. The monitor continuously measures your heart rate and rhythm.
Up to 4 million Americans may have silent ischemia without knowing it, and people who have already had a heart attack or have diabetes may be at greater risk.3-5 Some people with silent ischemia may be at risk for a heart attack without any previous warning. Doctors are still researching whether silent ischemia can be prevented or treated with antiangina medications.
There are many explanations for silent ischemia, but it seems that the real mechanism for this condition is not fully understood. Unfortunately, because the ischemia is ‘silent,’ sudden and severe coronary events may occur without warning. In effect, the heart does "suffer in silence."6
Unstable angina
Coronary arteries may suddenly become blocked, or almost completely blocked, because of a sudden burst and release of the contents of plaques, the fatty buildup along artery walls that leads to coronary artery disease (CAD). It is not clear why plaque ruptures, but when this happens, unstable angina symptoms may occur. 'Unstable' means angina happens unpredictably—during exercise or light exertion, but usually while you’re resting and not exerting yourself at all. Unlike chronic angina, which tends to occur while you are active, unstable angina often occurs when you’re taking it easy. It’s also called unstable if your angina pain or discomfort has become more severe and more frequent than before.
Typically, people with unstable angina have very bad coronary artery disease that has suddenly gotten worse. The attacks often last longer than ‘stable’ or chronic angina. If your angina becomes less predictable and begins to occur while you’re resting or using minimal effort and not while you are exercising, you may be close to having a heart attack. Angina that lasts, without relief from rest or your short-acting nitroglycerin, is usually considered a medical emergency. Seek help immediately.
Variant angina
The signs of variant
angina, also known as Prinzmetal's
angina, may be quite different from chronic angina. For example, people often describe angina pain or discomfort more often in clusters of two or three attacks in the night or early morning hours, or at the same time every day. Sometimes these clusters last for weeks, with pain-free periods in between.2 Patients may state that they experience attacks while at complete rest, but at times may be able to perform physically strenuous activities without triggering attacks. In fact, patients who have variant angina might not have any pain or discomfort while they are exerting themselves, but might feel pain as soon as they stop and rest.2 Often, the exercise tolerance test is negative.
Variant angina often seems to be caused by a more severe spasm or constriction of one of the arteries that lie on the outside surface of the heart, caused by small, usually unimportant plaque. However, spasm may occur in normal arteries too.2 Attacks are usually short and are often treated with short-acting nitroglycerin.
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More women than men have heart disease. True or False?
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Sources
1. Reis SE, Holubkov R, Conrad Smith AJ, et al. Coronary Microvascular Dysfunction is Highly Prevalent in Women with Chest Pain in the Absence of Coronary Artery Disease: Results from the NHLBI WISE Study. American Heart Journal. 2001;141:735-741.
PubMed
2. Sheridan PJ, Crossman DC. Diagnosing Chronic Stable Angina. Practitioner. 2003;247:208-210, 212, 214-5.
PubMed
3. American Heart Association. Silent Ischemia and Ischemic Heart Disease, 2004. Available at:
http://www.americanheart.org/presenter.jhtml?identifier=4720. Accessed May 26, 2004.
4. Almeda FQ, Kason TT, Nathan S, Kavinsky CJ. Silent Myocardial Ischemia: Concepts and Controversies. American Journal of Medicine. 2004;116:112-118.
PubMed
5. Cohn PF, Fox KM, Daly C. Silent Myocardial Ischemia. Circulation. 2003;108:1263-1277.
PubMed
6. Conti CR. Silent Cardiac Ischemia. Current Opinions in Cardiology. 2002;17:537-542.
PubMed
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