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Unstable Angina

Angina is a painful or tight feeling in or near your chest. It can occur if your heart muscle isn’t getting enough oxygen-rich blood. There are two kinds of angina: stable and unstable. Stable angina occurs at predictable times and can often be managed. Unstable angina does not occur at predictable times, and it may not respond to the usual forms of treatment for angina. It is a warning that a heart attack, also known as acute myocardial infarction, or AMI, is possible in the near future. For this reason, it should be treated right away. This sheet tells you more about unstable angina. If you have questions, be sure to ask your doctor.

CAD Causes Angina 

The heart is a muscle. It gets oxygen from the blood provided through the coronary arteries. Coronary artery disease (CAD) occurs when fatty material (plaque) builds up within your artery walls. This buildup reduces blood flow to your heart. As a result, your heart can’t get enough oxygen. This causes the chest pain of angina. Other symptoms, such as lightheadedness, shortness of breath, nausea, abdominal pain, or unexplained sweating, may also be symptoms of angina.

Image of artery with plaque
Unstable angina is usually caused by coronary artery disease (CAD).

The Difference Between Stable and Unstable Angina

  • Stable angina. This type of angina occurs most often during exercise or times of stress. Stable angina often goes away when you rest or take nitroglycerin. This is a medication that helps increase blood flow through your arteries.

  • Unstable angina. This type of angina is caused when a piece of plaque ruptures or breaks off. A blood clot can form at the site of the rupture, which reduces blood flow even further. Unstable angina is described as chest pain that occurs even at rest. You may also be diagnosed with unstable angina if you have stable angina that becomes more severe, lasts longer, or that is not relieved by rest or medication.

How Unstable Angina Feels

Unstable and stable angina have the same symptoms. With unstable angina, the symptoms are more severe and last longer. Symptoms include:

  • Discomfort, aching, heaviness, tightness, squeezing, or pressure. You may feel this in your chest or back. You may also feel it in your arm, shoulder, neck, jaw, or upper abdomen.

  • Feeling more tired than usual for no clear reason

  • Nausea

  • Unexplained sweating

  • Shortness of breath

Your Evaluation

Because unstable angina can lead to a heart attack, it is viewed as an emergency. If you are having symptoms of unstable angina, you should call 911 immediately. Your doctor will ask about your symptoms and examine you. Tests will be done quickly. Common tests include:

  • Blood tests. These can help tell if there is damage to your heart. They can also check for cholesterol in the blood, which leads to plaque buildup. They can check for other health problems that affect the heart as well, such as diabetes.

  • Electrocardiogram (ECG). This test records your heart’s electrical patterns. A resting ECG can show whether there is damage to your heart muscle. A stress ECG can show how well the blood flows to your heart during exercise.

  • Angiography. This test can pinpoint where your arteries are narrowed. A long tube (catheter) is placed in an artery in your leg. It is then slowly guided to your heart. Dye is sent through the tube and into the coronary arteries. This makes the arteries show up clearly on X-rays.

Treating Unstable Angina

Your treatment will depend on the results of your tests. Possible treatments include:

  • Observation. If your symptoms are severe, you may need to stay in the hospital to be monitored. If your chest pain improves, you’ll be allowed to go home.

  • Medications. Your doctor will likely give you nitroglycerin and medications that help prevent blood clots, such as aspirin. He or she may also give you medications to help reduce your blood pressure or slow your heart rate.

  • Procedures to improve blood flow. If your chest pain does not improve, your doctor may suggest procedures to improve blood flow to your heart muscle. These can include angioplasty and bypass surgery. Your doctor will tell you more about these treatments if you need them.

  • Lifestyle changes. These can include not smoking, eating healthy foods, and getting regular exercise. If you have other health problems, such as high blood pressure, diabetes, or high cholesterol, these need to be treated as well. They can increase your risk for a heart attack. Lifestyle changes can make unstable angina attacks less frequent and less severe. They also help you manage CAD and reduce your risk for a heart attack.

When Taking Nitroglycerin

If your doctor prescribes nitroglycerin, be sure to follow his or her instructions on how to use it. Also, be sure to tell your doctor if you’re taking any other medications. This includes other prescription and over-the-counter medications, as well as herbs and other supplements. DO NOT take nitroglycerin if you take medications to treat erectile dysfunction. These can include sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra).

When to Call 911

Call 911 or go to the emergency room (ER) right away if your chest pain:

  • Occurs when you’re not active.

  • Wakes you up from sleep.

  • Comes back and is not relieved by your usual dose of nitroglycerin.

  • Occurs with weakness, dizziness, fainting, heavy sweating, nausea, or vomiting.

  • Lasts longer than 5 minutes.

Online Medical Reviewer: Friday, Karen Jean, MD
Online Medical Reviewer: Zerwic, Julie A, PhD, RN
Last Review Date: 11/1/2011
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