Unstable angina happens when blood flow to the heart is suddenly slowed by narrowed vessels or small blood clots that form in the coronary arteries. Unstable angina is a warning sign that a heart attack may soon occur.
Unstable angina is an emergency.
Unstable angina symptoms are similar to a heart attack. They may include chest pain or pressure that occurs at rest or with less and less exertion. Symptoms may become severe and last longer. And they may not respond to nitroglycerin or rest.
Unstable angina is a change from stable angina—a pattern of predictable chest pain or other symptoms. Stable angina symptoms are relieved by rest or nitroglycerin.
Last Revised: April 17, 2013
Author: Healthwise Staff
Medical Review: Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
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If you or someone in your care has chest pains, difficulty breathing, or severe bleeding, it could be life-threatening. Call 9-1-1 or the local emergency number immediately. If you are concerned about a possible poisoning or exposure to a toxic substance, call Poison Control now at 1-800-567-8911.