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Heart Health Library

Our Health Library does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their heart health. Our providers may not see and/or treat all topics found herein.

Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their health. Our providers may not see and/or treat all topics found herein.

How a heart attack happens

Heart showing blocked coronary artery and area with blocked blood flow, with detail of blood clot in artery blocking blood flow

A heart attack is caused when not enough blood and oxygen reach part of the heart muscle. The heart muscle starts to die. This lack of blood and oxygen is most often caused by a blockage in one or more of the coronary arteries.

This blockage is usually the result of coronary artery disease, in which fatty deposits called plaque (say "plak") build up inside the coronary arteries. Plaques are covered by a fibrous cap. If the cap breaks open or ruptures, the body will try to repair the injured artery lining. A blood clot may form and block blood flow.

Sometimes a blood clot that forms over a ruptured plaque may not completely block the artery. But the clot may block blood flow enough to cause angina symptoms. These symptoms may happen with rest and may not go away with rest or nitroglycerin. These symptoms are an emergency, because the blood clot can quickly grow and block the artery. If the blood clot dissolves and an immediate heart attack is avoided, the body will try again over time to repair the tear on the surface of the plaque. But this newly repaired plaque can also be very unstable. It is more likely to rupture again, putting you at even greater risk of a heart attack.

Current as of: June 24, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

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