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Cardiac Arrest vs. Heart Attack: Is There A Difference?

Last updated Jan. 28, 2016

Approved by: Maulik P. Purohit MD, MPH

National Heart, Lung and Blood Institute

Figure A is an overview of a heart and coronary artery showing damage (dead heart muscle) caused by a heart attack. Figure B is a cross-section of the coronary artery with plaque buildup and a blood clot.

Is there a difference between cardiac arrest and heart attack? Simply put, yes. The two conditions are related, but it is incorrect to use the terms cardiac arrest and heart attack interchangeably.

The difference between cardiac arrest and heart attack:

The major difference is that cardiac arrest is an electrical problem while a heart attack is a blood flow problem. The heart needs both its electrical and blood flow systems working properly so that it can pump blood. If either system fails, the heart cannot pump efficiently and the tissues do not receive blood flow. Although cardiac arrest and heart attack are both heart ailments and could be fatal, their treatment regimens are very different.

What is a cardiac arrest?

Electrical impulses move across the heart, from top to bottom, to stimulate and coordinate contraction of the heart chambers. These impulses cause the atria and ventricles to contract in a precise sequence. This coordinated effort allows blood flow via the arteries to the tissues. Any disruption or aberration in the electrical conduction could cause abnormal/irregular heartbeat, also known as cardiac arrhythmia. When a cardiac arrhythmia leads to a malfunction of the heart, stopping blood flow to the body, it is called a cardiac arrest.

A person in cardiac arrest will be unresponsive and will either stop breathing or have ineffective breathing (e.g., agonal breathing or gasping). A cardiac arrest could be fatal within minutes if swift and decisive action is not taken, such as prompt cardiac defibrillation.

What is a heart attack?

Even though all of the blood in the body goes through the heart, the heart muscle itself relies on a separate blood flow from the coronary arteries. The relatively small coronary arteries branch off the aorta, extend around the outside of the heart, and descend into the heart muscle. When blood flow through one or more of these coronary arteries gets blocked, it leads to a heart attack or myocardial infarction (in medical terms). This might occur when a blood clot is lodged in the blood vessel. Just like other muscles and tissues, the heart needs oxygen and nutrients in order to function. If blood flow is interrupted to a region of the heart, the heart cells in that region stop functioning (e.g., they stop contracting). If blood flow is interrupted long enough, the heart cells will die.

A person having a heart attack often reports feeling a crushing pain, shortness of breath, dizziness/faintness, and having cold sweats. While massive heart attacks can be fatal over a short period of time, many do not kill as rapidly as cardiac arrest does. Nevertheless, people with symptoms of heart attack should receive medical attention immediately.

Can a heart attack become a cardiac arrest?

In some cases, heart attack can evolve into cardiac arrest. If blood flow is interrupted to a part of the heart that carries electrical impulses, the electrical conduction within the heart can be affected. It is possible that the heart attack causes the cardiac arrest. On the other hand, cardiac arrest does not cause a heart attack (though it does cause a global myocardial hypoxia, which is not the same thing).

Cardiac arrest and heart attack are both life-threatening conditions. Prompt attention can save a life!

Written by: ACLS Medical Training Staff

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Jan. 28, 2016
Last updated: Jan. 28, 2016