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What Is the Difference Between Cardiac Arrest and Heart Attack?
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Defibrillation
Defibrillation The administration of electric shocks to the heart with a defibrillator can reset normal heart rhythm in persons who are experiencing cardiac arrest or whose heart function is endangered because of severe arrhythmia (abnormality of heart rhythm).

What Is the Difference Between Cardiac Arrest and Heart Attack?

Written by
Kara Rogers
Kara Rogers is the senior editor of biomedical sciences at Encyclopædia Britannica, where she oversees a range of content from medicine and genetics to microorganisms. She joined Britannica in 2006 and...
Kara Rogers
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Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
Britannica Editors
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Cardiac arrest is an electrical malfunction in which the heart’s rhythm suddenly fails, and it stops beating without warning. A heart attack (myocardial infarction), by contrast, is a circulation problem—usually caused by a blocked artery that cuts off blood flow to part of the heart muscle. Cardiac arrest leads to collapse within seconds, whereas a heart attack typically causes progressive damage as the deprived heart tissue begins to die.

Cardiac arrest vs. heart attack: The risk factors

Cardiac arrest and heart attack are caused by different problems within the heart.

Risk factors for cardiac arrest
  • A frequent trigger is rhythm disturbance—especially ventricular fibrillation—in which the heart quivers instead of beating effectively.
  • A severe heart attack can set the stage for cardiac arrest by damaging heart muscle and disrupting its electrical pathways.
  • Other risk factors include congenital defects, heart failure, valve disease, cardiomyopathy, and inherited conditions such as long QT syndrome.
  • Severe external events—such as drug overdose, drowning, extreme allergic reactions, or electrical shock—can abruptly interrupt the heart’s rhythm and lead to cardiac arrest.
Risk factors for heart attack
  • The most common underlying cause is coronary artery disease, in which fatty deposits gradually narrow the arteries that supply the heart.
  • If a fatty deposit ruptures, a clot can quickly form and block blood flow—an event often linked to risk factors such as smoking, high blood pressure, and elevated cholesterol.
  • Less commonly, a powerful spasm of a coronary artery or a spontaneous tear in the vessel wall can also restrict blood supply and trigger a heart attack.

Warning indications

Cardiac arrest strikes suddenly and without sustained warning, causing immediate collapse, unconsciousness, absence of a pulse, and stopped breathing—or only brief gasping. A heart attack, by contrast, typically unfolds with warning symptoms such as chest discomfort or pressure, pain that may radiate to the arm, jaw, neck, or back, shortness of breath, and sometimes nausea, sweating, or lightheadedness. These signs can be less obvious in women, older adults, and people with diabetes, owing to factors such as preexisting health conditions that mask symptoms or atypical symptoms, such as fatigue or back pain.

Outcomes and survival

In both cardiac arrest and heart attack, the outcome depends on how quickly treatment begins. Cardiac arrest requires immediate treatment, since the loss of blood flow to the brain and other vital organs can quickly lead to death. Rapid intervention typically is with immediate cardiopulmonary resuscitation (CPR), which can keep blood circulating, and defibrillation, which delivers a powerful electric shock to reset heart rhythm. Emergency responders may also provide medications and breathing support. In the case of heart attack, prompt treatment to restore blood flow can limit injury and help preserve heart function, significantly improving chances of survival.

Kara Rogers