Heart Attack vs. Cardiac Arrest

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Question: 

What is the difference between a heart attack and a cardiac arrest?

Answer: After somebody famous has died suddenly, it is common to hear in news reports that the death was caused by a "heart attack" or a "cardiac arrest." These terms often are used interchangeably by reporters; some will use one term while others use the other, as if they indicate the same thing. It’s not just reporters, either.

Doctors, too, can be pretty sloppy about their usage of “heart attack” and “cardiac arrest” when somebody has suffered sudden death. 

Such imprecision on the part of the doctor can lead to confusion among the family members of the victim. Worse, creating confusion about the cause of death may cause relatives of the victim to miss potentially important clues about their own cardiac risk. 

A heart attack and a cardiac arrest are two different things, that often have two entirely different kinds of implications for the victims (if they survive the event), and for family members. 

What is a Heart Attack?

A heart attack is the common terminology for a myocardial infarction, or MI. An MI occurs when a coronary artery (one of the arteries that supplies blood to the heart muscle) becomes suddenly blocked. The sudden blockage robs a portion of the heart muscle of its vital blood supply, and the muscle dies.

So a heart attack is the death of a part of the heart muscle.

The sudden blockage of a coronary artery is usually caused by the rupture of a plaque in the artery. Plaque rupture can produce a variety of clinical conditions — including heart attacks and unstable angina — that are lumped together under the name acute coronary syndrome (ACS).

All forms of ACS are medical emergencies, and they generally need to be treated with medications, angioplasty and stenting, or surgery to restore normal blood flow through the blocked artery. If blood flow can be restored within a few hours, permanent damage to the heart muscle can usually be minimized.

One of the important risk factors for a heart attack is your family history. If a close relative has had a heart attack, especially at an early age, your own risk for premature coronary artery disease (CAD) may also be substantially elevated. In this case, it is especially important to take every opportunity to reduce your own risk for CAD

What Is a Cardiac Arrest?

A cardiac arrest, in contrast, is usually caused by a sudden heart arrhythmia called ventricular fibrillation. In ventricular fibrillation, the electrical signals within the heart suddenly become completely chaotic. Because these electrical signals control the timing and the organization of the heartbeat, when those signals degenerate to total chaos, the heart suddenly stops beating. That is, it goes into "cardiac arrest." The most common outcome of a cardiac arrest is sudden death.

The treatment for a cardiac arrest is to begin immediate cardiopulmonary resuscitation (CPR) to support the victim's circulation, and, as soon as possible, to deliver a large electrical shock to the heart with a device called a defibrillator.

The large shock allows the heart's electrical signal to reorganize itself, and the heart to begin beating again. Unfortunately, because death occurs within a few minutes of cardiac arrest unless help is available, the large majority of people who suffer cardiac arrest are not successfully resuscitated.

Cardiac arrest tends to be much more common in people who have various types of underlying heart disease — most commonly, a prior heart attack or any condition that produces heart failure. As a matter of fact, the risk for sudden death can be substantially elevated in people with underlying heart disease, to the extent that many of them should considered for insertion of an implantable defibrillator, a device that automatically resuscitates people who suffer cardiac arrests.

 

Other causes of cardiac arrest include certain inherited heart abnormalities that tend to increase the risk of ventricular fibrillation (the most common of these being hypertrophic cardiomyopathy) and the use of various illicit drugs (especially cocaine).

Heart Attack Vs. Cardiac Arrest - In Important Distinction

If a close relative has died suddenly, it is important to you and to your family members to try to learn the precise cause of death. That cause of death may affect your own cardiovascular risk profile, and those of your loved ones.

Be aware that even doctors may use the terms “heart attack” and “cardiac arrest” loosely after somebody has died suddenly. If such an event has affected your family, you should get as much information as you can about the cause, and should insist that the doctor speak precisely to you about what actually happened.

Sources:

Chugh SS, Jui J, Gunson K, et al. Current Burden of Sudden Cardiac Death: Multiple Source Surveillance Versus Retrospective Death Certificate-based Review in a Large U.S. Community. J Am Coll Cardiol 2004; 44:1268.

Marijon E, Uy-Evanado A, Dumas F, et al. Warning Symptoms Are Associated With Survival From Sudden Cardiac Arrest. Ann Intern Med 2016; 164:23.

O'Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA Fuideline for the Management of ST-elevation Myocardial Infarction: Executive Summary: a Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2013; 127:529.

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