Often the terms 'cardiac arrest' and 'heart attack' are used interchangeably. These two heart emergencies, however, are very distinct, and knowing the difference can save lives.
It’s a common misconception that sudden cardiac arrest (SCA) and heart attack are the same thing, according to the Sudden Cardiac Arrest Foundation (SCAF). SCAF and other medical societies compare the two heart emergencies to problems in a house: heart attack is a “plumbing” problem when the blood flow is blocked or reduced, and cardiac arrest is an “electrical” problem when electrical impulses in the heart malfunction, stopping the heartbeat.
Michael Grad, MD, an interventional cardiologist with Cardiovascular Specialists of Texas in Austin, told dailyRx News, “It’s difficult to differentiate between cardiac arrest and myocardial infarction [heart attack].”
A heart attack happens when part of the heart’s blood supply is reduced or blocked. The heart muscle can become injured or die. A person suffering a heart attack is awake and his or her heart is still beating.
Most heart attacks occur as a result of coronary heart disease (CHD), according to the National Heart, Lung and Blood Institute (NHLBI). With CHD, a waxy substance called plaque builds up inside of the coronary arteries—a condition called atherosclerosis.
When sudden cardiac arrest strikes, the heart stops beating altogether. SCAF says, “The person suddenly passes out, loses consciousness and appears lifeless—except for abnormal 'gasping' which may last for several minutes.”
A group of cells called the sinus node, located in the upper right chamber (right atrium) of the heart, sends electrical impulses through your heart. According to the Mayo Clinic, the impulses control the heart rate and the pumping of blood through your body.
Problems with the heart's electrical system can cause irregular heartbeats called arrhythmias.
During an arrhythmia, the heart can beat too fast, too slow or with an irregular rhythm. The NHLBI says that some arrhythmias can cause the heart to stop pumping blood to the body; these arrhythmias cause SCA.
An arrhythmia called ventricular fibrillation is the most common cause of cardiac arrest, according to Mayo Clinic. Ventricular fibrillation sends erratic electrical impulses, causing your heart's ventricles to quiver uselessly instead of pumping blood.
Just as coronary heart disease increases the risk of heart attack, it also increases the risk for SCA. Most cases of SCA are in people who have CHD. However, SCA can happen in people who appear healthy and have no known heart disease or other risk factors for SCA.
Taking Fast Action
“If this arrhythmia is not managed emergently, it can mean loss of life,” says Dr. Grad.
There are 300,000 to 400,000 deaths per year in the United States from cardiac arrest, according to the Occupational Safety and Health Administration (OSHA).
Most cardiac arrest deaths occur outside the hospital. Current out-of-hospital survival rates are 1 to 5 percent.
Whether someone is having a heart attack or cardiac arrest, fast action is required to save a life. The quicker the treatment, the better the outcome. In either case, the worst thing is to do nothing. Immediately call 9-1-1 in either case to get emergency medical services on the scene as soon as possible.
Know the Signs and Symptoms
Your next step is to quickly assess if the person is having a heart attack or cardiac arrest. Note that in some cases patients may have no signs of impending trouble. Here are possible symptoms, according to the SCAF:
Heart Attack Symptoms
- Discomfort in the center of the chest that lasts more than a few minutes or that goes away and comes back.
- Mild chest discomfort that comes and goes over a period of days. These are early “warning signs” that may precede a heart attack.
- Uncomfortable pressure, squeezing or fullness in the chest. It can change into crushing pain if nothing is done.
- Pain or discomfort in one or both arms, spreading to the shoulder, upper back, neck or jaw
- Shortness of breath
- Nausea, sweating, lightheadedness
- A general sense of anxiety
Sudden Cardiac Arrest Symptoms
- The heart stops beating altogether, so blood no longer flows throughout the body, including the brain. The person suddenly passes out, loses consciousness, and appears lifeless—except for abnormal “gasping” which may last for several minutes.
- Sometimes, SCA victims will experience 10 to 20 seconds of seizure activity (shaking of the arms and legs) at the onset of the event as the brain stops receiving blood and oxygen from the heart.
- The SCA victim is never awake and needs immediate help. If nothing is done, the victim will die within minutes. So don’t hesitate to take action.
No matter the emergency, call 9-1-1 first. Once you’ve identified a heart attack from cardiac arrest, you’ll know the most effective course of action to take.
Lifesaving Action for Heart Attack
A heart attack victim is awake and the heart is beating. As such, he or she will not require cardiopulmonary resuscitation (CPR) or use of an automated external defibrillator. Have the person lie down and rest until emergency medical help arrives.
Lifesaving Action for Sudden Cardiac Arrest
“Believe it or not, SCA does not always result in loss of life if the proper therapy is introduced quickly,” says Dr. Grad. “So, what we hope for, in essence, is ‘temporary’ sudden cardiac death.”
If no signs of life are present, give CPR. The American Heart Association (AHA) recommends using Hands-Only CPR if you see a teen or adult suddenly collapse. With the person lying on his or her back, push hard and fast in the center of the chest to the beat of the classic disco song "Stayin' Alive." CPR can more than double a person's chances of survival, and "Stayin' Alive" has the right beat for Hands-Only CPR.
Recent studies suggest dropping mouth-to-mouth, or rescue breathing, by bystanders and using "hands-only" chest compressions during the life-saving practice of CPR. The AHA lists some instances when breaths can help. To find out more, visit the AHA website.
Use an automated external defibrillator (AED) if one is available.
Defibrillators to the Rescue
Although most people who have SCA die from it—often within minutes—rapid treatment with a defibrillator can save a life. A defibrillator is a device that sends an electric shock to the heart to try to restore its normal rhythm.
OSHA reports that using a defibrillator to treat ventricular fibrillation (associated with most cardiac arrests) can increase survival to more than 90 percent. With each minute of delay in defibrillation, 10 percent fewer victims survive.
That’s why automated external defibrillators (AEDs) are being made available in more public places. They can now be found in shopping malls, golf courses, businesses, airports, airplanes, casinos, convention centers, hotels, sports venues and schools. They can be used by bystanders to save the lives of people who are having SCA.
Some people may be concerned that AEDs can hurt the person suffering a cardiac arrest. These devices, however, will only deliver a shock when an irregular heart rhythm is detected, according to the Heart Rhythm Society.
A computer inside the defibrillator analyzes the victim’s heart rhythm. The device decides whether a shock is needed. The shock is delivered through pads stuck to the victim's bare chest. The shock stuns the heart, stopping abnormal heart activity, and attempts to jolt the heart back to its normal rhythm.
Preventing Heart Attack and Cardiac Arrest
In the fall of 2012, the Heart Rhythm Society launched a multi-year, national awareness campaign called "Arrest the Risk.” The goal is to spotlight the issue of SCA prevention, early intervention and appropriate treatment among the African-American population. About 95 percent of SCA cases result in death; however, it appears most deadly in African Americans.
Living a healthy lifestyle—exercising regularly, eating healthy foods, maintaining a reasonable weight, and avoiding smoking—can help prevent both SCA and heart attack. Those with SCA may also consider an implantable cardioverter defibrillator (ICD), which is like a pacemaker with a small AED that will send a jolt to the heart when a patient undergoes cardiac arrest.
To learn more about who’s at risk of heart attack and cardiac arrest and prevention, visit the Sudden Cardiac Arrest Foundation (www. sca-aware.org), American Heart Association (www.heart.org) and the Heart Rhythm Society (http://www.hrsonline.org/).