On-site medical professionals administered CPR (cardiopulmonary resuscitation) for approximately 10 minutes before Hamlin was placed on a stretcher and transported via ambulance to the University of Cincinnati Medical Center, where he is undergoing further testing and treatment, per the statement.

What Is Cardiac Arrest and How Is It Different From Heart Attack?

In cardiac arrest, a malfunction of the heart’s electrical system causes the heart to stop beating properly, according to the American Heart Association (AHA). This in turn halts the flow of blood to the brain and other vital organs, according to MedlinePlus. Heart issues linked to cardiac arrest include ventricular tachycardia (fast heart rate) and ventricular fibrillation (a serious, abnormal heart rhythm). Some cardiac arrests are also caused by extreme slowing of the heart’s rhythm, called bradycardia. It’s estimated that there are more than 356,000 out-of-hospital cardiac arrests (OHCA) each year in the United States. They are most common in adults in their mid-thirties to mid-forties, according to Cleveland Clinic. Sometimes the terms cardiac arrest and heart attack are used interchangeably, but they are not the same. A heart attack is a circulation problem caused by a blockage of blood flow to the heart, not a malfunction of the heart’s electrical system. The heart usually doesn’t stop beating during a heart attack, as it does during cardiac arrest.

Only About 7 in 100 People Survive Cardiac Arrest Outside a Hospital

Sudden cardiac arrest usually causes death in minutes without immediate treatment (as with a defibrillator, a device that sends an electric pulse or shock to the heart to restore a normal heartbeat). It’s estimated that only about 7 in 100 people survive one outside a hospital setting, per StatPearls. It’s rare for cardiac arrest to occur in young people. According to the HealthyChildren.org, it’s estimated that about 2,000 young, seemingly healthy people under age 25 die in the United States each year as a result of cardiac arrest. Even though it’s highly unusual, sudden cardiac death is the leading nontraumatic cause of death in young athletes.

What Caused Hamlin to Go Into Cardiac Arrest?

“It’s not possible to know what caused the cardiac arrest simply by watching the collapse or the hit that preceded it,” says Mariell Jessup, MD, chief science and medical officer at the AHA. It’s likely that Hamlin’s physicians are not only trying to help his recovery from the cardiac arrest, but to also find out the cause of it, says Dr. Jessup. One possibility is a rare condition called commotio cordis, the lethal disruption of heart rhythm that occurs as a result of a blow to the area directly over the heart. “If the hit catches the person at a vulnerable point in the cycle of a heartbeat it can cause ventricular fibrillation, which is a lethal abnormal rhythm of the heart,” Jessup says. Commotio cordis most commonly happens to young men who play sports with hard balls, such as baseball or lacrosse, but it could affect anyone playing a contact sport, says Jessup. Because the thorax (chest area) of an adolescent is still developing, it is likely more prone to this injury — the average age of a young man experiencing commotio cordis is 15, according to the AHA.

An Abnormality of the Heart Muscle Is Often the Cause of Cardiac Arrest in Young Athletes

“Unfortunately, there have been multiple instances of athletes who seem to be in excellent health who suffer cardiac arrest. We have seen this in basketball and football. Almost always we later find out that they have an underlying cardiomyopathy, or abnormality of the heart muscle,” Jessup says. She adds, “It could be hypertrophic cardiomyopathy [when the walls of the heart become thicker than they should be, which leaves less room for blood to fill the heart] or another form of inherited cardiomyopathy.” Physicians may not identify cardiomyopathy in a routine medical exam. “In some cases, there is no indication of any type of heart condition until cardiac arrest occurs,” says Jessup. Cardiomyopathy is uncommon in young people, but it’s more common than commotio cordis, she adds.

What Are the Signs and Symptoms of Cardiac Arrest?

In the majority of cases, cardiac arrest happens without any symptoms, according to Cleveland Clinic. When there are symptoms, they can include one or more of the following:

Fainting or losing consciousnessRacing heartbeatChest painDizzinessLightheadednessShortness of breathNausea and vomiting

What Is the Treatment for Cardiac Arrest?

If an emergency medical team is able to stabilize the person experiencing cardiac arrest, physicians will then perform tests to find out what might have caused the heart to stop. Depending on what the doctors find, treatment might include medications, the implanting of a device to monitor heart rhythms and deliver a shock to correct any dangerous heart rhythm changes, or surgery, according to Mayo Clinic.

What’s the Prognosis for Cardiac Arrest?

Unfortunately, cardiac arrest is a highly lethal condition, says Jessup. “The good news is, Hamlin received immediate CPR and was surrounded by people who knew what to do. The faster people can start CPR on somebody who has suffered cardiac arrest, the better it is for the patient,” she says. That’s why the American Heart Association emphasizes the importance of learning how to do CPR, says Jessup. CPR, which stands for cardiopulmonary resuscitation, is an emergency lifesaving procedure that’s performed when the heart stops beating. Performing CPR immediately can double or triple a person’s chances of survival after cardiac arrest, according to the AHA.

Is Cardiac Arrest Preventable?

Some risk factors for cardiac arrest can’t be changed — for example, if a person was born with a cardiomyopathy or arrhythmia, according to the National Heart, Lung, and Blood Institute. But the vast majority of people who have a cardiac arrest outside of a hospital have coronary heart disease. Heart-healthy living (which includes never smoking, following a healthy eating pattern, and being physically active) is the best way to reduce your risk, per the agency. “Knowing your numbers for cholesterol and high blood pressure and following your doctor’s advice for managing any chronic conditions can also reduce your risk,” says Jessup. If you haven’t been an exerciser and want to start physical activity, check with a doctor first, she suggests. Vigorous physical activity for people — especially men — who don’t exercise regularly is often linked with cardiac arrest. “Cardiac arrest can’t always be prevented. Sometimes the event is the first sign that a person has any issues or underlying heart disease,” she says.

What Should You Do If You Suspect Someone May Be Experiencing Cardiac Arrest?

If you see someone collapse or come upon someone lying on the ground who is unresponsive — even if you tap them hard on the shoulders or ask if they are okay (in a loud voice), they don’t move, speak, blink, or react at all — the cause may be cardiac arrest, according to the AHA. Not breathing, only gasping for air, and having an undetectable pulse could also mean their heart has stopped. In that event, you should make sure the scene is safe, shout for help, immediately call 911 or have another bystander call, and begin performing CPR, per the AHA.

You Never Know When CPR Is Going to Save a Life

“I can’t emphasize this enough: As many people as possible should learn how to perform CPR. You never know when CPR is going to save a life,” says Jessup. The AHA offers an online tool to locate a CPR class in your area. Additionally, the American Red Cross Association offers classes to become certified in CPR. They also offer an online search tool to locate one near you.