Cardiac arrest is top cause of death in young athletes: Know these signs

Bronny James, the son of NBA star LeBron James, suffered a cardiac arrest on Monday, and cardiologists say there's an important message for parents in the 18-year-old's quick recovery.

Bronny James, a first-year student at the University of Southern California and one of the nation's top recruits last year, had to be rushed to the hospital during a basketball team workout on July 24, a James family spokesperson said in a statement to NBC News. He's since been released from the hospital.

In a statement on Wednesday, his famous father thanked fans for their support during this time. "Everyone doing great. We have our family together, safe and healthy, and we feel your love,” LeBron James wrote in a social media post.

In the wake of the news, many are wondering what may have led to Bronny James' sudden cardiac arrest and how common it is for kids and young athletes to experience cardiac arrest.

How common is cardiac arrest in young people?

Every hour, on average, a child collapses from cardiac arrest, which refers to when the heart stops beating suddenly, according to 2022 data from the Cardiac Arrest Registry to Enhance Survival (CARES). Cardiac arrest is the leading cause of death in young athletes, according to the Mayo Clinic.

That said, cardiac arrest kills less 200 children every year, Dr. Meghan E. Tozzi, pediatric cardiologist at Joseph M. Sanzari Children’s Hospital at Hackensack University Medical Center, tells TODAY.com. If you expand that age range to people under 25, about 2,000 die every year from sudden cardiac arrest, per data from the Centers for Disease Control and Prevention.

For context, car accidents kill about 11,000 children every year, Tozzi says. "When it comes to frequency, (cardiac arrest) is not very frequent. But obviously when it does happen, it's devastating, especially when there's something we could've done to prevent it."

Black male athletes also appear to be at the highest risk, but it's unclear why. A 2020 study in the British Journal of Sports Medicine found that NCAA Division I basketball players who were Black and male had the highest rates of sudden cardiac arrest and death of all athletes between 11 and 29 years old — 21 times higher than that of high school male athletes of all races. Genetics, lifestyle factors and the sport being played may all increase the risk, Dr. Richard Kovacs, a sports cardiologist and the chief medical officer at the American College of Cardiology, told NBC News.

Bronny James' cardiac arrest: Common causes in young people

The family has not publicly shared what caused Bronny James’ cardiac arrest.

Both Tozzi and Dr. Adam Kean, pediatric cardiologist at Riley Children's Health in Indianapolis, tell TODAY.com that the No. 1 cause of sudden cardiac arrest in young athletes (and people overall) is a condition called hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy, which is genetic, refers to when the heart grows "in a disorganized and thicker manner so that it is not able to function appropriately," Kean explains. "It causes lethal arrhythmia in all people (and) tends to come about in athletes of all ages, but certainly young athletes." It's a condition that a person is born with but may go undiagnosed for years until a doctor notices that the heart muscle has developed abnormally.

An arrhythmia is "when the heart is beating in an out-of-control fashion so that the heart is unable to sustain the body in terms of what’s needed in order to be alert and properly support blood flow to our brains into our bodies," Tozzi explains.

She adds that other types of cardiomyopathy can also lead to cardiac arrest in young people. Cardiomyopathy, in general, means the heart muscle isn't working "in a typical way," she says. For example, the heart muscle can become too thick, too thin or dilated, which can lead to an arrhythmia.

The two most common types of arrhythmia that lead to cardiac arrest are ventricular tachycardia, which starts in the heart's lower chambers, and atrial fibrillation, which starts in the upper chambers, Dr. Tara Narula, cardiologist at Northwell Health said on TODAY on July 26.

“This is definitely an uncommon occurrence. But when it happens, it’s emotionally jarring," she added.

Congenital heart disease, or defects that are present at birth that affect the structure of the heart, can also lead to sudden cardiac arrest as a young person, Tozzi says. But this is a less common cause than hypertrophic cardiomyopathy because congenital heart disease is more likely to be diagnosed early on, she adds.

Another possible cause of cardiac arrest in young people is myocarditis, inflammation in the heart that occurs when someone is sick, usually following a viral infection. In this case, chest pain may pop up suddenly a week or so after the infection, Tozzi says. Other "random things" can cause cardiac arrest in young people, such as commotio cordis, which is what happened to NFL player Damar Hamlin, she adds.

Warning signs of cardiac arrest in young people

Many young people who have a condition that increases their risk for cardiac arrest don't experience any warning signs beforehand, Kean says, adding, "This is the awful reality."

"Those who do will often describe either not necessarily feeling like they're able to participate to their peak performance and they're just feeling a little off, but that's a really vague description," he explains. "How many athletes feel that from time to time? Pretty much all of them, so you're not going to sideline someone because maybe they're just a little sluggish that morning."

"The real tragedy of it is, aside from those who are already diagnosed with (a heart condition), we can't predict when that terrible event is going to happen," Kean adds.

That said, some people do experience symptoms before cardiac arrest like chest pain, dizzy episodes or feeling that their heart is racing. But, Kean stresses, this doesn't definitively mean this person is at a higher risk for cardiac arrest; it just means it's important to see a cardiologist to assess these symptoms.

Specifically for hypertrophic cardiomyopathy, Tozzi says a person may experience "a burning or crushing chest pain" with physical exertion, such as exercising after eating or walking upstairs. She adds that passing out with physical activity is another "red flag" for a medical evaluation.

Both experts added that any family history of hypertrophic cardiomyopathy or possible symptoms of a genetic condition, such as passing out for an unknown reason or a heart murmur, are also reason to be seen by a doctor.

The NCAA and the American Heart Association added a pre-participation screening for college athletes in 2016, which has doctors ask about a player’s health history, Narula said.

“Have you ever passed out? What is your family history? Has someone died early? You do a physical exam, and the idea is with that, you may be able to catch some of these individuals who are at increased risk,” she said of the screening.

The screening is “not perfect,” she added, and many cardiologists are calling for more advanced testing, like routine EKGs or MRIS. “We’re not there yet, but this is really the best that we have,” she continued.

Some experts also recommend that before any teen plays a sport, even at the high school level, they should get a full medical screening for risk of cardiac arrest or heart problems.

When someone is actively experiencing a cardiac arrest, these symptoms, according to the CDC, include:

• Sudden collapse

• No pulse

• No breathing or gasping for air

• Loss of consciousness

• No response to shouting or shaking

Acting quickly in an emergency

Because it can be so hard to predict when a cardiac arrest will occur, it's important for schools and parents to advocate to have automated external defibrillators and people trained to perform CPR close by when a child may be at risk of a cardiac event. This applies to athletic games and practices, but musical theater, band and even test-taking may affect a child's heart, Kean says.

High quality CPR and using an AED are the difference between life and death — and whether the child may be able to continue to live normally after the cardiac arrest, Tozzi adds. A child may survive, but if they lose blood flow to certain organs, such as the brain or kidney, for a significant period, they may not function the same.

Ideally, in these situations, high quality CPR will maintain blood flow while someone gets an AED, which will shock the heart back to a normal rhythm, Tozzi explains.

Narula added that universities should practice an emergency action plan so medical professionals who know CPR can respond with a defibrillator. Because Bronny James was released from the ICU and later the hospital so quickly, “they clearly were ready,” Narula said of the staff who responded to his cardiac arrest.

A statement from Cedars-Sinai Medical Center, where Bronny James was treated, confirmed that he was "fully conscious, neurologically intact and stable" when he arrived at the hospital. "Although his workup will be ongoing, we are hopeful for his continued progress and are encouraged by his response, resilience, and his family and community support," it added.

This article was originally published on TODAY.com