Sudden cardiac arrest in young athletes is rare and hard to predict

Sudden cardiac arrest among young athletes is a low-probability, high-impact event.

Roughly one in 50,000 to one in 80,000 young athletes will die each year of sudden cardiac arrest, says Dr. Muhammad Aftab, a heart surgeon at UCHealth University of Colorado Hospital. It is the leading cause of exercise-related death in young competitive athletes, accounting for 75% of fatalities during sports or exercise.

That risk is far lower than the one-in-1,000 odds of sudden cardiac arrest across the broader U.S. population. But given their youth and high levels of fitness generally correlated with healthy hearts, it comes as a shock sudden cardiac arrest strikes a young, seemingly health athlete.

That’s what happened to Bronny James, the 18-year-old son of NBA superstar LeBron James. Bronny James was at a practice for the University of Southern California basketball team when he collapsed on July 24. Sudden cardiac arrests have struck other young athletes too, including: NFL player Damar Hamlin, who was 24 when he collapsed during a game in January and Danish soccer star Christian Eriksen, who was 29 when his heart stopped during a game against Finland in 2021.

All three survived – as more than 80% do if a certified athletic trainer is on-site and involved in resuscitation. While devastating, these high-profile cases can raise awareness and life-saving training and policies that improve the odds for other young athletes. Here are some common questions and answers about sudden cardiac arrest.

What is sudden cardiac arrest?

Sudden cardiac arrest is when the heart stops abruptly due to a malfunctioning of the heart’s electrical system. When the heart stops, it cuts off the blood supply to the brain and vital organs. The person no longer has a pulse, stops breathing and loses consciousness. Sudden cardiac arrest can lead to brain and organ damage or death within minutes. With each passing minute, the person chance of survival decreaases by about 10%.

Is sudden cardiac arrest the same thing as a heart attack?

No. A heart attack happens when there’s a blockage of blood to part of the heart, causing heart-muscle tissue to fail or die. Sudden cardiac arrest means the heart stops pumping. Heart attacks can, however, trigger electrical malfunctioning that can bring about sudden cardiac arrest.

Does sudden cardiac arrest only happen in athletes?

No. Sudden cardiac arrest is actually much more common in the general population.

Each year, about 350,000 people experience sudden cardiac arrest outside of hospitals in the United States. That’s compared to 100 to 150 instances among young athletes, according to the American College of Cardiology. The risk of dying is also much higher for the general population, for whom about 90% of out-of-hospital sudden cardiac arrests are fatal, according to the American Heart Association.

What can cause a sudden cardiac arrest in an athlete?

Underlying, typically undiagnosed heart problems are the most common cause. Hypertrophic cardiomyopathy, a disease affecting heart muscle, can cause structural changes to the heart. It accounts for more than one-third of cardiovascular disease-related cases. Loyola Marymount basketball star Hank Gathers, who collapsed and died during an NCAA game in 1990, had been diagnosed with it. Eriksen, the Danish soccer player, had ventricular fibrillation – a fluttering of the heart’s lower chambers caused by disruptions to electrical signaling. Hamlin, the football player, suffered commotio cordis, where blunt force trauma to the chest occurs during a very specific period in the cardiac electrical cycle and stops the heart.

Aftab says a variety of factors, from atypical coronary arteries to exhaustion to heatstroke, can also be implicated.

“There are multiple, multiple causes of cardiac arrest,” he said.

Conditions such as Long QT syndrome and Wolff-Parkinson-White syndrome can lead to arrhythmia that can cause sudden cardiac arrest. But often, the cause remains unknown, Aftab added.

“It’s a very, very broad presentation which results from multiple potential problems,” Aftab said. “It could be very benign, and it could be something very serious.”

Are there warning signs young athletes and their coaches should be aware of?

Sudden cardiac arrest usually strikes without warning. But in some cases, symptoms do present in advance, Aftab said.

Symptoms of sudden cardiac arrest include:

• Extreme fatigue
• Severe shortness of breath
• Heart palpitations
• Lightheadedness
• Chest pain
• Severe nausea
• Extreme dizziness

If the athlete loses consciousness, bystanders should immediately consider sudden cardiac arrest as a possible cause, Aftab said.

Can you detect sudden cardiac arrest in advance? 

An electrocardiogram (EKGs/ ECGs) can detect electrical disorders and some other heart problems that may put an athlete at risk, but they do little to help predict the risk of sudden cardiac arrest.

What are the keys to saving someone who has had sudden cardiac arrest?

Have a preparedness plan in place, have someone trained in cardiopulmonary resuscitation (CPR) on hand, and have an automated external defibrillator (AED), which shocks the heart back into action, at the ready, Aftab says.

“Having an AED and preparedness to deal with a sudden cardiac arrest so you can expeditiously intervene to save that person’s life is critical,” Aftab said. “Time is of the essence, and every second counts when an athlete has a cardiac arrest.”

CPR should start immediately, and defibrillation ideally happens within to two to three minutes.

What happens next for a young athlete who survives?

Young athletes who survive sudden cardiac arrest go through an in-depth cardiac workup as well as scans to check blood flow to the brain. Studies of the heart include assessing cardiac rhythm and function and checking for heart valve disease and congenital heart disease, Aftab said. Experts who provide follow-up care include cardiologists, cardiac surgeons, and electrophysiologists.

Typically, after monitoring, athletes can return to play. On rare occasions, an implantable cardiovert defibrillator (ICD) device can be implanted if the ongoing risk of ventricular tachycardia is deemed high. Hamlin is back in training camp with the Buffalo Bills. Eriksen, the soccer player, got an ICD, and he has continued to enjoy success on the field.

And Bronny James was recently able to leave the hospital.