What caused Bronny James' cardiac arrest? A cardiologist explains possible culprits

LOS ANGELES (KABC) -- Just what would cause a young athlete like Bronny James to go into cardiac arrest?

The eldest son of Los Angeles Lakers superstar LeBron James went into cardiac arrest during a basketball practice at USC, where the 18-year-old had just committed to begin playing as an incoming freshman.

Medical staff quickly responded to Bronny James' medical emergency on Monday and brought him to the hospital, where he is now in stable condition and out of the ICU.

It is a shocking and scary situation when a young athlete falls to the ground due to a sudden cardiac arrest, but it's important to remember it's rare, affecting 2,000 people under the age of 25.

Cardiologist Dr. Jahandar Saleh with Dignity Health Northridge says athletic trainers near Bronny James knew exactly what to do because they recognized what happened to the young star.

"Cardiac arrest means that the heart stops," he said.

It occurs when the heart malfunctions and stops beating unexpectedly. There are a number of causes.

"Most of them are congenital. One is hypertrophic cardiomyopathy, where the heart is thicker than normal," said Jahandar

Doctors believe hypertrophic cardiomyopathy was the underlying reason why Loyola Marymount player Hank Gathers collapsed after that famous slam dunk in 1990. Other causes include myocarditis or inflammation of the heart muscle, a hard hit as in the case of football player Damar Hamlin, heart rhythm disorders or even dehydration.

"Was this an issue of electrolyte imbalance? You know, low potassium. Low magnesium," said Jahandar.

Cardiac arrest is different from a heart attack, which occurs when blood flow to the heart is blocked.

Fast action saves lives. The first thing is to immediately start CPR.

"If you're not providing blood to the brain, the brain can die," said Jahandar.

The faster a patient can be treated with a defibrillator, the better the outcomes.

Depending on the cause, many players can safely return to play which is what Jahandar is hoping for Bronny James.

"There's so much that we are able to do in the field of cardiology, and I trust that he's in the best of hands," he said.

As for prevention, efforts to screen young athletes for any potential heart issues is available, but not universal. Although more and more schools are offering pre-participation screening.