What to know about ‘commotio cordis,’ a possible cause of Bills safety Damar Hamlin’s cardiac arrest

When Bills safety Damar Hamlin collapsed on the field after a tackle on live television, William Gray, a Philadelphia-area cardiologist, turned to his wife and said, “That’s a serious problem.”

Like millions of people across America, Gray was watching the Monday Night Football game between the Buffalo Bills and Cincinnati Bengals. During the first quarter, Hamlin tackled Bengals receiver Tee Higgins. Hamlin took a hit to his chest but sprang to his feet after the tackle. Moments later, he collapsed.

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The 24-year-old’s heart stopped, and a medical team resuscitated him on the field, according to a Bills statement. His heart resumed beating, and Hamlin was rushed to the hospital, where he is currently sedated and ventilated in critical condition. Neither the Bills nor the family shared an official diagnosis yet.

Hamlin grew up in the Pittsburgh area and is the former team captain of the University of Pittsburgh Panthers. In the hours after his injury, fans donated more than $4.5 million to a dormant GoFundMe page that Hamlin started a couple of years ago to raise money for toys for a child-care center in his hometown of McKees Rocks.

His collapse led some to draw comparisons to ex-Flyers defender Chris Pronger, who suffered a cardiac arrest after getting hit by the puck during Game 2 of the 1998 Stanley Cup. Pronger was unconscious for less than a minute due to an injury called “commotio cordis.”

Gray, chief of cardiovascular disease at Main Line Health in the Philly suburbs, said it is possible that the impact of the tackle caused Hamlin’s cardiac arrest.

A blunt force to the chest in a precise moment in the heart’s electrical cycle can cause the heart to stop. It is a rare injury known as “commotio cordis,” but it is the second most common cause of cardiac death among U.S. athletes, according to a 2009 study in Sports Health.

After the heart contracts, its electrical system resets ahead of the next beat. During the beginning of that reset, there is a moment that the system is vulnerable, Gray said. A disturbance can cause a form of heart arrest called ventricular fibrillation. During the ventricular fibrillation, parts of the muscles in the heart’s largest chambers contract in different times instead of a unison contraction that pushes blood out.

The heart is vulnerable to “commotio cordis” for only milliseconds after every beat. Gray says the vulnerability occurs during only 1% of the cardiac cycle.

“That’s why it’s so rare,” he said.

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No.

“Most people who have this happen to them have no underlying problem,” Gray said.

Not that strong.

A 2002 study published in the Journal of the American Medical Association found that both competitive and recreational baseball had more incidents of “commotio cordis” than any other sports. The hit itself is often low velocity and energy.

“It doesn’t take a 90-mile-an-hour fastball,” Gray said.

CPR.

The most important element of treatment is sustaining oxygen to the heart and brain by starting CPR as early as possible. If the heart is in a state of ventricular fibrillation, an electric shock could reverse it back to normal rhythm.

Brain cells can start dying due to lack of oxygen within minutes of cardiac arrest. Early CPR increases the chance of survival dramatically.

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It depends on time.

Because “commotio cordis” is not an injury of the heart muscle, once a spontaneous heart rhythm has been restored, the original heart problem has been resolved. The question then is how much damage happened during the cardiac arrest because of lack of oxygen to critical systems like the brain.

The death rate from “commotio cordis” is over 70% in some studies. More generally, the death rate from a cardiac arrest outside the hospital is closer to 90%.

But when CPR starts early, recovery can be miraculous.

In 2021, in the midst of a Euro 2020 game, Danish soccer star Christian Eriksen collapsed. He was not hit in the chest but had suffered a cardiac arrest. He was treated nearly instantly and following the injury had a defibrillator implanted next to his heart. This fall, he wore the Denmark uniform again for the World Cup in Qatar.

There are still many details that have not been shared with the public about Hamlin’s injury, resuscitation, and whether he had any unknown underlying cardiac condition — all of which could affect his prognosis.

No.

Fetterman and millions of other Americans have experienced a very different type of irregular heart rhythm, called atrial fibrillation (A-fib). In people with A-fib, the heart is still pumping plenty of blood. But this condition can nevertheless lead to serious consequences, as Fetterman learned in May.

Physicians said his irregular rhythm allowed a blood clot to form in his heart, which then migrated to his brain: a stroke. Fetterman underwent months of rehab before winning a U.S. Senate seat in November.

Athletes playing at the college and professional level go through extensive medical evaluations that include heart health, said James Rory Tucker, a family medicine specialist at Temple University and the Owls’ team physician.

He wants to make sure that no part of the heart is asymmetrically enlarged, a condition that’s called hypertrophic cardiomyopathy and can cause cardiac arrest.

Congenital abnormalities could also cause trouble. NBA All-Star Pete Maravich was born without the artery that usually feeds oxygen to the left side of the heart muscle. He died in 1988 at age 40.

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Lightheadedness, dizziness, or chest pain while working out are symptoms that athletes should talk to a doctor about, Tucker said. He also recommends sharing any history of heart disease with health providers because that might offer clues.

Young athletes may be tempted to withhold information out of fear they’ll be barred from playing. But safety has to be the first concern, and only the most serious issues would prevent someone from playing altogether, Tucker said.

The NFL reinforced that message when it suspended the game after Hamlin’s injury, he said.

“The most important thing is the health of the athlete, the game is second,” Tucker said.

Staff writer Tom Avril contributed to this article.