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What Is Commotio Cordis? Experts Speculate Cause Of NFL Star Damar Hamlin's Cardiac Arrest

Anti-vax conspiracy theories about the incident have already been circulating, but remain wholly unproven.


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

Buffalo Bills football players about to clash with another team at NFL game.

January 2's game between the Buffalo Bills and Cincinnati Bengals will not be resumed, the NFL has said. Image credit: Steve Jacobson/

Monday night’s football game between the Buffalo Bills and the Cincinnati Bengals was the first NFL game to be suspended mid-game in recent memory after Damar Hamlin collapsed after colliding with an opponent.

Hamlin was struck in the chest by another player and briefly fell to the ground. Upon getting up, he stood motionless for a second before crumbling to the floor. A grim scene unfolded where teammates and onlookers helplessly watched on as medical staff rushed onto the scene. 


His team said in a tweet early Tuesday morning that the 24-year-old experienced a cardiac arrest after a hit, adding that he was sedated and remained in critical condition.

The situation is still unfolding, but many experts are speculating that the NFL star may have experienced a rare condition known as commotio cordis. 

Commotio cordis is effectively a cardiac arrest that’s caused by a blunt blow to the chest. The sudden trauma disrupts the normal electrical signaling of the heart, causing the heart’s chambers to spasm and a chaotic heart rhythm. The end result is oxygenated blood failing to reach the vital organs and the heart stops, aka a cardiac arrest. 

Just 10 to 20 cases of commotio cordis are reported in the US each year, most of them sports injuries. Part of the reason this condition remains so rare is that it requires the impact to strike the chest at a very particular moment in the heart’s electrical cycle. 


"It has to be a perfect storm of events where there's an impact to the chest wall overlying the heart with just enough force, and what's most critical is the timing," Dr. Christopher Madias, the director of the New England Cardiac Arrhythmia Center at Tufts Medical Center, told NPR’s Morning Edition. "It happens within a critical period within the cardiac cycle. We're talking about 20 to 30 milliseconds within the cardiac cycle that the heart is vulnerable to this."

Now Hamlin is receiving medical care, doctors will be working hard to restore the electrical synchrony of his heart and ensure it maintains a steady rhythm. The extent of the impact on his body will come down to how long his brain and other vital organs were left without oxygenated blood. 

In previous decades, the majority of people who experience commotio cordi would not survive. However, in the past 10 years or so the survival rate has significantly improved, with approximately 58 percent of people surviving. 

Fortunately for Hamlin, he managed to receive expert medical assistance almost instantaneously after the injury. As noted by the Centers for Disease Control and Prevention (CDC): receiving CPR in the first few minutes of cardiac arrest can “double or triple a person's chance of survival”. 


Anti-vax conspiracy theories about the incident have already been circulating with some erroneously suggesting that the cardiac arrest was the result of the player's COVID vaccine.  However, this claim is wholly unproven and downright dangerous. According to the NFL, nearly 95 percent of their players are fully vaccinated against COVID-19, but there have been no similar reports of heart problems in the slightest. 

Here’s hoping that things work out for the best and Hamlin has a smooth recovery. 


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  • commotio cordi