Damar Hamlin went into cardiac arrest due to a rare condition called commotio cordis, which occurs when a blunt hit to the chest disrupts the heart’s rhythm at a precise, vulnerable moment. On January 2, 2023, during a Monday Night Football game between the Buffalo Bills and Cincinnati Bengals, Hamlin tackled wide receiver Tee Higgins after a reception over the middle of the field. Higgins led with his right shoulder and struck Hamlin directly in the chest. Seconds later, Hamlin collapsed.
What Is Commotio Cordis?
Commotio cordis is not caused by structural damage to the heart. The heart itself isn’t bruised or torn. Instead, it’s a matter of timing. The heart goes through a repeating electrical cycle with each beat, and there’s a tiny window during that cycle, representing roughly 1% of each heartbeat, when the heart muscle is electrically resetting itself. If a blow lands on the chest directly over the heart during that fraction of a second, the mechanical force stretches heart muscle cells and triggers ion channels to fire abnormally. This can throw the heart into ventricular fibrillation, a chaotic quivering that stops it from pumping blood.
That 1% window gets slightly wider when heart rate increases, which is why athletes mid-game are at higher risk than someone sitting still. The impact doesn’t need to be unusually hard. What matters is location (directly over the heart) and timing (that narrow electrical window). It’s essentially a freak alignment of force and physiology.
Why It’s So Rare and So Dangerous
About 60% of reported commotio cordis cases have involved sports, with baseball being the most common, particularly among youth players. Young males between ages 4 and 18 are at the greatest risk, likely because their chest walls are thinner and more flexible, transmitting force more directly to the heart. Seeing it in a professional adult athlete like Hamlin was exceptionally unusual.
The condition carries a high fatality rate. Historically, survival has hovered between 10% and 15%. When CPR and defibrillation begin within three minutes, survival rises to about 25%. After three minutes, it drops to just 3%. Speed of response is everything.
How the On-Field Response Saved His Life
Hamlin collapsed midway through the first quarter. Within moments, Bills medical staff began CPR and applied an automated external defibrillator (AED). The defibrillator delivered a shock that restored a normal heart rhythm. Hamlin was placed into an ambulance that left the stadium around 9:25 p.m. ET and was transported to a Cincinnati hospital, where he was listed in critical condition.
The game was postponed roughly 90 minutes after kickoff. The speed and preparedness of the medical team on the sideline was widely credited as the reason Hamlin survived. Without immediate defibrillation, his odds would have been dramatically worse.
Recovery and Return to the NFL
Four months after the cardiac arrest, Hamlin was fully cleared to resume playing football. The clearance came after he met with three independent specialists, all of whom agreed he could return without elevated risk of setbacks or complications. He rejoined the Bills’ voluntary workout program in April 2023.
His comeback was more than symbolic. During the 2024 season, Hamlin recorded 89 tackles and two interceptions for a Bills team that reached within one game of the Super Bowl. He has since signed a contract extension with Buffalo.
Chest Protectors and Prevention
One lingering question after the incident was whether better equipment could prevent commotio cordis. The answer is complicated. Standard commercial chest protectors worn in sports like baseball and lacrosse have not been reliably shown to reduce the risk. The National Operating Committee on Standards for Athletic Equipment (NOCSAE) developed a testing standard for chest protectors, finalized in 2021, designed to evaluate whether a protector can reduce impact force below dangerous thresholds. Several sports organizations have since mandated NOCSAE-certified chest protectors: high school and college baseball catchers must wear them, as must lacrosse goalkeepers and, in some leagues, all field players.
In football, however, the dynamics are different. Shoulder pads provide some chest coverage, but they aren’t specifically designed or tested against commotio cordis. Given how rare the condition is in adult football and how dependent it is on precise timing rather than force alone, no equipment change can eliminate the risk entirely. The most effective protection remains what saved Hamlin: having trained personnel and an AED immediately available on the sideline.
Hamlin’s Impact Off the Field
Since his recovery, Hamlin has led CPR education clinics around the world, donated roughly $700,000 worth of AEDs to youth sports programs, and partnered with health organizations to connect with heart patients. His case brought commotio cordis into mainstream awareness and renewed focus on emergency cardiac preparedness at all levels of athletics, not just professional sports where full medical teams are standard.