Sudden death on an athletic field is, fortunately, an uncommon if not rare event. However, when such an incident occurs, it can be devastating to the athlete, their family, teammates, coaches, spectators and the medical professions who respond to the situation.  There are several etiologies that both predispose and cause sudden cardiac death during sports participation. Some of these issues can be screened by simple medical tests and are preventable with intervention. In light of this week’s terrible sequence involving Damar Hamlin on Monday Night Football, it is important to recognize that some causes cannot easily be predicted nor completely avoided.

Commotio Cordis (CC) can occur when a seemingly noncritical blunt force blow to the chest happens during a very specific point in the cardiac electrical rhythm.  The usual sequence of events after the impact is instant loss of consciousness, but can include a short moment of lightheadedness.4  Of note, autopsy results indicate no significant cardiac abnormalities that predisposed the athlete to the injury.4 This differs significantly from identifiable conditions such as hypertrophic cardiomyopathy, Wolff-Parkinson-White Syndrome, and coronary artery anomalies, among others.  

Male athletes between the age of 5 to 18 years of age are at the highest risk for and most frequently experience CC, but this can occur in adults also.1, 4  Experimental studies have found the dangerous heart rhythm, known as ventricular fibrillation, can be produced by projectile objects (typically a baseball or lacrosse ball) moving as little as 30 mph.4  The heart muscle must be in an early repolarization phase, or when the electrical activity is resetting before the next beat, which only lasts for 15-30 milliseconds.2 It tends to occur more likely at velocities over 40 mph.1,4  Softer than normal balls do seem to offer some protection.1,4  In addition, immediate access to defibrillation with an Automated External Defibrillator (AED) is critical for resuscitative measures to succeed.4

A study from 1999 analyzed 70 cases of Commotio Cordis and found that 34 occurred during organized competitions, while the other 36 occurred during recreational events.2  Seventy percent of these cases were observed in athletes over 16 years old, while the range of ages was 2 to 38.2 The most common sports to incur such risk were baseball (40 cases), softball (7) and hockey (7).  Unfortunately, only 7, or 10%, of the participants survived.  It is notable that 11 instances (16%) occurred even with protective chest padding being worn.2  A newer study in 2002, analyzed 128 cases of CC in which they found a larger age range (3 months to 45 years), 62% during organized sports, higher adoption of chest protection (28%) and equal survival rates.3 Research is ongoing attempting to identify new protective devices to further reduce the risk of CC in athletic participants.5

Despite the tragedy witnessed on Monday, it is well-documented that the benefits of sports participation far outweigh the risks at all skill levels of competition.  The pre-participation physical examination can be an invaluable tool in helping physicians delineate those at highest risk and guide those athletes on the need for disqualification or redirection to a different sport.  However, not all risks are identifiable, which is why the advent of mandatory AED in most situations is so critical to optimizing safety on the field, pitch or court.  It is notable that Damar Hamlin was attended to quickly, and his heart was returned to a normal rhythm within minutes on the field. We hope his recovery is quick without long-term consequence; and, as with every serious medical event, that we can learn to identify and respond swiftly when the next problem arises.

1. Link MS, Wang PJ, Maron BJ, Estes NA. What is commotio cordis, Cardiol Rev. 1999 Sep-Oct;7(5):265-9.
2. Maron BJ, Link MS, Wang PJ, Estes NA 3rd. Clinical profile of commotio cordis: an underappreciated cause of sudden death in the young during sports and other activities. J Cardiovasc Electrophysiol. 1999 Jan;10(1):114-20
3. Maron BJ, TE Gohman, SB Kyle, et al. Clinical Profile and Spectrum of Commotio Cordis, JAMA. 2002;287(9):1142-1146.
4. Link MS. Mechanically induced sudden death in chest wall impact (Commotio Cordis), Prog Biop & Mol Biol. 82 (2003) 175-186.
5. Johnson BK, Comstock RD. Epidemiology of Chest, Rib, Thoracic Spine, and Abdomen Injuries Among United States High School Athletes, 2005/6 to 2013/14, Coin J Sport Med. 2017; 27(4) 388-393.