Earlier this year, the nation’s attention was captured by Damar Hamlin’s story after he collapsed on the field from sudden cardiac arrest (SCA) during Monday Night Football. After Hamlin’s collapse, teammates, fans and most of America watched as CPR was performed and he was taken to the hospital in an ambulance. In the days that followed, many watched the news closely, hoping for any positive update. Thankfully, due to timely intervention and a well-trained medical staff, he survived and was released from the hospital nine days later. In the meantime, stories of other athletes who had cardiac events on the field re-emerged into the engaged, collective audience.
While the cause of Hamlin’s SCA has not been released, it has brought a discussion of cardiac arrest into the spotlight. What are the potential causes of SCA? Why does it appear to be more common in athletes? What are the benefits and controversies surrounding screening athletes for heart disease? What role does genetic testing play?
Although it is statistically rare, SCA is emotional and frightening. According to the National Collegiate Athletic Association (NCAA), “Sudden fatality from a heart condition remains the leading medical cause of death in college athletes.” (1) It is important for athletes at all levels of competition to participate in screening in an attempt to reduce their risk of SCA.
Cardiac disease can result from both environmental and genetics influences. One potential cause of SCA is a blow to the chest at a very precise moment in the rhythm of the heart. If the impact occurs with an exact force, in an exact place, and at an exact time during the heartbeat, an erratic heartbeat (arrhythmia) can result; this is called commotio cordis. Commotio cordis is a relatively common cause of SCA among athletes; however, there are many other potential causes, including underlying hereditary heart abnormalities.
The most common hereditary cause of heart disease in US athletes is hypertrophic cardiomyopathy (HCM). HCM occurs when the walls of the heart become thick and stiff. Over time, the heart is no longer able to pump blood efficiently. Rigorous exercise can also lead to a thickened heart wall, and differentiating between exercise-induced wall thickening (which is harmless) and HCM (which requires further investigation) can be difficult to evaluate through clinical evaluation alone. Health care providers tasked with the evaluation of athletes can end up in a tough spot. On the one hand, an incorrect diagnosis of HCM could lead to unnecessary exclusion from athletics, where many athletes find camaraderie, physical well-being and self-identity. In addition, an incorrect diagnosis could lead to unneeded, costly medical evaluations and emotional distress. On the other hand, missing an underlying diagnosis of HCM could have devastating consequences, such as cardiac arrest.
This is where genetic testing can provide helpful information. If an athlete has a borderline increased ventricular wall thickness, or a family history suggestive of inherited heart disease, a genetic diagnosis could provide more certainty. A thorough clinical examination and family history are key in addition to genetic counseling and testing.
Other potentially hereditary causes of heart disease in athletes include aortic dissection/rupture (including Marfan syndrome), atherosclerotic coronary artery disease, hereditary arrhythmias (such as long QT syndrome) and arrhythmogenic right ventricular cardiomyopathy. All these conditions are associated with underlying genetic components that have implications for the athlete’s diagnosis, management and treatment, as well as potential recommendations for family members health care planning.
Genetic testing for inherited cardiac conditions can help confirm a diagnosis when the clinical picture is unclear and can provide prognostic information about the potential severity of disease, triggers of cardiac events and exercise restrictions. Genetic testing is recommended by many professional societies including the American Heart Association and the American College of Cardiology, among others (2, 3). Genetic testing is widely available and has decreased in cost dramatically over the last few years but is still underutilized in cardiology. Awareness is still growing in the medical and sports communities, with events such as this serving as a catalyst for important conversations.
While we may not ever learn the exact cause of Damar Hamlin’s SCA (4), we can remain hopeful that the national attention and conversations generated by his experience will positively impact the safety of athletes through CPR education, AED access and awareness and screening for underlying heart disease.
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Footnotes:
1. Cardiac health. NCAA.org. (2023). Retrieved February 13, 2023, from https://www.ncaa.org/sports/2021/2/10/sport-science-institute-cardiac-health.aspx
2. Musunuru K, et al. Genetic Testing for Inherited Cardiovascular Diseases: A Scientific Statement From the American Heart Association. Circ Genom Precis Med. 2020 Aug;13(4):e000067.
3. Writing Committee Members et al. 2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2020 Dec 22;142(25):e558-e631
4. News outlets continue to update his story. Here are two: CBS News shared when he was released from the hospital. https://www.cbsnews.com/news/damar-hamlin-update-buffalo-bills-injury-nfl-condition-news/ As of the publishing of this blog, speculation on the impacts to his career were being shared by USA Today. https://www.usatoday.com/story/sports/nfl/bills/2023/02/28/damar-hamlin-update-bills-still-evaluating-his-health-playing-future/11364792002/