Sudden Cardiac Death in Athletes

Who’s more at risk for sudden death – young healthy athletes, or older, sedentary adults? Read on to learn more about how sudden cardiac death (SCD) affects everyone, no matter their age, race or gender. Surprisingly, SCD takes the lives of healthy athletes every day.

Athletes are often idolized for their physical prowess, but despite society’s assumptions of their health and fitness, this group in particular is prone to sudden cardiac death (SCD). When a young athlete is lost to SCD, the impact of this loss can be felt throughout their family, friends, school, and community. Such losses are often reported widely in the media, which has led some to suggest that the rate of SCD in young athletes may seem higher due to the publicity that generally accompanies such an event. In reality, the actual rate of SCD in athletes is unknown, and the estimated rates can vary widely.[1]

Estimates of sudden cardiac death in American athletes have a wide range of reported rates. Out of the seven studies reviewed for background information in Dr. Harmon, et al.’s study of SCD the rates in athletes, reported rates ranged from 1 in 23,000 athletes to 1 in 300,000 athletes. The studies reviewed relied on a variety of methods for collecting their data from media reports, retrospective surveys, voluntary registries, and insurance claims as ways of identifying an appropriate number of athlete SCD instances a year to be used as a numerator. The number of athlete participants per year must also be determined to calculate an appropriate rate of SCD in athletes. Dr. Harmon, et al. determined previous methods of calculating the denominator to be imprecise at best.[2]

Determining an accurate rate of sudden cardiac death in athletes is essential for such medical necessities as screening and emergency response planning, but in order for an accurate rate to be determined both a precise number of SCD in athletes per year and an exact number of athletic participants per year must be determined. Currently, there is no mandatory reporting system for sudden deaths in juveniles in the U.S. This lack of consistent reporting makes the current rates reported for SCD in young athletes debatable, and the current variance in reported rates inevitable.[3]

Statistical Findings

In their study of the National Collegiate Athletic Association (NCAA), Dr. Harmon, et al. estimated that in any given year there are around 400,000 student-athletes between the ages of 17 to 23 years old. These athletes compete in 40 different sports that are included in three distinct NCAA divisions. Every institution participating in the NCAA has a medical and media staff, which means that deaths within this athletic population are less likely to go unreported. The NCAA also publishes records of the number of participating athletes each year. These factors contribute to the calculations of a much more accurate rate of sudden cardiac death within the studied population. Out of this athletic population, Dr. Harmon, et al. determined that the leading medical cause of death was cardiac, which contributed to 16% of the total number of deaths and 56% of medical deaths. The incidence of SCD among student-athletes in the NCAA was determined to be 1 in 43,770 per year.[4]

A study of student-athletes participating in the Minnesota State High School League (MSHSL) was conducted with the records from 19 academic-years. The study found a total of four sudden cardiac deaths that occurred at a practice or game. Of the SCDs, all occurred in male student-athletes.  Two occurred during cross country, one during basketball, and one during wrestling. Based on these deaths and the total number of participating athletes, it was calculated that there were 0.24 deaths per 100,000 athlete-years. This rate is much lower than rates reported by the NCAA study, which found an incidence of 3.45 per 100,000 athlete-years in Division I, 2.38 per 100,000 in Division II, and 1.05 in Division III. The athletes covered by the MSHSL study were younger, and they were also required to undergo a standardized sports pre-participation history and physical evaluation. Both of these factors may have contributed to the lower incidence rate of SCD.[5]

Although not directly related to school sports, deaths that occur during the physically rigorous basic military training also shed light on instances of sudden cardiac death in young adults. These deaths even occur after a pre-enlistment health screening, which consists of a personal medical history questionnaire and a physical examination with a clinical evaluation. A range of cardiovascular diagnoses can cause an individual to be rejected from enlistment, but this type of disqualification is rare and only occurs in 0.15% of enlisted applicants. Eckart, et al. studied military autopsy records in order to identify non-traumatic recruit deaths. Deaths were included in the study if they were idiopathic or due to cardiac, exertional heat illness, vascular, asthma, or they were exercise-related in some other way. The results demonstrated a non-traumatic sudden death rate of 13 per 100,000 recruit-years. Of these non-traumatic sudden deaths, roughly half were caused by an identified cardiac abnormality that was not identified at the pre-enlistment health screening.[6]

Table 1: A comparison of athlete and recruit deaths across the MSHSL, the NCAA, and the military.

	Deaths per 100,000 athlete-years/recruit-years
MSHSL	0.24
NCAA Division I	3.45
NCAA Division II	2.38
NCAA Division III	1.05
Military	13

Risk of Sudden Cardiac Death in Young Athletes

Risk rates within the NCAA were calculated by Dr. Harmon, et al. The study found the incidence of SCD in male athletes to be 1 in 33,134 per year, and the incidence of SCD in female athletes to be 1 in 76,646 per year. These rates show that male athletes within the NCAA are more than twice as likely to suffer from an SCD.[7]

The study of the NCAA athletes also calculated SCD rates by division. Division I athletes were calculated as having an SCD rate of 1 in every 30,301 athletes per year. Division II was calculated as having an SCD rate of 1 in 42,457, and Division III was found to be 1 in 84,473. These rates show that the student athletes that compete in Division I teams are the most likely to suffer an SCD, and those that compete in Division III are the least likely.[8]

Finally, Dr. Harmon, et al. also calculated SCD rates based upon race. The authors found that white student-athletes had an SCD rate of 1 in 58,653, and black student-athletes had a higher risk of 1 in 17,696. The study also calculated risk by sport with basketball being the highest-risk sport with a 1 in 11,394 overall yearly death rate. The athletic group with the highest risk of SCD were Division I, male basketball players of any race with a risk of 1 in 3,126 annually.[9]

Risk Management through Cardiac Screening

The European Society of Cardiology (ESC) has published guidelines supporting a screening protocol including the use of a resting 12-lead ECG for athletes. Similarly, the American Heart Association (AHA) has also supported the cardiovascular screening of athletes, but instead recommends screenings based on personal and family history, as well as physical examination. Despite these high level endorsements, the cardiac screening of athletes is still under debate. It has been suggested that instead of focusing on making these screenings mandatory, the debate should be shifted to focus on which screening protocols are medically and scientifically recommended. With a long list of medical, ethical, economical, and logistical considerations for such protocols, the determination of best practices for such screenings has yet to be set.[10]

Risk Management through AED Programs

Although the exact rates and numbers are still up for debate, it is obvious that SCD is a risk for student athletes. As a countermeasure for this possibility, many U.S. high schools have begun purchasing automated external defibrillators (AEDs) for use on campus. In a study of 1,710 schools listed on the National Registry for AED Use in Sports, it was found that 83% of schools with an AED also have an established emergency response plan for a sudden cardiac arrest (SCA) incident, but only 40% of these schools practice and review the plan annually. Of the schools studied, 2.1% reported an incidence of SCA within the past six months. These cases included 14 high school student-athletes and 22 older individuals who were not students, but were on campus as employees or spectators. Of the cases reported, 97% were witnessed, 94% were given CPR by a witness, and 83% received a shock from an AED. A total of 64% the SCA victims survived until hospital discharge. Implementing AED programs in schools and athletic programs is highly recommended as a part of a comprehensive emergency response plan to instances of SCA.[11]

Final Thoughts

Sudden cardiac death is a leading cause of death in not only young athletes, but also in young adult military recruits. Sudden cardiac arrest has been consistently linked with physical exertion like that which occurs during a sports game, sports practice, or basic military training. While a majority of research in this area has focused on the often highly publicized deaths of young student athletes, the sports arena is by no means the only danger zone for these occurrences. Any area with high levels of physical activity should consider the possibility of a sudden cardiac arrest occurring. This includes sports centers, practice fields, and obstacle courses, but the list could easily be expanded to include gyms and parks. The availability of an AED, related supplies like extra electrode pads and battery, and the development of a comprehensive emergency program for instances of sudden cardiac arrest should be seriously considered for any public place where physical exertion is common.

References

Borjesson, Mats, and Jonathan Drezner. “Cardiac Screening: Time to Move Forward!” British Journal of Sports Medicine 46, (2012): i4-i6. doi: 10.1136/bjsports-2012-091621.

Drezner, Jonathan A., Ashwin L. Rao, Justin Heistand, Megan K. Bloomingdale, and Kimberly G. Harmon. “Effectiveness of Emergency Response Planning for Sudden Cardiac Arrest in United States High Schools with Automated External Defibrillators.” Circulation 120, (2009): 518-525. doi: 10.1161/CIRCULATIONAHA.109.855890.

Eckart, Robert E., Stephanie L. Scoville, Charles L. Campbell, Eric A. Shry, Karl C. Stajduhar, Robert N. Potter, Lisa A. Pearse, and Renu Virmani. “Sudden Death in Young Adults: A 25-Year Review of Autopsies in Military Recruits.” Annals of Internal Medicine 141, no. 11 (2004): 829-834. doi: 10.7326/0003-4819-141-11-200412070-00005.

Harmon, Kimberly G., Irfan M. Asif, David Klossner, and Jonathan A. Drezner. “Incidence of Sudden Cardiac Death in National Collegiate Athletic Association Athletes.” Circulation 123, no. 15 (2011): 1594-600. doi:10.1161/CIRCULATIONAHA.110.004622.

Roberts, William O., and Steven D. Stovitz. “Incidence of Sudden Cardiac Death in Minnesota High School Athletes 1993-2012 Screened with a Standardized Pre-Participation Evaluation.” Journal of the American College of Cardiology 62, no. 14 (2013): 1298-1301.

Footnotes

[1]. Kimberly G. Harmon, et al., “Incidence of Sudden Cardiac Death in National Collegiate Athletic Association Athletes,” Circulation 123, no. 15 (2011): 1594-600, doi:10.1161/CIRCULATIONAHA.110.004622.

[2]. Ibid.

[3]. Ibid.

[4]. Harmon, et al., “Incidence of Sudden Cardiac Death in National Collegiate Athletic Association Athletes,” 1594-600.

[5]. William O. Roberts, and Steven D. Stovitz, “Incidence of Sudden Cardiac Death in Minnesota High School Athletes 1993-2012 Screened with a Standardized Pre-Participation Evaluation,” Journal of the American College of Cardiology 62, no. 14 (2013): 1298-1301.

[6]. Robert E. Eckart, et al., “Sudden Death in Young Adults: A 25-Year Review of Autopsies in Military Recruits,” Annals of Internal Medicine 141, no. 11 (2004): 829-834, doi: 10.7326/0003-4819-141-11-200412070-00005.

[7]. Harmon, et al., “Incidence of Sudden Cardiac Death in National Collegiate Athletic Association Athletes,” 1594-600.

[8]. Ibid.

[9]. Ibid.

[10]. Mats Borjesson, and Jonathan Drezner, “Cardiac Screening: Time to Move Forward!” British Journal of Sports Medicine 46, (2012): i4-i6, doi: 10.1136/bjsports-2012-091621.

[11]. Jonathan A. Drezner, et al., “Effectiveness of Emergency Response Planning for Sudden Cardiac Arrest in United States High Schools with Automated External Defibrillators,” Circulation 120, (2009): 518-525, doi: 10.1161/CIRCULATIONAHA.109.855890.