The definition of sudden cardiac death in athletes varies with respect to age, sex, race, or ethnic group, sport, and timing of the event.
An athlete can be defined as a person, engaged in habitual and vigorous training for the purposes of obtaining a high level of fitness.
Athletes are divided into age groups: prepubertal of approximately less than 12 years, adolescent approximately 13 to 17 years, young adult approximately 18 to 24 years, and adult approximately 25 to 34 years, and masters 35 years and above.
Sudden cardiac arrest (SCA) is the leading medical cause of death in athletes, with an estimated incidence of approximately 1-2 per 100,000 person-years in young competitive athletes.
Risk is higher in male athletes, Black athletes, and participants in high-intensity sports such as basketball, American football, and soccer.
Risk Factors and Demographics
Male sex: markedly higher risk than female athletes
Black athletes: higher incidence compared with White athletes, and higher false-positive ECG screening rates
Sport type: basketball, American football, soccer, and endurance sports carry the highest risk
Age: masters athletes (>35 years) have higher overall SCD rates, driven primarily by occult coronary artery disease
Among US collegiate athletes the annual SCD incidence was approximately 1 in 63,682.
The incidence of sudden death from cardiac causes among prepubertal athletes show the rate of death of one in 500,000 athlete-years. In the study involving athletes 7 to 18 years of age one athlete was resuscitated from sudden cardiac death for a rate of one death in67,000 athlete-years.
In the adolescent age group, 13 to 17 years, the overall incidence of sudden cardiac death is reported to be one case in 66,000 to 88,000 athlete-years with a higher in specific populations such as elite male soccer players (one in 14,794 athlete – years) and male basketball players (1 21,000 athlete-years).
One in 300 people 35 years of age or younger had a condition associated with sudden cardiac arrest and death.
Incidence of one case in 51 to 67,000 athlete-years.
There is a sharp increase in the incidence of sudden death from cardiac causes, beginning at age 25 years, reflecting a great prevalence of coronary disease among adults than among younger persons.
Male athletes have a high risk of sudden cardiac arrest and death than female athletes, with one case in 35 to 83,000 athlete years among male athletes as compared with one case in 93,000 to 323,000 athlete-years among female athletes.
Causes of death from sudden cardiac death in athletes, is age related.
Etiology by Age Group
In athletes younger than 35 years, SCA is predominantly caused by inherited, congenital, or acquired cardiac conditions, including:
Hypertrophic cardiomyopathy (HCM) and other cardiomyopathies
Anomalous coronary artery origins
Channelopathies (long QT syndrome, Wolff-Parkinson-White syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia)
Myocarditis and commotio cordis
In masters athletes (>35 years), atherosclerotic coronary artery disease is the predominant cause.
In athletes younger than 25 years the primary causes of sudden cardiac death are congenital, electrical and structural diseases.
Acquired cardiac conditions, particularly coronary artery disease, become increasingly prevalent with age and account for the majority of death among athletes, 25 years of age older.
In contemporary studies of athletes, 11 to 40 years of age, sudden death from cardiac causes with pathologically normal heart on autopsy is the most common finding, suggesting that a arrhythmia due to diseases that affect the electrical system, such as channelpathathies is the cause of death.
Autopsy-negative sudden unexplained death (ANSUD) is characterized by a structurally normal heart and is now the most common finding in contemporary registries.
ANSUD likely reflects undiagnosed inherited arrhythmia syndromes or ion channelopathies.
Hypertrophic cardiomyopathy, historically considered the leading cause (previously attributed to ~36% of cardiovascular deaths), now accounts for less than 15% of SCD cases in contemporary data, likely due to improved clinical detection, enhanced screening, and better access to AEDs.
In addition, in cases of sudden cardiac death with a negative autopsy in young people, a molecular autopsy reveals irrelevant cardiac gene variant in 27% of cases.
EKG identifies disorders associated with sudden death from cardiac causes in about 2/3 of cases, including: hypertrophic cardiomyopathy, other cardiomyopathies, and electrical disorders, such as the Wolff-Parkinson-White syndrome and long QT syndrome, and this approach outperforms history and physical examination alone.
A study of 47,137 athletes found the most common EKG diagnosis of one in every 703 athletes to have Wolff-Parkinson-White syndrome, and the prevalence of hypertrophic cardiomyopathy and that of long QT syndrome was 1 in 2613.
Echocardiography can identify most coronary artery abnormalities, proximal aortopathy and congenital conditions associated with sudden cardiac arrest.
Athletes who collapse and are nonresponsive should be considered in cardiac arrest, and an automated external defibrillator should be applied.
Emergency action plans are required for sporting organizations, as well as coordination with local EMS providers.
Survival among athletes with sudden cardiac arrest has increased over the past two decades and ranges from 48 to 89%.
Diagnostic evaluation of a survivor of sudden cardiac death is evaluated as any survivor of cardiac arrest of a similar age.
Diagnostic evaluation includes history taking, physical exam, EKG with additional focus on exercise related cardiovascular events.
Evaluation includes inquiry about performance enhancing drugs, a history of chest trauma, evaluation for long QT syndrome, toxicology analysis., echocardiographic evaluation for various cardiomyopathies.
Other considerations include cardiac MRI, CT angiography and testing for cardiac adaptation to vigorous exercise and electrical system evaluation.
Genetic testing, maybe useful as well as evaluation of family members for potentially inherited entities.
Data suggest the many athletes who have survived sudden cardiac arrest, can be appropriately managed to return to sports or without having a high risk of recurrence.
For most survivors of sudden cardiac arrest management includes ICD implantation.
If there is a history of commotio cordis treatment is not required.
Athletes in whom a fully reversible cause is identified can return to play after treatment, such as ablation of the accessory pathway with the WPW syndrome.
For most entities that lead to sudden cardiac arrest, including cardiomyopathies and most electrical diseases, ICD implantation is indicated for secondary prevention.
Study suggest that a return to play is a reasonable option for an athlete who has had a sudden cardiac arrest with subsequent ICD implantation.
Screening
Screening remains a controversial component of prevention.
Approximately 1 in 300 individuals aged 35 years harbors a condition associated with SCA.
History taking and physical examination alone have low sensitivity (10-20%) and a high false-positive rate.
The addition of a 12-lead ECG improves sensitivity to >90% for detecting conditions such as HCM, other cardiomyopathies, and electrical disorders, with a low false-positive rate when contemporary athlete-specific interpretation criteria are applied.
In a meta-analysis of 47,137 athletes, the most commonly detected diagnosis on ECG screening was Wolff-Parkinson-White syndrome (1 in 703 athletes), while HCM and long QT syndrome were each found in approximately 1 in 2,613 athletes.
An Italian population-based study demonstrated an 89% reduction in SCD incidence among athletes over 20 years following implementation of mandatory ECG screening: methodologic concerns limited the definitiveness of these findings and was not replicated in an Israeli study.
Many institutions incorporate ECG into screening and has recommended standards for those that do.
Echocardiography can identify most coronary artery anomalies and proximal aortopathy, but data on screening are limited, and it adds complexity and cost.
Emergency Preparedness
Survival from SCA in athletes has improved substantially with widespread AED availability and bystander CPR..