Sudden Cardiac Death in Athletes

---

​Sudden cardiac death = most frequent medical cause of sudden death in athletes

• A recent estimate of SCD incidence ranged from 1 in 40,000 to 1 in 80,000 athletes per year

 
Jason Collier, 28 (2005), basketball
Eddie Guerrero, 38 (2005), wrestling
Fab Melo, 26 (2017), basketball
 
What is an “athlete?”

•  “One who participates in an organized team or individual sport that requires competition against others as a central component, places a high premium on excellence and achievement, and requires some form of systematic (and usually intense) training.” 

 
When estimating SCD incidence, the population of athletes “at risk” may be difficult to quantify
 
Definition? 

1. Deaths with exertion or shortly (< 1 hour) after exertion, 
2. Any SCD in an athlete (exertional or outside of exertion) and also episodes of resuscitated sudden cardiac arrest

 
These inconsistencies help account for the wide range of estimated incidence of SCD in athletes in prior reports, from 1 in 3,000 up to 1 in 1 million
 
Risk among male Division 1 basketball players = 10x that in the overall athlete population

• Mechanism is NOT clear
•  Marfan syndrome and resulting aortic dissection have most commonly occurred in male basketball players, this accounts for a small fraction of the deaths in this population

 
Causes

• Athletes <35
  • Inherited cardiac conditions predominate: hypertrophic cardiomyopathy and anomalous origin of a coronary artery (two most common causes in the United States)
• Athletes >35
  • Most SCD events are due to acquired atherosclerotic coronary artery disease 

• Many of these diagnoses may not be clinically apparent and first symptom may be sudden death
• Approximately 30% of athletes with SCD have been reported to have had symptoms such as chest pain, shortness of breath, performance decline, palpitations, near syncope, or syncope leading up to the event

 
The Young Athlete

• MCC = HCM
  • Genetic condition characterized by left ventricular hypertrophy and cardiac myocyte disarray
    • Predisposes to ventricular arrhythmias
  • Prevalence = 1 in 200 individuals
  • First presenting symptom may be Sudden Cardiac Death (SCD)
• Congenital coronary artery anomalies, consisting of a variety of abnormalities of coronary origin and proximal course, are the second most common cause of SCD
• The remaining causes of SCD in athletes include other inherited or acquired myocardial diseases, other structural cardiovascular disease, or primary arrhythmogenic disorders
• Recently, data from NCAA athletes suggests that the most common causes of SCD may merit re-evaluation.
  • Most common finding at autopsy for SCD cases was a structurally normal heart (25%), implying that arrhythmias and other electrical disorders may be the most common etiology.
  • Coronary anomalies were the second most common finding and were present at a similar proportion as was previously reported, but definitive HCM was far less frequent compared to prior information
• Reports from other countries such as Italy and Denmark have found that the most common cause of SCD in young athletes is arrhythmogenic right ventricular cardiomyopathy (ARVC)-- the artist formerly known as ARVD
  • ARVC is a genetic cardiomyopathy that is typified by fibro-fatty infiltration and dilation of the right ventricle
  • Risk of ventricular arrhythmia is increased by exercise, and exercise training itself may accelerate phenotypic expression of ARVC
  • ARVC remains an important diagnosis to consider in U.S. athletes but is less common

SCD Prevention: Athlete Screening and Evaluation 
The American Heart Association (AHA) and American College of Cardiology (ACC) recommend screening that is limited to a targeted medical history and physical exam
 ​

 
In contrast to the American recommendations, the European Society of Cardiology (ESC) and International Olympic Committee (IOC) advocate for screening that also includes a resting 12-lead electrocardiogram (ECG)

• The role of the ECG in preparticipation screening has garnered considerable debate
• ECG-inclusive screening appears to increase the sensitivity of preparticipation screening for identifying cardiovascular disorders that predispose to SCD
• ECG in athlete screening remains unclear, and athletic programs should consider using ECG-inclusive screening based on the characteristics of their athlete population, the local screening resources available, and access to expert ECG interpretation specific to athletes.

 
 
Anatomic/Physiologic Changes 

• Sports with significant isometric exercise may induce left ventricular hypertrophy to the same range as that of mild HCM (“gray zone” hypertrophy)
• A small but significant proportion of endurance athletes will have dilated left ventricular (LV) cavities with low normal LV function, which overlaps with findings of a dilated cardiomyopathy
  • These physiologic changes to the left ventricle may be accompanied by right ventricular (RV) dilation and reduced systolic function, which could raise concern for ARVC in the appropriate context

 
 
SUMMARY:
Although rare, SCD in the athlete is a traumatic event that has a large impact on society
 
Incidence of SCD varies widely depending on the athlete population

• Older athletes, SCD is primarily due to CAD and associated complications
• Younger athletes, it is due to congenital or genetically mediated cardiovascular disease, such as HCM, coronary artery anomalies, other cardiomyopathies, or primary arrhythmogenic disorders

 
All preparticipation screening programs aimed at identifying athletes at high risk of SCD begin with a focused history and physical.
 
The addition of the 12-lead ECG and/or additional cardiac testing is a source of considerable ongoing debate.
 
It is highly unlikely that any screening program will be effective at appropriately identifying all athletes at risk of SCD; therefore, increased access to automated external defibrillators as well as training in cardiopulmonary resuscitation at a community level are important means of reducing SCD in athletes.