Identifying Athletes at Risk for Sudden Cardiac Death

By Sally Beattie, MS, RN, CS, GNP

Summary—The sudden cardiac death (SCD) of a young, seemingly healthy athlete is a tragic and devastating occurrence. Hypertrophic cardiomyopathy (HCMP) claims only about one in 200,000-300,000 young athletes each academic year, yet each occurrence shocks millions of sports fans and participants. About one-third of sudden cardiac deaths in young athletes are caused by HCMP.

A study by Italian investigators indicated that performing a cardiovascular preparticipation screening evaluation might prevent premature SCD from HCMP. After screening, only one of 49 sudden deaths in competitive athletes could be attributed to HCMP. During the follow-up period, researchers recorded 16 sudden deaths secondary to HCMP. Clinicians performing routine preparticipation examinations need to pay particular attention to identifying signs and symptoms indicative of this and other cardiac abnormalities and make appropriate referrals.

The collapse and death of a young competitive athlete on the playing field is a frightening and tragic occurrence. These events are acknowledged to be rare, occurring in only about 1/200,000-1/300,000 high school or college athletes per academic year, but their emotional, medical, and societal impact is far-reaching.1 The most common cause of sudden cardiac death (SCD) in young athletes (about 1/3 of cases) is hypertrophic cardiomyopathy (HCMP).2 (See Table 1, below.)

Table 1 
Causes of Sudden Cardiac Death in Young Competitive Athletes 
Abnormality
Frequency 
• Hypertrophic cardiomyopathy
36%
• Coronary anomalies
19%
• Increased cardiac mass 
10%
• Ruptured aortic aneurysms
5%
• Tunneled left anterior descending coronary artery
5%
• Aortic stenosis
4%
• Myocarditis
3%
• Dilated cardiomyopathy
3%
• Arrhythmogenic right ventricular dysplasia
3%
• Mitral valve prolapse
2%
• Coronary artery disease
2%
• Other
6%
Causes of sudden cardiac death in young competitive athletes (median age 17), based on systematic tracking of 158 athletes in the United States from 1985 to 1995. Adapted from Maron et al, with permission of the American Medical Association. 
Source: Maron BJ, Shirani J, Poliac LC, et al. Sudden death in young competitive athletes; clinical, demographic, and pathological profiles. JAMA 1996;276:199-204.

HCMP is a complex, genetically acquired malformation of the heart characterized by an asymmetrically hypertrophied and nondilated left ventricle in the absence of another cardiac or systemic disease known to cause hypertrophy. It carries the risk for sudden and unexpected cardiac death, often during physical exertion1,2,3 and afflicts persons of all ages. (See cautionary note, p 39.)

Study Tests Strategy — Results Encouraging

Since 1971, Italian law has mandated annual medical evaluation for competitive athletes. Screening for cardiac disease is part of a more comprehensive medical examination.4 (See Table 2, p. 38.) Positive findings during this examination trigger echocardiography, 24-hour ambulatory Holter monitoring, and/or a submaximal exercise test. Researchers wanted to know if this evaluation could prevent SCD secondary to HCMP.4 From 1979-1996, the investigators studied sudden deaths among athletes and non-athletes ages 35 or less in 33,735 individuals (28,539 male; 5,196 female, with a mean age of 19±5 years) who underwent screening. Investigators defined competitive athlete as "a participant in an organized sports program requiring regular training and competition."

Table 2
Components of the Italian Athletic Preparticipation Screening Examination 
General Examination 
    • history, review of systems 
    • physical examination 
    • orthopedic examination 
    • spirometry 
    • urinalysis 
Cardiovascular Examination 
    • family and personal history 
    • 12-lead electrocardiogram 
    • limited exercise test 
Source: Corrado D, Basso C, Schiavon M, et al. Screening for hypertrophic cardiomyopathy in young athletes. NEJM 1998;339:364-369.

During follow-up, 269 sudden deaths occurred. Of those, 49 occurred in competitive athletes who participated in a variety of dynamic and static sporting activities (44 males and five females, with a mean age of 23±7 years).

The most common causes of SCD were:

• arrhythmogenic right ventricular dysplasia;

• coronary atherosclerosis;

• and anomalous origin of a coronary artery.

HCMP caused only one sudden death among athletes, but it was cited as the cause in 16 of the non-athletes. None of the 22 disqualified athletes with HCMP died during a mean follow-up of 8.2±5 years. Based on these results, the authors suggest that preparticipation screening may have prevented SCD secondary to HCMP. Their conclusions were supported by a previous study conducted in the United States.5

No Standardized Evaluation in United States

Unfortunately, a nationally mandated, standardized cardiovascular (CV) prescreening evaluation for young athletes does not yet exist in the United States. Experts agree the uncommon occurrence of SCD associated with HCMP (and other CV lesions) in the general population, as well as the large size of the competitive athletic population (8-10 million/year), limits the practicality and utility of the screening process.6 Current preparticipation examinations are performed at the discretion of examiners, based on requirements of high schools and colleges.

Many times, both examination and examiner are woefully inadequate. Recently, a consensus panel of the American Heart Association (AHA) in Dallas supported the principle of preparticipation CV screening for young competitive athletes.1 (See Table 3, below.) For now, screening is the most practical and best available strategy, considering the large athletic population.

Table 3 
American Heart Association Consensus Panel Recommendations for Preparticipation Screening of Young Athletes 
Family History
    • premature sudden death or heart disease in surviving relatives
Personal History
    • heart murmur
    • systemic hypertension
    • fatigability
    • syncope
    • exertional dyspnea or chest pain
    • parental verification of the history
Physical examination
    • heart murmur*
    • femoral pulses
    • stigmata of Marfan syndrome
    • blood pressure measurement
* Precordial auscultation is recommended in supine/sitting and standing positions to identify heart murmurs consistent with left ventricular outflow tract obstruction.
Source: Maron BJ. Cardiovascular risks to young persons on the athletic field. Ann Int Med 1998;129:382. Used with permission from American College of Physicians-American Society of Internal Medicine.

Practice Implications

Clinicians should be guided by recommendations from the AHA targeted to identify and detect HCMP and other CV lesions that may induce SCD.

Eliciting a comprehensive personal and family history with parental verification is an essential part of the prescreening assessment. Most individuals with HCMP are only mildly or asymptomatic. Most have the non-obstructive form of the disease expressed only by a soft murmur, if any.6 Often patients are identified during screening of relatives with HCMP. Clinicians must familiarize themselves with what is developmentally appropriate and normal in terms of activity tolerance. The most common symptom of HCMP is dyspnea with exertion. It is important to ask these questions:

• Do the athletes stop to catch their breath after walking up a moderate incline?

• For no other apparent reason, do they have to stop to catch their breath during routine drills more frequently than their peers do?

• Have their levels of tolerance for physical exertion declined in recent months?

Adolescents, especially males, may minimize or be unwilling to admit activity intolerance. Learning they should not compete in sports, or any form of physical exertion, is contradictory to their stage of development.

During the physical examination, the following reliably identify the systolic ejection murmur of HCMP:3

• increases during standing from a squatting position, and/or the valsalva maneuver;

• and decreases during squatting from a standing position, passive leg elevation, and/or a handgrip.

Positive findings mandate referral to a CV specialist for more noninvasive testing. If an abnormality is identified, the clinician is wise to use recommendations compiled during the 26th Bethesda Conference sponsored by the American College of Cardiology in Bethesda, MD, to determine athletic eligibility.7

References

1. Maron BJ. Cardiovascular risks to young persons on the athletic field. Ann Int Med 1998;129:379-386.

2. Maron BJ, Shirani J, Poliac LC, et al. Sudden death in young competitive athletes; clinical, demographic, and pathological profiles. JAMA 1996;276:199-204.

3. Wynne J, Braunwald E. "The Cardiomyopathies and Myocarditis in Heart Disease." In: A Textbook of Cardiovascular Medicine. 5th edition. Philadelphia: W.B. Saunders Co.; 1997:1404-1463.

4. Corrado D, Basso C, Schiavon M, et al. Screening for hypertrophic cardiomyopathy in young athletes. NEJM 1998; 339:364-369.

5. Burke AP, Farb A, Virmani R, et al. Sports-related and non-sports-related sudden cardiac death in young adults. Am Heart J 1991;121:568-575.

6. Maron BJ, Thompson PD, Puffer JC, et al. Cardiovascular preparticipation screening of competitive athletes. A statement for health professionals from the Sudden Death Committee (clinical cardiology) and congenital Cardiac Defects Committee (cardiovascular disease in the young), American Heart Association. Circulation 1996;94:850-856.

7. Bethesda Conference. Recommendations for determining eligibility for competition in athletes with cardiovascular abnormalities. J Am Coll Cardiol 1994;24:845-899.