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Sudden cardiac death in young athletes
Causes, athlete's heart, and screening guidelines
Jonathan A. Drezner, MD
VOL 108 / NO 5 / OCTOBER 2000 / POSTGRADUATE MEDICINE
-----------------------------------------------------------------------CME learning objectives
*
*
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To review the causes of sudden cardiac death in young athletes
To understand the physiologic changes seen in so-called athlete's heart
To recognize key features of the preparticipation sports evaluation
The author discloses no financial interests in this article.
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Preview: The sudden, unexpected death of a young athlete from a cardiac cause, while rare,
often captures the public's attention and raises questions about the need for more
comprehensive screening before athletes are allowed to participate in vigorous sports. In this
article, Dr Drezner addresses the questions surrounding such tragedies and discusses the
causes of sudden cardiac death, the physiologic adaptations seen in so-called athlete's heart,
and guidelines for cardiovascular screening.
Drezner JA. Sudden cardiac death in young athletes: causes, athlete's heart, and screening
guidelines. Postgrad Med 2000;108(5):37-50
-----------------------------------------------------------------------When a young athlete dies unexpectedly, the impact often extends beyond the local
community and medical establishment to attract regional and national media attention. As a
result, primary care and sports medicine physicians are often asked to screen athletes for
relatively rare cardiac-related diseases that may predispose an athlete to sudden death.
Physicians involved in the care of athletes play the dominant role in prevention of sudden
cardiac death and should be familiar with its various causes and the current recommendations
for screening of athletes before their participation in sports.
This article outlines the major causes of sudden cardiac death, reviews the physiologic
cardiovascular adaptations seen in so-called athlete's heart, and defines key features of the
preparticipation sports evaluation.
Background and prevalence
Sudden cardiac death in an athlete has been defined as nontraumatic and unexpected sudden
cardiac arrest that occurs within 6 hours of a previously normal state of health (1). In athletes
less than 35 years of age, congenital cardiovascular disease is usually responsible. This
catastrophic event typically occurs during or shortly after training or competition, suggesting
that intense physical exertion is a precipitating factor (2). Recently, the list of recognized
cardiovascular risks during athletic competition has been expanded to include cardiac arrest
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resulting from blunt trauma to the chest wall in the absence of underlying cardiovascular
disease (3).
The earliest documented case of sudden cardiac death occurred in 490 BC, when Pheidippides,
a Greek soldier and conditioned runner, ran from Marathon to Athens to announce military
victory over Persia, only to deliver his message, then collapse and die (4). More recently, the
sudden deaths of a number of high-profile athletes--Olympic gold medal skater Sergei Grinkov
in 1995, professional basketball player Reggie Lewis in 1993, college basketball player Hank
Gathers in 1990, Olympic volleyball champion Flo Hyman in 1986--have received national
publicity, raising public interest in this infrequent event. Young competitive athletes are
generally perceived as the healthiest segment of our society, and their unexpected collapse
often sparks public debate on prevention of sudden cardiac death and the appropriateness of
established screening guidelines.
Fortunately, sudden cardiac death in young athletes is rare. Its exact prevalence is unknown,
since there is no national database to track death in athletes. The largest available studies
estimate the risk among high school and collegiate athletes to be between 1 per 100,000 and
1 per 300,000 each year (5-7). An estimated 50 to 100 cases occur in the United States
annually (6,8).
Researchers have also found that sudden cardiac death is about five times more common in
males than in females (5). The incidence increases in persons over 35 years of age, largely
because of the increasing prevalence of atherosclerotic heart disease. Estimates of the
incidence in the older population of joggers or people who exercise vigorously range from 1 per
15,000 to 1 per 18,000 (9,10).
Causes of sudden cardiac death
Most cases of sudden cardiac death in young people are secondary to congenital cardiac
abnormalities. The common denominator in all cases is the development of electrical instability
that leads to a fatal arrhythmia (8). Table 1 lists the various causes of sudden cardiac death in
young athletes.
Table 1. Causes of sudden cardiac death in young athletes
Most common
Hypertrophic cardiomyopathy
Idiopathic left ventricular hypertrophy
Congenital coronary artery anomalies
Less common
Ruptured aortic aneurysm
Myocarditis
Dilated cardiomyopathy
Arrhythmogenic right ventricular dysplasia
Aortic valve stenosis
Tunneled left anterior descending coronary artery
Atherosclerotic coronary artery disease
Rare
Wolff-Parkinson-White syndrome
Long QT syndrome
Mitral valve prolapse
Commotio cordis
Drugs
Unknown/other
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Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy is the most common cause of sudden cardiac death in young
competitive athletes. Maron and associates (2) studied autopsy results of 134 athletes who
died of cardiovascular causes and found that hypertrophic cardiomyopathy accounted for 36%
of the deaths. This familial autosomal dominant disorder has variable expression. Its
prevalence is 1 per 500 in the general US population and higher in blacks (11). Researchers
have found more than 100 mutations in genes encoding proteins for the cardiac sarcomere
that result in hypertrophic cardiomyopathy (3).
Characteristic morphologic features of hypertrophic cardiomyopathy include asymmetric left
ventricular hypertrophy (usually involving the ventricular septum), left ventricular wall
thickness of 16 mm or more (normal, <12 mm; borderline, 13 to 15 mm), a ratio between the
septum and free wall of more than 1.3, and a nondilated left ventricle (12). Thus, the
ventricular hypertrophy occurs in the absence of left ventricular cavity dilatation, a feature
distinguishing it from the physiologic changes seen in athlete's heart. This pathologic
hypertrophy contributes to decreased ventricular compliance and diastolic dysfunction with
impaired filling. Results of histologic analysis show a disorganized cellular architecture.
Intramural tunneling (myocardial bridging), in which a segment of coronary artery is
completely surrounded by myocardium, is present in about one third of cases and has been
identified as a risk factor for poor outcome in children with this condition (13).
Hypertrophic cardiomyopathy has also been called hypertrophic obstructive cardiomyopathy or
idiopathic hypertrophic subaortic stenosis--names which falsely imply that obstruction of the
left ventricular outflow tract is an invariable component of the disease. In fact, the
nonobstructive form of this disease accounts for about 75% of cases (11). Therefore,
previously used criteria, such as obstruction of the left ventricular outflow tract, systolic
anterior motion of the mitral valve, and a loud systolic ejection murmur, although suggestive,
are no longer required for the diagnosis.
Unfortunately, most athletes with hypertrophic cardiomyopathy remain asymptomatic until the
time of death and are difficult to identify on the basis of history or physical examination. In
one study (2), only 21% of athletes who died from this condition had signs or symptoms of
cardiovascular disease before their death. Symptoms may include exertional chest pain,
dyspnea, light-headedness, or syncope.
Hypertrophic cardiomyopathy should be suspected in any athlete in whom a harsh systolic
ejection murmur is heard on examination. This characteristic murmur increases in intensity
with any maneuver that decreases venous return, such as a sustained Valsalva's maneuver.
Similarly, a systolic ejection murmur that decreases with squatting and increases upon
standing is suspicious. Examination may also reveal the presence of a fourth heart sound and a
rapid initial upstroke of the carotid pulse. Ultimately, the diagnosis is confirmed by
echocardiography.
Athletes with a genetic predisposition to hypertrophic cardiomyopathy should undergo serial
echocardiography every 12 to 18 months until about age 18, because phenotypic expression
may not occur until physical maturation and development are complete (12).
Idiopathic left ventricular hypertrophy
Idiopathic left ventricular hypertrophy is another cause of sudden cardiac death in young
athletes, accounting for 9% to 10% of cases (2,8). It is marked by an unexplained increase in
cardiac mass that exceeds the limits of physiologic hypertrophy in athlete's heart. The increase
in cardiac mass does not meet criteria for hypertrophic cardiomyopathy because the
hypertrophy is symmetric (concentric) and histologic examination does not show the cellular
disarray characteristic of hypertrophic cardiomyopathy. Furthermore, no genetic basis of the
disease has been established.
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Controversy exists as to whether idiopathic left ventricular hypertrophy is a separate disease
or whether it may be a variant of hypertrophic cardiomyopathy without the latter's
characteristic asymmetry or genetic transmission (1).
Congenital coronary artery anomalies
Congenital anomalies of the coronary arteries account for 17% to 19% of cases of sudden
cardiac death (2,8). Origin of the left coronary artery from the right sinus of Valsalva (figure 1:
not shown) is the coronary anomaly that most commonly leads to sudden death. Among
athletes who died of this disorder, only 31% were found to have symptoms before death (2).
Symptoms included exertional syncope or near-fatal arrhythmia, dyspnea, chest pain,
pressure, and tightness. Possible mechanisms of ischemia in anomalous origin of the left
coronary artery include a slitlike ostium that narrows with aortic dilatation during exercise, an
acute-angled takeoff, and impingement of the artery as it passes between the aorta and
pulmonary trunk (1,2,4).
Anomalous coronary artery origin can be investigated by echocardiography and exercise
testing but ultimately may require coronary arteriography for diagnosis.
Other coronary anomalies include origin of the right coronary artery from the left sinus of
Valsalva or from the pulmonary artery, presence of a single coronary artery, hypoplasia (ie,
small size or short course), aneurysm, and acute-angled takeoff of the left main coronary
artery (1,2,5). Intramural tunneling of the left anterior descending coronary artery has also
been implicated as a cause of sudden death. However, necropsy studies have shown that this
condition exists in about 20% of all persons, and its role in sudden cardiac death remains
uncertain (1).
Aortic rupture
Rupture of an aortic aneurysm is a less common cause of sudden cardiac death. Half of these
cases occur in athletes with Marfan syndrome (1,2), which is an autosomal dominant, systemic
connective tissue disorder with a prevalence in the general US population of 1 per 10,000 (14).
A defect in the gene for the structural protein fibrillin leads to intrinsic weakening of the aortic
wall, known as cystic medial necrosis.
The diagnosis of Marfan syndrome is based on clinical features and confirmed by eye
examination and echocardiography. Skeletal features include tall stature with arm span greater
than height, arachnodactyly (long fingers and toes), hyperextensible joints, scoliosis, a high
arched palate, and anterior chest-wall deformities, such as pectus excavatum. Ophthalmologic
examination may show myopia and ocular lens subluxation (ectopia lentis), and
echocardiography may reveal a dilated aortic root or mitral valve prolapse.
Myocarditis and dilated cardiomyopathy
Myocarditis is another infrequent cause of sudden cardiac death in young athletes. This
inflammatory condition of the myocardium is most commonly viral. Coxsackievirus B is
implicated in more than 50% of cases (4). Other viral origins of myocarditis include echovirus,
adenovirus, and influenza. Chlamydia pneumoniae has been noted in several cases in Sweden
(15).
Characteristic symptoms of myocarditis include a prodromal viral illness followed by
progressive exercise intolerance and congestive symptoms of dyspnea, cough, and orthopnea.
Sudden cardiac death may occur in the presence of either active or healed myocarditis. Thus, a
convalescent period of at least 6 months is recommended before a return to sports (16).
Dilated cardiomyopathy may result from viral infections or be secondary to infiltrative diseases
(eg, sarcoidosis, amyloidosis, hemochromatosis) or toxins (eg, ethanol).
Arrhythmogenic right ventricular dysplasia
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Arrhythmogenic right ventricular dysplasia involves fatty infiltration and fibrosis of the right
ventricle, which predisposes an athlete to exercise-induced ventricular tachyarrhythmias.
Although rare in the United States, this disease causes 22% of sudden cardiac deaths in the
Veneto region of northern Italy, implying a genetic basis (17). Diagnosis is made by
echocardiography or magnetic resonance imaging, which demonstrates fatty infiltration of the
myocardium.
Aortic valve stenosis
Aortic stenosis in young athletes results from congenital abnormalities, such as a bicuspid
valve. Diagnosis should be suspected in the presence of a systolic ejection murmur or early
systolic click heard on cardiac examination. The murmur of aortic stenosis can be distinguished
from the murmur of hypertrophic cardiomyopathy because it will diminish with maneuvers that
decrease venous return. These include Valsalva's maneuver or assumption of the standing
position (opposite to the findings in hypertrophic cardiomyopathy). Aortic stenosis can be
evaluated by Doppler echocardiography, but cardiac catheterization may be required to
distinguish moderate from severe disease (16).
Cardiac conduction abnormalities
Supraventricular tachyarrhythmias are no more frequent in athletes than in the general
population (18,19). Wolff-Parkinson-White syndrome, or ventricular preexcitation, is present in
0.15% to 0.20% of persons and predisposes an athlete to sudden cardiac death (8). Athletes
may complain of palpitations, light-headedness, or syncope. The electrocardiogram (ECG) may
show an initial slurred upstroke (delta wave), short PR interval, and wide QRS complex.
Sudden death results from the development of atrial fibrillation with rapid atrioventricular
conduction via a bypass tract and subsequent ventricular fibrillation.
Long QT syndrome involves prolonged ventricular repolarization and may lead to the
development of polymorphic ventricular tachycardia (torsades de pointes). The syndrome can
be congenital (Romano-Ward and Jervell and Lange-Nielson syndromes) or may be acquired
from administration of certain drugs (eg, group IA antiarrhythmics, tricyclic antidepressants,
antifungals, nonsedating antihistamines, antibiotics, promotility agents) or from certain
metabolic abnormalities (eg, hypokalemia, hypomagnesemia).
Commotio cordis
Although sudden cardiac death in young athletes is most often associated with congenital heart
disease, the cardiovascular risk to athletes playing either organized or recreational sports
includes cardiac arrest resulting from direct, nonpenetrating trauma to the chest wall. This
occurrence, known as commotio cordis, results in almost instantaneous cardiac death following
blunt chest impact over the heart. Trauma is usually caused by a projectile, such as a baseball
or ice hockey puck, or a direct blow from an opposing player.
In contrast to other causes of sudden cardiac death, commotio cordis occurs in the absence of
underlying cardiovascular disease or structural injury to the heart itself. The timing of chestwall impact as it relates to the cardiac cycle appears to be critical in producing commotio
cordis. The precise mechanism of death is unknown but is believed to involve an exquisitely
timed precordial blow that occurs during a period of electrically vulnerable ventricular
repolarization and leads to a fatal dysrhythmia (20). Only about 10% of reported victims of
commotio cordis are known to survive (21).
Recently, an experimental model reproducing commotio cordis in swine found that softer-thanstandard baseballs reduced the risk for ventricular fibrillation (22). This finding suggests that
modified athletic equipment may prevent some deaths in athletes.
Other causes of sudden cardiac death
Mitral valve prolapse occurs in 5% to 10% of the general US population (1). Its association
with sudden cardiac death has not been clearly established. Physical examination may reveal a
midsystolic click and a late systolic murmur. Athletic participation need not be restricted unless
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mitral valve prolapse is associated with syncope, exertional chest pain, moderate or severe
mitral regurgitation, or a family history of sudden cardiac death (16).
Illicit drugs that cause coronary vasospasm, such as cocaine, have also been linked to sudden
cardiac death (4). Interestingly, atherosclerotic coronary artery disease, the cause of more
than 75% of sudden cardiac deaths in athletes over 40 years of age, accounts for only 2% to
3% of sudden deaths in young athletes (2,5).
Athlete's heart
The heart of an athlete involved in long-term athletic training undergoes normal physiologic
and morphologic changes, known as athlete's heart or the athletic heart syndrome (23). These
adaptations are considered a normal response to repetitive exercise.
Physiologic hypertrophy
The myocardial adaptations that occur in athlete's heart depend on the frequency, duration,
and intensity of physical conditioning (24). An athlete can place either of two types of load on
the heart--volume or pressure--depending on the type of exercise (23).
Athletes involved in isotonic (dynamic) exercise, such as running, cycling, or swimming,
present a volume load to the heart. Isotonic exercise increases venous return and thus left
ventricular end-diastolic diameter, allowing for a larger stroke volume and cardiac output. In
response to a chronic volume demand, the left ventricular wall thickens proportionately in
order to normalize wall stress. Changes occur according to Laplace's law (wall stress =
[pressure X radius]/[wall thickness X 2]) (23), and the myocardium hypertrophies in an
eccentric fashion such that the mass-to-volume ratio remains unchanged.
Athletes involved in isometric (static) exercise, such as weight lifting or shot-putting, place a
pressure load on the heart by brief increases in systemic blood pressure during training. Wall
thickness increases in response to a chronic pressure demand in accordance with Laplace's
law. Without an increase in left ventricular end-diastolic diameter, the myocardium
hypertrophies in a concentric fashion such that the mass-to-volume ratio increases.
Because training for most competitive athletes involves a combination of both isotonic and
isometric exercise, cardiac adaptations are usually a blend of eccentric and concentric
hypertrophy. The result is an overall increase in cardiac mass due to an increase in left
ventricular diastolic cavity dimension, wall thickness, or both (12).
Physiologic hypertrophy in athlete's heart is always symmetric and reversible with
deconditioning (decreasing about one third in 3 weeks) (23). Asymmetry or a failure of
myocardial hypertrophy to resolve with the cessation of regular exercise suggests the presence
of hypertrophic cardio-myopathy.
Pathologic versus physiologic hypertrophy
Left ventricular wall thickness in athlete's heart is usually within normal limits or only mildly
increased (<12 mm). Some athletes, however, have larger increases, approaching pathologic
values (>16 mm) and raising the possibility of hypertrophic cardiomyopathy (12). Wallthickness values in the range of 13 to 15 mm are described as the morphologic gray zone, and
criteria have been outlined to distinguish pathologic from physiologic hypertrophy in these
cases (12). An unusual pattern of left ventricular hypertrophy, a left ventricular end-diastolic
cavity dimension of less than 45 mm, left atrial enlargement, bizarre ECG patterns, abnormal
left ventricular filling, and a positive family history support a diagnosis of hypertrophic
cardiomyopathy. In contrast, a left ventricular end-diastolic cavity dimension of more than 55
mm and a decrease in thickness with deconditioning support a diagnosis of athlete's heart.
ECG changes
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Athlete's heart is also associated with many common ECG alterations (table 2). Changes are
related to either an increase in resting parasympathetic (vagal) tone or an increase in cardiac
mass from physiologic hypertrophy. The most common ECG finding related to increased vagal
tone is a resting sinus bradycardia, which is found in the majority of aerobically trained
athletes (18,19,23,25). Sinus arrhythmias, first-degree atrioventricular block, Mobitz type I
(Wenckebach) second-degree atrioventricular block, and junctional rhythms are also seen
more often in athletes than in the general population (23). These changes are readily reversed
with exercise as increased sympathetic drive overcomes baseline parasympathetic tone.
Increased QRS voltage, related to an increase in cardiac mass, is present in up to 80% of wellconditioned athletes (19,23) and should be considered a normal variant in young
normotensive, asymptomatic athletes with normal findings on examination.
Table 2. Common electrocardiographic changes in athlete's heart
Changes due to increased resting vagal tone*
Sinus bradycardia
Sinus arrhythmia
Wandering atrial pacemaker
First-degree atrioventricular block
Mobitz type I (Wenckebach) second-degree atrioventricular block
Junctional rhythms
Changes due to physiologic hypertrophy**
Increased P-wave amplitude
Increased QRS voltage (LVH*** or RVH+ criteria)
Early repolarization (J-point ST-segment elevation)*
Tall, peaked T waves
T-wave inversion*
Prominent U waves
Incomplete RBBB (intraventricular conduction delays)
Vertical QRS axis
-----------------------------------------------------------------------LVH, left ventricular hypertrophy; RBBB, right bundle branch block; RVH, right ventricular
hypertrophy.
*Changes normalize with exercise.
**Changes regress with cessation of regular exercise.
***LVH criteria = S in V1 + R in V5 >35 mm.
+RVH criteria = R in V1 + S in V5 >10.5 mm.
Compiled from Zehender et al (19) and Huston et al (23).
-----------------------------------------------------------------------Other common changes secondary to physiologic hypertrophy include voltage criteria
suggestive of left or right ventricular hypertrophy; early repolarization with J-point ST-segment
elevation and tall, peaked T waves; T-wave inversion; and a vertical QRS axis (19,23). These
ECG changes should regress with the cessation of regular exercise as the myocardium returns
to its previous, smaller size. A representative ECG tracing of athlete's heart is shown in figure
2 (not shown). Some ECG findings are clearly abnormal and should be further investigated for
the presence of organic heart disease. ECG warning signs are listed in table 3.
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Table 3. Electrocardiographic warning signs for risk of sudden cardiac death in
athletes
Downsloping ST segment or horizontal depression
Left ventricular hypertrophy with downsloping ST segment and T-wave inversion that does not
normalize with exercise
Persistent second-degree atrioventricular block with exercise
Third-degree atrioventricular block
Complex ventricular arrhythmias
Dramatic increase in QRS voltage*
Prominent Q waves*
Deep negative T waves*
-----------------------------------------------------------------------*Changes may suggest hypertrophic cardiomyopathy.
-----------------------------------------------------------------------Preparticipation physical evaluation
The American Heart Association Science Advisory and Coordinating Committee developed
consensus recommendations and preparticipation screening guidelines in 1996 (26). The
purpose of screening is to identify preexisting cardiovascular abnormalities that place athletes
at increased risk for sudden cardiac death and to provide medical clearance by means of
routine and systematic evaluations. The committee recommended that a screening history and
physical examination be performed on all athletes before participation in high school and
collegiate sports. For high school athletes, the screening should be repeated every 2 years and
an interim history should be obtained in the intervening years. For college athletes, a history
and blood pressure measurement should be obtained each year after the initial evaluation
(27).
A standardized questionnaire is helpful in guiding examiners. Parents are the persons who
should be responsible for completing the questionnaire for athletes of high school age or
younger. The monograph Preparticipation Physical Evaluation (28) provides a useful form that
is widely accepted. This monograph was updated in 1996 by the American Academy of Family
Physicians, American Academy of Pediatrics, American Medical Society for Sports Medicine,
American Orthopaedic Society for Sports Medicine, and American Osteopathic Academy of
Sports Medicine.
The cardiovascular history should include questions about prior exertional chest pain or
discomfort, exertional syncope or light-headedness, dyspnea or fatigue disproportionate to the
degree of exertion, and any history of palpitations or irregular heart beats. Previous detection
of a heart murmur or elevated blood pressure and the use of cocaine or other drugs should be
noted. Questions pertaining to a family history of premature sudden death (before age 50) or
cardiovascular disease and the presence of specific conditions, such as hypertrophic
cardiomyopathy, Marfan syndrome, or long QT syndrome, should also be investigated.
Physical examination should include brachial blood pressure measurement in the sitting
position, palpation of the femoral artery pulses to exclude coarctation of the aorta, recognition
of the physical stigmata of Marfan syndrome, and precordial auscultation in both supine and
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standing positions in a quiet environment (26). Detectable heart murmurs should be further
elucidated by Valsalva's maneuver or by the athlete moving from a squatting to a standing
position to identify changes consistent with hypertrophic cardiomyopathy.
The American Heart Association does not recommend noninvasive diagnostic tests such as
electrocardiography or echocardiography in the routine screening of asymptomatic athletes for
cardiovascular disease (26). Recommendations are based on practicality and cost efficiency,
given the large number of competitive athletes in the United States and the relatively low
incidence of cardiovascular disease and sudden cardiac death. Because of the low incidence of
disease and the relatively high frequency of normal morphologic and ECG alterations occurring
in athlete's heart, the specificity of electrocardiography and echocardiography in correctly
diagnosing cardiovascular disease is poor. The number of false-positive results, which would
very likely exceed the number of true-positive results, would lead to the unnecessary
disqualification of athletes (26).
Electrocardiography or echocardiography has been used in several studies (29-32) to screen
large populations of athletes. Few definitive examples of potentially lethal cardiovascular
abnormalities were detected. Two studies (29,30) used screening echocardiograms of 3,262
athletes, and a third study (31) used screening ECGs of 501 collegiate athletes, 90 of whom
underwent subsequent echocardiography. No athlete in these studies was thought to be at
high risk for sudden cardiac death or was barred from competition.
In another study (32), electrocardiography was added to the preparticipation evaluation of
5,615 high school athletes. Echocardiography was performed on 146 athletes thought to have
abnormal screening ECGs, and no abnormalities were found. Sixteen (0.3%) of the athletes
were not approved for competition because of conduction abnormalities found on ECG, but no
results of follow-up studies to determine final eligibility were provided.
Screening echocardiography is very costly. For example, taking the prevalence of hypertrophic
cardiomyopathy in the general US population as 1 per 500 and the cost of an echocardiogram
as $500 per study, it would cost an estimated $250,000 to detect just one previously
undiagnosed case of hypertrophic cardiomyopathy (26).
Although a properly performed preparticipation evaluation is the best and most practical
screening tool, several limitations exist. In a retrospective study of 134 athletes who died
suddenly of cardiovascular-related disease (2), only 18% had cardiovascular symptoms in the
36 months preceding death. In this study, 115 athletes had undergone standard
preparticipation screening and 15 had undergone individualized medical evaluation for signs or
symptoms of disease. Among these, an appropriate diagnosis was made in only eight (6%)
prior to death.
Despite the American Heart Association recommendations, not all athletes are being properly
screened. A 1997 survey of high school athletic associations from the 50 states and the District
of Columbia (33) revealed that 8 states did not have approved history and physical
questionnaires to guide examiners, 12 states had questionnaires that were judged to be
inadequate according to the American Heart Association recommendations, and 1 state had no
formal screening requirement.
Referral to a specialist is indicated for any cardiovascular abnormality that is identified or
suspected on the preparticipation evaluation, any systolic murmur grade 3/6 or higher, any
diastolic murmur, or a family history of sudden cardiac death. Further evaluation includes
electrocardiography and selective use of echocardiography, exercise testing, and coronary
arteriography. Temporary disqualification must be considered until workup is complete.
When cardiovascular abnormalities are found, eligibility for competition should be determined
in accordance with the joint recommendations of the American College of Cardiology and the
American College of Sports Medicine at the 26th Bethesda Conference (16). The objective of
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this conference was to identify, by way of consensus and review of available studies, the types
and degree of severity of cardiovascular abnormalities that place a competitive athlete at
increased risk for disease progression or sudden death and, therefore, justify a medical
recommendation against participation. The guidelines consider the type and intensity of
exercise performed, the risk of bodily injury from collision, and the estimated stress of the
sport on the cardiovascular system. A review of the Bethesda recommendations is beyond the
scope of this article, but the guidelines should be used by the primary care physician and
consulting specialist when determining eligibility for competition in athletes with identified
cardiovascular abnormalities.
Summary
Sudden cardiac death of a young competitive athlete is a rare but tragic event. Hypertrophic
cardiomyopathy and coronary artery anomalies are the most frequent causes. Most
cardiovascular abnormalities go unrecognized until the time of death owing to the lack of
preceding signs or symptoms suggestive of disease. Physicians responsible for the care of
athletes should be familiar with the various causes of sudden cardiac death, the physiologic
adaptations seen in so-called athlete's heart, and existing cardiovascular screening guidelines.
The preparticipation evaluation, although it has limitations, is the major instrument readily
available for prevention of sudden cardiac death. Effort should be made to follow established
consensus guidelines.
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Dr Drezner completed a sports medicine fellowship and is now clinical instructor in the
department of family medicine, University of Washington School of Medicine, Seattle.
Correspondence: Jonathan A. Drezner, MD, Family Medical Center, University of Washington,
Box 354775, 4245 Roosevelt Way NE, Seattle, WA 98105. E-mail: [email protected].