The sudden unexpected death of a young athlete during training or competition is a particularly devastating tragedy. A previously well adolescent who is participating in an especially healthy, wholesome activity suddenly collapses, and on-the-field resuscitation efforts appear to be almost invariably unsuccessful. Fortunately, such events are very rare; it has been suggested, in fact, that the number of lectures and articles dealing with this issue far exceed the actual number of athletic-related deaths. Nonetheless, the sudden death of an athlete creates a shock-like impact on the community, and invariably questions are directed to the school and physician: Could this death have been prevented? If so, what can be done to assure that such catastrophes do not recur? This article addresses these questions, particularly as they relate to the practicing physician who carries the responsibility for clearing young athletes for sports participation.
The specific risk of sudden death in the previously healthy athlete has not yet been clearly defined. Epstein and Maron estimated that one such tragedy might be expected to result annually from heart disease, the most common etiology, among every 200 000 participants (.0005% per year).1 This means that in a city of one million inhabitants, a sudden cardiac death during sports participation might be expected to occur approximately once every 4 years. Among the estimated five million boys and girls who participate in high school athletics, then, about 25 will die unexpectedly each year during training or competition from heart disease.
In reviewing data from the National Center for Catastrophic Sports Injury Research at the University of North Carolina, Mueller and Cantu reported a total of 75 sudden deaths from "indirect causes" in high school athletes in the 5 -year period between 1982 and 1986.2 These causes included not only heart disease, but also other problems such as heat stroke, sickle cell crisis, and asthma.
It is of importance to place the risk of a previously healthy adolescent dying during sports participation in perspective with other risks of unexpected fatality during the teenage years (Table 1 ).
A large number of etiologies have been incriminated in the sudden unexpected death of athletes. This article focuses on cardiovascular causes as the most likely and ignores others that may be less amenable to medical screening or prevention (eg, trauma, dehydration, and drugs). Although perhaps debatable, it is likely that most if not all cardiac causes of sudden death in athletes are related to underlying anatomic or electrophysiologic heart disease. Most reports of sudden death in athletes do include a small number categorized as idiopathic, but this may reflect the difficulties in identifying anomalies of the cardiac conduction system and focal coronary disease at autopsy. It seems unlikely that sudden death can occur in the athlete with a previously normal heart.
The corollaries of such a conclusion are that disease states that predispose to death from physical activity should potentially be identifiable and that the preparticipation evaluation should serve as an effective preventive tool. Fortunately, the forms of heart disease known to predispose to sudden death during sports participation in young athletes are rare; unfortunately, they are often occult and in many cases not easily detected by routine preparticipation screening examinations. It is the role of the physician to recognize those anomalies that can be identified; some, however, can be expected to defy detection by all but the most sophisticated diagnostic techniques.
Four cardiovascular anomalies constitute the majority of lesions that pose a risk for sudden death in young athletes: hypertrophic cardiomyopathy, Marfan syndrome, congenital coronary artery anomalies, and valvular aortic stenosis.3,5
Hypertrophic cardiomyopathy (asymmetric septal hypertrophy, idiopathic hypertrophic subaortic stenosis [IHSS]) is probably the leading cause of sudden unexpected death in young athletes. This autosomal dominant condition is characterized by idiopathic hypertrophy of the entire left ventricle, which asymmetrically involves the ventricular septum to a greater extent than the posterior free wall. Such hypertrophy can be truly dramatic, sometimes virtually obliterating the left ventricular cavity. Significant obstruction to outflow is evident in only a minority of cases and does not relate to symptoms or risk of death. Instead, sudden death is presumably associated with abnormalities in diastolic filling (a "muscle-bound'' heart) and insufficiencies in myocardial perfusion.6
Accidental Deaths In Adolescents*
By whatever means, sudden death is not uncommon, with a risk as high as 2% to 4% per year in some series. This risk has traditionally been associated with exercise. An analysis of 75 adult patients dying with hypertrophic cardiomyopathy indicated that 37% died at rest (four were asleep), 24% during mild exertion, and 29% during moderate to severe exertion (running, hiking, lifting, or horseback riding).7 At least in this series, then, sudden death from IHSS did not occur disproportionately during high levels of activity, but death did appear to be reasonably common during more vigorous exercise.
Whether limiting these patients from physical activities will improve their longevity is unknown. However, based on data such as these, restriction of these patients from participation in competitive sports is considered important. Detection of patients with IHSS is not, however, always easy. History-taking may prove valuable since about 60% of patients will complain of symptoms (dyspnea, angina, and syncope), particularly with exercise, and a family history of IHSS can be obtained in 20% of cases.8
The physical examination, unfortunately, is often deceptively benign. One fourth of patients will have only a faint or absent murmur. The murmur is louder along the left sternal border if there is obstruction to aortic outflow, but this can be mistaken for either a ventricular septal defect or innocent flow murmur. Certain clues can be helpful but are not always present; in patients with hypertrophic cardiomyopathy, the murmur intensifies with standing or with the Valsalva maneuver, the pulse may be bifid, and a separate murmur of mitral insufficiency may be audi' ble at the apex.
The electrocardiogram is frequently abnormal, and up to 90% will demonstrate left ventricular hypertrophy, deep Q waves, or ischemic changes. The echocardiogram, however, is the most definitive test for IHSS, showing the marked, asymmetric septal hypertrophy.
In summary, the clinical diagnosis of IHSS can be difficult without laboratory testing, particularly if the history is negative for symptoms or an affected family member. Fortunately, IHSS is rare. Its incidence is unknown, but based on the author's experience, it is probably no greater than 1:40 000. Those examiners who feel anxiety that a murmur in an athlete might reflect the presence of IHSS should be reminded that the incidence of innocent murmurs in young athletes may be as high as 50%9 (ie, on a statistical basis, one would have to investigate 20 000 athletes with a murmur before finding a case of hypertrophic cardiomyopathy).
Marfan syndrome is a hereditary disorder characterized by laxity of connective tissue. Its full-blown expression includes ocular abnormalities (dislocated lens and myopia), musculoskeletal disorders (scoliosis and pectus excavatum), tall stature, ara' chnodactyly, and hyperextensible joints. The major morbidity and mortality from Marfan syndrome results, however, from its cardiovascular manifestations. Aortic root dilatation, aortic valve incompetence, and mitral valve prolapse develop in a high percentage of cases, and the mean life expectancy of 32 years is accounted for by progressive aortic valve disease and dissecting aneurysms of the ascending aorta. The incidence of Marfan syndrome is approximately 1 :20 000. The frequency and clinical course of patients with partial manifestations of the syndrome (particularly those with limited cardiac involvement) is uncertain.
The potential risk of sports participation by individuals with Marfan syndrome became crystallized for both the lay public and medical profession by the sudden death of volleyball player Flo Hyman. This 31 -year-old star of the 1984 United States Olympic volleyball team collapsed during a game in Japan and died shortly thereafter, and cardiovascular findings at autopsy were regarded as typical of Marfan syndrome; death had resulted from a ruptured aortic aneurysm with pericardial tamponade.
The death of Flo Hyman shook the sports world and raised concern regarding the frequency and risk of Marfan syndrome in tall basketball and volleyball players. From the standpoint of physicians, it led to recommendations that individuals with Marfan syndrome be restricted from certain activities that might contribute to increased intra-aortic pressure and risk of predisposing to increased aortic dilatation - specifically, resistance training (weight lifting), sports that might involve a blow to the chest, and endurance athletic training.10 At present, there is no scientific evidence that such restrictions will slow the progression of aortic dilatation or decrease the risk for sudden death in these patients; however, such advice for those with cardiovascular manifestations of Marfan syndrome appears prudent.
At present, the detection of Marfan syndrome is based on recognizing the constellation of characteristic physical features, with echocardiography and ophthalmologic assessment as useful confirmatory diagnostic adjuncts. TKe mid-systolic click of mitral valve prolapse is usually the initial cardiac finding in children, with murmurs of aortic and mitral insufficiency appearing later. Chest x-rays and electrocardiograms are of no value, while echocardiography allows accurate qualitative and quantitative assessment of cardiac manifestations. A careful family history seeking to identify other members with Marfan syndrome is important; a family history of tall but otherwise healthy individuals, however, is more supportive of familial tall stature. Referral for echocardiography of the tall, healthy athlete without other clinical features or a family history of Marfan syndrome is not necessary.
Coronary Artery Anomalies
The sudden death of another famous athlete, basketball star Pete Maravich, highlighted the risk of congenital anomalies of the coronary arteries. One of the best basketball players ever, Maravich apparently demonstrated no signs of cardiovascular disease during a highly productive career. He died suddenly playing a recreational game when he was 40 years old. Autopsy showed a complete absence of the left main coronary artery. The right coronary served the left coronary distribution and a hypoplastic left anterior descending branch, and diffuse myocardial fibrosis was evident.11
Other congenital coronary anomalies have been associated with sudden death, particularly ectopic origin of the left coronary artery from the right sinus of Valsalva or the base of the main pulmonary artery.5 Fibromuscular stenosis of key coronary branches (ie, to the atrioventricular node) has also been described in children dying suddenly.
While symptoms of angina, palpitations, and syncope with exercise might be expected in such individuals, reported cases have typically involved previously asymptomatic youngsters with normal physical examinations. Whether electrocardiograms or treadmill stress tests would detect these anomalies is unknown.
Valvular Aortic Stenosis
Congenital stenosis of the aortic valve is the most common cardiac anomaly that can predispose the young athlete to sudden death.12 In fact, however, valvular aortic stenosis is not commonly reported in such tragedies because, in contrast to the previously described conditions, aortic stenosis is readily detected clinically. The finding of a loud murmur at the upper right sternal border radiating into the neck, with an associated thrill, prompts cardiac referral, assessment, and judgment regarding the safety of sports participation based on the severity of the outflow gradient.
Table 2 summarizes the effectiveness of screening methods for the most common cardiac causes of sudden death in athletes. The history and physical examination are clearly important and should allow initial detection of most individuals with Marian syndrome and valvular aortic stenosis as well as some with hypertrophic cardiomyopathy. If an electrocardiogram is added, more cases of IHSS will be detected, and an echocardiogram should identify all these patients. Most coronary artery anomalies are probably not screenable, although some cases can be potentially diagnosed echocardiographically.
It is generally agreed that the history and physical examination carry sufficient diagnostic power to screen for cardiovascular disease in the routine preparticipation screening of young athletes.4 Although laboratory testing, particularly echocardiography, might add to that diagnostic acumen, the expense and logistical considerations of using these procedures renders their routine use prohibitive. (At an approximate cost of $500 per study, for instance, the expense of detecting one potential fatality among 200 000 screened participants by echocardiography would be 100 million dollars - as well as about 50 000 hours of technician time.)
RESPONSIBILITIES OF THE PHYSICIAN
Concerns regarding sudden death during sports has been amplified by recent well-publicized tragedies of star athletes. Analysis of these cases has led to the conclusion that sufficient medical preparticipation scrutiny might prevent such deaths in a majority of cases. Certain realities, however, need to be considered:
Effective Screening Methods
1. The number of incidents of sudden death in athletes and the frequency of the diseases that cause them are both extremely rare. It is unlikely that a given physician will encounter a case in a lifetime of practice.
2. Many of the conditions causing sudden death in athletes are not easily detectable. It is not possible by any screening tools to make sports risk-free.
3. There is no proof that restriction of patients with these conditions from physical activity has any effect on their clinical outcome.
This is not to say that physicians shouldn't try. Physicians should be alert to conditions that predispose to sudden death with sports activities and intervene appropriately. In such efforts, however, it is important to avoid overzealous evaluations that defy the common sense assessment of costs and benefits. The history and physical examination remain the most efficient tools for evaluating risks for athletic participation. Additional laboratory testing should be reserved for those situations where a high suspicion of heart disease exists.
1. Epstein SE, Maron BJ. Sudden death and the competitive athlete: perspectives on pre-particiaption screening studies. J Am Coil Cardiol. 1986:7:220-230.
2. Mueller FO, Cantu RC. Catastrophic injuries and fatalities in high school and college sports, tall 1982-spring 1988, Med Sd Sports Exerc. 1990i22:73?-741.
3. McFaul RC Death on the playing field. Adolescent Medicine. 1991;2:93-107.
4. McCaffrey FM, Braden DS, Strong WB. Sudden cardiac death In young adnletes. Am JTXsChM. 1991;145:177-183.
5. Maron BJ, Epstein SE, Roberts WC, Causes of sudden death in competitive athletes. J Am CoU Cardia. 1986;7:204-214.
6. Maron BJ, Bonow RO, Cannon RO, Leon MB, Epstein SE. Hypertrophic catdlorayopathy, N Engl J Med. 1987;316:844-852.
7. Maron BJ, Roberts WC, Epstein SE. Sudden death in hypertrophic cardiomyopathy: a profile of 78 patients. Circulation. 1982:65:1388-1394.
8. Fiddler Gl, Tajik AJ, Weidman WH, McGoon DC, Ritter DG, Giuliani ER, Idiopathic hypertrophic subaortic stenosis in the young. AmJ Cardiol. 1978:42:793799.
9. Rowland TW, Delaney BS, Siconolfi SF. Athlete's heart in prepubertal children. Pediatrics. 1987;79:800-804.
10. Pyerict RE, McKusick VA. The Marfan syndrome: diagnosis and management. N Engl; Med. 1979;300:772-777
11. Van Camp SP, Choi JH. Exercise and sudden death. The Physician and Sportsmcdiant. 1988:16:49-52.
12. Lambert EC, Menon VA, Wagner HR, Vlad P. Sudden unexpected death from cardiovascular disease in children. AmJ Cardiol. 1974;34:89-96.
Accidental Deaths In Adolescents*
Effective Screening Methods