Sudden cardiac death is defined as a nontraumatic, nonviolent, unexpected event resulting from sudden cardiac arrest within six hours of a previously witnessed state of normal health.1 Reliable estimates of the frequency of sudden cardiac death in young athletes are lacking. Such events are believed to occur in about 1 per 200,000 high school athletes per academic year.2,3 From 1983 to 1993, the National Center for Catastrophic Sports Injury Research4 found that non-traumatic sports-related deaths occurred in 126 high school athletes and 34 college athletes (about 16 deaths per year); 100 of these deaths were cardiovascular in origin. Estimated death rates in high school and college athletes were fivefold higher in men than in women (7.5 per million per year versus 1.3 per million per year).4
Most fatalities in child and adolescent athletes are caused by underlying congenital cardiac anomalies, primarily hypertrophic cardiomyopathy (36 percent), coronary artery abnormalities (19 percent) and increased cardiac mass (10 percent).3 The remaining percentage is composed of a constellation of cardiovascular and noncardiovascular causes including myocarditis, Marfan syndrome, mitral valve prolapse, dysrhythmias, aortic stenosis, Wolff-Parkinson-White syndrome, idiopathic long QT syndrome, arrhythmogenic right ventricular dysplasia, cocaine and anabolic steroid use, bulimia, anorexia nervosa, bronchospasm and heat-related illness.3,5–11 Coronary artery disease in adolescent athletes, unlike in the adult population, is an uncommon cause of sudden death. Detection of cardiovascular abnormalities that may cause substantial morbidity or sudden death is difficult, considering that congenital cardiac abnormalities relevant to athletic screening account for a combined prevalence of about 0.2 percent in athletic populations.3
The low yield of clinically significant cardiac abnormalities from screening has generated debate about the usefulness of the cardiac portion of the sports preparticipation physical evaluation (PPE).3,6,12–17 The practicality and utility of screening are limited by the low prevalence of relevant cardiovascular lesions in the general youth population, the low risk of sudden death even among persons with an unsuspected abnormality and the large size of the competitive athletic population (approximately 8 million high school and college sports participants each year).3,13 It is estimated that 200,000 children and adolescents would have to be screened to detect 1,000 athletes who are at risk for sudden death and one person who would actually die.14 Despite their rare occurrence, underlying cardiac anomalies in young athletes are emphasized because of the potential they pose for causing cardiovascular collapse during competition.
Currently, there is no cost-effective battery of tests to identify all, or even most, of the dangerous cardiovascular conditions.3,12,14 Various screening methods for sudden cardiac death have been investigated, including history and physical examination alone or coupled with screening echocardiography and electrocardiography, but no clear-cut cost-effective method has emerged.
AHA Recommendations for Screening
Because of heightened concern about sudden death in competitive athletes, the American Heart Association (AHA) issued consensus recommendations in 1996 (Tables 1 and 2) for the cardiovascular component of the PPE.3 According to the AHA, the focus of cardiovascular PPE screening is “to provide medical clearance for participation in competitive sports through routine and systematic evaluations intended to identify clinically relevant and preexisting cardiovascular abnormalities and thereby reduce the risks associated with organized sports.”
A complete, careful personal and family history and physical examination are recommended to identify or raise suspicion of cardiovascular lesions known to cause sudden cardiac death or disease progression in young athletes. The cardiac history focuses on questions that screen for congenital heart disease and symptoms that suggest an underlying cardiac problem. When cardiovascular abnormalities are identified or suspected, the athlete should be referred to a specialist for further evaluation or confirmation.
Despite a lack of compelling evidence to show that cardiovascular PPE screening is effective, it is recommended based on cost and medicolegal considerations. While this method may be imperfect, the AHA panel considered it the most practical and best available strategy for screening large populations of athletes.
Noninvasive testing (e.g., echocardiography and electrocardiography [ECG]) can enhance the diagnostic power of the standard history and physical examination, but it is not recommended for cardiovascular PPE screening. Comprehensive and expensive screening tests have not proved to be cost-effective, nor can they consistently identify athletes at risk. This considers the large number of competitive athletes in the United States, the relatively low frequency of cardiovascular lesions responsible for these deaths and the low rate of sudden cardiac death in young athletes. The widespread use of non-invasive testing in athletic populations is impractical and could result in many false-positive test results, with the likelihood that the number of false-positive results would greatly exceed the number of true-positive results.
Consensus Guidelines of PPE Task Force
Some form of preparticipation screening of athletes is customary medical practice in many high schools, colleges and universities in the United States. Through PPEs, physicians have an opportunity to evaluate and counsel a large segment of the population who may not otherwise have sought medical care. As indicated in Table 3, the PPE is not intended to exclude athletes from participation but to maintain their health and safety. The PPE should focus on ensuring the safety of the adolescent athlete by assessing health problems that could interfere with athletic performance and, to the extent possible, be used as an opportunity to counsel young athletes on the important health issues of adolescence.12,18
In 1997, the Preparticipation Physical Evaluation Task Force,12 composed of members of the American Academy of Family Physicians (AAFP), American Academy of Pediatrics (AAP), American Medical Society for Sports Medicine, American Orthopaedic Society for Sports Medicine and American Osteopathic Academy of Sports Medicine released the second edition of a guide for physicians who perform PPEs. The monograph covers the goals of the PPE, gives detailed instructions on how to obtain a preparticipation history and perform a physical examination, and information on determining clearance for participation, and discusses medicolegal precautions. It establishes the minimum content for PPEs and provides an outline for primary care physicians regarding appropriate steps in the PPE. No optimal method of delivery of PPEs is endorsed. If the athlete's history and physical examination findings raise suspicion, further diagnostic work-up is recommended, including echocardiography, ECG or exercise stress testing. Like the AHA panel,3 the PPE Task Force determined that routine use of such procedures in preparticipation screening is not cost-effective.
The monograph includes a “Preparticipation Physical Evaluation” form (Figure 1) that physicians can copy and use for each examination. Three items recommended by the AHA are not included on this form (i.e., family history of heart disease, a specific item for recognition of a heart murmur in the physical examination and a specific item for recognition of the physical stigmata of Marfan syndrome).19 While these discrepancies may be considered by the PPE Task Force in the future, use of the current PPE form can help ensure that examining physicians consider the following components of the cardiac evaluation recommended by the PPE Task Force.
It is unlikely that many young athletes who experience chest pain, syncope, exercise intolerance or palpitations, or who have a clinically significant family history will reveal such information unless specifically asked. The medical history is therefore a critical aspect of the cardiac evaluation. Careful attention to the cardiac history is warranted because several of the conditions known to cause sudden cardiac death (e.g., arrhythmias, premature coronary artery disease and aberrant coronary arteries) have no auscultatory findings. If possible, the student athlete and a parent should complete the history form together before the physical examination.
Dizziness, lightheadedness or syncope during or after exercise may indicate underlying hypertrophic cardiomyopathy, conduction abnormalities, arrhythmias or valvular problems such as aortic stenosis and mitral valve prolapse. Chest pains during or after exercise may indicate a coronary artery anomaly or advanced cardiovascular disease. Dyspnea that is out of proportion to activity may indicate structural abnormalities, valve problems or underlying lung disease.
Palpitations during or after exercise may signal arrhythmias or conduction abnormalities. A history of high blood pressure, high cholesterol levels, recent viral illness (e.g., myocarditis, mononucleosis) or prior restriction from participation in sports for cardiovascular reasons warrant further investigation. A history of heart murmur merits concern, although a benign murmur may be detected on examination of many athletes.
Relevant history should include recent legal and illegal drug use (including alcohol and tobacco), eating disorders, history of congenital heart disease or previous cardiac surgery. A family history of sudden death before age 50 is extremely important, as some causes of death can be familial (premature coronary artery disease, Marfan syndrome and hypertrophic cardiomyopathy). Any history that suggests a risk for congenital heart disease should stimulate more in-depth cardiac evaluation.
A complete physical examination is not indicated in a sports PPE. Screening is generally limited to physical examination of the cardiovascular and musculoskeletal systems, eyes, oral cavity, ears, nose, lungs, abdomen, genitalia (males) and skin. Anthropometric measurement includes height, weight and blood pressure. Cardiovascular examination should include resting blood pressure, palpation of radial and femoral pulses and auscultation of the heart.
Auscultation of the Heart. Auscultation of the heart should be performed with the patient in standing and supine positions to detect murmurs and dysrhythmias. Murmurs in adolescents are common, and various maneuvers can be performed to help differentiate functional from pathologic murmurs. Murmurs should be evaluated on the basis of intensity, loudness, location and timing during the cycle. Any systolic murmur grade 3/6 or higher, any diastolic murmur and any murmur that gets louder with the Valsalva maneuver should be evaluated further before the athlete is cleared for participation.
Attention should also be given to the presence of clicks and extra heart sounds. If the physician is in doubt regarding the cause of any murmur, the athlete should be referred to a cardiologist for further evaluation, and clearance should be deferred pending results of that examination. Detected arrhythmias also may require further cardiac evaluation.
Blood Pressure and Pulses. In children and adolescents, blood pressure should be compared to age-adjusted tables. If the blood pressure remains elevated above the age-related criteria for hypertension after a 10- to 15-minute rest period, the athlete should be questioned about the use of caffeine, nicotine or even over-the-counter stimulants such as ephedrine, and referred to his or her own personal physician for evaluation before clearance. Peripheral pulses (radial and femoral) also should be measured for rate and rhythm and to rule out coarctation of the aorta.
When a significant cardiovascular problem is identified, management decisions must include the magnitude of that person's risk for sudden death with continued participation in competitive sports and whether the athlete should be disqualified from such participation. In addition to clinical judgment, physician decisions regarding clearance for a particular sport may be based on guidelines established by the AAP Committee on Sports Medicine and Fitness or, for cardiovascular abnormalities, on the 26th Bethesda Conference guidelines.20 The report of the 26th Bethesda Conference (sponsored by the American College of Cardiology [ACC] and the American College of Sports Medicine [ACSM]) reviews the nature and severity of about 70 relevant cardiovascular abnormalities and diseases, and provides specific recommendations for athletic eligibility. The AAP recommendations address cardiac problems in addition to other potentially disqualifying medical conditions and divide sports into contact categories, based on risk of injury from collision, and categories based on degree of strenuousness.21
Any restriction to activity should be fully explained to the athlete, parents, coaching staff and other school personnel.12 If an athlete has not been cleared for a particular sport, the physician needs to act as the athlete's advocate and advise the athlete, family and athletic staff regarding the risk of participation. Physicians who perform PPEs should inform athletes and their parents of the limitations of cardiovascular screening and the small risks that may remain despite normal findings in the screening examination. Should the athlete and parents risk participation, it is generally necessary for them to sign a legal document stating that they understand the potential risk of participation to the athlete, although such documents are not always legally binding. If the athlete's condition is thought to be too great a risk to the person or a danger to the health of other participants, the athlete still may be excluded from participation.
Status of Preparticipation Screening
No uniformly accepted standards exist for conducting sports PPEs or certifying health professionals who perform these examinations.3,22 Decisions on PPE content are often made locally by school districts and even individual schools, resulting in great variation in the way PPEs are conducted. While all states that designate specific examiners recommend that physicians be responsible for preparticipation screening, 21 states allow nurses or physician assistants to conduct PPEs, and 11 states allow chiropractors to provide athletic clearance.22
A survey of state high school athletic associations in the 50 states and Washington, D.C., revealed that eight states did not offer an approved history and physical examination questionnaire to guide PPE examiners, and one state (Rhode Island) had no preparticipation screening requirement.22 Of 43 states that had approved PPE forms, only 17 (40 percent) had history and physical examination questionnaires that incorporated most of the 1996 AHA recommendations. Despite the availability and medical endorsement of a standard PPE form,12 a nationwide survey of 254 high schools revealed that only 17 percent used forms that contained all the elements of the cardiac history recommended for identifying athletes at risk for sudden death.23
A survey of 879 National Collegiate Athletic Association colleges and universities found that PPE screening was required by 855 schools (97 percent) and was required annually by 446 schools (51 percent).24 Analysis of PPE forms from 625 of these schools revealed that 163 (26 percent) incorporated most of the 1996 AHA recommendations for cardiovascular PPE screening.
Cardiovascular PPE screening poses problems because potentially fatal abnormalities are uncommon and in some cases undetectable without sophisticated tests. Most sudden cardiac deaths in athletes are caused by anomalies that are clinically silent, rare or difficult to detect by history and physical examination. Many athletes may not experience symptoms consistent with heart disease or may not report family histories of sudden cardiac death. Important clues to a cardiac abnormality include history of syncope, chest pain and family history of sudden death. Any underlying condition suspected on the basis of history or physical examination requires further diagnostic evaluation before the athlete can be cleared for activity.
Because of variability and inconsistency among state requirements for PPEs, adoption of a more uniform PPE screening process must be encouraged to close the gap between screening practices recommended by sports medicine experts and actual practice. Training or accreditation of PPE examiners also should be considered.
While the extent of screening continues to be debated, clinical guidelines for performing PPEs and determining clearance have been established. For cardiovascular screening, a focused personal and family history and physical examination are recommended by the AHA and seven other medical organizations as the best available methods of identifying risk factors for sudden death in young athletes. Without standardized methods for screening athletes for occult and possibly lethal heart disease, it is not possible to assess the value of a focused history and physical examination in detecting and preventing cardiovascular death.
Future advances in the diagnosis, treatment and understanding of cardiovascular disease will likely provide better tools for preventing sudden death in young athletes. Physicians should be alert to the emerging role of genetic testing for cardiovascular diseases in athletes with a family history of heart disease or sudden cardiac death (e.g., hypertrophic cardiomyopathy, long QT syndrome) or a known genetic disorder in which cardiac problems may be a component (Marfan syndrome). Currently, genetic screening (i.e., for hypertrophic cardiomyopathy) is not practical or feasible in large populations.3,25 As this technology becomes more available, the medical, ethical and legal implications of genetic testing of athletes will require careful deliberation.