The overall rate of sudden death in male athletes younger than 35 years is quite low, approximately 0.75 per 100,000 participants per year.¹ Congenital cardiac anomalies account for most sudden deaths in these patients. The most common anomalies are hypertrophic cardiomyopathy and coronary artery anomalies.¹

The most common coronary abnormality is a left main coronary artery originating off the right sinus. Myocarditis, rupture of the aorta, arrhythmogenic right ventricular dysplasias, idiopathic left ventricular hypertrophy, aortic stenosis and premature coronary artery disease account for most of the remaining fatalities.²

When large groups of young athletes are evaluated, few are disqualified because these disorders are suspected. Rather, the most common abnormalities leading to disqualification are musculoskeletal conditions, followed by other cardiac problems.³ Even when cardiac abnormalities are detected, the leading disqualifiers are rhythm and conduction abnormalities, systemic hypertension and valvular heart disease,⁴ not the cardiac abnormalities listed in the opening paragraph.

Screening History

CARDIOVASCULAR

The personal and family history of the athlete reveals 64 to 78 percent of conditions that could prohibit or alter sports participation, making it a more sensitive tool than the physical examination.⁵

The history more reliably detects risk factors and symptoms of coronary artery disease in older athletes than in younger athletes.² Hypertrophic cardiomyopathy, the most common cause of death among 12- to 32-year-old athletes on the field, may not produce symptoms before sudden death.⁶ All potential athletes should be asked about previous injuries and levels of physical activity. The latter information is particularly important in a potential athlete more than 35 years of age who has been sedentary and is now contemplating a vigorous exercise program.

A personal history of congenital or acquired heart disease, as well as a history of hypertension or murmurs, should be noted. Symptoms of chest discomfort, shortness of breath, palpitations, syncope or near-syncope with exercise are important. A known family history of hypertrophic cardiomyopathy, Marfan syndrome or atherosclerosis (especially premature), as well as a history of unexplained sudden death in family members younger than 50 years, are all of concern.

Hypertrophic cardiomyopathy is a heterogeneous group of disorders acquired through autosomal dominant transmission with incomplete penetrance, and signs and symptoms may not become manifest until early adulthood.⁷ Detecting persons with Marfan syndrome before they participate in sports is important because the defective aortic media can rupture during basketball, volleyball and, presumably, other sports activities.⁸ Table 1 is a representative checklist of historical cardiovascular questions to ask in the preparticipation examination. The patient giving an affirmative answer to any of these questions would merit a more detailed assessment.

NEUROLOGIC

A report of burning pain, weakness, numbness or tingling in all four or only the upper extremities raises concerns of cervical spine impingement. Possible etiologies for this condition would include atlantoaxial instability, congenital fusions and disk herniations.

Medications and Substance Abuse

A medication history provides clues to current medical conditions, as well as a bridge into inquiries about nutritional supplements. Asking about the use of cocaine or anabolic steroids is particularly appropriate during a preparticipation physical examination because of the known cardiotoxic effects of these drugs.⁹ Eliciting information about patterns and amounts of alcohol use and the potential to be in an automobile with drunken drivers is appropriate in view of the overall mortality associated with these issues in the young adult population. Although alcohol use and the likelihood of riding with drunken drivers have nothing to do with the ability to participate in sports, this is a good opportunity to address these issues with young athletes.

Female Athletes

The American Heart Association does not recommend any gender-specific cardiovascular alterations in the screening of female athletes.² Young women are even less likely to experience sudden death on the athletic field than young men; women account for only about 15 percent of such deaths.² In female athletes, however, several predispositions should be considered.

Anorexia nervosa and other eating disorders are more common among female athletes than among male athletes. Screening questions about desires to change weight or displeasure with body habitus identify many of these women. Female runners are 12 times more likely to develop stress fractures than are male runners.¹⁰ Osteoporosis occurs in amenorrheic female athletes and its finding should prompt further consideration of the possibility of an eating disorder. Women who play soccer and basketball are also more susceptible to patellofemoral syndrome, foot disorders (i.e., hammertoes, bunions, plantar fasciitis), stress fractures to the forefoot, and anterior cruciate ligament injuries.^11,12

Preparticipation Physical Examinations

The purpose of these examinations is to detect conditions that put the proposed athlete at risk for sudden death, but they have not been shown to be highly effective in this regard.¹³ A recent Italian study⁴ showed potential benefits in preventing sudden deaths when persons with certain conditions were disqualified (e.g., physical features of Marfan syndrome; delayed femoral arterial pulses; single, wide or fixed splits in the second heart sound; systolic or diastolic murmurs of grade 2/6 or greater; irregular rhythms; or blood pressures greater than 145/90 mm Hg). This study raises the issue of whether efforts to provide national screening and standards would be effective in the United States.

Table 2 presents the components of an appropriate physical examination. Individual alterations are appropriate, especially if the physician has had recent contacts with or recently examined the athlete, or has knowledge of the athlete's previous injuries and family history. Several items on the examination merit additional attention. Blood pressure must be interpreted on the basis of the patient's age, gender and height. For example, taller children may have higher readings and still be normotensive. Table 3 offers representative values, and the National High Blood Pressure Education Program's update on high blood pressure in children and adolescents offers more detailed coverage of this topic.¹⁴

Dynamic auscultation of the heart is critical in the detection of hypertrophic cardiomyopathy. In patients with this disorder, a soft systolic murmur along the left sternal border may be appreciated only when the patient stands up or during the straining phase of the Valsalva's maneuver, as these maneuvers decrease preload and the end diastolic volume of the left ventricle. Table 4 summarizes potential physical findings in patients with hypertrophic cardiomyopathy.

Ancillary Studies

ELECTROCARDIOGRAPHY

Routine screening use of 12-lead electrocardiography (ECG) for preparticipation physical examinations of high school and collegiate athletes is not recommended by the American Heart Association or other organizations.

In a normal, well-conditioned young athlete, the heart may develop ECG changes that falsely suggest ventricular hypertrophy; the specificity of the test is poor in this population.² Nevertheless, selective use of ECG can be useful in assessing young athletes who, on the grounds of history, family history or physical examination, are thought to be at potentially higher risk.

The resting ECG rate is abnormal in 80 to 90 percent of patients with hypertrophic cardiomyopathy, coronary anomalies and right ventricular dysplasias, as well as long QT interval syndrome. Figure 1 demonstrates a typical ECG from a patient with hypertrophic cardiomyopathy. The most common ECG abnormalities in patients with this condition are voltage criteria for left ventricular hypertrophy, abnormal ST-segments, T-wave inversion and deep Q waves.

ECHOCARDIOGRAPHY

Two-dimensional echocardiogrphy remains the diagnostic study of choice for detection of hypertrophic cardiomyopathy when the history and physical examination raise a suspicion of this disorder. Because hypertrophic cardiomyopathy represents a heterogeneous group of disorders, DNA testing is not a practical substitute. Echocardiograms can also confirm valvular pathology and demonstrate left ventricular dysfunction, aortic root dilatation and sometimes even aberrant origins of the left main coronary artery. They are not cost effective in large-scale general screening programs. Problems with false-positive results (e.g., enlargement in left ventricular wall thickness that occurs as a normal physiologic adaptation in the athlete) and false-negative results (e.g., hypertrophic cardiomyopathy may not demonstrate septal thickening until the end of adolescence) can occur.²

EXERCISE STRESS TESTING

Exercise stress testing has also not been shown to be cost effective in large screening programs of young athletes. It is appropriate in the older athlete with known coronary artery disease or when symptoms suggest stable angina or exercise-induced anginal variants. Table 5¹⁵ presents stress test exercise levels that are associated with less risk of sudden exercise-related cardiac events. Exercise stress testing is also appropriate when risk factors (e.g., hypertension, smoking, diabetes mellitus) are present and the patient is contemplating an increase in exercise intensity. The American College of Sports Medicine¹⁶ recommends exercise stress testing in men older than 40 years and women older than 50 years before starting a vigorous exercise program.

OTHER TESTS

The yield of urinalysis, complete blood counts and determination of serum ferritin levels is poor in asymptomatic, healthy sports participants. The results, even if abnormal, do not usually affect sports participation. These tests are not recommended in this setting.⁵

Medical Conditions and Sports

If the physician has identified a medical or orthopedic problem, the issue is whether to disqualify the athlete from the sport or allow the athlete to play with restrictions, with or without treatment. Most athletes are healthy; only 3 to 13 percent require further evaluation, and the disqualification rate for 10 million annual examinations is less than 1 percent.¹⁷

CARDIOVASCULAR DISEASES

A much more detailed assessment, often with specialist consultation, is required to define the nature and intensity of sports participation when conditions are discovered on screening. Some conditions that would prohibit any sports activity, or certain sports activities (as indicated by parentheses) are shown in Table 6. The potential for adverse outcomes cannot be clearly defined on the basis of whether a condition exists or not, but instead requires a more exact knowledge of the status of that condition. Although recent studies have shown that some patients with hypertrophic cardiomyopathy do not experience sudden premature death, 1 percent of persons diagnosed with the condition die of it each year.¹⁸

Cardiologist evaluation and clearance for a patient with hypertrophic cardiomopathy would be mandatory before any athletic participation. Survival is decreased in patients with advanced symptoms at the time of diagnosis, an obstruction gradient of more than 30 mm Hg, left ventricular wall thickness greater than 25 mm on ECG or associated atrial fibrillation.

Mitral valve prolapse (MVP) would not prohibit sports participation in the vast majority of patients. However, there is increased risk if MVP is associated with repetitive supraventricular dysrhythmias or ventricular dysrhythmias with a family history of sudden death, or with a history of embolism or marked mitral regurgitation; therefore, patients with these conditions should be limited to low-intensity sports.¹⁹ Sinus bradycardia and similar dysrhythmias are common in young athletes and, like non–exercise-induced ectopic beats, are not a basis for restriction in asymptomatic patients without structural heart disease.

Other dysrhythmias such as pre-excitation syndromes, atrial fibrillation, paroxysmal supraventricular tachycardia and ventricular tachycardia usually require that the athlete be asymptomatic, with documented control of the rhythm, for six months before sports participation can be approved. Associated structural problems with the heart or certain medications used to treat dysrhythmia-related conditions impose additional restrictions (e.g., no contact sports in a patient taking warfarin [Coumadin] for atrial fibrillation). The recommendations of the 26th Bethesda Symposium include a more detailed discussion of athletic participation in persons with cardiac abnormalities.¹⁹

MUSCULOSKELETAL INJURIES

Most studies have shown that musculoskeletal findings are the major category of abnormalities leading to restriction from sports activities.³ The most common musculoskeletal injury to restrict an athlete from activity is a knee injury, followed by an ankle injury.²⁰ In knee injuries, the chance of reinjury is high without proper rehabilitation.²¹ If the athlete must actively use a joint in the sport for which he or she is seeking clearance, several criteria must be fulfilled. There should be no joint effusion, reduced range of motion or symptomatic ligament instability, and at least 80 to 90 percent of normal strength must be present in the affected extremity. Ligament laxity can be a normal physical finding or trait, but symptomatic instability is pathologic.

HEAD AND CERVICAL SPINE INJURY

Concussions are the most common injuries in football. There is no clear agreement on definitions or classifications of concussion severity, treatment or clearance guidelines.²² Individual assessment and clinical judgment should prevail. In general, however, athletes with a history of concussion who have been asymptomatic for at least one week and show no residual neurologic deficits are allowed to participate in sports.

Any persistent symptoms of postconcussion syndrome (headache, dizziness, sensory changes or mental difficulty) are a contraindication to contact sports, even though they may take weeks to resolve. This cautious approach may prevent fatal second-impact syndrome in athletes who have a second concussion while recovering from a first.²³ The first concussion is believed to disrupt autoregulation of the brain's blood supply. If a second impact follows, vascular engorgement and increased intracranial pressure result, sometimes producing brain-stem herniation. This syndrome can occur even when the first concussion is mild, with symptoms of decreased alertness or postconcussion amnesia only.

“Burners” or “stingers” are usually secondary to a brachial plexus stretch or cervical root irritation. The athlete should be free of any neck or radicular pain, and have full range of motion and strength in all movements of the cervical spine before returning to sports participation.²⁴ Recurrent episodes or transient quadriplegia requires cervical radiographic studies before clearance.

CONVULSIVE DISORDERS

Guidelines from the American Academy of Pediatrics (AAP) ²⁵ clear young athletes with well-controlled convulsive disorders for participation in conventional school-sponsored sports. However, if a sport entails high risk (e.g., skiing, gymnastics, high diving), neurologic consultation should be considered. Athletes with poorly controlled seizures should be withheld from contact or collision sports and hazardous noncontact sports such as archery, riflery, swimming and weight lifting.

EXERCISE-INDUCED ASTHMA

Status asthmaticus is one of the nontraumatic causes of death in high school and college athletes. However, the incidence in survey populations is only four deaths in 30 million athletes.¹ Evidence of exercise-induced asthma is sought in the preparticipation examination so that medical prophylaxis (typically with a beta agonist) can be implemented, not to disqualify the athlete.

HEAT-RELATED ILLNESS

Leading causes of nontraumatic, noncardiac sports death are exertional hyperthermia, followed by exertional rhabdomyolysis and status asthmaticus.¹ Physicians can screen for a tendency toward exertional hyperthermia by asking about a previous history of heat-related illness. Athletes with this condition are usually allowed to participate in sports, but temperature extremes must be avoided, and hydration must be ensured.

SICKLE CELL TRAIT

The AAP and the National Collegiate Athletic Association recommend that persons with sickle cell trait be allowed to participate in sports without any restrictions.²⁵ There is evidence that persons with sickle cell trait have increased susceptibility to exertional rhabdomyolysis, with the potential for renal failure and death. Patients with sickle cell trait should be counseled about appropriate hydration and acclimatization to reduce risks.

High exertion and contact or collision sports are generally contraindicated in patients with sickle cell disease, even if appropriate hydration can be ensured.

SOLITARY ORGANS

Whether athletes with one paired organ, especially one kidney, should participate in sports is a topic of controversy. All such patients need to understand the risks so they can make an informed decision. No contact or collision sports are allowed if a single kidney is polycystic or abnormally located.

When an athlete has only one functional eye (with less than 20/40 corrected visual acuity), further evaluation by an ophthalmologist is recommended.²⁶ These athletes can participate only in sports (such as swimming, track and field, and gymnastics) that permit the use of protective eyewear and do not involve projected objects. Wrestling, boxing and martial arts are contraindicated sports.

The only modification for an athlete with one testicle is the use of a protective cup during contact sports. The chance of injury and the subsequent possibility of loss of fertility should be mentioned in counseling.

Final Comment

Although exercise-related sudden deaths in young athletes are rare, efforts to detect potential causes of such deaths are appropriate. Detection of solitary organs and preventive strategies for patients with this condition, especially those who are functionally uniocular, can avert morbidity. The preparticipation examination can achieve these goals and allow the family physician an opportunity to address the major health issues in young adults, such as alcohol and drug use, suicide, sexually transmitted diseases and pregnancy prevention.