Alfred A. Bove, M.D., Ph.D., F.A.C.C.; Peter C. Block, M.D., F.A.C.C.



In This Article


In 2005, consensus panel recommendations of the 36th Bethesda Conference were published, reviewing the eligibility and disqualification of competitive athletes. The first Task Force report focused on preparticipation screening and the diagnosis of cardiovascular disease in athletes.[1] The ultimate objective of preparticipation screening carried out in general populations of trained athletes is the recognition of "silent" cardiovascular abnormalities that can progress or cause sudden cardiac death.

Screening may be valuable if it raises the clinical suspicion of potentially deadly cardiovascular diseases. This approach might reveal a heart murmur with potential clinical significance, cardiac symptoms (e.g., exertional chest pain, disproportionate dyspnea, or impairment in consciousness), or a family history of heart disease or sudden unexpected death.

For the past 25 years, Italy has supported a formal program of preparticipation screening and medical clearance that is mandated for young competitive athletes in organized sports. The nationwide effort is unique in that it requires annual evaluations that routinely include a 12-lead electrocardiogram (ECG) as well as a history and physical examination. Data emerging from the Italian program suggest, for example, that the ECG itself is useful in identifying many previously undiagnosed athletes with hypertrophic cardiomyopathy (HCM).[2]

After evaluating the deaths of 158 competitive athletes in the United States who died suddenly, Maron et al. found that HCM was the most common structural cardiovascular disease identified at autopsy as the primary cause of death.[3] (Other cardiovascular causes of death in this study are listed on (Figure 1).) So, should the U.S. adopt a mandated preparticipation screening program like that in Italy?

Figure 1.

Cardiac Issues in Athletes

That's a complicated question. The Bethesda Conference Report participants said that the largest obstacle to implementing a large-scale screening program in the U.S. is the substantial number of young athletes eligible for evaluation (about 10 to 12 million) and the rarity of the cardiac diseases capable of causing sudden death in this population (estimated prevalence: ≥0.3%).[1] Also, a substantial proportion of false-positive test results would potentially represent a major burden to athletes, their families, and the testing facilities.

Another issue: The previously mentioned review of deaths among U.S. athletes determined that 115 of them had undergone a standard preparticipation medical evaluation, but only 4 (3%) were suspected of having cardiovascular disease. Moreover, the cardiovascular abnormality responsible for sudden death was correctly identified in only one athlete (0.9%). The authors concluded: "Preparticipation screening appeared to be of limited value in identification of underlying cardiovascular abnormalities."

Bethesda Conference Report participants did acknowledge concerns regarding the quality of cardiovascular screening for U.S. high school and college athletes. The design of approved questionnaires has come under scrutiny based on evidence that they are inadequate when measured against official recommendations. These recommendations for preparticipation athletic screening are shown in Figure 2 and include a cardiovascular history (based on both family and personal history) and a physical examination, including brachial artery blood pressure measurement.[4]

Figure 2.

Recommendations for Preparticipation Athletic Screening

"Athlete's Heart"

Compounding the problem of trying to assess risk in highly trained athletes is an area of overlap between structural changes due to intense training regimens and pathological conditions such as cardiomyopathies, myocarditis, and arrhythmogenic right ventricular cardiomyopathy (ARVC) (Figure 3). Differentiating these cardiac problems from the non-pathological "athlete's heart" presents an important clinical challenge.[5,6]

Figure 3.

Gray Area of Overlap between "Athlete's Heart" and Cardiomyopathies

For example, left atrial (LA) size was examined in 1,777 competitive athletes in Italy. LA size greater than the conventional upper limit of normal (40 mm) was observed in 20% (up to 50 mm in males and 45 mm in females).[7] Multivariate analysis showed that LA enlargement in competitive athletes was largely explained by left ventricular (LV) cavity enlargement and participation in dynamic sports such as rowing and bicycling. In the U.S., professional basketball players also may exhibit increased LA size, usually related to their large body size.

Another study trying to determine what's normal and what's pathological sought to measure the physiological upper limits of ventricular cavity size in 900 elite adolescent athletes from the British national sports training grounds and Olympic Medical Institute.[8] They were compared with 250 healthy controls matched for age, sex, and size. These highly trained junior athletes had only modest increases in LV cavity size (50.8 mm vs. 47.9 mm) when compared with controls.

A proportion of the trained athletes (117 or 13%) had LV cavity size exceeding predicted values but, in absolute terms, none of the athletes had an LV cavity larger than 60 mm as in patients with dilated cardiomyopathy. Left atrial diameter and LV wall thickness were enlarged, too, but systolic and diastolic function were both normal. LV cavity size correlated with age, sex, heart rate, and body surface area. The authors recommended that in highly trained athletes with an LV cavity size >60 mm, the diagnosis of dilated cardiomyopathy should be considered, even without impairment of systolic or diastolic function.

Could the increased size of the highly trained athlete's heart be problematic? Sudden death in athletes is usually mediated by ventricular tachyarrhythmias and there is evidence that these structural changes may contribute to frequent and complex ventricular tachyarrhythmias. Whether this finding actually increases risk is a question asked by Maron and colleagues who prospectively evaluated the clinical relevance of ventricular arrhythmias assessed by 24-hour ambulatory ECGs in 355 competitive athletes.[9] The athletes were studied either because of palpitations, the presence of >3 premature ventricular depolarizations on resting 12-lead ECG, or both.

The authors found that these arrhythmias were usually unassociated with underlying cardiovascular abnormalities, which were detected in only 26 (7%) of the young athletes. During follow-up (mean: 8 years), only one athlete died suddenly (of arrhythmogenic right ventricular cardiomyopathy) while participating in a field hockey game against medical advice. The researchers concluded that such ventricular arrhythmias, when unassociated with cardiovascular abnormalities, do not convey adverse clinical significance. They appear to be an expression of "athlete's heart syndrome," and probably do not per se justify a disqualification from competitive sports.

What happens when there is diagnostic uncertainty as to whether the changes in a specific athlete are or are not pathological in nature? The Bethesda Conference Report consensus was that the issue may be resolved in many athletes by a number of independent noninvasive clinical parameters, including the response of cardiac mass to short periods of deconditioning, or assessment of diastolic filling (Figure 4).

Figure 4.

Criteria to Distinguish Hypertrophic Cardiomyopathy (HCM) from Athlete's Heart

The final report emphasized: "It is the premise of the expert panel that firm recommendations for temporary or permanent sports disqualification be confined to individual athletes with probable or conclusive evidence of disease rather than those with only borderline findings or the presumption of a diagnosis. In this way, unnecessary restrictions from sports and the stigma of a cardiac diagnosis in healthy individuals may be minimized."

In this interview, Cardiosource Editor Alfred A. Bove, MD, PhD, FACC, discusses issues important to any cardiologist who is faced with evaluating young athletes. Topics include recommendations for preparticipation screening, when to consider additional tests, and what has been learned from studying "athlete's heart."


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