Sudden cardiac death in young athletes

Which screening strategy should be used to identify young athletes at risk for sudden cardiac death is a highly controversial matter. For many years the medical community has disputed the cost effectiveness, feasibility, and accuracy of including 12 lead electrocardiography in the cardiovascular screening of athletes. Discordant recommendations from the American Heart Association and the European Society of Cardiology have fuelled a global debate about the usefulness of such screening in athletes.1 2 In the linked study, Sofi and colleagues analyse data from 30 065 Italian athletes who underwent a complete pre-participation cardiovascular evaluation including resting and exercise electrocardiography.3

Sudden cardiac death in young athletes (<35 years) is caused by a diverse set of structural diseases of the heart (such as cardiomyopathies) and electrical defects (such as ion channelopathies). In the United States alone, one young competitive athlete dies every three days from an unrecognised cardiovascular disorder.4 American and European authorities have recommended a comprehensive pre-participation evaluation, which includes a detailed patient and family history and a physical examination, in all athletes of 12 years or more.1 2

Warning symptoms of underlying cardiovascular disease—exertional chest pain, syncope or near syncope, palpitations, excessive dyspnoea, and unexplained seizures—warrant cessation of sports activity pending the results of diagnostic tests. A family history of sudden unexplained death or sudden death before the age of 50 as a result of cardiac problems may also indicate the presence of a genetic cardiovascular disorder. Unfortunately, standardised questionnaires developed to help healthcare providers perform a comprehensive pre-participation evaluation are underused.5 Thus, important elements of the athlete’s history often go unrecognised.

A substantial challenge to screening is that apparently healthy asymptomatic athletes may have unsuspected cardiovascular disease—death is the first clinical manifestation of cardiac disease in up to 60-80% of athletes with sudden cardiac death.6 To date, no study monitoring sudden cardiac death has shown that a pre-participation evaluation based on history and physical examination can prevent or detect athletes at risk for sudden death.

The value of adding non-invasive cardiovascular tests such as electrocardiography to the screening process in athletes is widely debated. In 2007, the American Heart Association reaffirmed their recommendations against universal electrocardiographic screening in athletes, citing a low prevalence of disease, poor sensitivity, high false positive rate, poor cost effectiveness, and a lack of clinicians to interpret the results.1

In contrast, the European Society of Cardiology, International Olympic Committee, and the governing associations of several US and international professional sports leagues endorse the use of electrocardiography in the pre-participation screening of athletes.2 These recommendations are supported by studies showing that electrocardiography is more sensitive than history and physical examination alone at identifying athletes with underlying cardiovascular disease.7 8 9 10 In 1998, one study found that electrocardiography had a 77% greater power than history and physical examination to detect hypertrophic cardiomyopathy.9 In 2006, another study reported data from a national pre-participation screening programme in Italy in 42 386 athletes over 25 years.8 It found that disqualification on the basis of a standardised history, physical examination, and electrocardiography produced a 10-fold reduction in the incidence of sudden cardiac death in young competitive athletes, and an 89% reduction of sudden cardiac death as a result of cardiomyopathy.8 Although only 0.2% of athletes were disqualified for potentially lethal cardiovascular conditions, the study reported a 7% false positive rate and a 2% overall disqualification rate.8 This raised concerns that adopting such a programme would lead to an unacceptable number of disqualifications in athletes with low risk of sudden cardiac death.

Recent studies have refined the electrocardiography criteria used to distinguish normal from abnormal results—producing lower false positive rates. 10 11 12 A study of 2720 athletes and physically active schoolchildren in the United Kingdom reported that only 1.5% of those screened had a positive electrocardiogram.10 Another study reported preliminary findings of electrocardiographic screening in 9125 young adults (age 14-18) from the US and found that only 2% of tests were abnormal.11 These studies indicate that electrocardiographic screening in athletes results in an acceptable proportion of abnormal findings that can be of clinical significance.

The combined disease prevalence of all cardiovascular disorders that predispose young athletes to sudden cardiac death is around 0.3% (1/333).1 This estimate is confirmed by several studies using electrocardiographic screening in athletes with reported true positive rates of 0.2-0.4%.7 8 10 The consistency of these results across several studies in three different countries suggests that such screening may have similar value in different populations.

An important element of Sofi and colleagues’ study is that only a small proportion (1.2%) of athletes had distinct abnormalities identified on resting electrocardiography. As a result, false positives were few. Importantly, 153 of the 159 true positives involving athletes ultimately disqualified from sport with an identified cardiovascular disorder would have been overlooked on history and physical examination alone. 3 Thus, although a detailed personal and family history and physical examination will detect an important but limited number of athletes with underlying cardiovascular disease, adding electrocardiography to the screening process will detect more athletes with silent cardiovascular disorders at risk of sudden death.

The existing evidence supports a systematic pre-participation screening programme for all competitive athletes, using a comprehensive personal and family history questionnaire, physical examination, and screening electrocardiography to identify those at risk.