Statistics from Altmetric.com
Sudden death (SD) in athletes represents a cardiac ‘earthquake’ affecting apparently healthy and highly trained individuals. This is not due to excessive demands on a normal heart, as occurred to Phidippides in Marathon, because our body has built-in safeguard mechanisms—dyspnea, angina, fatigue—to protect us from physical exhaustion. Autopsy investigations reveal that SD in athletes occurs three times more often than in non-athletes, and is caused by concealed cardiovascular abnormalities, mostly structural, that are unmasked by activity-triggered electrical instability.1–5 The structural culprits may be any of the cardiovascular components, including aorta, coronary arteries, myocardium, valves, conduction system and ion channels.1 The ECG is often abnormal, and its implementation in Italy for obligatory preparticipation screening has resulted in progressive reductions by 90% of SD in athletes aged 12–35 years between 1979 and 20024 (figure 1). This was mostly attributable to identification and disqualification of people affected by cardiomyopathies.
Arrhythmogenic right ventricular cardiomyopathy—unknown until the 1980s—is the major cause of SD in Italian athletes (relative risk 5.4 compared with non-athletes), and can now be identified at preparticipation screening by application of specific diagnostic criteria. Hypertrophic cardiomyopathy, on the other hand, was a rare cause of athlete SD in Italy compared with the US.4 ,6 In fact, abnormalities of the screening 12-lead ECG prompted echocardiography, which was diagnostic in 80% of cases compared with 23% of cases based only on physical examination and personal family history criteria.6 Nevertheless, only 50%–60% of disorders causing SD in athletes produce ECG abnormalities and other factors, apart from ECG screening, may have contributed to the 90% reduction in SD during the Italian programme. Certainly, the ECG alone is of limited value for screening atherosclerotic coronary artery disease,4 which ranks second as a cause of SD among athletes,1 ,3 ,4 with a relative risk of 2.8 compared with non-athletes. Congenital coronary anomaly, with origin from the wrong sinus, is the third most common cause of SD in US and Italian athletes,1 ,4 with a relative risk of 79.0 compared with nonathletes, but the ECG is of no help for early identification.7 This is a particularly high-risk group,3 best diagnosed by CT angiography or cardiac magnetic resonance. Similarly, structural valve abnormalities, like bicuspid aortic valve or mitral valve prolapse, may escape ECG examination, and in this setting, 2D echocardiography is the only way to make the diagnosis.1
How to detect diseases at risk of SD through cardiological screening
In the Italian system of preparticipation screening, there is a first-level examination consisting of personal and family history, physical examination, 12-lead ECG which, if negative, permits eligibility for competition. If the results are positive or borderline, a second-level examination is deemed necessary and should consist of non-invasive procedures (2D echo, stress test ECG, Holter monitoring, cardiac magnetic resonance, cardiac CT), and eventually third-level invasive procedures (coronary angiography, electrophysiological study, endomyocardial biopsy) (figure 2).3–5 Negative second-level and third-level investigations permit eligibility for competition. Otherwise, eligibility is denied, and the athlete becomes a patient and is managed according to established protocols, including genetic analysis when deemed necessary.
We believe that preparticipation screening for competitive sport should be applied worldwide.8 Limiting the process to personal and family history plus physical examination, as done in the US, cannot be considered sufficient.9 An increasing body of US opinion now agrees with this.10 The ECG plays a pivotal role, and is now recommended by the International Olympic Committee,11 with further endorsement by the European Society of Cardiology.8
Efficacy of the Italian screening programme
Critics claim that our Italian study of preparticipation screening was not a randomised trial, and its association with large reductions in SD among competitive athletes was not, therefore, necessarily linked. However, compelling features in support of a causal relation are (1) the coincident timing between the decline of SD and implementation of the screening programme, (2) the fact that declines in SD were most sharp for cardiomyopathies, and this coincided with a marked rise in the identification of cardiomyopathies among young athletes and (3) there was no change in the incidence of SD among the unscreened age-matched non-athletic population during the study period (figure 1).4 Critics argue that SD rates among screened Italian athletes remain excessive and are no different from SD rates reported in studies of unscreened US athletes, but this overlooks the fact that in those studies the athletes were younger, and a smaller proportion were male compared with the Italian data.12 ,13 The questionable accuracy of retrospective data collection further confuses the picture, and robust national registries of SD among athletes are essential.
False positive ECG findings
Critics argue that preparticipation screening may lead to exclusion of many athletes who are not at risk of SD, based on the misconception that physiologic ECG changes, caused by the heart`s adaptation to physical exercise (‘athlete's heart’), overlap with ECG abnormalities of cardiovascular disease. However, among 42 386 athletes initially screened by history, physical examination, and 12-lead ECG, 9% resulted positive and, with further investigation, 2% were diagnosed with cardiovascular disorders putting them at risk of SD, and 0.2% were ultimately disqualified.4 The percentage of false positive results was 7% for all cardiovascular disorders, and 8.8% for heart diseases at high risk of SD. In the UK, false positive rates of only 3.7% have been reported.14 In certain ethnic groups, particularly black athletes, there is a higher prevalence of ECG abnormalities with greater potential for false positive findings.15 Recently, updated guidelines for ECG interpretation in the athlete have been proposed,16 and these have now been shown to significantly reduce the rate of false positive ECGs among athletes.17 Reducing the rate of unnecessary disqualifications among athletes, and to adapt rather than restrict sporting activity, remain central screening objectives.
Cost-effectiveness of ECG screening
This is often seen as a major issue, but there is evidence of the cost-effectiveness of ECG screening compared with history and physical examination alone. Thus, in California high school and college athletes aged 14–22 years, a screening ECG, in addition to history and physical examination, was found to save 2.06 life-years per 1000 athletes screened at an incremental cost of US$89 per athlete, with an overall cost-effectiveness ratio of US$42 900 per life-year saved (US$76 100 compared with no screening). The authors concluded that screening with an ECG can be cost-effective for SD prevention compared with common interventions, such as public access defibrillation or implantable cardioverter defibrillator.18 Nevertheless, we recognise that a screening ECG will not pick up all potential causes of SD among athletes, particularly coronary disease, while other causes of cardiac arrest, such as acute myocarditis (or commotio cordis) will be unaffected by screening. It is important, therefore, that secondary prevention strategies, particularly the availability of defibrillators at sporting events and people trained to use them, should proceed hand in hand with primary prevention screening strategies to synergistically reduce SD in competitive athletes.13 ,19
In conclusion, although antagonists usually base criticism of preparticipation screening around its questionable potential to fulfil Wilson and Jungner's screening criteria,20 they fail to provide robust arguments to disprove its efficacy. The 30-year Italian experience of preparticipation screening in millions of athletes has shown that such a population-based preventive strategy allows successful identification of young athletes affected by potentially malignant cardiovascular diseases, and leads to substantial reduction of mortality. No hypothetical considerations are sufficient to disprove this and, in the absence of evidence to the contrary, existing data provide the best evidence that screening by history, examination and ECG effectively decreases the risk of cardiac SD in athletes. Consideration should now be given to screening all school children aged 14–18 years, to extend protection against SD to all young people. This should no longer be considered a dream, but a reality.1 ,21
Contributors GT and CB drafted the article. All the authors revised it critically for important intellectual content and final approval of the version to be published.
Competing interests None.
Provenance and peer review Commissioned; internally peer reviewed.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.