Paediatric athletes are not just little athletes: setting up criteria for electrocardiogram and cardiac ultrasound evaluation of children practising sport

This editorial refers to ‘How to evaluate resting ECG and imaging in children practising sport: critical review and proposal of an algorithm for ECG interpretation’, by F.D. Ascenzi et al., https://doi.org/10.1093/eurjpc/zwac218. Participation in sports is perceived as ‘good for your health’. Indeed, science provides us with data to confirm this.1 Consequently, when sudden cardiac death (SCD) occurs in a young, healthy appearing athlete; this causes a shock in both close relatives and, through the usually ample press coverage, society as a whole. A feeling of injustice and fear arises in (parents of) athletes urging for an effective and early screening to prevent future events. Precisely, both of these aspects are of importance: what type of screening is effective and from what age can screening effectively be performed? Historically, pre-participation screening programmes have aimed to detect all individuals at risk of SCD and provide them with preventive measures to minimize or abolish this risk. The challenge of this process lies in the fact that the screened population consists of a predominantly asymptomatic and mostly healthy population, i.e. those not at risk. In terms of the Bayes’ theorem, the a priori probability of disease is very low (the incidence of SCD in young athletes is estimated to be around 1–2 in 100 000 athlete years.2) In this context, Roberts et al.3 have elegantly argumented that even a (non-existent) ‘super test’ that identifies all cases and gives a false positive result in only 5% of cases has a ratio of false positive over true positive of about 5000. In other words, the cost of preventing the one SCD is 100 000 tests plus additional tests for the 5000 false positives, making abstraction of the anxiety and insecurity in this latter group that is caused by the abnormal test result. This is not an argument against testing, but rather an argument to test wisely. In fact, we would argue for a paradigm shift: the purpose of a screening program should be to facilitate sports participation in a maximum of individuals while minimizing the risk of undesired events. This would take into account the simple mathematical reality that our current human, logistic, and scientific possibilities are insufficient to accurately detect all individuals at risk. This also implies that the best available means and optimal moment for testing should be employed in case a test is performed. It is a reality that even young athletes are being tested, and when they are tested both electrocardiogram (ECG) and echocardiography are commonly used tests. Previously, formal guidance to the interpretation of pre-adult ECG and echocardiography was lacking. This is where the authors of the current review4 are to be applauded. They provide a comprehensive overview of the scientific evidence on both these tests in the pre-adult population. The current European guidelines advocate the use of ECG next to taking a personal and family history and a full clinical examination in preparticipation screening of athletes.5 For adults, well-defined criteria have long been described to decide on the (ab)normality of an ECG in an athlete.6 In children, this matter is actually more complicated than in adults: the heart continues to develop during childhood with major changes taking place during puberty.7 Hence, adult criteria cannot be simply applied to children. Indeed, poor diagnostic accuracy was demonstrated when applying the 2010 European Society of Cardiology recommendations and fair diagnostic accuracy when applying Seattle criteria for children aged 11 to 18 years.8 Raggazzoni et al.9 point at the areas of interest: for example, ECG criteria for left atrial enlargement are mentioned as borderline ECG findings in the (adult) Seattle criteria, but research has pointed out that these have poor diagnostic value in children. For this reason, these criteria have been omitted in the paediatric criteria. Also resting heart rate is higher in children than in adults, and therefore the cut-off for bradycardia is set at 40 bpm for children under 14 years in contrast to 30 bpm in adults. Also, low QRS voltages are very rare in children,10 prompting the authors to include this as an abnormal finding. The authors do not mention formally which cut-off to use. A recent paper, however, points to the conventional 0.5 mV for the extremity leads.11 Therefore low voltage might be defined as <0.5 mV in the extremity leads. Previous studies have demonstrated that the addition of echocardiography to screening by medical history taking, physical examination, and ECG has little diagnostic value.12,13 However, when the resting ECG suggests an underlying pathology or when paediatric athletes have symptoms, suggesting cardiac disease echocardiography will be the first exam to perform. In this part of the review, the authors elegantly describe normal cardiac adaptation of paediatric athletes to training, which does occur early and in a relatively short time, even in preadolescent athletes.4 They also point towards the fact that different types of sports (as defined by Mitchell et al.14) result in different types of remodeling (increased wall thickness vs. dilatation of the cavities), with differences between the sexes and ethnicities. For the right ventricle, the authors conclude that where RV dilatation (in the absence of symptoms, ECG abnormalities, a positive family history of SCD and abnormal echo findings) is probably a physiological adaptation to exercise, while wall motion abnormalities are not. In conclusion, the current paper provides a comprehensive overview of the state of the art. However, it also demonstrates the presence of largely uncharted territories, highlighting an active need for more research on this topic. Certainly, a validation study is necessary to investigate the sensitivity and specificity of the suggested criteria, and further exploration of the normal physiological changes caused by training in paediatric athletes is warranted. After all, safeguarding our societies’ paediatric athletes without unnecessarily withholding them to perform sports or physical activity as a result of false positive test results is and will remain the main goal of (paediatric) cardiologists and other clinicians involved. All authors contributed to the writing of this paper. Funding: None declared. Data sharing is not applicable to this article as no new data were created or analyzed in this study.