7 July 2008
Sudden cardiac death (SCD) in younger athletes is typically the result of structural or electrical defects of the heart, many of which are the result of inherited (genetic) cardiovascular disorders. Unfortunately it is common for death to occur without any previous symptoms in apparently healthy athletes, which has led to the suggestion that screening, including physical examination, electrocardiography (ECG), and the taking of a family history, is advisable to prevent sudden cardiac death in this group. The cost effectiveness and utility of cardiovascular screening of athletes has been a subject of some debate, with the American Heart Association recommending against universal ECG screening in athletes whilst the European Society of Cardiology and the International Olympic Committee advocate it [Drezner JA, Khan K BMJ 2008;337:a309].
A new paper published in the BMJ reports on a national study of more than 30,000 Italian athletes, with a mean age of 30, screened by resting and exercise electrocardiography prior to participation in athletic events over a five-year period. Cardiovascular screening and demonstration of clinical eligibility to compete is a legal requirement in Italy; researchers from the Institute of Sports Medicine in Florence looked at the results of cardiovascular evaluation of prospective participants between 2002 and 2006 [Sofi F et al. BMJ 2008;337:a346].
Resting ECG patterns showed abnormalities in 6% of the athletes, but the majority of these were found to be ‘innocent’ (not of clinical significance). Exercise ECG patterns showed abnormalities in 4.9% of the athletes, including a total of 1227 in whom resting ECG patterns had been normal. Altogether, a total of 196 participants (0.6% of the total) were judged ineligible to participate in competitive sports, and of these a total of 159 were disqualified on the basis of cardiac findings. 126 of these (79.2%) had shown innocent or negative findings with resting ECG, but disease-associated abnormalities with exercise ECG. Although this research has been discussed in the context of young athletes, these individuals were generally older than those with normal ECG patterns, and age over 30 was found to be significantly associated with an increased risk of disqualification on the basis of abnormal exercise ECG findings.
The authors conclude that exercise ECG screening before participation in sporting events can identify those with cardiac abnormalities who are at risk of sudden cardiac death, and propose that follow-up studies should be performed in the expectation of demonstrating that disqualification of such individuals from participation would reduce the incidence of cardiovascular events among athletes. They note, however, that the diagnostic accuracy of the ECG screening was not demonstrated, since the results of subsequent medical investigations were not available.
Overall, 81% of athletes barred from sporting events on medical grounds were found to have cardiovascular disorders associated with a substantially increased risk of SCD. Notably, of these 159 individuals found to have cardiac abnormalities, family history of sudden cardiac death and physical examination had suggested problems in only six cases, and resting ECG patterns were normal in 126 cases. The use of exercise electrocardiography in addition to medical examination and assessment of family history as part of screening therefore made a substantial improvement on the detection rate of serious cardiovascular disorders, with a low rate of false positives.
Comment: The authors note the absence of follow-up data and analysis for this study, and it certainly has inherent limitations. For example, further investigative testing was only performed on individuals who screened positive; without performing the same clinical work-up on a group of people who had negative screening results, it is not possible to provide overall figures for the performance of the screening test. In particular we do not know the final sensitivity of the test, and thus do not know how many cases were missed, and we do not know whether any of the cases who screened negative were real negatives or, possibly had just been missed by the screening (negative predictive value)
The cost of the screening programme in Italy is reportedly estimated at around estimated €30 (£24) per participant, although without evidence that the actual numbers of sudden cardiac deaths are reduced (and by how many) as a result of this screening, the cost implications for health services cannot be accurately calculated. However, this recent study lends weight to the argument that exercise ECG screening of athletes is of value. Alison Cox of the charity Cardiac Risk in the Young, which carries out ECG screening in the UK commented: "The test we do costs £35, but when you consider the cost of the pair of trainers that the athlete is wearing, it seems a small price to pay for a test that could save your life" (see BBC news).