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A recent article by Wilson and colleagues 1 proposes the mandatory ECG screening of athletes as a means of reducing the risk of sudden cardiac death in this population. The idea of such screening originated with the studies of Dr Corrado and his colleagues in Italy. 2 The concept has subsequently received support from several European groups, Dr Corrado being involved in some of these: the International Olympic Committee Medical Commission, 3 the European Society of Cardiology 4 and the Féderation Internationale de Football Association (FIFA). 5
A proper starting point for a consideration of this issue is Bayes' theorem. This theorem makes clear that mass screening cannot be effective and will inevitably lead to a high proportion of false positive results if one is using a fallible test procedure when attempting to detect a rare risk. Wilson and associates 1 attempted to increase the frequency of their positive outcomes by assessing the frequency with which their ECGs detected certain "abnormalities" such as the Wolff-Parkinson-White (WPW) syndrome, thought to be associated with an increased risk of sudden death. One problem inherent in this approach is that most athletes have substantial left ventricular hypertrophy, and their ECGs (in essence the algebraic sum of 50 mV signals traversing both the left and right ventricles) are unlikely to conform to standards that in general have been developed on sedentary individuals. Perhaps for this reason, Wilson and associates 1 diagnosed three times the anticipated number of WPW syndromes in their sample of athletes. Italian evaluations of ECG screening were based on a flawed sample of 785 ostensibly healthy athletes and 220 individuals who had been referred for cardiac evaluation; these studies also used an indirect criterion of success, namely a correspondence between reported ECG "abnormalities" and a combination of clinical judgment and echocardiographic criteria. 6 However, the...