Purpose To evaluate the prevalence of structural cardiac lesions using echocardiography in apparently healthy boys referred for pre-participation screening (PPS).

Subjects and methods 3100 male soccer players were evaluated by echocardiography in addition to the standard PPS.

Results In 56 subjects (1.8%), a structural cardiac lesion with potential future complication was detected. Specifically, hypertrophic cardiomyopathy (HCM) was found in two boys; bicuspid aortic valve (BAV) in 24; mitral valve prolapse in 10 and atrial septal defects (ASDs) in 20. Resting physical examination (PE) failed to identify any abnormalities in the majority of the subjects. All the boys presented an uncomplicated echocardiography, except two boys with HCM, one with BAV associated with aortic dilatation and one with a large ASD.

Conclusion Asymptomatic young athletes may have a structural cardiac alteration with the potential of present or future haemodynamic and arrhythmic consequences. A majority of mild cardiac lesions are difficult to diagnose or suspect by the current screening based on medical history, PE and ECG. Transthoracic echocardiography significantly improves the diagnostic power of screening in the detection of both mild and serious cardiac conditions in the athletic population.