There are approximately 3000 to 5000 sudden-death episodes per
year in children and adolescents in the United States. There are
between 5 and 10 million children and adolescents participating
in organized sports activities, so the percentage of athletes dying suddenly
is quite small. Highly trained athletes are thought to represent
the most fit and healthy members of our society, so these tragic,
early, and unexpected deaths make a deep impression on us. The majority,
approximately 40% to 50% of sudden deaths, are
caused by hypertrophic cardiomyopathy. Between 10% and 20% will
be caused by coronary abnormalities (usually the left or right coronary
artery arising from the wrong sinus origin or a single-coronary
artery origin). The remaining 30% will be caused by such
lesions as myocarditis, dilated cardiomyopathy including noncompaction,
ion channelopathies (long QT) syndrome, Brugada syndrome, catecholaminergic
polymorphic ventricular tachycardia (CPVT), arrhythmogenic right
ventricular dysplasia (AVRD), Wolff-Parkinson-White (WPW) syndrome,
previous Kawasaki disease with undiagnosed coronary involvement,
commotio cordis, and connective tissue disorders with dilated aortic
roots (eg, Marfan’s). The incidence in the population of these
disorders is at most 0.3%. The percentage presenting for
screening would be thought to be even less, secondary to self-selection
not to participate in sports.