Figure 2  .

Prevalence of ventricular preexcitation in schoolchildren. High school students have significantly higher prevalence of ventricular preexcitation and left free wall pathway than elementary and junior high school students. Prevalence of ventricular preexcitation: p = 0.00086 v elementary school; p = 0.00036 v junior high school. Prevalence of left free wall accessory pathway: p = 0.0021 v elementary school; p = 0.00032 v junior high school. Prevalence of ventricular preexcitation in elementary v junior high school was not significant.