ADHD Drug Affects on the Hearts of Kids

This article talks about the effects that ADHD drugs are having on kid's hearts. Apparently, the drugs are causing increased heart rate and other issues in kid's hearts. With heart disease being one of the top killers in the US, I don't see how this is not a big deal. Also, who knows what the long term effects such drugs can have on the hearts of children. What happens when they become adults? This question remains unanswered.