Treating ADHD with LQTS?

hey all! i(26F) was diagnosed with LQTS about 14 years ago, and have also had very clear signs of ADHD my entire life. i was finally officially diagnosed with ADHD recently after meeting with a psychiatrist for the first time, and she prescribed me 18mg of Concerta. i'm a little nervous because it's a stimulant and i know that those of us with LQTS are naturally more susceptible to complications when it comes to stimulants. have any of you experienced taking stimulants to treat other issues, and what can i expect as someone with LQTS? just feeling nervous lol