Negative T-waves & prolonged QT

Hi, I am a 22 year old male that has been having strange cognitive difficulties for about 7 years now. I got a sleep study done to rule out any sleep problems. My sleep study came back normal except they found something wrong with my heart. Throughout the entire night while I was asleep, I had negative T-waves and prolonged QT interval. Also, I think they said my heart beat was a little on the low side and asked me if I was an athlete. I am not an athlete and I do not do any form of exercise/physical activity for about 10 years.

I would like to ask some people on the board what could possibly be wrong. They referred me to a cardiologist, but my appointment is about a month away. Can anyone please give me some explanations as to what could possibly be wrong with my heart?  Also, could this heart problem be responsible for my difficulties in mental tasks/cognitive impariment?

Thanks for reading!