Thanks! You're right--I need to have a doctor looking at the whole picture.
You need to discuss these issues with your doctor, you need to have one doctor who knows all of the prescriptions and other medications/preparations you are taking. I know my cardiologist nurse goes through the list with me every time I have a visit. Same for my primary care.
I think you can take the mitral valve prolapse off your list of concerns relative to the medication subject...but if you cardiologist thinks otherwise, then that's the answer.
I think any stimulant would aggravate most, if not all, forms of heart rhythm problems. How much is an unknown until tried. As for taking a beta blocker to counteract a stimulant, sounds like a strange idea to me, but I have no information on how they would interact/react/conflict..