Metoprolol
"I was put on 25mg once daily a little over a year ago and it seemed to work wonders for a good while. Due to some other issues though we increased my dose to 100mg a day and I am pretty much tired most of the day, but at least I can walk up stairs and not pass out or my heart doesn't feel like it will leap out of my chest... kind of the price to pay not to deal with the SVT. Hoping the tiredness wears off soon."