I have had issues with Lisinopril causing higher heart rates (thought i had super secret POTs at one point) was to the point i could not even move without palpitating all over the place. 20mg will definitely bring down the BP but, for me was way too much so i am now OFFICIALLY banned from it. IMO Lisinopril is a nasty little drug for some folks.
I am now only taking a beta-blocker and mestinon (pyridostigmine) HR's have been good so far, my low BP's are under control for the most part (not perfect) downside is i have issues with high BP spikes so we are working on that.