Not sure if this is the right forum for this but...
Roy - I take beta blockers - Sotalol - same as you - and I can get into Ketosis and although it's slow progress I am losing weight - try taking L-Carnitine supplements too that helps and it's good for your heart.
I have not been able to lose at Weight Watchers or on Fit for Life since taking Sotalol and I'm not stopping them and risking tachy cardia. But LC is working.
It will work -you just have to be really strict.
Good luck