I have PAD as well as CAD and I have leg cramps in the calves quite often. I also take Lopressor for my blood pressure and heart ryhthm, but think my cramps are from the blockages.
There is evidence Toprol CAN cause leg cramps. Also, low potassium is murder on your legs, they hurt, they cramp,etc. so I think I'd check that first.
Hope this helps and thanks for the question. Take care.