Lopressor can be the cause of your low HR, although I would not be too concerned with 42-50, as long as you are not feeling dizzy.
I too take Lopressor and when I started with it, my resting heart rate went from 45 to 33! After lowering the Lopressor dose it is now 40. That is ok with me. No fainting or dizzyness.
Whether 42-50 is too low, I think, also depends on what your HR was before you started taking Lopressor. A too big decrease in HR is probably not good. And of course, if there is no good reason to take it, you would be better off leaving it out.
If it were me -- and I'm just talking as a patient, not as an expert -- I would want to get off the Lopressor. Lopressor depresses heart rate, and it's obviously not controlling your blood pressure, so I personally would not see any reason for taking it. I was on Lopressor for blood pressure control for several years and was in the same situation as yourself -- my heart rate was too low, and my blood pressure was still too high.
But why are you on the nitro patch? If you've had a heart attack, if you have angina, if you have an arrhythmia, or if you have congestive heart failure, there may be another reason besides blood pressure control for your doctor to prescribe Lopressor. Under those circumstances, maybe the Lopressor dosage could at least be reduced; I don't know, but I would at least talk to the doctor about it.
Anyway, that's where I would start, in my discussions with the doctor: the Lopressor. You've got to do something to get the blood pressure down, that's true, and maybe the Ramapril is a reasonable addition to your regimen for that, but it seems you do have an uncomfortably slow heart rate, and Lopressor is not going to help that part of the situation at all. Good luck.