Have ms. medrol (methylprednisolone) always causes low heart rate in me / chest pain when breathe too . tests always fine aside from heart rate. safe to take for relapse?

Medrol (methylprednisolone) is safe: in general for the heart. As long as you have discussed this occurrence with your docs and they are not worried, I don't think you need be either. The side effects of a relapse could be much worse! Good luck.

Unusual: Given that medrol (methylprednisolone) enhances one's sympathetic nerve response, fast heart rate is a more likely consequence. However you did get chest pain with breathing from it, you will need to tell your doctor about this.