OP - it should be treatable and manageable. Until then, I would probably not ride until you get the "all clear" from your doctor.
I have a heart condition which causes my heart to have arrythmias, only pumps half of the blood it should and I have an implanted cardiac defibrillator. I still ride. My cardiologist approves. So, don't give up. My heart is crap but I still do what I love. Just talk with your doctor and work with him/her.
Imagining life without a horse is like imagining life without food, water and air.