Very sorry to hear about your issues.
I had an irregular heart beat when I was working my job in FL that included 14 months of 6 - 12s. I ate too much and gained to my all time peak weight. When the job ended, I retired and lost 25 lbs, got back to walking 50 minutes 3 times a week and on alternate days I did a set of pullovers and arm curls on the Total Gym, pushups from the knee, situps, and squats. My heartbeat got back to normal. I was 70 at the time.
So, my advice would be to lose weight and exercise, gently at first, the best two things you could ever do for your body.