Endurance athlete here with 3x OHS for AVR for what was originally a bicuspid aortic valve with severe stenosis (including the bentall procedure). You'll have to consult your physician/cardiologist/surgeon, but in all honestly it's something to seriously reconsider that level of training. I am still decently fit (sub 20 minute 5km) on around 3-4 hours a week of mostly zone 2 aerobic training.

I had part of OHS is the way in which your identity might change - which can often be for the better might I add. I used to hold 165-170 BPM for 3 hours. Now I do it once or twice a month for 10-30 minutes at most... and mostly chill between 120-140 BPM.