People with valve problems are considered priority patients for the flu shot. Your cardio will give you a note, if shots are scarce.
The only year I haven't had one since being diagnosed was when we had the shortage. I had a note from the cardio in my hand, and was about three people in front of a lady in a wheelchair with oxygen, one of many very frail-looking people in line behind me. They announced how many shots were available, and plainly there were not enough for those in line. I couldn't do it. What if they ran out of shots right after me, and that lady didn't get one?
Still, you should get the shot, as long as you're not allergic.
Best wishes,