I have taken care of several patients who have had aortic valve replacements, and many of them do very well. I tell everybody that Heart surgery by any means is not a routine procedure, but it is more common than it used to be, even for much of our older generation. If you're father is young, I would tell him to go ahead and have it done, but I don't know about how old he is. I also do not know his history, because his history can mean a lot. I can say for sure though that if he doesn't have the surgery done, something will happen, and he could make it worse for himself in the future.
By your description, it sounds as if his heart is already failing. If you wait too long, his heart will be become weaker, and it will eventually hinder his quality of life, esp. if he has the surgery done. Also, I think it is better to have it done when one's heart is stronger. We just did an aortic valve replacement on a lady who wanted to give birth to a child of her own, but couldn't until she had her aortic valve replaced.
If it does come down to an emergency situation, emergency personnel can be very persuasive, and my bet is that he will end up having it done in an emergency situation. Aortic Valve replacement does require the use of the heart and lung machine, and this sometimes has complications, such as renal failure, stroke, heart attack, and infection among others. If you're wondering will he ever have a quality life after heart surgery, by all means I think he could depending on his history. We have done a lot of aortic valves, and had a lot of good outcomes. Yes, sometimes this surgery requires one to be on blood thinners for the remainder of one's life, but if the patient is old enough, they may use a tissue valve, and that would not neccesitate the long term use of blood thinners.
I hope you make the right decision for your father and your family