Ronan,
The fact that there is a history of heart-related early death in your family could mean that there is some hereditary issue at work here - something beyond the usual things many of us have dealt with. That said, the path the disease takes is similar, regardless of its cause. Usually our stenotic valves do degrade over time. I was originally diagnosed as having moderate-to-severe aortic stenosis at age 51. I finally had my valve replaced at age 63. During the interim years, I did just about everything a man my age (or younger) would do. I maintained a high-stress executive career, raised a family, ran, lifted weights, did home improvements -- you name it. As long as I had no "real" symptoms, I was simply monitored - initially once a year, eventually twice a year. Only in the final year prior to surgery did I admit that I had any symptoms, and mine were simply those of losing my stamina and exercise tolerance.
I had my valve replaced almost 4 years ago now, and I feel better and am in better shape now than I was in the years ramping up to surgery.
At your present status, they may or may not feel that you are ready for surgery. Either way, it all works out. If you're not yet ready, just live life as you ordinarily would, with the addition of scheduled cardiac exams. If you are told that you are ready now for surgery, just do it. It sounds scary, and you will have all sorts of questions (which the folks here can help with), but the statistics are overwhelmingly in your favor. For younger patients (my surgeon said that even at 63, I was younger than a lot of his patients) with no serious co-morbidities, the surgical survival rate is over 98%. That is right up there almost with a simple appendectomy!
Hang in there! Welcome to The Waiting Room - the virtual room where many folks await their own turns at valve surgery. Pull up a chair and stick around. Ask all the questions you want. We'll be here to help.