Hi emka,
Let me take your questions one at a time.
1. can I be retaining fluid because of the valve issues even thoug the lv is not dilated and my ef is above 50%, for example if it's beginning to worsen?
Usually not. If you have new and significant edema associated with weight gain, you need an answer why.
The typical offenders of liver disease, kidney disease and heart disease, although sometimes hypothyroidism can do this as well. If it isolated to one leg (?), the idea of a blood clot needs ruled out. With your creatinine increasing, it is worth having your doctor check your urine for protein, red blood cells, white blood cells, or sedimate. If your valve isn't leeking badly and your EF is normal, I don't think this is from your heart.
2. Are myxomatous valves a condition that will probably worsen and need to be followed?
It is worth following myxomatous valves with serial physical exams. IF the murmur changes or worsens, then echocardiography is indicated to evaluate for changes.
3. Does a myxomatous valve without regurg need antibiotic prophyactic (I know the AI does).
Not without significant regurgitation.
I hope this helps and good luck investigating the cause of your edema.
Not only are you retaining fluid, you are also retaining metabolic waste (creatinine). Your kidneys are doing a less than sufficiently effective job in removing water and poisonous waste from your body. This can result in systemic poisoning (uremia).
Get checked throuroughly for high BP and diabetes, these both damage kidneys.