I am so sorry to hear of your condition. You seem like such a nice fellow. I'm sure that you are. Unfortunately heart disease doesn't discriminate....
Be careful with the exercise, if you have cardiomyopathy don't lift over 10 lbs., and stay away from SALT. If you haven't been diagnosed as such, be careful anyway...That is a great idea though, that is getting into the best shape you possibly can, prior to the procedure.
Then again I think...How could any exercise, aerobic or anaerobic be good for you at this point? I'm sure that you have been warned when to back off. Know when to rest your heart by lying down or reclining. I know a tad about mechanical pumps and valves, and I know that the leaky aortic valve will over work your heart. When you are standing, gravity will apply a downward force on the blood discharged from your left ventricle, or the big pumper of our hearts, because some amount of this discharged blood is not stopped from flowing backward, due to your aortic valve. The aortic arch, or the discharge header of our fresh oxygenated blood, is higher than our heart. When you are prone, your heart and aortic arch have the same force of gravity applied, which relieves the load on your heart. Hey, I am just a chucklehead, so this is my opinion only, and is my theory.....but based on real physics though.
Heart valve replacement has come a long way, I have read. Maybe someone will drop by, who has personal experience with this.
Try not to worry too much. Keep posting and let your fear(s) be known to your friends here. This can only help you, it seems to me. You will be in my prayers for sure.