Read more about congestive heart failure
http://www.heart-attacksymptoms.com/congestive-heart-failure
The chest pain is unlikely to be of any cardiac significance and so I would not be too concerned about it and no further work up is necessary at this point. I am assuming that you had a catheterization which showed normal coronary arteries. As far as the systolic heart failure goes, it is difficult to say what it's caused by. One possible etiology of your heart failure, is that after the valve was repaired, the heart function declined which occurs not uncommonly. If that were the case, the likelihood of heart function improvement is very low. If on the other hand, the heart dysfunction is caused by a case of viral myocarditis, then if the infections has cleared and the heart muslce is recovering, then there may be an improvement in the function. Only time will tell. The fact that your heart function has increased to 40% is very promising.