Enlarged heart with no symptoms?

I'm a 38 year-old male diagnosed with MVP 15 years ago. At my last echo (Sept. 2008), I was told my Left Vent. was enlarged (6.4 cm). That's about 1/2 cm larger than at my echo prior to this one (April 2000). I feel fine except for various MVP symptoms (palpitations, anxiety - which I've always dealt with), EF was normal, normal sinus rhythm, blood pressure has always been normal, pulse rate in the 50's and I tolerate physical exertion very well. I was told everything mitral-valve related looked fine, was told not to worry, and to come back next year for another echo. I'm still worrying though. Should I get a second opinion or can you have an enlarged heart forever - with no further problems or issues?  
Thank You so much for your time and willingness to share your knowledge.

[kenkeith]

An enlarged left ventricle (dilated) will, if unsuccessfully treated, continue to enlarge (over compensation), and the enlargement will eventually cause weaker contractions (EF loss) and heart failure.  

The strong contraction with some compensating dilation can be explained by Frank-Starling mechanism (google for more info), but over compensation with greater enlargement will cause a loss of contractility and is analofous to stretching a hang spring...some stretching increase recoil, but over stretching causes the handspring to lose recoil properties.

A Mayo Clinic heart surgeon states the biggest problem he sees with valve problem patients is they have waited too long.  If the heart enlarges and there is a loss of EF, a valve operation may not or will not return the heart to a normal systole function.