No personal experience either, but it seems enlarged hearts are a condition that are treated with medication, since it cannot be cured. In humans, there are a couple procedures to shrink an enlarged heart, but it is nowhere anyone would consider on a rabbit. An enlarged heart can present a lot of issues, so certain medications can help counterbalance it.
A lot of people on other forums talk about getting an echo or cardiogram in order to confirm an enlarged heart first. I read upon a number that said their rabbit lived quite long and it was just managed with medication and keeping a watchful eye out for major developments, like signs of heart failure.
Best wishes to you and your bun!
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.