I was diagnosed with an enlarged heart when i was younger.... should i be concerned at 39?

Probably not: An enlarged heart as a youth in the absence of any clinical issues is likely a spurious diagnosis, often based on a chest x-ray and sometimes diagnosed in athletes. If there are no symptoms or signs, like heart murmur or arrhythmia, there is probably nothing to worry about. An echocardiogram would be the most definitive tool to sort out whether there really is any substance to the diagnosis.

See the expert: You should be evaluated by a cardiologist, preferably one that has had training in dealing with adult congenital patients. They can best evaluate your current condition. Any information you have regarding the initial diagnosis, your past medical history, current status (such as medications you take, including over the counter) will help.

Possibly: It would be nice the exact diagnosis of your cardiomegaly (enlarged heart). Without that, it is really hard to tell on how severe and potentially dangerous your condition is. Please describe your symptoms and if you have any work up data, it would be helpful to review as well.