If there was excess fluid around the heart, could this cause the heart to seem enlarged on an x-ray?
Sorry, missed the "NON"-smoker. Trust the echo.
As a smoker, it is very likely that your lungs were more dense than a non-smoker and therefore it would be more difficult to get a clear visualization of the hear. This would not be an issue with the echo, those results should be accurate.
Jon
What was the ultimate diagnosis of your doctor? I would go with that. Does he also agree that you have an enlarged heart? And if they do, what is the treatment they advised?
X-rays aren't as accurate as echos regarding this issue. Perhaps breast tissue or other reasons gave some hint of an enlarged heart, but the echo defines it much more carefully. Trust the echo.