Any measurement taken in cardiology can be indexed to body size in fact.
Working out alot will make it bigger too. So if you were a big guy who hit the gym like Rocky Balboa yeah, it's gonna be chunky.
The more important thing to consider is how is it big? They look at like the thickness of the muscle compared with the surrounding chamber, how efficiently the heart is able to fill and how efficiently it pumps. All these metrics are more important then the overall size per se.
Hearts that are big for bad reasons will have other abnormalities.. For example; the ventricle may be dilated and the muscle may be "stretched" and thin. Maybe the heart doesn't fill up with blood as fast, or maybe the valves got more 'leaky' then normal.
A healthy person on the other hand might have a heart with all the appropriate "symmetry" and "proportions", just bigger.
In terms of reversing it, you bet losing weight can reduce it! The heart is literally a muscle, it works the same way.
Small muscles exposed to more weight or workload get big, big muscles that don't hit the gym lose their gains.
If an individual is a body builder I wouldn't expect their muscles to go completely down go the size they were before they started lifting, but they'll go down for sure. Heart does the same thing.
I asked the doc about it and he said the size was “on the high end of normal” and assured there was nothing yo worry about. My pvcs/palps had reduced with the weight loss.