The LV dilates to compensate for other system factors (heart rate,
blood pressure variations, etc.) to maintain a balance of
blood flow between the heart's left and right side.
When the heart (LV) dilates there are stronger contractions and an EF increase (normal range 50-70). If there is a pathological underlying cause, the LV can/will over compensate and the dilated LV loses EF percentage.
If there is no heart muscle damage, you should experience an increase in your EF.