Earliest sign of left atrial enlargement is -
Posterior displacement of esophagus
Widening of carinal angle
Elevation of left bronchus
Double shadow of right border
Left atrial enlargement presents radiologically with elevation of left main bronchus which is the earlier feature ,splaying or widening of carina ,indentation and displacement of oesophagus posteriorly , double contour / shadow / density or double right hea border and prominent left atrial appendage.
Cardiovascular system