ASD is associated with all of the following features, except:

Left atrial hyperophy or dilatation is not seen in ASD, instead it is seen in Mitral stenosis. In ASD, left atrium has two outflow tracts. One into L.V through mitral valve and the other into R.A through ASD. These two outflow tracts cause resistance against which the L.A pump is decreased, thus explaining absence of LA hyperophy. Ref: Textbook of Cardiovascular Medicine, Pages 356-357 ; ECG Interpretation By D.C Randall, Page 39 ; Harrison's Internal Medicine, 18th Edition, Pages 1921-22