Its presence was associated with RV enlargement at rest and an exaggerated increase in right-ventricular-to-right-atrial pressure gradient ( 25 7 mm Hg vs 15 9 mm Hg , P < .001 ) and a blunted increase in fractional area change of the right ventricle ( 3 % [ -1 % , 5 % ] vs 7 % [ 3 % , 16 % ] , P = .008 ) during mild exercise .