If the right heart failure is due to heart enlargement from the blood flow across the ASD, then yes, that might improve (but it really depends upon how old you are and how badly your heart is functioning). If the right heart failure is due to
pulmonary hypertension, then NO, it may not improve, and could actually be a contraindication to ASD closure (depending upon your degree of left to right shunting through the ASD and how abnormal is the pulmonary vascular resistance).