Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear . There is no pneumothorax or pleural effusion . Mild cardiomegaly is stable in this patient with prior sternotomy for CABG and AVR . The aortic valve prosthesis is difficult to see on this chest x-ray . Mild pulmonary artery dilatation is also stable .
    OUTPUT:
    
There is no significant change since ___ . There are no acute cardiopulmonary findings .