Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post sternotomy , with mild to moderate cardiomegaly . There is upper zone redistribution , without overt CHF . There is mild increased retrocardiac opacity , but the left hemidiaphragm remains visible . Otherwise , no focal opacities are identified . No effusion seen on either side . Right upper quadrant cholecystectomy clips noted . Compared with an outside chest x-ray on PACs from___ dated ___ , the retrocardiac opacity has improved . CHF findings to probably also improved slightly .
    OUTPUT:
    
Upper zone redistribution , without overt CHF . Retrocardiac opacity , consistent with left lower lobe collapse and / or consolidation . The possibility an infectious infiltrate in this area can not be excluded , but the appearance is improved compared with the outside film from ___ .