Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest were provided . Midline sternotomy wires and prosthetic cardiac valve are again noted . The heart remains mildly enlarged . There is mild retrocardiac atelectasis . No large effusion or pneumothorax is seen . There is no pneumothorax . Bony structures are intact .
    OUTPUT:
    
Mild cardiomegaly . Mild retrocardiac atelectasis . Otherwise , unremarkable .