Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Status post CABG with median sternotomy wires and mediastinal clips seen . Low lung volumes again noted . Small pleural effusion on the left with improvement in perihilar pulmonary edema and mild improvement in the left base atelectasis . No pneumothorax is seen . Moderately enlarged heart .
    OUTPUT:
    
Persistent small left pleural effusion and mild improvement in left base atelectasis and perihilar pulmonary edema . Moderately enlarged heart .