Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are low in volume and show a mild left lower lobe opacity . The cardiac silhouette is enlarged . The mediastinal silhouette and hilar contours are normal . There may be a small left pleural effusion . A right - sided pacer terminates with its leads in the right atrium and right ventricle . Abandoned leads are noted within the left chest . Sternal wires are intact . Clips suggest prior CABG .
    OUTPUT:
    
Left lower lobe opacity could represent atelectasis or pneumonia with an associated effusion .