Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post coronary artery bypass graft surgery . A dual - lead pacemaker / ICD device appears unchanged . Allowing for small differences in technique , substantial cardiomegaly is probably unchanged . Mediastinal and hilar contours are also probably unchanged . New opacity is suggested by vague opacification projecting over the lower spine on the lateral view probably localizing to the left lower lobe . There are no pleural effusions or pneumothorax .
    OUTPUT:
    
Patchy opacity in the posterior left lower lobe , atelectasis versus pneumonia . Marked , but similar , cardiomegaly .