Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post coronary artery bypass graft surgery . The cardiac , mediastinal and hilar contours appear stable . There is a peripheral wedge - shaped opacity at the base of the left chest associated probably with the lingula , most likely atelectasis . Elsewhere , the lungs appear clear . There are no pleural effusions or pneumothorax .
    OUTPUT:
    
Peripheral opacity in the left lower lung suggesting atelectasis , although small infarct could have a similar appearance .