Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . Left chest wall pacer again noted with leads extending to the region of the right atrium and right ventricle . There is elevation of the left hemidiaphragm , new from prior with opacity in the left lower lung which likely represents atelectasis given the associated volume loss though difficult to exclude a pneumonia in this region . Right lung is clear . Cardiomediastinal silhouette is unchanged . Bony structures appear intact .
    OUTPUT:
    
Left basal opacity likely atelectasis though difficult to exclude pneumonia .