Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP and lateral views of the chest are compared to previous exam from ___ and from ___ . There is subtle opacity in the retrocardiac space which may localize to left lower lobe on the frontal exam . The lungs are otherwise clear without effusion . Cardiomediastinal silhouette is within normal limits . Dual - lead pacing device is seen with lead tips to the right atrium and right ventricle . Hypertrophic changes seen in the spine as well as mild wedge deformity of the lower thoracic vertebral body , unchanged .
    OUTPUT:
    
Subtle opacity in the retrocardiac region likely on the left , which could represent atelectasis ; however , infiltrate is not completely excluded and correlation should be made clinically .