Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal upright views of the chest were obtained . Tracheostomy tube is in stable position . Right subclavian central catheter terminates in the lower SVC . Leads of a left chest wall pacer terminate over the right atrium and right ventricle . Moderate cardiomegaly is similar to prior , allowing for difference in patient position . Retrocardiac opacity is stable and compatible with atelectasis , although infection may have a similar appearance . Left lung volume loss is similar to prior . No pneumothorax is visualized , though the patient 's chin obscures the left apex .
    OUTPUT:
    
Moderate cardiomegaly with stable left lung volume loss . Stable retrocardiac opacity is compatible with atelectasis but may represent pneumonia in the correct clinical setting .