Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The inspiratory lung volumes are slightly decreased from the most recent prior study . No pleural effusion or pneumothorax is present . There is no overt pulmonary edema . Increased opacification at the lateral left lung on the frontal view , without definite correlate on the corresponding lateral view may represent underpenetration of soft tissues . There is mild atelectasis of the left lower lobe . The cardiac silhouette remains mildly enlarged . The mediastinal and hilar contours are within normal limits . Multiple mediastinal surgical clips are compatible with prior CABG . A left pectoral pacemaker is unchanged with three leads in stable position . The patient is status post median sternotomy .
    OUTPUT:
    
Slightly decreased lung volumes with increased opacification at the left lung base , most likely representing atelectasis .