Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral radiographs of the chest demonstrate persistent massive left - sided pleural effusion , occupying at least two - thirds of the left hemithorax . Minimal aeration of the left upper lobe . Slight interval increase in rightward shift of the mediastinum . Trace pleural effusion at the right base . Again seen are diffuse bilateral pulmonary nodules which are unchanged from the prior study . A single - chamber pacemaker is present with the tip terminating in the right ventricle . No pneumothorax .
    OUTPUT:
    
Large left pleural effusion with minimal aeration of the left upper lobe , and slight interval increase in rightward shift of the mediastinum .