Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . The patient is status post median sternotomy and cardiac valve replacement . There is a small - to - moderate left pleural effusion with overlying atelectasis . No right pleural effusion is seen . The right lung is clear . The cardiac and mediastinal silhouettes are stable , as are the hilar contours . No pneumothorax is seen .
    OUTPUT:
    
Small - to - moderate left pleural effusion with overlying atelectasis .