Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post median sternotomy , mediastinal clips , and mitral valve repair . Mild cardiomegaly is re - demonstrated . The aortic knob is calcified . Mediastinal and hilar contours are unchanged . Pulmonary vasculature is not engorged . Lungs remain hyperinflated . Blunting of the costophrenic angles on the lateral view posteriorly suggests trace bilateral pleural effusions , decreased in size from the prior exam . Patchy retrocardiac opacity may reflect atelectasis , but infection is difficult to exclude . No pneumothorax is seen . Moderate multilevel degenerative changes are noted in the thoracic spine .
    OUTPUT:
    
Decreased size of small bilateral pleural effusions . Patchy retrocardiac opacity could reflect atelectasis though infection is difficult to exclude .