Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post median sternotomy and CABG . Mild cardiomegaly is re - demonstrated . The mediastinal and hilar contours are unchanged . Pulmonary vasculature is not engorged . Low lung volumes are present with atelectasis in the lung bases , more so on the left , but improved from prior . No focal consolidation , pleural effusion or pneumothorax is present . Fixation hardware in the left humeral head is incompletely imaged .
    OUTPUT:
    
Mild atelectasis in the lung bases , more pronounced on the left , but overall improved from the previous examination .