Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The previously seen pulmonary vascular congestion has resolved . There is left basilar atelectasis however early pneumonia can not be ruled out . No pleural effusion . The right lung is clear . No pneumothorax . Mild cardiomegaly is stable . Mediastinal and hilar contours are normal . Left - sided pacemaker leads end in appropriate position . Median sternotomy wires are intact .
    OUTPUT:
    
Left basilar opacity likely represents atelectasis however pneumonia can not be ruled out .