Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post median sternotomy and CABG . Evaluation of the cardiac silhouette size is difficult due to the presence of a chronic , moderate - to - large left pleural effusion , which appears slightly increased in size when compared to prior study . There is persistent left basilar opacification , likely reflecting compressive atelectasis . The right lung demonstrates mild atelectasis at the lung base , but is otherwise clear . No pneumothorax is identified . There is no pulmonary vascular congestion . The aorta remains tortuous and calcified .
    OUTPUT:
    
Moderate - to - large chronic left pleural effusion , slightly increased compared to the prior study with persistent left basilar opacification , likely reflecting compressive atelectasis , though infection can not be completely excluded .