Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patient is status post coronary artery bypass graft . Median sternotomy wires appear grossly intact . There is a prosthetic mitral valve in place . The left chest wall pacemaker has leads terminating in the right atrium and right ventricle . There is new dense opacity at the left base obscuring the hemidiaphragm and apparently contiguous with the pleural surface , likely loculated pleural effusion , however underlying pneumonia or mass can not be excluded . There is atelectasis at the right base . Remaining lung fields are relatively clear . Mild to moderate cardiomegaly is exaggerated by low lung volumes but likely unchanged . The mediastinal and contours are normal . There is no pneumothorax . There is no frank pulmonary edema . Multiple old healed right lateral rib fractures are again identified .
    OUTPUT:
    
1 . Dense opacity at the left base likely reflects pleural effusion , in part loculated , however underlying consolidation / pneumonia can not be excluded . 2 . Moderate cardiomegaly is likely stable . There is no frank pulmonary edema .