Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left chest wall pacemaker - defibrillator has leads terminating in the right atrium and right ventricle . The heart is not enlarged . The mediastinal and hilar contours are normal . There is no pleural effusion or pneumothorax . There is no pulmonary edema . The lung volumes are lower . Possible new retrocardiac opacity is seen only on the lateral projection .
    OUTPUT:
    
New retrocardiac opacity seen only on the lateral projection may reflect pneumonia . Followup chest radiograph in 6 weeks is recommended to confirm resolution .